Artykuły w czasopismach na temat „Aseismic moment”
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Xin, Chun Lei, i Bo Gao. "Composite Lining Aseismic Design for Fault-Crossing Tunnel Structures". Advanced Materials Research 971-973 (czerwiec 2014): 30–34. http://dx.doi.org/10.4028/www.scientific.net/amr.971-973.30.
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Although underground structures have stronger aseismic performance than ground structures, seismic disasters of mountain tunnels were fairly conspicuous in Wenchuan Great Earthquake. On the basis of seismic disaster analysis, a composite lining designfor tunnel structures across active fault was put forward. Three-dimensional numerical simulation method was used to analyze aseismic and damping effect of this structure. The results show that: (1)After setting aseismic and damping structure, the maximum internal forces value in lining the pattern of internal forces will not change. (2)Aseismic and damping structure setting can directly reduce the bending moment value and increase the axial force and stress force value in lining structure. (3) Relative to aseismic and damping structure, grouting region around damping layer can ameliorate internal force condition in lining structure and improve the effect of aseismic and damping structure. The above research results contribute to provide reference for seismic fortification of tunnel structures across active faults.
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Passarelli, Luigi, Paul Antony Selvadurai, Eleonora Rivalta i Sigurjón Jónsson. "The source scaling and seismic productivity of slow slip transients". Science Advances 7, nr 32 (sierpień 2021): eabg9718. http://dx.doi.org/10.1126/sciadv.abg9718.
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Slow slip events (SSEs) represent a slow faulting process leading to aseismic strain release often accompanied by seismic tremor or earthquake swarms. The larger SSEs last longer and are often associated with intense and energetic tremor activity, suggesting that aseismic slip controls tremor genesis. A similar pattern has been observed for SSEs that trigger earthquake swarms, although no comparative studies exist on the source parameters of SSEs and tremor or earthquake swarms. We analyze the source scaling of SSEs and associated tremor- or swarm-like seismicity through our newly compiled dataset. We find a correlation between the aseismic and seismic moment release indicating that the shallower SSEs produce larger seismic moment release than deeper SSEs. The scaling may arise from the heterogeneous frictional and rheological properties of faults prone to SSEs and is mainly controlled by temperature. Our results indicate that similar physical phenomena govern tremor and earthquake swarms during SSEs.
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McGarr, A., i Andrew J. Barbour. "Injection‐Induced Moment Release Can Also Be Aseismic". Geophysical Research Letters 45, nr 11 (5.06.2018): 5344–51. http://dx.doi.org/10.1029/2018gl078422.
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Qi, Kang. "Aseismic Performance Analysis of High-Strength Concrete Circular Pier". Applied Mechanics and Materials 431 (październik 2013): 161–66. http://dx.doi.org/10.4028/www.scientific.net/amm.431.161.
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Circular pier are widely used in bridge substructure. Strength and ductility are two important indicators reflect its aseismic performance. Based on the analysis of complete bending moment-curvature curve curvature, bending strength and ductility on reinforced concrete circular pier cross-section, this paper analyzes the aseismic performance of high-strength concrete circular pier. And it can provide reference for using high strength concrete more reasonable.
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Huang, Xing, Yanchuan Li, Xinjian Shan, Dezheng Zhao, Zhiyu Gao, Wenyu Gong i Chunyan Qu. "InSAR Observations Reveal Variations in Shallow Creep on the Kangding Segment of the Xianshuihe Fault". Seismological Research Letters 94, nr 5 (30.06.2023): 2291–300. http://dx.doi.org/10.1785/0220230053.
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Abstract Investigating the spatiotemporal characteristics of aseismic shallow creep provides insights into interseismic steady-state and/or postseismic transient behavior of faults. In this study, we focus on the Kangding segment of the Xianshuihe fault in eastern Tibet, where the 2014 Mw 5.9 Kangding earthquake occurred. Previous geodetic observations in 1999–2021 identified apparent shallow creep along this segment; however, whether the aseismic slip is secular creep, afterslip of the 2014 Kangding earthquake, or the combined effect remains unresolved. We process descending and ascending Interferometric Synthetic Aperture Radar data in the 2014–2021 period and investigate the creep rate variations on the fault plane. Our results reveal an ∼55-km-long aseismic slip section between Huiyuan Temple and Kangding Airport, of which the ∼15-km-long section between Huiyuan Temple and Jinlong Temple is in steady creep at a rate of 13 ± 2.0 mm/yr. Along the remaining ∼40-km-long section that overlaps the rupture of the Kangding earthquake, the creep rate decays from ∼40 to 0 mm/yr between 2014 and 2019, implying that the aseismic slip here is most likely the postseismic afterslip. We also identify a northwestward migration of aseismic creep from Huiyuan Temple to Longdengba during 2017–2021, which might be related to fluid diffusion. On the basis of the aseismic slip distribution, we quantitatively calculate the moment budget on the Kangding segment. The results show that the Huiyuan Temple-Longdengba section can produce an Mw 6.9 earthquake. Despite the 2014 Kangding earthquake, which ruptured the ∼40-km-long Jinlong Temple-Kangding Airport section, the accumulated seismic moment since the last major earthquake in 1748 is still sufficient for an Mw 7.0 earthquake.
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Yang, Qingshan, Bo Li i Na Yang. "Aseismic behaviors of steel moment resisting frames with opening in beam web". Journal of Constructional Steel Research 65, nr 6 (czerwiec 2009): 1323–36. http://dx.doi.org/10.1016/j.jcsr.2009.01.007.
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Bürgmann, R., M. G. Kogan, V. E. Levin, C. H. Scholz, R. W. King i G. M. Steblov. "Rapid aseismic moment release following the 5 December, 1997 Kronotsky, Kamchatka, Earthquake". Geophysical Research Letters 28, nr 7 (1.04.2001): 1331–34. http://dx.doi.org/10.1029/2000gl012350.
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Sawires, Rashad, José A. Peláez, Federica Sparacino, Ali M. Radwan, Mohamed Rashwan i Mimmo Palano. "Seismic and Geodetic Crustal Moment-Rates Comparison: New Insights on the Seismic Hazard of Egypt". Applied Sciences 11, nr 17 (25.08.2021): 7836. http://dx.doi.org/10.3390/app11177836.
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A comparative analysis of geodetic versus seismic moment-rate estimations makes it possible to distinguish between seismic and aseismic deformation, define the style of deformation, and also to reveal potential seismic gaps. This analysis has been performed for Egypt where the present-day tectonics and seismicity result from the long-lasting interaction between the Nubian, Eurasian, and Arabian plates. The data used comprises all available geological and tectonic information, an updated Poissonian earthquake catalog (2200 B.C.–2020 A.D.) including historical and instrumental datasets, a focal-mechanism solutions catalog (1951–2019), and crustal geodetic strains from Global Navigation Satellite System (GNSS) data. The studied region was divided into ten (EG-01 to EG-10) crustal seismic sources based mainly on seismicity, focal mechanisms, and geodetic strain characteristics. The delimited seismic sources cover the Gulf of Aqaba–Dead Sea Transform Fault system, the Gulf of Suez–Red Sea Rift, besides some potential seismic active regions along the Nile River and its delta. For each seismic source, the estimation of seismic and geodetic moment-rates has been performed. Although the obtained results cannot be considered to be definitive, among the delimited sources, four of them (EG-05, EG-06, EG-08, and EG-10) are characterized by low seismic-geodetic moment-rate ratios (<20%), reflecting a prevailing aseismic behavior. Intermediate moment-rate ratios (from 20% to 60%) have been obtained in four additional zones (EG-01, EG-04, EG-07, and EG-09), evidencing how the seismicity accounts for a minor to a moderate fraction of the total deformational budget. In the other two sources (EG-02 and EG-03), high seismic-geodetic moment-rates ratios (>60%) have been observed, reflecting a fully seismic deformation.
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Gan, Shurong, Wen Pan, Hexian Su, Yucheng Jin, Chuanwei Zhu i Shibin Yu. "Experimental Study and Numerical Simulation Analysis on Reinforcement of Mortise-Tenon Joints with Flat Steel Strips". Advances in Civil Engineering 2023 (2.03.2023): 1–24. http://dx.doi.org/10.1155/2023/5398662.
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To study the aseismic performance after the reinforcement of the mortise-tenon joints of folk houses with traditional Chuan-Dou style wood structure and their steel plate, test specimens of joints—two for Tou mortise-tenon joints, two for Ban mortise-tenon joints, and two for dovetail mortise-tenon joints—were fabricated out of hemlock, and steel plates were utilized to reinforce one of the joint specimens of each type on the middle part of the mortise-tenon joint. By carrying out pseudo-static tests on the joints and building ABAQUS numerical model; the position where the mortise-tenon joints were to be reinforced by the steel plates was optimized for a comparative analysis into the test results on reinforced and unreinforced mortise-tenon joints and the numerically simulated bending moment-turning angle hysteresis curve, skeleton curve, energy-dissipating capacity, and rigidity degeneration curves. The results showed the following: the pulling-out phenomenon of tenons was severe, and the aseismic performance of Tou tenons was superior to Ban tenons and dovetail tenons; reinforcing the middle part of mortise-tenon joints with steel plates could effectively reduce the pulling-out amount of joints and promote the aseismic performance of mortise-tenon joints but have an insignificant promotive effect for the bearing capacity of Tou mortise-tenon joints; the aseismic performance was improved significantly after the flat steel strip reinforced position was moved to the upper and lower ends of mortise-tenon joints, with the ultimate bearing capacities being 1.5∼2.4 times that on the middle part of flat steel strip reinforced joints.
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Plattner, Christina, Alessandro Parizzi, Sara Carena, Stefanie M. Rieger, Anke M. Friedrich, Amir M. Abolghasem i Francesco DeZan. "Long-lived afterslip of the 2013 Mw 6.1 Minab earthquake detected by Persistent Scatterer Interferometry along the Irer fault (western Makran-Zagros transition zone, Iran)". Geophysical Journal International 229, nr 1 (16.11.2021): 171–85. http://dx.doi.org/10.1093/gji/ggab456.
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SUMMARY The ratio of seismogenic to aseismic deformation along active faults is needed to estimate their seismogenic potential and hazards. Seismologic and geodetic methods routinely capture coseismic displacements, but data acquisition requirements to fully document post-seismic deformation are not well known. Our study documents afterslip between about 18 months and 4 years after a mid-size earthquake and, based on remote structural mapping, we document fault rupture segments not previously associated with that earthquake. Persistent scatterer interferometric analysis of Sentinel-1A aperture radar data acquired between October 2014 and December 2018 reveals prolonged post-seismic deformation following the 11 May 2013 Mw 6.1 Minab earthquake and its aftershocks. The surface deformation data yield a sharp contrast across both the main seismogenic fault (here named the Irer fault) and its northeastern splay, and it is compatible with left-lateral motion along both faults. The PSI data helped us to identify and map the splay fault in the satellite imagery. We could then measure the geological offset along both faults, finding maximum displacements of about 1 km (main fault) and 350 m (splay). Our modelling of the observed post-seismic surface deformation pattern shows that post-seismic deformation was accommodated by left-lateral afterslip, not viscoelastic relaxation. This result is consistent with previous propositions that Mw 6 earthquakes do not measurably excite deeply seated viscoelastic relaxation mechanisms. Our afterslip modelling yields a slip pattern from the surface to a depth of 6 km to maximum 16 km, in agreement with the depth of the coseismic slip-distribution, and a maximum displacement of ∼7 cm along the fault, but located ∼8 km to the east of the coseismic slip maximum. Moment release during the observed afterslip in our study is Mw 5.7, or 12% of the coseismic moment released by main shock and aftershocks together. Combined with previously published results for the early post-seismic period (first 2 months), we estimate the aseismic moment to be at least ∼37% of the total, implying a high ratio of aseismic to seismic moment release for the Irer fault. Our results show that observation time windows well beyond 5 years are needed to record afterslip following mid-sized earthquakes. Thus, progress in understanding the transition from post-seismic to interseismic fault behaviour critically depends on the availability of data provided by satellite missions such as Copernicus Sentinel-1A. Similarly, robust comparison of the post-seismic rates with long-term geological rates requires palaeoseismic study and dating of related morphotectonic features.
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Wang, Jing Feng, Xin Yi Chen i Lin Hai Han. "Structural Behaviour of Blind Bolted Connection to Concrete-Filled Steel Tubular Columns". Advanced Materials Research 163-167 (grudzień 2010): 591–95. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.591.
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This paper studies structural behaviour of the blind bolted connections to concrete-filled steel tubular columns by a serial of experimental programs, which conducted involving eight sub-assemblages of cruciform beam-to-column joints subjected to monotonic loading and cyclic loading. The moment-rotation hysteretic relationships and failure models of the end plate connections have been measured and analyzed. A simplified analysis model for the blind bolted connections is proposed based on the component method. It is concluded that the blind bolted end plate connection has reasonable strength and stiffness, whilst the rotation capacity of the connection satisfies the ductility requirements for earthquake-resistance in most aseismic regions. This typed joint has excellent seismic performance, so it can be used in the moment-resisting composite frame.
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Li, Bo, Qingshan Yang i Na Yang. "An Investigation on Aseismic Connection with Opening in Beam Web in Steel Moment Frames". Advances in Structural Engineering 14, nr 3 (czerwiec 2011): 575–87. http://dx.doi.org/10.1260/1369-4332.14.3.575.
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Melnikova, V., N. Gileva, Ya Radziminovich i A. Filippova. "THE SEPTEMBER 2, 2015, КR=14.0, Mw=5.1, I0=7–8 TALLAY EARTHQUAKE at the NORTH-EASTERN FLANK of the BAIKAL RIFT". Earthquakes in Northern Eurasia, nr 24 (14.12.2021): 305–13. http://dx.doi.org/10.35540/1818-6254.2021.24.29.
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We consider September 2, 2015, Mw=5.1 Tallay earthquake occurred in the previously aseismic area of the North-Muya Ridge adjoining to the Muya-Kuanda basin from the north. Instrumental and macroseismic data on this seismic event are presented. Its seismic moment tensor is calculated from surface wave amplitude spectra. New data on strong ground motions are obtained within the north-eastern flank of the Baikal rift. The Tallay earthquake is found to be connected with seismogenic renewal of the second-order multidirectional faults activated in the rift stress field.
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Yang, Hao Lin, Xin Zhi Dang, Wan Cheng Yuan i De Qin Song. "A Self-Centering Seismic Design for Bridge with Pile-Cap Foundation". Advanced Materials Research 743 (sierpień 2013): 155–58. http://dx.doi.org/10.4028/www.scientific.net/amr.743.155.
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In this paper, an alternative aseismic system for bridge with pile-cap foundation called a separated pile-cap with proper material set in the gap layer was proposed. To simulate the system, a 3-dimensional finite element model for a continuous beam bridge was built. The seismic responses of the model, including behavior of the restrainer, moment at the bottom of the pier and pullout force of the piles with different restrainer lengths under 3 longitudinal artificial earthquake waves were analyzed. The results show that this system can reduce the seismic response significantly.
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Liu, Chun Yang, Zhen Bao Li, Shuang Qu, Xue Jun Zhou i Xin Ping Wang. "Research Progress on Bending Strength Calculation of Biaxial Compression-Bending Reinforced Concrete Column". Applied Mechanics and Materials 351-352 (sierpień 2013): 392–95. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.392.
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Lots of bulidings had collapsed in Wenchuan big earthquake in 2008, one important reason is that the structure design has been launched only in X or Y axis of the building respectively, which means the oblique direction compression-bending characteristic has not been fully considered in the actual structure design process. In addition, the moment bearing strength in oblique direction is smaller than the moment strength about the principle axis of the column, so the research on bending strength calculation of biaxial/oblique compression-bending RC column is important to improve the aseismic safty of the buildings under actual earthquake effects. In this paper research achievements about bearing capacity calculation of column under oblique compression-bending action are summarized and analyzed. At last the advice for actual application has also been given.
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Chaves, E. J., S. Y. Schwartz i R. E. Abercrombie. "Repeating earthquakes record fault weakening and healing in areas of megathrust postseismic slip". Science Advances 6, nr 32 (sierpień 2020): eaaz9317. http://dx.doi.org/10.1126/sciadv.aaz9317.
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Repeating earthquakes (REs) rupture the same fault patches at different times allowing temporal variations in the mechanical behavior of specific areas of the fault to be interrogated over the earthquake cycle. We study REs that reveal fault weakening after a large megathrust earthquake in Costa Rica, followed by fault recovery. We find shorter RE recurrence intervals and larger slip areas immediately following the mainshock that both gradually return to pre-earthquake values. RE seismic moments remain nearly constant throughout the earthquake cycle. This implies a balance between fault weakening (reducing slip) and transient embrittlement (increasing rupture area by converting regions from aseismic to seismic slip), induced by the increased loading rate following the mainshock. This interpretation is consistent with positive, negative, and constant moment versus RE recurrence interval trends reported in other studies following large earthquakes and with experimental work showing slip amplitudes and stress drop decrease with loading rate.
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Zhang, Yumin, i Jiawu Li. "Effect of Material Characteristics of High Damping Rubber Bearings on Aseismic Behaviors of a Two-Span Simply Supported Beam Bridge". Advances in Materials Science and Engineering 2020 (23.09.2020): 1–8. http://dx.doi.org/10.1155/2020/9231382.
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There are a large number of damping materials in high-damping rubber (HDR) bearings, so the HDR bearings have the characteristics of both common rubber bearings and damping measures and show good aseismic effect. In this paper, the time-history dynamic analysis method is used to study the seismic effects of HDR bearings on the aseismic behaviors of two-span simply supported beam bridge under Northridge earthquake by changing the damping characteristics of the bearings. It is found that, with increasing damping of the bearings, both the horizontal shear and the displacement of the HDR bearings decrease, and the seismic energy dissipates through both the yield deformation and damping of the bearings. Although the girder and bearings have smaller displacement, when the HDR bearings with larger damping, the seismic responses, including displacement of pier top, shear force of pier bottom, and bending moment of pier bottom, are hardly affected by the change of the damping of the bearings. The HDR bearings with higher damping and yield characteristics separate and dissipate the seismic energy transmitted to the superstructure of the bridge and have better seismic effect on the structure in an earthquake.
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Wang, Zhen Feng, i Ke Sheng Ma. "Character Analysis of Balance and Imbalance of Varying Rigidity of Rigid Pile Composite Foundation under Seismic Load". Advanced Materials Research 1065-1069 (grudzień 2014): 19–22. http://dx.doi.org/10.4028/www.scientific.net/amr.1065-1069.19.
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Based on ABAQUS finite element analysis software simulation, the finite element model for dynamic analysis of rigid pile composite foundation and superstructure interaction system is established, which selects the two kinds of models, by simulating the soil dynamic constitutive model, selecting appropriate artificial boundary.The influence of rigid pile composite foundation on balance and imbalance of varying rigidity is analyzed under seismic loads. The result shows that the maximum bending moment and the horizontal displacement of the long pile is much greater than that of the short pile under seismic loads, the long pile of bending moment is larger in the position of stiffness change. By constrast, under the same economic condition, the aseismic performance of of rigid pile composite foundation on balance of varying rigidity is better than that of rigid pile composite foundation on imbalance of varying rigidity.
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Zhao, Nan, Kai Ma, Shao Xue Tang, Bin Lei Chen i Ting Li. "Seismic Reaction Analysis on High-Rise Isolated Structure with Multi-Tower". Advanced Materials Research 217-218 (marzec 2011): 137–46. http://dx.doi.org/10.4028/www.scientific.net/amr.217-218.137.
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Structural reaction analysis under frequent earthquake and rare earthquake was carried out using time- history method. Every single-tower structure was chosen as an analysis modal, which can reflect real structural reaction. The results show that seismic response decreases obviously and story shear force and overturning moment are far less than that of aseismic structures. Horizontal reduction coefficient is lower under rare earthquake. Story drift is mainly centralized at isolator layer, which approaches zero on superstructure. The isolated structure shows whole translational motion. Reduction degree of seismic response for the three towers is more or less from each other.
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Rousset, Baptiste, Roland Bürgmann i Michel Campillo. "Slow slip events in the roots of the San Andreas fault". Science Advances 5, nr 2 (luty 2019): eaav3274. http://dx.doi.org/10.1126/sciadv.aav3274.
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Episodic tremor and accompanying slow slip are observed at the down-dip edge of subduction seismogenic zones. While tremors are the seismic signature of this phenomenon, they correspond to a small fraction of the moment released; thus, the associated fault slip can be quantified only by geodetic observations. On continental strike-slip faults, tremors have been observed in the roots of the Parkfield segment of the San Andreas fault. However, associated transient aseismic slip has never been detected. By making use of the timing of transient tremor activity and the dense Parkfield-area global positioning system network, we can detect deep slow slip events (SSEs) at 16-km depth on the Parkfield segment with an average moment equivalent toMw4.90 ± 0.08. Characterization of transient SSEs below the Parkfield locked asperity, at the transition with the creeping section of the San Andreas fault, provides new constraints on the seismic cycle in this region.
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Erickson, Brittany A., Junle Jiang, Michael Barall, Nadia Lapusta, Eric M. Dunham, Ruth Harris, Lauren S. Abrahams i in. "The Community Code Verification Exercise for Simulating Sequences of Earthquakes and Aseismic Slip (SEAS)". Seismological Research Letters 91, nr 2A (29.01.2020): 874–90. http://dx.doi.org/10.1785/0220190248.
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Abstract Numerical simulations of sequences of earthquakes and aseismic slip (SEAS) have made great progress over past decades to address important questions in earthquake physics. However, significant challenges in SEAS modeling remain in resolving multiscale interactions between earthquake nucleation, dynamic rupture, and aseismic slip, and understanding physical factors controlling observables such as seismicity and ground deformation. The increasing complexity of SEAS modeling calls for extensive efforts to verify codes and advance these simulations with rigor, reproducibility, and broadened impact. In 2018, we initiated a community code-verification exercise for SEAS simulations, supported by the Southern California Earthquake Center. Here, we report the findings from our first two benchmark problems (BP1 and BP2), designed to verify different computational methods in solving a mathematically well-defined, basic faulting problem. We consider a 2D antiplane problem, with a 1D planar vertical strike-slip fault obeying rate-and-state friction, embedded in a 2D homogeneous, linear elastic half-space. Sequences of quasi-dynamic earthquakes with periodic occurrences (BP1) or bimodal sizes (BP2) and their interactions with aseismic slip are simulated. The comparison of results from 11 groups using different numerical methods show excellent agreements in long-term and coseismic fault behavior. In BP1, we found that truncated domain boundaries influence interseismic stressing, earthquake recurrence, and coseismic rupture, and that model agreement is only achieved with sufficiently large domain sizes. In BP2, we found that complexity of fault behavior depends on how well physical length scales related to spontaneous nucleation and rupture propagation are resolved. Poor numerical resolution can result in artificial complexity, impacting simulation results that are of potential interest for characterizing seismic hazard such as earthquake size distributions, moment release, and recurrence times. These results inform the development of more advanced SEAS models, contributing to our further understanding of earthquake system dynamics.
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Sparacino, Federica, Mimmo Palano, José Antonio Peláez i José Fernández. "Geodetic Deformation versus Seismic Crustal Moment-Rates: Insights from the Ibero-Maghrebian Region". Remote Sensing 12, nr 6 (16.03.2020): 952. http://dx.doi.org/10.3390/rs12060952.
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Seismic and geodetic moment-rate comparisons can reveal regions with unexpected potential seismic hazards. We performed such a comparison for the Southeastern Iberia—Maghreb region. Located at the western Mediterranean border along the Eurasia–Nubia plate convergence, the region has been subject to a number of large earthquakes (M ≥ 6.5) in the last millennium. To this end, on the basis of available geological, tectonic, and seismological data, we divided the study area into twenty-five seismogenic source zones. Many of these seismogenic source zones, comprising the Western Betics, the Western Rif mountains, and the High, Middle, and Saharan Atlas, are characterized by seismic/geodetic ratio values lower than 23%, evidencing their prevailing aseismic behavior. Intermediate seismic/geodetic ratio values (between 35% and 60%) have been observed for some zones belonging to the Eastern Betics, the central Rif, and the Middle Atlas, indicating how crustal seismicity accounts only for a moderate fraction of the total deformation-rate budget. High seismic/geodetic ratio values (> 95%) have been observed along the Tell Atlas, highlighting a fully seismic deformation.
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Du, Juan, Xiao-Peng Lei, Di-Fan Ren, Zai-Cheng Wang i Yang Zhang. "Dynamic Response of Pile-Raft Systems with Various Forms of Connection under Cyclic Condition". Shock and Vibration 2023 (3.11.2023): 1–12. http://dx.doi.org/10.1155/2023/3775654.
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This study aimed to examine the aseismic performance of the pile-raft systems with various connection forms. The related shaking table test and numerical simulation were performed for in-depth investigation. The acceleration response spectra on the top of the soil layer and raft were obtained and plotted for contrastive analysis based on the model test at a reduced scale of 1 : 30 and finite element numerical simulation. Accordingly, the working mechanisms of the pile-raft systems in conventional connections with the embedment of the compressible blocks and cushion layers under cyclic loading were explored. The results showed that the embedment of the cushion layer on the pile top could most significantly mobilize the potential of the foundation soil, effectively reduce the bending moment peak of the pile, and reduce the acceleration amplification effect on the top of the soil layer and raft. The embedment of the compressible block on the pile top most markedly reduced the bending moment peak of the pile and effectively mobilized the potential of the foundation soil, which was most favorable for lowering the amplification effect of acceleration on the top of the soil layer and raft.
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Boudin, F., P. Bernard, G. Meneses, Ch Vigny, M. Olcay, C. Tassara, J. P. Boy i in. "Slow slip events precursory to the 2014 Iquique Earthquake, revisited with long-base tilt and GPS records". Geophysical Journal International 228, nr 3 (28.10.2021): 2092–121. http://dx.doi.org/10.1093/gji/ggab425.
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SUMMARY The M= 8.1, 1 April 2014 Iquique earthquake, which broke part of the northern Chile seismic gap, was preceded by a strong foreshock sequence starting early January 2014. The reported analysis of the continuous records of the nearby GPS stations from the Integrated Plate Observatory Chile, North Chile array lead to contradictory results concerning the existence and location of slow slip events (SSEs) on the interplate contact. Resolving this controversy is an important issue, as although many SSEs are reported in subduction zones, only a few were found to be precursory to large earthquakes. Here we show that the records of a long base tiltmeter installed near Iquique, when corrected for coseismic steps, long-term drift, tidal signals and oceanic and atmospheric loading, show significant residual signals. These can be modelled with a sequence of four SSEs located close to Iquique. Their signature was already reported on some GPS stations, but their source was then characterized with a very low resolution in time and space, leading to contradicting models. With the tilt records, we can rule out the previously proposed models with a single large SSE closer to the main shock. Combining tilt with GPS records greatly improves the resolution of GPS alone, and one could locate their sources 100–180 km south–southeast to the main shock epicentre, with moment magnitudes between 5.8 and 6.2, at the edge of the main aftershock asperities. These moderate SSEs thus did not directly trigger the main shock, but contributed to trigger the main foreshock and the main aftershock. Only the sensitivity and resolution of the tiltmeter, added to the GPS records, allowed us to describe with unprecedented accuracy this precursory process as a cascade of cross-triggered, short-term aseismic slip events and earthquakes on the interplate contact. This three months of precursory activation appears to be the final acceleration burst of a weaker, longer term SSE which started mid-2013, already reported, with a moment release history which we could quantify. From the methodological point of view, our study takes advantage of an interesting complementarity of tilt and GPS measurements, due to their different dependence in distance to the source of strain, which turns out to be very efficient for resolving location and moment of strain sources, even when both instruments are close to each other. It finally demonstrates the efficient removal of sequences of small or even undetected coseismic steps from high resolution tilt record signal in order to retrieve the purely aseismic signal, a presently impossible task for high time resolution GPS records due to low signal to noise.
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Sasmi, Annisa Trisnia, Andri Dian Nugraha, Muzli Muzli, Sri Widiyantoro, Zulfakriza Zulfakriza, Shengji Wei, David P. Sahara i in. "Hypocenter and Magnitude Analysis of Aftershocks of the 2018 Lombok, Indonesia, Earthquakes Using Local Seismographic Networks". Seismological Research Letters 91, nr 4 (27.05.2020): 2152–62. http://dx.doi.org/10.1785/0220190348.
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Abstract The island of Lombok in Indonesia is located between the Indo-Australian and Eurasian subduction trenches and the Flores back-arc thrust, making it vulnerable to earthquakes. On 29 July 2018, a significant earthquake Mw 6.4 shook this region and was followed by series of major earthquakes (Mw>5.8) on 5, 9, and 19 August, which led to severe damage in the northern Lombok area. In this study, we attempt to reveal the possible cause of the sequences of the 2018 Lombok earthquakes based on aftershock monitoring data. Twenty stations were deployed to record earthquake waveform data from 4 August to 9 September 2018. In total, 3259 events were identified using 28,728 P- and 20,713 S-wave arrival times during the monitoring. The aftershock hypocenters were determined using a nonlinear approach and relocated using double-difference method. The moment magnitude (Mw) of each event was determined by fitting the displacement spectrum amplitude using a Brune-type model. The magnitudes of the aftershocks range from Mw 1.7 to 6.7. The seismicity pattern reveals three clusters located in the Flores oceanic crust, which fit well with the occurrences of the four events with Mw>6. We interpret these events as the main rupture area of the 2018 Lombok earthquake sequence. Furthermore, an aseismic zone in the vicinity of Rinjani extending toward the northwestern part of Lombok was observed. We propose that the crust in this area has elevated temperatures and is highly fractured thus inhibiting the generation of large earthquakes. The aseismic nature is therefore an artifact of the detection threshold of our network (Mw 4.6).
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Li, Qing Hua, i Shi Lang Xu. "Four Point Bending Experimental Investigation on Reinforced Ultra High Toughness Cementitious Composite Beams". Key Engineering Materials 400-402 (październik 2008): 395–401. http://dx.doi.org/10.4028/www.scientific.net/kem.400-402.395.
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Ultra high toughness cementitious composite (abbreviated as UHTCC) shows significant pseudo strain hardening behavior and offers prominent tension strain ability of more than 3% when subjected to uniaxial tension load. The failure pattern of the UHTCC components exhibits multiple fine cracks with crack width lower than 100μm even corresponding to the ultimate tensile strain state. Four-point bending investigations of reinforced ultra high toughness cementitious composite (RUHTCC) members without web reinforcement have been carried out due to the excellent crack dispersion and strain energy absorption abilities of UHTCC material, aiming at design issues of strictly anti-cracking structures or aseismic design in key parts of structures such as beam column joint when using UHTCC. The moment-curvature curves have been measured and compared with the theoretical analysis proposed before. There is a reasonable agreement between them, especially that both moment and curvature present little difference before yielding. According to experimental results of RUHTCC beams with three different reinforcement ratios, UHTCC can delay yielding of reinforcements and improve load bearing capacity and ductility of structures or components compared with ordinary reinforced concrete beams, then steel products can be saved. The possibility of corrosion should be evidently reduced in respect that RUHTCC can effectively control crack. Accordingly, durability of structures improves by using UHTCC members.
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Stein, Ross S., i Thomas C. Hanks. "M ≧ 6 earthquakes in southern California during the twentieth century: No evidence for a seismicity or moment deficit". Bulletin of the Seismological Society of America 88, nr 3 (1.06.1998): 635–52. http://dx.doi.org/10.1785/bssa0880030635.
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Abstract A broadly based report on seismic hazards in southern California (WGCEP, 1995) concluded that the predicted seismicity exceeds that observed since 1850; a subsequent independent analysis argued that infrequent huge (M > 8) earthquakes are needed to explain the low rate of large earthquakes (Jackson, 1996). Frequency-magnitude relationships and earthquake reporting suggest that the 1903 to 1997 catalog we present here, with a b-value of 1.0 and a rate of M ≧ 6 shocks of 0.42 to 0.49 yr−1, is nearly complete. In contrast, the 1850 to 1994 catalog used by WGCEP is incomplete before the turn of the century, and thus its reported seismicity rate of 0.32 M ≧ 6 shocks yr−1 is too low. Principally because the WGCEP (1995) model results in b-values of up to 4.0 for regions of lesser and blind faults, the rate of M ≧ 6 shocks off the San Andreas system predicted by the WGCEP (1995) model is three times greater than that observed in this century. Because they obtained b = 0.4 for M < 7.3 and b = 2.2 for M ≧ 7.3 on major faults, their expected rate of M ≧ 7 San Andreas shocks is twice as high as observed. Thus, part of the seismicity and moment discrepancy identified by WGCEP was caused by use of an incomplete catalog, and part was caused by inappropriate b-values. We obtain a southern California moment release rate of 8 to 12 × 1018 N-m yr−1, which cannot be distinguished from the moment release estimated by fault slip, or the moment accumulation inferred from plate motions or geodetically measured shear strain. We thus find no evidence for a moment deficit, significant aseismic moment release, or for rare M > 8 earthquakes off the San Andreas fault system. Finally, the number of M ≧ 6 earthquakes per decade does not depart significantly from a Poisson process during this century, and thus we find no evidence that the rate of seismicity is increasing, now or at any other time since 1900.
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Cauchie, L., O. Lengliné i J. Schmittbuhl. "Seismic asperity size evolution during fluid injection: case study of the 1993 Soultz-sous-Forêts injection". Geophysical Journal International 221, nr 2 (3.02.2020): 968–80. http://dx.doi.org/10.1093/gji/ggaa051.
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SUMMARY The injection of fluid in the upper crust, notably for the development or exploitation of geothermal reservoirs, is often associated with the onset of induced seismicity. Although this process has been largely studied, it is not clear how the injected fluid influences the rupture size of the induced events. Here we re-investigate the induced earthquakes that occurred during an injection at Soultz-sous-Forêts, France in 1993 and studied the link between the injected fluid and the source properties of the numerous induced earthquakes. We take advantage that deep borehole accelerometers were running in the vicinity of the injection site. We estimate the moment and radius of all recorded events based on a spectral analysis and classify them into 663 repeating sequences. We show that the events globally obey the typical scaling law between radius and moment. However, at the scale of the asperity, fluctuations of the moment are important while the radii remain similar suggesting a variable stress drop or a mechanism that prevents the growth of the rupture. This is confirmed by linking the event source size to the geomechanical history of the reservoir. In areas where aseismic slip on pre-existing faults has been evidenced, we observed only small rupture sizes whereas in part of the reservoir where seismicity is related to the creation of new fractures, a wider distribution and larger rupture sizes are promoted. Implications for detecting the transition between events related to pre-existing faults and the onset of fresh fractures are discussed.
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Jiang, Junle, Yehuda Bock i Emilie Klein. "Coevolving early afterslip and aftershock signatures of a San Andreas fault rupture". Science Advances 7, nr 15 (kwiecień 2021): eabc1606. http://dx.doi.org/10.1126/sciadv.abc1606.
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Large earthquakes often lead to transient deformation and enhanced seismic activity, with their fastest evolution occurring at the early, ephemeral post-rupture period. Here, we investigate this elusive phase using geophysical observations from the 2004 moment magnitude 6.0 Parkfield, California, earthquake. We image continuously evolving afterslip, along with aftershocks, on the San Andreas fault over a minutes-to-days postseismic time span. Our results reveal a multistage scenario, including immediate onset of afterslip following tens-of-seconds-long coseismic shaking, short-lived slip reversals within minutes, expanding afterslip within hours, and slip migration between subparallel fault strands within days. The early afterslip and associated stress changes appear synchronized with local aftershock rates, with increasing afterslip often preceding larger aftershocks, suggesting the control of afterslip on fine-scale aftershock behavior. We interpret complex shallow processes as dynamic signatures of a three-dimensional fault-zone structure. These findings highlight important roles of aseismic source processes and structural factors in seismicity evolution, offering potential prospects for improving aftershock forecasts.
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Michel, Sylvain, Jean‐Philippe Avouac, Romain Jolivet i Lifeng Wang. "Seismic and Aseismic Moment Budget and Implication for the Seismic Potential of the Parkfield Segment of the San Andreas Fault". Bulletin of the Seismological Society of America 108, nr 1 (28.11.2017): 19–38. http://dx.doi.org/10.1785/0120160290.
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Jeong, Seong Ju, Brian W. Stump i Heather R. DeShon. "Stress Drop Variations of Induced Earthquakes near the Dallas–Fort Worth Airport, Texas". Seismic Record 2, nr 2 (1.04.2022): 68–77. http://dx.doi.org/10.1785/0320220003.
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Abstract We estimate stress drops for injection-induced earthquakes near the Dallas–Fort Worth Airport in the Fort Worth basin (FWB), Texas, to investigate source properties in response to fluid injection. The stress drops for the Airport sequence show three unique characteristics compared to those estimated for other earthquake sequences in the FWB: (1) stress drops have lower mean and median values; (2) stress drops increase with moment magnitude; and (3) stress drops increase in size over the first 1.5 km in radial distance from the injection point. The low stress drop Airport events occurred shortly after the initiation of injection near a fault within hundreds of meters of the well. Pore pressure perturbations in the Airport area are 1 order of magnitude lower than those from the other sequences, suggesting that absolute pore pressure changes may not be the main factors of stress drop variations. We suggest that the low stress drop events may be related to transition from aseismic slip to seismic rupture previously observed in laboratory and field experiments.
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Louie, John N., Clarence R. Allen, David C. Johnson, Paul C. Haase i Stephen N. Cohn. "Fault slip in southern California". Bulletin of the Seismological Society of America 75, nr 3 (1.06.1985): 811–33. http://dx.doi.org/10.1785/bssa0750030811.
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Abstract Measurements of slip on major faults in southern California have been performed over the past 18 yr using principally theodolite alignment arrays and tautwire extensometers. They provide geodetic control within a few hundred meters of the fault traces, which complements measurements made by other techniques at larger distances. Approximately constant slip rates of from 0.5 to 5 mm/yr over periods of several years have been found for the southwestern portion of the Garlock fault, the Banning and San Andreas faults in the Coachella Valley, the Coyote Creek fault, the Superstition Hills fault, and an unnamed fault 20 km west of El Centro. These slip rates are typically an order of magnitude below displacement rates that have been geodetically measured between points at greater distances from the fault traces. Exponentially decaying postseismic slip in the horizontal and vertical directions due to the 1979 Imperial Valley earthquake has been measured. It is similar in magnitude to the coseismic displacements. Analysis of seismic activity adjacent to slipping faults has shown that accumulated seismic moment is insufficient to explain either the constant or the decaying postseismic slip. Thus the mechanism of motion may differ from that of slipping faults in central California, which move at rates close to the plate motion and are accompanied by sufficient seismic moment. Seismic activity removed from the slipping faults in southern California may be driving their relatively aseismic motion.
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Orecchio, Barbara, Silvia Scolaro, Josep Batlló, Giancarlo Neri, Debora Presti, Daniel Stich i Cristina Totaro. "New Results for the 1968 Belice, South Italy, Seismic Sequence: Solving the Long-Lasting Ambiguity on Causative Source". Seismological Research Letters 92, nr 4 (10.03.2021): 2364–81. http://dx.doi.org/10.1785/0220200277.
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Abstract We present the first estimates of moment tensor solutions and probabilistic nonlinear hypocenter locations for the 1968 Belice earthquake sequence, which is the most relevant seismic activity occurred in western Sicily in historical times. This seismic phase, including six earthquakes with magnitude between 5 and 6.4, produced severe damages and fatalities in a sector of the Nubia–Eurasia plate margin, previously considered aseismic. Poorly constrained and often controversial hypocenter locations and focal mechanism solutions available from the literature have led to a long-lasting ambiguity on the possible causative source of the sequence, also having primary effects on the regional seismotectonic modeling and seismic hazard evaluations. The two main fault models proposed in the literature alternatively assigned a primary role to the north-northwest-trending Nubia–Eurasia plate convergence, causing thrust faulting on about east-trending structures or to the differential foreland retreat driving dextral strike-slip movements on about north–south-oriented faults. By focusing on the starting and the most energetic phase of the 1968 sequence, we computed the moment tensor solutions for three of the strongest earthquakes using digitized waveforms and a time-domain waveform inversion technique. Then, we also analyzed, by means of a Bayesian hypocenter location technique, the spatial distribution of the 1968 earthquakes. All the results indicate that the 1968 Belice sequence was characterized by predominant reverse faulting occurring on about east-to-northeast-trending structures, thus solving the dualism between models previously proposed in the literature. Our findings well agree both with the geodynamic framework governed by the Nubia–Eurasia north-northwest-trending convergence and with the geological reconstructions of the regional thrust front in the western Sicily area. The results of moment tensor estimations and nonlinear hypocenter locations furnishing an improved knowledge of the most relevant seismic activity of western Sicily also concur to better constraint the seismotectonic modeling of the region.
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Luo, Bin, Benchun Duan i Dunyu Liu. "3D Finite-Element Modeling of Dynamic Rupture and Aseismic Slip over Earthquake Cycles on Geometrically Complex Faults". Bulletin of the Seismological Society of America 110, nr 6 (1.09.2020): 2619–37. http://dx.doi.org/10.1785/0120200047.
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ABSTRACT We develop a new dynamic earthquake simulator to numerically simulate both spontaneous rupture and aseismic slip over earthquake cycles on geometrically complex fault systems governed by rate- and state-dependent friction. The method is based on the dynamic finite-element method (FEM) EQdyna, which is directly used in the simulator for modeling 3D spontaneous rupture. We apply an adaptive dynamic relaxation technique and a variable time stepping scheme to EQdyna to model the quasi-static processes of an earthquake cycle, including the postseismic, interseismic, and nucleation processes. Therefore, the dynamic and quasi-static processes of an earthquake cycle are modeled in one FEM framework. Tests on a vertical strike-slip fault verify the correctness of the dynamic simulator. We apply the simulator to thrust faults with various dipping angles, which can be considered as the simplest case of geometrically complex faults by breaking symmetry, compared with vertical faults, to examine effects of dipping fault geometry on earthquake cycle behaviors. We find that shallower dipping thrust faults produce larger seismic slip and longer recurrence time over earthquake cycles with the same rupture area. In addition, we find an empirically linear scaling relation between the recurrence interval (and the seismic moment) and the sinusoidal function of the dip angle. The dip-angle dependence is likely due to the free-surface effect, because of broken symmetry. These results suggest dynamic earthquake simulators that can handle nonvertical dipping fault geometry are needed for subduction-zone earthquake studies.
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Kasimzade, A. A., A. Dushimimana, S. Tuhta, G. Atmaca, F. Günday i O. Abrar. "A Comparative Study on Effectiveness of Using Horasan Mortar as a Pure Friction Sliding Interface Material". European Journal of Engineering Research and Science 4, nr 2 (27.02.2019): 64–69. http://dx.doi.org/10.24018/ejers.2019.4.2.1166.
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In this study, the possibility to use Horasan mortar as a sliding interface material for pure friction aseismic isolation system is investigated. Both experimental and numerical studies are conducted to examine the effectiveness of using this material in structural isolation systems of buildings with no overturning moment, as it has shown some attractive experiences in time based on the existing related literature. Responses of four storey lightweight building are numerically investigated by finite element modelling in MATLAB; whereas the University Consortium on Instructional Shake Table (UCIST) is used to study the responses of the same building during experimental works. Comparison of both studies is shown to be in a good agreement in terms of resulting structural response accelerations, velocity and displacements. Approximately 28 - 31 % reduction of base floor acceleration is achieved; and the maximum sliding velocity and displacement are found to lie between 0.33-0.45 m/sec and 0.0353-0.0559 m respectively; which fall within the recommended standards’ limits. As a result, these findings demonstrate the effectiveness of using Horasan mortar as friction interface material which has additionally gained experience in more than ten centuries.
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Kasimzade, A. A., A. Dushimimana, S. Tuhta, G. Atmaca, F. Günday i O. Abrar. "A Comparative Study on Effectiveness of Using Horasan Mortar as a Pure Friction Sliding Interface Material". European Journal of Engineering and Technology Research 4, nr 2 (27.02.2019): 64–69. http://dx.doi.org/10.24018/ejeng.2019.4.2.1166.
Pełny tekst źródłaStreszczenie:
In this study, the possibility to use Horasan mortar as a sliding interface material for pure friction aseismic isolation system is investigated. Both experimental and numerical studies are conducted to examine the effectiveness of using this material in structural isolation systems of buildings with no overturning moment, as it has shown some attractive experiences in time based on the existing related literature. Responses of four storey lightweight building are numerically investigated by finite element modelling in MATLAB; whereas the University Consortium on Instructional Shake Table (UCIST) is used to study the responses of the same building during experimental works. Comparison of both studies is shown to be in a good agreement in terms of resulting structural response accelerations, velocity and displacements. Approximately 28 - 31 % reduction of base floor acceleration is achieved; and the maximum sliding velocity and displacement are found to lie between 0.33-0.45 m/sec and 0.0353-0.0559 m respectively; which fall within the recommended standards’ limits. As a result, these findings demonstrate the effectiveness of using Horasan mortar as friction interface material which has additionally gained experience in more than ten centuries.
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Kaviris, George, Panagiotis Elias, Vasilis Kapetanidis, Anna Serpetsidaki, Andreas Karakonstantis, Vladimír Plicka, Louis De Barros i in. "The Western Gulf of Corinth (Greece) 2020–2021 Seismic Crisis and Cascading Events: First Results from the Corinth Rift Laboratory Network". Seismic Record 1, nr 2 (1.07.2021): 85–95. http://dx.doi.org/10.1785/0320210021.
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Abstract We investigate a seismic crisis that occurred in the western Gulf of Corinth (Greece) between December 2020 and February 2021. This area is the main focus of the Corinth Rift Laboratory (CRL) network, and has been closely monitored with local seismological and geodetic networks for 20 yr. The 2020–2021 seismic crisis evolved in three stages: It started with an Mw 4.6 event near the northern shore of the Gulf, opposite of Aigion, then migrated eastward toward Trizonia Island after an Mw 5.0 event, and eventually culminated with an Mw 5.3 event, ∼3 km northeast of the Psathopyrgos fault. Aftershocks gradually migrated westward, triggering another cluster near the junction with the Rion–Patras fault. Moment tensor inversion revealed mainly normal faulting; however, some strike-slip mechanisms also exist, composing a complex tectonic regime in this region dominated by east–west normal faults. We employ seismic and geodetic observations to constrain the geometry and kinematics of the structures that hosted the major events. We discuss possible triggering mechanisms of the second and third stages of the sequence, including fluids migration and aseismic creep, and propose potential implications of the Mw 5.3 mainshock for the seismic hazard of the region.
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Caputa, Alicja, Adam Talaga i Łukasz Rudziński. "Analysis of post-blasting source mechanisms of mining-induced seismic events in Rudna copper mine, Poland". Contemporary Trends in Geoscience 4, nr 1 (1.10.2015): 26–38. http://dx.doi.org/10.1515/ctg-2015-0003.
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Abstract The exploitation of georesources by underground mining can be responsible for seismic activity in areas considered aseismic. Since strong seismic events are connected with rockburst hazard, it is a continuous requirement to reduce seismic risk. One of the most effective methods to do so is blasting in potentially hazardous mining panels. In this way, small to moderate tremors are provoked and stress accumulation is substantially reduced. In this paper we present an analysis of post-blasting events using Full Moment Tensor (MT) inversion at the Rudna mine, Poland, underground seismic network. In addition, we describe the problems we faced when analyzing seismic signals. Our studies show that focal mechanisms for events that occurred after blasts exhibit common features in the MT solution. The strong isotropic and small Double Couple (DC) component of the MT, indicate that these events were provoked by detonations. On the other hand, post-blasting MT is considerably different than the MT obtained for strong mining events. We believe that seismological analysis of provoked and unprovoked events can be a very useful tool in confirming the effectiveness of blasting in seismic hazard reduction in mining areas.
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Su, Jizhi, Boquan Liu, Guohua Xing, Yudong Ma i Jiao Huang. "Influence of Beam-to-Column Linear Stiffness Ratio on Failure Mechanism of Reinforced Concrete Moment-Resisting Frame Structures". Advances in Civil Engineering 2020 (10.01.2020): 1–24. http://dx.doi.org/10.1155/2020/9216798.
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The design philosophy of a strong-column weak-beam (SCWB), commonly used in seismic design codes for reinforced concrete (RC) moment-resisting frame structures, permits plastic deformation in beams while keeping columns elastic. SCWB frames are designed according to beam-to-column flexural capacity ratio requirements in order to ensure the beam-hinge mechanism during large earthquakes and without considering the influence of the beam-to-column stiffness ratio on the failure modes of global structures. The beam-to-column linear stiffness ratio is a comprehensive indicator of flexural stiffness, story height, and span. This study proposes limit values for different aseismic grades based on a governing equation deduced from the perspective of member ductility. The mathematical expression shows that the structural yielding mechanism strongly depends on parameters such as material strength, section size, reinforcement ratio, and axial compression ratio. The beam-hinge mechanism can be achieved if the actual beam-to-column linear stiffness ratio is smaller than the recommended limit values. Two 1/3-scale models of 3-bay, 3-story RC frames were constructed and tested under low reversed cyclic loading to verify the theoretical analysis and investigate the influence of the beam-to-column linear stiffness ratio on the structural failure patterns. A series of nonlinear dynamic analyses were conducted on the numerical models, both nonconforming and conforming to the beam-to-column linear stiffness ratio limit values. The test results indicated that seismic damage tends to occur at the columns in structures with larger beam-to-column linear stiffness ratios, which inhibits the energy dissipation. The dynamic analysis suggests that considering the beam-to-column linear stiffness ratio during the design of structures leads to a transition from a column-hinge mechanism to a beam-hinge mechanism.
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Brengman, Clayton M. J., William D. Barnhart, Emma H. Mankin i Cody N. Miller. "Earthquake‐Scaling Relationships from Geodetically Derived Slip Distributions". Bulletin of the Seismological Society of America 109, nr 5 (23.07.2019): 1701–15. http://dx.doi.org/10.1785/0120190048.
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Abstract Empirical earthquake scaling relationships describe expected relationships between moment magnitude and various spatial descriptors of the earthquake rupture (along‐strike length, down‐dip width, rupture area, and peak and mean slip). These scaling relationships play important roles in many seismological, geological, and hazards‐assessment applications. Historically, scaling relationships were defined from various seismological criteria, such as teleseismic finite‐fault models or aftershock distributions. The proliferation of earthquake slip distributions from geodetic observations presents an opportunity to reassess earthquake scaling relationships using observations that more directly sample the spatial characteristics of an earthquake than seismological observations. Here, we present a database of 111 earthquake slip distributions from 73 different earthquakes that were derived from geodetic observations. The earthquakes range in magnitude from Mw 5.3 to 9.1. We extract common spatial descriptors from these slip distributions in four different ways to account for biases introduced by inversion regularization, and we regress these spatial descriptors with moment magnitude to derive new empirical scaling relationships. We additionally assess the shape characteristics of the slip distributions and report the average earthquake shape. We find that our scaling relationships differ in important ways from previous studies, and we show that these differences originate from our use of a geodetic slip‐distribution database rather than from methods for extracting spatial descriptors. Notably, we find that geodetic slip distributions systematically predict smaller fault areas than seismically derived scaling relationships. Because geodetic source inversions are likely contaminated to some degree by aseismic afterslip, this relationship suggests that seismologically determined scaling relationships systematically overpredict earthquake dimensions. We find that fault length, fault width, peak slip, and mean slip differ from previous studies in ways that are more complex and magnitude dependent. Given the high‐model resolution afforded by geodetic observations, our earthquake scaling relationships derived from geodetic slip distributions provide improved constraints on empirical scaling relationships.
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Gómez Alba, Sebastián, Carlos A. Vargas i Arno Zang. "Evidencing the relationship between injected volume of water and maximum expected magnitude during the Puerto Gaitán (Colombia) earthquake sequence from 2013 to 2015". Geophysical Journal International 220, nr 1 (7.10.2019): 335–44. http://dx.doi.org/10.1093/gji/ggz433.
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ABSTRACT Since 2013 to date more than 1000 seismic events have been recorded by the Servicio Geologico Colombiano (Colombian Geological Survey, SGC) in the municipality of Puerto Gaitán (Colombia). A total of 14 earthquakes are moment magnitude Mw > 4.0. The largest event ever recorded in the area occurred in November 2015 with Mw 4.8. It seems like the case of Puerto Gaitán is associated with the deep injection of coproduced wastewater from oil and gas extraction. The data presented in this work suggests a close relationship in space and time between injection operations and seismicity. An analysis of temporality between both data sets resulted in a time lag equivalent to about 218 d. For this paper, we computed the input and output energy during injection operations from 2013 to 2015 in order to estimate the fraction of total input energy that is radiated as seismic waves. Our results suggest that the seismic energy is only a small fraction of the total energy into the system. Although Puerto Gaitan is one of the places with the most significant volume of wastewater injected among the ones reported in the literature, the energy efficiency of the system is the lowest reported to date in comparison with other applied technologies. The low efficiency seems to be associated to the aseismic deformation of the reservoir rocks. The observed clustering of earthquakes is delimited by the basement crystalline depth. From an operational point of view, we determine that, like most cases associated with fluid injection, volume of fluid is the variable that determines change in the seismic moment released. Furthermore, the sequence of events in Puerto Gaitán may not fit into a well-known correlation between the volume of fluid injected and the maximum expected magnitude. The observed magnitudes in Puerto Gaitan are well bellow compared to those reported in the literature for similar volumes of injected fluid.
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He, Zhongqiu, Ting Chen, Mingce Wang i Yanchong Li. "Multi-Segment Rupture Model of the 2016 Kumamoto Earthquake Revealed by InSAR and GPS Data". Remote Sensing 12, nr 22 (12.11.2020): 3721. http://dx.doi.org/10.3390/rs12223721.
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The 2016 Kumamoto earthquake, including two large (Mw ≥ 6.0) foreshocks and an Mw 7.0 mainshock, occurred in the Hinagu and Futagawa fault zones in the middle of Kyushu island, Japan. Here, we obtain the complex coseismic deformation field associated with this earthquake from Advanced Land Observation Satellite-2 (ALOS-2) and Sentinel-1A Interferometric Synthetic Aperture Radar (InSAR) data. These InSAR data, in combination with available Global Positioning System (GPS) data, are then used to determine an optimal four-segment fault geometry with the jRi method, which considers both data misfit and the perturbation error from data noise. Our preferred slip distribution model indicates that the rupture is dominated by right-lateral strike-slip, with a significant normal slip component. The largest asperity is located on the northern segment of the Futagawa fault, with a maximum slip of 5.6 m at a 5–6 km depth. The estimated shallow slips along the Futagawa fault and northern Hinagu fault are consistent with the displacements of surface ruptures from the field investigation, suggesting a shallow slip deficit. The total geodetic moment release is estimated to be 4.89 × 1019 Nm (Mw 7.09), which is slightly larger than seismological estimates. The calculated static Coulomb stress changes induced by the preferred slip distribution model cannot completely explain the spatial distribution of aftershocks. Sensitivity analysis of Coulomb stress change implies that aftershocks in the stress shadow area may be driven by aseismic creep or triggered by dynamic stress transfer, requiring further investigation.
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Mesimeri, Maria, Athanassios Ganas i Kristine L. Pankow. "Multisegment ruptures and Vp/Vs variations during the 2020–2021 seismic crisis in western Corinth Gulf, Greece". Geophysical Journal International 230, nr 1 (24.02.2022): 334–48. http://dx.doi.org/10.1093/gji/ggac081.
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SUMMARY On 2020 December 23, a seismic crisis initiated in the western Corinth Gulf offshore Marathias, lasted several months, and generated thousands of small magnitude earthquakes. The Gulf of Corinth is well known for earthquake swarm occurrence and short-lived burst-like earthquake sequences, mostly triggered by crustal fluids. Here, we perform a detailed seismic analysis aiming to identifying earthquake clusters within the seismic crisis and define their spatial and temporal characteristics. Thanks to the dense seismic station coverage in the area, operated by the Hellenic Unified Seismological Network and Corinth Rift Laboratory, we relocate shallow seismicity and compile a high-resolution earthquake catalogue containing ∼1400 earthquakes spanning the first two months of the seismic crisis. We identify 19 earthquake clusters by applying spatio-temporal criteria and define the geometry (strike and dip) using principal component analysis for 11 of them. Our results are consistent with moment tensor solutions computed for the largest earthquake in each cluster. A striking feature of the seismic activity is the west-towards-east migration with a notable increase in Vp/Vs values for each cluster and a slight increase of the dip angle for the identified fault segments. Furthermore, we find that each cluster contains several burst-like, short interevent time, repeating earthquakes, which could be related to aseismic slip or fluid migration. Overall, we show that the 2020–2021 seismic crisis consists of earthquake clusters that bifurcate between swarm-like and main shock–aftershock-like sequences and ruptured both north- and south-dipping high-angle fault segments. The 2020–2021 seismic activity is located between 5 to 8 km, shallower than the low angle north-dipping (∼10°) seismic zone which hosts long-lived repeating sequences at ∼9–10 km depth. This study supports a hypothesis that the low-angle north-dipping seismicity defines the brittle-ductile transition in the western Corinth Gulf, with seismic bursts occurring at shallower depths in the crust.
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Mazzotti, Stéphane, Hervé Jomard i Frédéric Masson. "Processes and deformation rates generating seismicity in metropolitan France and conterminous Western Europe". BSGF - Earth Sciences Bulletin 191 (2020): 19. http://dx.doi.org/10.1051/bsgf/2020019.
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Most of metropolitan France and conterminous Western Europe is currently located within the Eurasia intraplate domain, far from major plate boundaries (the Atlantic ridge and Nubia – Eurasia convergence zone). As in other intraplate regions, present-day deformation and seismicity rates are very slow, resulting in limited data and strong uncertainties on the ongoing seismotectonics and seismic hazards. In the last two decades, new geological, seismological and geodetic data and research have brought to light unexpected deformation patterns in metropolitan France, such as orogen-normal extension ca. 0.5 mm yr−1 in the Pyrenees and Western Alps that cannot be associated with their mountain-building history. Elsewhere, present-day deformation and seismicity data provide a partial picture that points to mostly extensive to strike-slip deformation regimes (except in the Western Alps foreland). A review of the numerous studies and observations shows that plate tectonics (plate motion, mantle convection) are not the sole, nor likely the primary driver of present-day deformation and seismicity and that additional processes must be considered, such as topography potential energy, erosion or glacial isostatic adjustment since the last glaciation. The exact role of each process probably varies from one region to another and remains to be characterized. In addition, structural inheritance (crust or mantle weakening from past tectonic events) can play a strong role in deformation localization and amplification up to factors of 5–20, which could explain some of the spatial variability in seismicity. On the basis of this review, we identify three research directions that should be developed to better characterize the seismicity, deformation rates and related processes in metropolitan France: macroseismic and historical seismicity, especially regarding moment magnitude estimations; geodetic deformation, including in regions of low seismicity where the ratio of seismic to aseismic deformation remains a key unknown; an integrated and consistent seismotectonic framework comprising numerical models, geological, seismological and geodetic data. The latter has the potential for significant improvements in the characterization of seismicity and seismic hazard in metropolitan France but also Western Europe.
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Valenzuela-Malebrán, Carla, Simone Cesca, Sergio Ruiz, Luigi Passarelli, Felipe Leyton, Sebastian Hainzl, Bertrand Potin i Torsten Dahm. "Seismicity clusters in Central Chile: investigating the role of repeating earthquakes and swarms in a subduction region". Geophysical Journal International 224, nr 3 (21.11.2020): 2028–43. http://dx.doi.org/10.1093/gji/ggaa562.
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SUMMARY Seismicity along subduction interfaces is usually dominated by large main-shock–aftershock sequences indicative of a continuum distribution of highly coupled large asperities. In the past decades, however, the increased resolution of seismic catalogues at some subduction zone seems to indicate instead a more complex rheological segmentation of the interface. Large and megathrust earthquake ruptures seem interspersed among regions of low seismic coupling and less stress buildup. In this weaker zone, the strain is primarily released via a combination of moderate-size swarm-like seismicity and aseismic slip. Along the Chilean subduction zone, the densification of the seismic network allowed for the identification of localized seismic clusters, some of them appearing in the form of swarms before megathrust earthquakes. The origin and driving processes of this seismic activity have not yet been identified. In this study, we follow a systematic approach to characterize the seismicity at two persistent clusters in Central Chile, one located offshore Navidad and one inland, at ∼40 km depth beneath Vichuquén, which occurred throughout ∼20 yr. We investigated these clusters, by deriving high-resolution hypocentral locations and moment tensors and performing a detailed analysis of spatio-temporal patterns, magnitude and interevent time distributions of the clustered earthquakes. Both clusters are characterized by weak to moderate seismicity (below Mw 6) and stand out as clear seismicity rate and Benioff strain anomalies. At the Navidad cluster, seismicity occurs in the form of swarms, with a characteristic duration of 2–7 d and location and thrust mechanisms compatible with activity on the slab interface. Conversely, we find at Vichuquén activity dominated by thrust earthquakes occurring as repeaters on the slab interface, with a slip rate of approximately ∼5.0 cm yr−1. We attribute these clusters to local features of the subducting plate: the Navidad swarms are likely driven by repeated high pore pressure transients along a pre-fractured patch of the slab, while the seismicity at the Vichuquén cluster is interpreted as the result of a subducting seamount. Both clusters have been active before and after the Mw 8.8 Maule earthquake and persisted afterwards with the seismicity decay following the Omori law. These interactions are especially evident for the Vichuquén cluster, where the seismicity rate increased considerably after the Maule earthquake and continues to be an area of clearly elevated seismicity rate compared to its surroundings.
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Li, Yong He, Ren Xiong, Ai Rong Liu i Jun Ping Zhang. "The Study of Aseismatic Performance of Continuous Rigid-Frame Bridge". Advanced Materials Research 243-249 (maj 2011): 1901–7. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.1901.
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The aseismatic performance of long span continuous rigid-frame bridge is an important but difficult research topic. To explore the impact of pier height and reinforcement ratio on long span continuous rigid-frame bridge’s aseismatic performance, Midas/Civil bridge Finite Element program is used to construct the three-dimensional model of a continuous rigid-frame bridge in this research. Fiber element and plastic hinge are used in pier simulation. Through the adjustment of pier height and ratio of reinforcement, the internal force, displacement and plastic rotation of bridge pier’s critical sections are analyzed under the action of seismic loading. Thereby, the impact of pier height and plastic hinge on such bridge’s aseismatic performance is obtained. It is shown that: maximum displacement, bending moment and plastic rotation increase at pier cap with pier height, indicating that pier height has strong impact on seismic response. And with increasing reinforcement ratio, the bending moment and yielding moment at pier cap and base both increase. Therefore, suitable pier height and reinforcement ratio should be selected for better aseismatic performance.
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Berberian, Manuel, i Robert S. Yeats. "Patterns of historical earthquake rupture in the Iranian Plateau". Bulletin of the Seismological Society of America 89, nr 1 (1.02.1999): 120–39. http://dx.doi.org/10.1785/bssa0890010120.
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Abstract The Iranian plateau accommodates the 35 mm/yr convergence rate between the Eurasian and Arabian plates by strike-slip and reverse faults with relatively low slip rates in a zone 1000 km across. Although these faults have only locally been the subject of paleoseismological studies, a rich historical and archeological record spans several thousand years, long enough to establish recurrence intervals of 1000 to 5000 yr on individual fault segments. Several clusters of earthquakes provide evidence of interaction among reverse and strike-slip faults, probably due to adjacent faults being loaded by individual earthquakes. The Dasht-e-Bayaz sequence of 1936 to 1997 includes earthquakes on left-lateral, right-lateral, and reverse faults. The Neyshabur sequence of four earthquakes between 1209 and 1405 respected the segment boundary between the Neyshabur and Binalud reverse fault systems. The two pairs of earthquakes may have ruptured different faults in each segment, similar to the 1971 and 1994 San Fernando, California, earthquakes. The 1978 Tabas reversefault earthquake was preceded by the 1968 Ferdows earthquake, part of the Dasht-e-Bayaz sequence. The North Tabriz fault system ruptured from southeast to northwest in three earthquakes from 1721 to 1786; a previous cluster may have struck this region in 855 to 958. The Mosha fault north of Tehran ruptured in three earthquakes in 958, 1665, and 1830. Five large earthquakes struck the Tehran region from 743 to 1177, but only two that large have struck the area since 1177. Other earthquakes occurred in pairs in the Talesh Mountains near the Caspian Sea (1863, 1896), the Iran-Turkey border (1840, 1843), and the Nayband-Gowk fault system (both in 1981). Other historical events did not occur as parts of sequences. The historic seismic moment release in Iran accounts for only a small part of the plate convergence rate, which may be due to aseismic slip or to the Iranian historical record, long as it is, being too short to sample long-term deformation across the plateau. No historic earthquakes of M ≧ 8 have struck Iran. However, several long, straight strike-slip faults (Doruneh, West Neh, East Neh, and Nayband) have not sustained large historical earthquakes, raising the possibility that these long faults could produce earthquakes of M ≧ 8, thereby removing at least part of the apparent slip deficit. An increased understanding of Iran's seismic hazard could be obtained by an extensive paleoseismology program and space-geodetic arrays, supplementing the abundant historical and archaeological record.
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Cassidy, John F., i Garry C. Rogers. "The rupture process and aftershock distribution of the 6 April 1992 MS 6.8 earthquake, Offshore British Columbia". Bulletin of the Seismological Society of America 85, nr 3 (1.06.1995): 716–35. http://dx.doi.org/10.1785/bssa0850030716.
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Abstract On 6 April 1992, a magnitude 6.8 (MS) earthquake occurred in the triple-junction region at the northern end of the Cascadia subduction zone. This was the largest earthquake in at least 75 yr to occur along the 110-km-long Revere-Dellwood-Wilson (RDW) transform fault and the first large earthquake in this region recorded by modern broadband digital seismic networks. It thus provides an opportunity to examine the rupture process along a young (<2 Ma) oceanic transform fault and to gain better insight into the tectonics of this triple-junction region. We have investigated the source parameters and the rupture process of this earthquake by modeling broadband body waves and long-period surface waves and by accurately locating the mainshock and the first 10 days of aftershocks using a well-located “calibration” event recorded during an ocean-bottom seismometer survey. Analysis of P and SH waveforms reveals that this was a complex rupture sequence consisting of three strike-slip subevents in 12 sec. The initial rupture occurred 5 to 6 km to the SW of the seafloor trace of the RDW fault at 50.55° N, 130.46° W. The dominant subevent occurred 2 to 3 sec later and 4.3 km beneath the seafloor trace of the RDW fault, and a third subevent occurred 5 sec later, 18 km to the NNW, suggesting a northwestward propagating rupture. The aftershock sequence extended along a 60- to 70-km-long segment of the RDW fault, with the bulk of the activity concentrated ∼30 to 40 km to the NNW of the epicenter, consistent with this interpretation. The well-constrained mechanism of the initial rupture (strike/dip/slip 339°/90°/−168°) and of the largest aftershock (165°/80°/170°) are rotated 15° to 20° clockwise relative to the seafloor trace of the RDW fault but are parallel to the Pacific/North America relative plate motion vector. In contrast, the mechanisms of the dominant subevent (326°/87°/−172°), and the long-period solution derived from surface waves aligns with the RDW fault. This suggests that small earthquakes (M < 6) in this area occur along faults that are optimally aligned with respect to the regional stress field, whereas large earthquakes, involving tens of kilometers of rupture, activate the RDW fault. For the mainshock, we estimate a seismic moment (from surface waves) of 1.0 × 1026 dyne-cm, a stress drop of 60 bars, and an average slip of 1.2 m. This represents only 21 yr of strain accumulation, implying that there is either a significant amount of aseismic slip along the RDW fault or that much of the strain accumulation manifests itself as deformation within the Dellwood and Winona blocks or along the continental margin.
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Ning, Xiao Jun, i Yi Tang Zhou. "Analysis for Seismic Response of Long Span Rigid Frame Bridge". Advanced Materials Research 194-196 (luty 2011): 1962–66. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.1962.
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Rigid frame bridge is widely used in China because of its lower cost. The aseismatic ability of rigid frame bridge is difficult to judge for designer when the bridge is used to span valley in intensity region. The seismic response of one rigid frame bridge with 160m span is calculated. It is indicated that the aseismatic ability of rigid frame bridge is good and bridge design is controlled by bending moment at bottom of pier.
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Zhang, Jingye, Ke Sun, Junqing Zhu, Ning Mao i Dimitar Ouzounov. "Application of Model-Based Time Series Prediction of Infrared Long-Wave Radiation Data for Exploring the Precursory Patterns Associated with the 2021 Madoi Earthquake". Remote Sensing 15, nr 19 (28.09.2023): 4748. http://dx.doi.org/10.3390/rs15194748.
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Taking the Madoi MS 7.4 earthquake of 21 May 2021 as an example, this paper proposes using time series prediction models to predict the outgoing long-wave radiation (OLR) anomalies and study short-term pre-earthquake signals. Five time series prediction models, including autoregressive integrated moving average (ARIMA) and long short-term memory (LSTM), were trained with the OLR time series data of the aseismic moments in the 5° × 5° spatial range around the epicenter. The model with the highest prediction accuracy was selected to retrospectively predict the OLR values during the aseismic period and before the earthquake in the area. It was found, by comparing the predicted time series values with the actual time series value, that the similarity indexes of the two time series before the earthquake were lower than the index of the aseismic period, indicating that the predicted time series before the earthquake significantly differed from the actual time series. Meanwhile, the temporal and spatial distribution characteristics of the anomalies in the 90 days before the earthquake were analyzed with a 95% confidence interval as the criterion of the anomalies, and the following was found: out of 25 grids, 18 grids showed anomalies—the anomalies of the different grids appeared on similar dates, and the anomalies of high values appeared centrally at the time of the earthquake, which supports the hypothesis that pre-earthquake signals may be associated with the earthquake.