Дисертації з теми "Earthquakes precursors"
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1
Lopes, da Silva Valencio Arthur. "An information-theoretical approach to identify seismic precursors and earthquake-causing variables." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=237105.
Повний текст джерелаАнотація:
Several seismic precursors and earthquake-causing variables have been proposed in the last decades based on physical considerations and case observations, however none has been confirmed on long datasets using linear analysis. This work adopts an information-theoretical approach to investigate the occurrence of causal flow between these precursors and causing variables and seismicity. It starts by introducing the key concepts in seismology and presenting the current main precursor candidates. Four variables will be considered as possible precursors or anomalies leading to earthquakes: large tidal amplitudes, temporal fluctuations in the Gutenberg-Richter's b-value, surface gravity changes, and preceding anomalous seismicity patterns. To perform the causality test between these variables and their effects, it is developed a method which allows the fast calculation of Transfer Entropy for any two time-series, detecting the direction of the flow of information between the variables of interest. The method is tested to coupled logistic maps and networks with different topologies before application to geophysical events. The analysis shows mutual information relating to coupling strength and also allows inference of the causal direction from data using the Transfer Entropy, both in bivariate systems and in networks. The method was then applied to the earthquake analysis for an interval of 4018 days on an area comprising the Japan trench. Within a conservative margin of confidence, the results could not at this point confirm any of the four precursor options considered, but future work can clarify initial suggestions regarding tidal amplitudes link to seismicity, and pre-seismic gravity changes and cumulative daily magnitude anomalies. The Matlab/Octavecodes for our method are open-source and available at https://github.com/artvalencio/causality-toolbox We hope the method is able to support the quest for other precursor candidates, and to assist other fields of knowledge.
2
Nuannin, Paiboon. "The Potential of b-value Variations as Earthquake Precursors for Small and Large Events." Doctoral thesis, Uppsala universitet, Institutionen för geovetenskaper, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6885.
Повний текст джерелаАнотація:
The potential of variations of b-values in the G-R relation, logN=a-bM as earthquake precursors for small events (rockbursts) in Zinkgruvan mine, Sweden and for tectonic (large) earthquakes in the Andaman-Sumatra region were investigated. The temporal frequency-magnitude distribution, b(t), of rockbursts in Zinkgruvan mine was examined using high quality data recorded during the period November 1996 to April 2004 with magnitude ranges from Mw= -2.4 to 2.6. A sliding time-window was applied to compute b-values. The windows contain 50 events and were shifted with steps of 5 events. The results indicated that b-values significantly drop preceding rockbursts of magnitude Mw≥1.6. Temporal and spatial variations of b-values were also examined for tectonic earthquakes, magnitude Mw≥4.1, in the Andaman-Sumatra region. Earthquake data from the ISC, IDC, NEIC and HVRD earthquake catalogs for a period from 01/01/1995 to 12/26/2004 were used for analysis. Spatial variations of b were calculated from circular areas containing 50 events, with nodes on a 0.5° x 0.5° grid. The analysis shows that b(t) estimates using data from different catalogs are comparable and that large earthquakes are preceded by a drop in b(t) of about 0.3~1. The distribution of stress deduced from b-value mapping shows that large earthquakes occurred in the high stress, i.e. low b-value, areas. Aftershock sequences of the Mw=9, December 26, 2004 and the Mw=8.7, March 28, 2005 shocks were investigated by using the same methods. Results from aftershock sequences show similar behaviour as for the large and presumed independent main events. The observed variations of b-values with time and in space support the hypothesis that b-values have a precursory potential. The method can be used for a wide range of earthquake magnitude, from microearthquakes (Mw<3) to giant tectonic shocks (Mw~9) and for both of independent shocks and aftershocks.
3
Eisenbeis, Julian. "Ionospheric Dynamics by GNSS total electron content observations : the effect of Solar Eclipses and the mystery of Earthquake precursors." Thesis, Université de Paris (2019-....), 2020. http://www.theses.fr/2020UNIP7027.
Повний текст джерелаАнотація:
Cette thèse porte principalement sur deux sujets: l'un est la signature ionosphérique des éclipses solaires, l'autre est le débat ‘Hole vs Enhancement’. Le 21 août 2017, l'ombre d'une éclipse totale a changé radicalement l'état de l'ionosphère au-dessus des Etats-Unis. Cet effet est visible dans le contenu total en électrons (TEC) mesuré par ~3000 stations GNSS qui voient des multiples satellites GPS et GLONASS. Ce formidable ensemble de données permet une caractérisation à haute résolution du contenu en fréquences et des longueurs d'onde - en utilisant une analyse omega-k basée sur la Transformée de Fourier Rapide (FFT) 3D - de la signature de l'éclipse dans l'ionosphère afin d'identifier complètement les perturbations ionosphériques mobiles (TID). Nous confirmons la génération de TIDs associées à l'éclipse, y compris les TIDs interprétées comme des ondes de proue dans les études précédentes. De plus, nous révélons, pour la première fois, des TID de courte (50-100 km) et de longue (500-600 km) longueurs d'onde avec des périodes entre 30 et 65 min (Eisenbeis et al., 2019). Le 2 juillet 2019, une autre éclipse solaire totale s'est produite à travers le continent sud-américain. Bien que nous n'ayons que des données provenant de plus de cent stations GNSS et situées dans une zone proche du coucher du soleil, nous pouvons montrer la preuve évidente de la signature ionosphérique de l'éclipse (Eisenbeis & Occhipinti in prep.a). Le deuxième grand sujet de ce travail est le débat sur la possibilité de précurseurs de séismes. Heki (2011) a suscité ce débat en publiant les résultats du séisme de Tohoku montrant une amélioration de la TEC avant le séisme. L'amélioration revendiquée par Heki (2011) a été interprétée comme une diminution de la TEC après l'événement, le soi-disant trou ionosphérique dans la littérature. L'existence de l'amélioration a été promue par plusieurs articles (e.g. He & Heki, 2017) étendant l'observation à plusieurs événements de magnitude modérée (M> 7.5) et propose une nouvelle vision de la dynamique de rupture. En essayant de reproduire leurs résultats, nous montrons que la courbe de référence utilisée par Heki (2011) est affectée par l'ordre d'ajustement polynomial ainsi que par les fenêtres temporelles sélectionnées. Ceci montre que l'amélioration du TEC pourrait en fait n'être qu'un artefact, subjectivement sélectionné pour créer le précurseur présumé (Eisenbeis & Occhipinti in prep.b)This thesis focuses mainly on two topics: one is the ionospheric signature of solar eclipses, the second is the Hole vs Enhancement debate about earthquake precursors. On the 21st August 2017 the shadow of a total eclipse drastically changed the state of the ionosphere over the USA. This effect is visible in the total electron content (TEC) measured by ~3000 GNSS stations seeing multiple GPS and GLONASS satellites. This tremendous dataset allows high-resolution characterization of the frequency content and wavelengths -using an omega-k analysis based on 3D Fast-Fourier-Transform (FFT)- of the eclipse signature in the ionosphere in order to fully identify traveling ionospheric disturbances (TIDs). We confirm the generation of TIDs associated with the eclipse including TIDs interpreted as bow waves in previous studies. Additionally we reveal, for the first time, short (50-100 km) and long (500-600 km) wavelength TIDs with periods between 30 and 65 min (Eisenbeis et al., 2019). On 2nd July 2019 another total solar eclipse happened across the South American continent at magnetic conjugate latitudes as the Great American Eclipse, and consequently useful to visualize the difference response. Although for the South American eclipse we have only data from more than hundred GNSS stations and located in a zone close to the sunset, we can show the clear evidence of the ionospheric signature of the eclipse (Eisenbeis & Occhipinti in prep.a).The second major topic in this work is the still ongoing debate about the possibility of earthquake precursors. Heki (2011) sparked this debate when he published results of the Tohoku earthquake showing a TEC enhancement before the earthquake. The enhancement claimed by Heki (2011) has been interpreted as a decrease in the background TEC after the seismic event, the so called ionospheric hole in literature. The existence of the enhancement has been promoted by several papers (e.g. He & Heki, 2017) extending the observation to several events with moderate magnitude (M> 7.5) and proposes a new vision of the rupture dynamics. By trying to reproduce their results we show that the reference curve used by Heki (2011) to define the TEC background is strongly affected by the order of polynomial fit as well as the selected time windows. This shows that the TEC enhancement could be, in fact, just an artifact, subjectively selected to create the presumed precursor (Eisenbeis & Occhipinti in prep.b)
4
Lam, Huu Quang. "DEVELOPMENT OF HAZARD ASSESSMENT TECHNOLOGY OF THE PRECURSOR STAGE OF LANDSLIDES." Kyoto University, 2018. http://hdl.handle.net/2433/232065.
Повний текст джерела
5
Adamaki, Angeliki. "Seismicity Analyses Using Dense Network Data : Catalogue Statistics and Possible Foreshocks Investigated Using Empirical and Synthetic Data." Doctoral thesis, Uppsala universitet, Geofysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-328057.
Повний текст джерелаАнотація:
Precursors related to seismicity patterns are probably the most promising phenomena for short-term earthquake forecasting, although it remains unclear if such forecasting is possible. Foreshock activity has often been recorded but its possible use as indicator of coming larger events is still debated due to the limited number of unambiguously observed foreshocks. Seismicity data which is inadequate in volume or character might be one of the reasons foreshocks cannot easily be identified. One method used to investigate the possible presence of generic seismicity behavior preceding larger events is the aggregation of seismicity series. Sequences preceding mainshocks chosen from empirical data are superimposed, revealing an increasing average seismicity rate prior to the mainshocks. Such an increase could result from the tendency of seismicity to cluster in space and time, thus the observed patterns could be of limited predictive value. Randomized tests using the empirical catalogues imply that the observed increasing rate is statistically significant compared to an increase due to simple clustering, indicating the existence of genuine foreshocks, somehow mechanically related to their mainshocks. If network sensitivity increases, the identification of foreshocks as such may improve. The possibility of improved identification of foreshock sequences is tested using synthetic data, produced with specific assumptions about the earthquake process. Complications related to background activity and aftershock production are investigated numerically, in generalized cases and in data-based scenarios. Catalogues including smaller, and thereby more, earthquakes can probably contribute to better understanding the earthquake processes and to the future of earthquake forecasting. An important aspect in such seismicity studies is the correct estimation of the empirical catalogue properties, including the magnitude of completeness (Mc) and the b-value. The potential influence of errors in the reported magnitudes in an earthquake catalogue on the estimation of Mc and b-value is investigated using synthetic magnitude catalogues, contaminated with Gaussian error. The effectiveness of different algorithms for Mc and b-value estimation are discussed. The sample size and the error level seem to affect the estimation of b-value, with implications for the reliability of the assessment of the future rate of large events and thus of seismic hazard.Οι προσεισμοί αποτελούν τα πλέον υποσχόμενα πρόδρομα φαινόμενα για τη βραχυπρόθεσμη πρόγνωση των σεισμών, παρόλο που παραμένει άγνωστο το αν μια τέτοια πρόγνωση είναι εφικτή. Η χρήση της προσεισμικής δραστηριότητας ως ένδειξη ενός επερχόμενου μεγάλου σεισμού είναι αμφιλεγόμενη, κυρίως λόγω του περιορισμένου πλήθους των προσεισμών, γεγονός που πιθανά οφείλεται στην ανεπαρκή καταγραφή σεισμικών δεδομένων. Η άθροιση σεισμικών σειρών είναι μια μέθοδος που εφαρμόζεται προκειμένου να μελετηθεί η πιθανή παρουσία ενός γενικευμένου μοτίβου σεισμικότητας πριν από ισχυρούς σεισμούς. Η υπέρθεση σεισμικών ακολουθιών που προηγήθηκαν των κυρίων σεισμών αναδεικνύει μια αυξανόμενη μέση δραστηριότητα πριν από τους κύριους σεισμούς. Μια τέτοια συμπεριφορά θα μπορούσε να προκύψει και από την εγγενή τάση των σεισμών να ομαδοποιούνται χωρικά και χρονικά, με αποτέλεσμα τα παρατηρούμενα μοτίβα να έχουν περιορισμένη προγνωστική αξία. Τυχαιοποιημένοι έλεγχοι των πραγματικών δεδομένων υποδηλώνουν ότι ο παρατηρούμενος αυξανόμενος ρυθμός είναι στατιστικά σημαντικός σε σύγκριση με τη μεταβολή που οφείλεται στη γένεση απλών συστάδων σεισμών, αναδεικνύοντας την ύπαρξη προσεισμών αιτιολογικά συσχετιζόμενων με τους κύριους σεισμούς. Μια ενδεχόμενη αύξηση της ευαισθησίας των σεισμικών δικτύων πιθανά να συμβάλει στην αποτελεσματικότερη αναγνώριση των προσεισμών. Η πιθανότητα μιας τέτοιας βελτίωσης ελέγχεται με τη χρήση συνθετικών δεδομένων τα οποία προκύπτουν υπό προϋποθέσεις ως προς τη σεισμική διαδικασία. Οι επιπλοκές που μπορεί να προκύψουν από την παρουσία σεισμικότητας υποβάθρου και των μετασεισμικών ακολουθιών διερευνώνται αριθμητικά, με γενικευμένες περιπτώσεις και σενάρια που βασίζονται σε πραγματικά δεδομένα. Οι κατάλογοι που περιλαμβάνουν μικρότερους και επομένως περισσότερους σεισμούς μπορούν πιθανώς να συμβάλουν στην καλύτερη κατανόηση των σεισμικών διεργασιών και στη μελλοντική πρόγνωση των σεισμών. Σημαντική πτυχή σε τέτοιες μελέτες αποτελεί η σωστή εκτίμηση των ιδιοτήτων των σεισμικών καταλόγων, όπως είναι το μέγεθος πληρότητας και η παράμετρος b. Η επίδραση των σφαλμάτων των μεγεθών που υπάρχουν στους σεισμικούς καταλόγους στην εκτίμηση των προαναφερθέντων ιδιοτήτων ερευνάται χρησιμοποιώντας συνθετικά μεγέθη στα οποία ενυπάρχουν κανονικώς κατανεμημένα σφάλματα. Κατά τη διερεύνηση της αποτελεσματικότητας των διαφόρων μεθόδων που χρησιμοποιούνται για την εκτίμηση του μεγέθους πληρότητας προκύπτει ότι το μέγεθος του δείγματος και του σφάλματος των μεγεθών μπορούν να επηρεάσουν την εκτίμηση της παραμέτρου b, με επιπτώσεις στην εκτίμηση του ρυθμού των μελλοντικών ισχυρών σεισμών και την αξιολόγηση του σεισμικού κινδύνου.
6
Charlie and 陳仕恩. "Using the seismicity,to research into the precursors of great earthquakes." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/22571046485519695349.
Повний текст джерела
7
Chun-YuLin and 林純玉. "Application of groundwater radon precursors for recurrent dominant earthquakes near Antung, Taiwan." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/82740027208792384494.
Повний текст джерела
8
Yu-HsuanTu and 杜宇軒. "Analyzing Earthquake Precursors with High-rate GPS Signal." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/71477515572067134500.
Повний текст джерелаАнотація:
碩士國立成功大學
資源工程學系碩博士班
98
There is evidence shows large earthquakes will release ultra-low frequency electromagnetic wave to the surface and thus disturb the concentration of ion within atmosphere recently. With the development of global navigation satellite system (GNSS) technology, applications of using high-rate GPS signal in atmospheric perturbation detecting and coseismic displacement measuring are also increased. In this study, 20 Hz GPS data was used to observe the signal variations of ionosphere concentration prior to 14 days of Kaohsiung Jiaxian earthquake (ML 6.4), March 4th, 2010, to analyze the possible abnormal signs. GPS displacement data with kinematic filter technique is used to compare with seismograph data. Results showed that three days before the earthquake ruptured a lower value of total electron content (TEC) in low-data-resolution carrier phase variations have found. After the data resolution is enhanced, there is no significant change under such circumstances due to the increasing of signal to noise ratio. After extracting the high-frequency signals, we found that there is no significant change prior to the earthquake. On the other hand, the GPS filtered displacement signal and signal of seismograph are highly similar except the GPS has more noise in very low frequency part (＜ 0.002 Hz). The measurements of data from main frequency of earthquake are very similar to each other within this study, which proved the feasibility of using high-rate GPS for strong motion displacement measurement, and provides the true ground motion without interference from the instrument response of seismograph.
9
Sulçe, Ardit. "Is land surface temperature an earthquake precursor?" Master's thesis, 2013. http://hdl.handle.net/10362/9188.
Повний текст джерелаАнотація:
Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial TechnologiesThis study aims to investigate and explain the land surface temperature variations before and after the earthquake of August 11, 2012 that struck Iran, by making critical considerations of weather factors. This goal underlies two main objectives. The first objective was to detect land surface temperature anomalies over time in respect to the day of the earthquake, and over space relative to the location of the earthquake epicentre. The other main objective was to determine whether the detected anomalies originated from the weather, or the earthquake. To meet these objectives, observations of remote sensing land surface temperature, near-ground air temperature and air temperature of multiple atmospheric levels were used. All the datasets were daily night-time observations extending to a period of five years, repeatedly from July 11, to August 31. All the observations of the three datasets were visualized in space and time to seek anomalous temperature patterns. The results showed several prominent land surface temperature increases over the 5-year period, but none of them fell out a few days before the earthquake. The most enduring land surface temperature increase occurred two days after the earthquake. In contrast to the land surface temperature, air temperature exhibited the sharpest anomalies of the entire period a few days before the earthquake. Both the air and the land surface temperature increased periodically few times within the 5-year period. The high temperature patterns that were detected in the near-ground air also matched in time with the patterns found in the temperature of multiple atmospheric levels. All three approaches undertaken in this study were consistent with each-other in terms of results. Based on those results, it was concluded that there were no land surface temperature anomalies in the expected few days before the earthquake. All the detected temperature increases were indeed seasonal patterns repeating roughly in the same period of the year, and in the same spatial extent and intensity. These warm patterns were due to normal weather cycles. The sharp air temperature anomalies detected in the few days preceding the earthquake may suggest that the focus, if thermal precursors exist at all, should indeed be set on the air temperature instead of land surface temperature.
10
Yi-HueiHsu and 許逸惠. "Monitoring Groundwater Radon for Earthquake Precursors near Antung, Taiwan." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/64645503435054869167.
Повний текст джерелаАнотація:
碩士國立成功大學
資源工程學系碩博士班
101
We monitored groundwater-dissolved radon at both well D1 and well A in the Antung hot spring to catch earthquake precursors. Prior to the 2011 MW 5.0 Chimei earthquake, the groundwater’s radon concentration at well D1 decreased from a background level of 752 ± 24 pCi/L to a minimum of 447 ± 18 pCi/L. No precursory changes in the groundwater’s radon concentration were observed at well A precursory to the 2011 MW 5.0 Chimei earthquake. Recurrent anomalous declines in groundwater radon were observed at the Antung D1 monitoring well prior to the four major earthquakes – (1) 2003 MW = 6.8 Chengkung, (2) 2006 MW = 6.1 Taitung, (3) 2008 MW = 5.4 Antung, and (4) 2011 MW = 5.4 Chimei. Post the 2011 Chimei earthquake, additional recurrent anomalous declines in groundwater radon were observed at well D1 prior to four local earthquakes with ML ≥ 4.7. For earthquakes occurring on the Longitudinal Valley Fault in eastern Taiwan, the observed radon minima decrease as the earthquake magnitude increases.
11
Yu-ChenCheng and 鄭羽辰. "Monitoring Groundwater Radon for Earthquake Precursors near Shitou, Taiwan." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/97561550354736108824.
Повний текст джерелаАнотація:
碩士國立成功大學
資源工程學系碩博士班
101
Radon anomalous declines prior to the 2012 ML 5.3 Alisan, 2013 ML 6.2 Nantou, and 2013 ML 6.5 Nantou earthquakes were recorded at the Shitou spring. Specifically, radon decreased from background levels of 360 ± 9, 364 ± 24, and 322 ± 29 pCi/L to minima of 251 ± 25, 238 ± 8, and 168 ± 10 pCi/L prior to the 2012 ML 5.3 Alisan, 2013 ML 6.2 Nantou, and 2013 ML 6.5 Nantou earthquakes, respectively. The study at the Shitou spring in southern Taiwan confirms that groundwater radon can be a consistent precursor for strain changes in the crust preceding an earthquake when observed in a low-porosity fractured aquifer.
12
Hsu, Shih-Hung, and 許世弘. "Precursory swarms of moderate-sized earthquakes in eastern Taiwan." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/74488369337706005734.
Повний текст джерелаАнотація:
碩士國立成功大學
地球科學系碩博士班
97
Earthquake bursts are known as many earthquakes striking in limited space and time. Bursts in general are caused by the elastic fault rupture, the influence of fluids or aseismic slip and common in volcanic areas and transform faults. We investigate bursts occurred in Taiwan from January 1991 to March 2009 and find numbers of them occurred in the Turtle Island and Hualien area. Evidence suggested that volcanic activities and plate collision are the major causes. We also find that six of swarms located at the collision corner of eastern Taiwan occurred before moderate-sized (M>5.5) earthquakes with distances less than fifty kilometers. The moderate-sized earthquake in general located on the east of the seismic zone between one and forty-eight days after individual swarm. The accumulated moments of the preceding swarms is inversely related to the time-separation between the swarms and the moderate-sized earthquakes. We suggest that precursory swarms-mainshock sequences found at Hualien area were due to process of stress accumulation and release on a given fault planes that contain several asperities and a number of subfaults. As the stress increases, the subfaults break on short time and cause a precursory swarm. When the tectonic stress increases further, the asperity breaks in the form of the moderate-sized earthquake.
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Jung, Chuo Yue, and 卓裕榮. "A statistic study of ionospheric precursor of strong earthquakes." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/11678604361494007584.
Повний текст джерелаАнотація:
碩士國立中央大學
太空科學研究所
87
This research work studies the ionospheric penetration frequency foF2 recorded by an ionosonde to understand ionospheric density variations priori the occurrence of earthquakes. A statistic method is introduced to construct a reference which is employed to find the precursor of the earthquakes. Base on the derived reference, a typical feature of earthquake precursor is isolated from ionospheric foF2 recorded during earthquakes Mw≧5.0, 1994-1997. It is found that the probabilities of observing the features 1-3 days and 1-5 days priori the occurrence of earthquakes are 69% and 82%, respectively. Meanwhile, the greater earthquake magnitude is, the greater probability is. A certain characteristics and tendency in ionospheric foF2 seems to be related to the appearing day of the feature. A analysis shows that ionospheric variation is foF2 observed during earthquake events, 1998 generally agree with the characteristics and tendency.
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Tzu-ChiWang and 王資琦. "Monitoring Groundwater Radon and Methane for Earthquake Precursors : HengChung Peninsula." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/26937379956360558401.
Повний текст джерелаАнотація:
碩士國立成功大學
資源工程學系碩博士班
99
We started to monitor groundwater radon and carbon dioxide at Kenting in September 2009 for earthquake precursory study. The radon-monitoring station at Kenting is about 5 km east of the Hengchung fault. The samples are spring water from a fractured limestone aquifer. We have recorded anomalous declines in both radon and carbon dioxide prior to 2010 MW = 6.4 Chiashien earthquake. Prior to the earthquake, groundwater radon and carbon dioxide decreased from 147±14 pCi/L and 51±1 mg/L to 92±3 pCi/L and 34±2 mg/L, respectively.
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Chia-HaoYu and 游家豪. "Monitoring Groundwater Radon for Earthquake Precursors: Shitou 2011/2－2011/6." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/12215276377881204272.
Повний текст джерела
16
Yu-HsuanLin and 林雨璇. "Monitoring Groundwater Radon, Methane and Ethane as Earthquake Precursors Nearby Chishang Fault." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/36413725081194683267.
Повний текст джерелаАнотація:
碩士國立成功大學
資源工程學系碩博士班
100
The Chihshang Fault is the present-day plate suture between the Eurasian and the Philippine Sea plates and is one of the most active faults in eastern Taiwan. The Chishiang well (D1) in the Antung hot spring, which is located only about 3 km southeast of the Chihshang Fault, was selected in this study for the radon monitoring site. The Antung hot spring is situated in a brittle basaltic block surrounded by a ductile mudstone. We hypothesized that rock cracks were generated at a rate faster than the recharge rate of pore water and gas saturation developed preceding the earthquake. In-situ radon volatilization into the gas phase may explain the groundwater radon anomalous decrease precursory to earthquakes. To verify the mechanism of in-situ volatilization, we monitored groundwater-dissolved ethane in addition to radon and methane at well D1 in the Antung hot spring between July 2011 and April 2012. The mechanism of in-situ radon volatilization has been corroborated by the simultaneous concentration changes in groundwater-dissolved radon, methane, and ethane observed during the above time period.
17
Shao, Yi-lien, and 邵宜蓮. "Application of LURR for Precursory Phenomenon of Taiwanese Large Earthquakes since 1994." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/27569959348163552600.
Повний текст джерелаАнотація:
碩士國立中央大學
地球物理研究所
100
The load-unload response ratio (LURR) has recently shown promising performance for earthquake forecasting in China, Japan and California. From the viewpoint of fracture mechanics, the preparation process of an earthquake is basically the damage process of the hypocentral media. LURR has been proposed as a measure characterizing the evolution of the damage process of the crust and is calculated from the seismicity variations during loading cycles respectively during the unloading cycles. The loading-unloading cycles are performed by the stress changes induced by the Earth tides acting upon some specific fault plane. In this study, the LURR has been used to detect the precursory damaging process before six large earthquakes, 1998 Rueili, 1999 Chi-Chi, 1999 Chiayi, 2000 Hualien, 2006 Peinan, 2009 Mingjian and 2010 Jiashian, Taiwan, earthquakes. LURR is defined as Y=X+/X-, where X+ and X- are the response rates during loading and unloading cycles, respectively. When a seismogenic system is relatively stable Y ~ 1. To the contrary, when the system is in an unstable state Y > 1. The response rates can be determined from either earthquake numbers, the Benioff strain, the size (length or area) scales of the focal zone or the seismic energy. Using the LURR index as presented in this study, the epicenters of these main shocks was found to exhibit anomalous high LURR values before these two events. We therefore suggest that the LURR approach could be helpful in detecting the anomalous seismicity and catastrophic damaging process of the crust.
18
Bruce, Nicholas. "Development of a phased-array ionospheric imaging system." Thesis, 2019. http://hdl.handle.net/1828/10704.
Повний текст джерелаАнотація:
A novel approach to ionospheric imaging with the purpose of weather/distaster prediction and climate study is introduced. This feasibility study combines traditional material imaging techniques with high frequency (HF) radio via SDR (software defined radio) systems in order to capture three-dimensional images of the atmosphere. An experiment is devised and the necessary instrumentation built in order to capture coherent images of the ionosphere. The experimental results show these three-dimensional images as well as a novel approach to measuring ionospheric height. The novelty of the research comes from the use of a closely spaced phased-array of radio antennas in conjunction with a post-correlation beamformer repurposed from radio astronomy. Experiments were run at both the University of Victoria and DRAO (Dominion Radio Astrophysical Observatory), the results which led to a successful proposal for extending the research onto a larger array with support from research groups in New Mexico.Graduate
19
FRANCHINI, STEFANIA. "Hydrogeochemical seismic precursors: pilot study for future hydrogeochemical networks." Doctoral thesis, 2021. http://hdl.handle.net/11573/1517316.
Повний текст джерелаАнотація:
The aim of this thesis is to illustrate the importance of establishing a method of investigation of seismic precursors based on the investigation of possible relationships between groundwater and earthquakes, through hydrogeological, hydrogeochemical and seismic monitoring of the territory under consideration.
This will be done through a detailed and systematic study of hydrogeological and hydrogeochemical factors that can be potentially influenced by seismic activity, such as: piezometric levels, temperature, electrical conductivity, chemical composition of groundwater and dissolved gases in solution. The analysis of these factors will allow to verify the existence and the modalities of manifestation of a cause / effect relationship between the hydrogeological, hydrogeochemical and seismic signals.
The objective of this PhD project is therefore the study of potential geochemical precursors that will allow the short-term forecast (from days to months) of seismic phenomena of medium-high magnitude (M ≥ 5.0) in order to initiate an effective preventive action.
In particular, through this study, I want to highlight the importance of collecting data from a network of monitoring stations spread over a seismic territory and for a long time, with the construction of a national hydrogeochemical monitoring network.
The advances in identifying the earthquakes hydrogeochemical precursors depends on the systematic and patient acquisition of long-term multiparametric data set. Long records are therefore essential to identify precursor signals of earthquake responses, especially in regions with abundant seismicity. Well-developed documentation is required to assess the uniqueness and statistical significance of possible precursor signals and to identify and screen out meteorological and seasonal signals. The solid statistical significance of the results therefore depends on the length of the time series, that is the observations of more than one seismic event and the multiparametric nature of the recorded data (Ingebritsen and Manga, 2014).
The aim of this PhD project is therefore the better understanding of seismic precursors of hydrogeochemical nature and the related processes to facilitate the understanding of site-specific phenomena and their possible applicability to other sites or their general and global value.
20
Ye, Jia-Ciao, and 葉佳喬. "The Study of Analysis of Ionospheric Data by Recurrent Neural Network to Identify Earthquake Precursors." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/uk6392.
Повний текст джерелаАнотація:
碩士國立交通大學
土木工程系所
106
This study uses Recurrent Neural Network (RNN) to establish a neural network model for analysis ionospheric data to identify earthquake precursors. Using the time series characteristic of ionospheric electron content (TEC), the neural network model is built through converting the data to RNN training data. Among those, the parameters of model such as training times (epochs), batch size, time series length, and the length of training data are discussed first. These parameters range are individually tested on the earthquake of 2017/10/6. The abnormal value is defined as three times the standard deviation of the average value of the training data. In this work, the abnormal value is employed to compare the number of abnormal values on the normal day (16-30 days before the earthquake) and the abnormal day (15 days before the earthquake). Then, four real TEC data sets in 2016 and 2017 are conducted as training and forecast data to identify a particular 6 magnitude earthquake following the data, and there are no any earthquake above magnitude of 6 and above in the data sets. The parameters of RNN are set as followings: training epoch is 200, batch size is 100, time series duration is 2 days, and training data length is 45 days. The results of identification for the four data sets meet the trend that abnormal values on the abnormal days are more than normal days. In comparison to previous application of median method and our study of RNN model, the RNN model prove to have a better distinguishing ability for earthquake with a magnitude of 6 or above.
21
Hui-YunLiang and 梁卉昀. "Monitoring Groundwater Radon and Carbon Dioxide as Earthquake Precursors at Hengchun Peninsula:2010/7 – 2012/6." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/63878409930839724076.
Повний текст джерелаАнотація:
碩士國立成功大學
資源工程學系碩博士班
100
The Kenting spring located in southern Taiwan was selected in this study for the monitoring site of groundwater radon and carbon dioxide to catch earthquake precursors. Groundwater radon and carbon dioxide anomalies were observed at the Kenting spring prior to the 2012 ML 6.4 Wutai earthquake. Specifically, radon and carbon dioxide decreased from background levels of 170 ± 14 pCi/L and 56.3 ± 2.2 mg/L to minima of 136 ± 16 pCi/L and 49.1 ± 0.2 mg/L prior to the 2012 earthquake, respectively. The Kenting spring is a brittle limestone aquifer surrounded by a ductile mudstone and shale. We hypothesized that rock cracks were generated at a rate faster than the recharge rate of pore water and gas saturation developed preceding the earthquake. In-situ volatilization into the gas phase may explain the anomalous decreases in groundwater radon and carbon dioxide precursory to earthquakes.
22
Okyay, Ünal. "Evaluation of thermal remote sensing for detection of thermal anomalies as earthquake precursors: a case study for Malatya-Pütürge-Doganyol (Turkey) Earthquake, July 13, 2003." Master's thesis, 2012. http://hdl.handle.net/10362/8318.
Повний текст джерелаАнотація:
Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.Several studies in last two decades indicated that presence of positive thermal anomalies associated with seismic activities can be detected by satellite thermal sensing methods. This study evaluates the potential of thermal remote sensing for detection of thermal anomalies prior to Malatya-Pütürge-Doğanyol (Turkey) earthquake using MODIS/Terra V5 LST/E (MOD11A1) data. In the previous studies, different methods based on different approaches have been suggested. In this particular study, four of the suggested methods were selected for evaluation as well as for comparison of different approaches. The analyses were carried out for fortnight before and after the earthquake. Depending on the method 4 to 7 years of daily daytime and nighttime MOD11A1 data were utilized. Furthermore, same set of analyses carried out for non-earthquake years as well as the earthquake year for the area. The results show that when only the earthquake year considered, all the methods used for the analyses detected the LST changes successfully and consistently not only before but also after the earthquake. However, thermal anomalies were not unique for the earthquake year and were also observed in the absence of seismic activity within defined time interval. Therefore, there exist no coherent evidence that indicates a direct link between the occurrence of seismic activity and the land surface temperature anomaly for Malatya-Pütürge-Doğanyol earthquake. Based on the information extracted, it can be said that, the reason for observing LST changes even in the absence of the seismic activity is the effect of environmental factors which have considerable influence on the methods and thus the detection of LST anomalies. Therefore, it can be said that since the effect of the Sun’s irradiation is minimal during night nighttime images would be more appropriate for thermal anomaly detection purpose. The findings support the argument that not every earthquake is preceded by detectable thermal precursor (Freund 2007; Saraf et al. 2009). On the other hand, not every LST anomaly is followed by an earthquake. Additionally, since the mechanism is not very well understood yet, it is not possible to identify earthquakes which would have thermal precursor prior to the incident. Therefore, it is concluded that utilizing LST anomalies based on satellite imagery for monitoring impending earthquake would not be adequate and feasible unless the mechanism of thermal precursors are very well understood.
23
Ma, Tsu-Chi, and 馬祖琪. "Thermal anomaly detection using MODIS data-A study of thermal anomaly as earthquake precursor." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/74477425741152459624.
Повний текст джерелаАнотація:
碩士國立中央大學
遙測科技碩士學位學程
100
When earthquakes happen, the Earth’s crust will release energy. Therefore, the abnormal temperature rise may portend future earthquakes. In many ways, the telemetry field can applied thermal infrared images to monitor surface temperature to know if there is a wide range of warming for predict the occurrence of earthquakes. The advantages of this method are the satellite images data is easy to access, and remote sensing imagery can obtain information on large area. The large scale earthquake prone a wide range of areas to show an anomaly. Some research and literature also found that the thermal anomaly before the earthquake may be the earliest signs. If we can grasp the thermal anomaly before earthquake, we may establish early warning mechanisms to enhance the earthquake forecast. In order to gain an insight into the fact whether the existence of pre-earthquake abnormal temperature increase is a stable phenomenon, and also to detect this portend (for pre-earthquake abnormal temperature increasing phenomenon) in more scientific way, this thesis will first review literature documentations to investigate into the possible mechanism of thermal anomalies. This research will also adopt methods proposed by Ouzounov and Freund (2004) to conduct an evaluation of those large-scale strong earthquakes (M>5), aiming to find out the best process to detect the abnormal temperature increasing portend before strong earthquakes happened. The data used in this thesis is MODIS Land Surface Temperature and Emissivity (MOD11A1). The result of this research shows: the pre-earthquake abnormal temperature can be detected by thermal infrared satellite images. By spatial and temporal analysis of surface temperature change, and to accumulate more knowledge to observe, analyze and explore for earthquake precursory phenomena. To facilitate future of this anomaly monitoring, and further used in a rigorous and accurate earthquake prediction work. We hope to provide the high quality large earthquake prediction in the community.
24
Li, Hsien-chi, and 李賢琦. "Precursory Phenomena of the 1999 Chichi, Taiwan, and 2008 Wenchuan, China, Earthquakes Using Modified Pattern Informatics." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/34717567859632822071.
Повний текст джерелаАнотація:
博士國立中央大學
地球物理研究所
99
Pattern informatics (PI) is developed by Rundle and Tiampo et al. in 2002 as a calculation method to evaluate seismic anomalies and is already applied in several researches to high seismicity regions, such as California and Japan. However, two fundamental premises of PI about statistical stability of seismicity are rarely concerned in previous researches. This disregard led to serious doubt about these published results. On the other hand, the contradiction between the fundamental premises of PI and real seismicity also results in further difficulty in applying PI to Taiwanese seismicity. We applied Thirumalai-Mountain (TM) metric to identify the effectively ergodic intervals in Taiwanese seismicity. Seismicity in the identified effectively ergodic intervals are stable in statistical distribution and can be used to evaluate seismic anomalies disregarding statistical fluctuations. Through several tests we concluded that the original PI is very sensitive to statistical fluctuations and can’t be improved merely by the assistance of TM metric. On the other hand, we modified the original PI by using average seismic rate change as statistical quantity and by introducing spatial normalization to cease the inherent difference of seismicity due to tectonic environment. A seismic activation process before the 1999 Chichi earthquake is proposed by Chen in 2003. We used the modified PI to identify the distribution of seismic anomalies corresponding to the seismic activation. The identified seismic anomalies marked most of the locations of the Chichi main shock and big aftershocks. To overcome the difficulty of identifying precursory phenomenon and parametric selection, we used a combination of modified PI and genetic algorithms (GA) to objectively confirm the existence of precursory seismic anomalies before big earthquakes without any manual selection, tuning, or tests. Once the seismic anomalies are obtained, we can further explore which underlying forecasting mechanisms result in these anomalies. This strategy is successfully applied to the research for the 2008 Wenchuan, China, earthquake and identified this catastrophic earthquake as another example of seismic activation.
25
Fan, Kai-Chun, and 范愷軍. "A Mechanism for Anomalous Decline in Radon Precursory to 2003 Mw6.8 Chengkung Earthquake: Eastern Taiwan." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/77607056937605441012.
Повний текст джерелаАнотація:
博士國立成功大學
資源工程學系碩博士班
97
The 2003 Chengkung earthquake of magnitude (Mw) 6.8 on December 10, 2003 was the strongest earthquake near the Chengkung area in eastern Taiwan since 1951. The Antung radon-monitoring station was located 24 km from the epicenter. Approximately 65 days prior to the 2003 Chengkung earthquake, precursory changes in the radon concentration of ground-water were observed. The radon anomaly was a decrease from a background level of 780 pCi/L to a minimum of 330 pCi/L. Mechanisms and geological conditions for interpreting anomalous decreases in ground-water radon prior to earthquakes are seldom discussed in the literature. The Antung hot spring is situated in a basaltic fractured block inside mudstone. Under such geological conditions, we made a hypothesis that the dilation of rock masses was produced at a rate faster than the recharge rate of pore water and gas saturation developed in rock cracks preceding the earthquake. Radon partitioning into the gas phase may explain the ground-water radon anomalous decrease precursory to the 2003 Chengkung earthquake. To support the hypothesis, vapor-liquid two-phase radon-partitioning experiments were conducted at formation temperature (60 ℃) using formation brine from the Antung hot spring. Experimental data indicated that the anomalous decrease of radon concentration from 780 pCi/L to 330 pCi/L required a developed 10 % rock cracks relative to water volume.
26
Ying-YingHuang and 黃盈穎. "Monitoring Groundwater Radon and Methane for Earthquake Precursors Nearby Chishang Fault: 2011/1/1 - 2011/5/31." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/73732853128059823765.
Повний текст джерела
27
Wen-ChingCheng and 鄭文菁. "Corroboration of in-situ volatilization :Simultaneous declines in radon and methane precursory to 2008 Mw5.4 Antung earthquake." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/44442997767686761365.
Повний текст джерелаАнотація:
博士國立成功大學
資源工程學系碩博士班
99
Radon volatilization mechanism into the gas phase was hypothesized to explain the anomalous decline in groundwater radon precursory to the 2003 MW 6.8 Chengkung earthquake in Taiwan. We initiated the monitoring of both radon and methane in the groundwater since November 2007 at well D1 in the Antung hot spring. The mechanism of in-situ radon volatilization has been corroborated by the simultaneous anomalous declines in groundwater-dissolved radon and methane precursory to the 2008 Mw 5.4 Antung earthquake. Specifically, radon and methane decreased from background levels of 735 ± 48 pCi/L and 6.1 ± 0.5 mg/L to minima of 480 pCi/L and 1.9 mg/L prior to the 2008 Mw 5.4 Antung earthquake, respectively. The maximum gas saturation developed in newly created cracks preceding the 2008 Mw 5.4 Antung earthquake was estimated at 6.72 % and 5.88 % based on the anomalous declines of groundwater-dissolved radon and methane, respectively. The close agreement of gas saturation values estimated independently from the decline data of radon and methane supports the validity of the mathematical model of in-situ volatilization.
28
Ebel, Kevin. "Design of the digital satellite link interface for a system that detects the precursory electromagnetic emissions associated with earthquakes." Thesis, 1986. http://hdl.handle.net/10945/21772.
Повний текст джерела
29
Chan, Chun-Hsiang, and 詹竣翔. "Applying Ultra Low Frequency Remote Sensing Techniques in the Earthquake Precursor Analysis —Using Taiwan as an Example." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/t795a2.
Повний текст джерелаАнотація:
碩士國立臺灣大學
地理環境資源學研究所
103
Throughout worldwide, earthquakes have deprived lots of life and property. However, earthquakes cannot be predicted precisely in terms of the epicenter, time, seismic scale, and depth with various means. Most of errors were caused by misleading signal processing. The goal of this study provide a better signal processing method to depict the potential zone of seismic epicenter. In order to realize the significant signal and frequency, this study utilizes Fast Fourier Transform (FFT) to analyze Ultra Low Frequency (ULF) signals and define a warning line for dividing normal and abnormal signals. In this study, an epicenter location can be inferred by intersection of at least three abnormal angles from different stations. In addition, epicenter estimation analysis imports probability buffer concept in spatial cross analysis, moreover, this concept also applies in depth estimation. Break time estimation concludes both lots of papers information and abnormal signal pattern, so this study define that break time of earthquake is one week after abnormal signal appearance. For magnitude regression, this study utilizes three different parameter, MAEQ, MMEQ and IAEQ, to regress the correlation with Richter magnitude scale. Up to day, this study has successfully found significant signal of earthquake precursors and also calculated the potential zone of seismic epicenter, break time, depth potential and magnitude beforehand. In conclusion, this research provides a new method for epicenter prediction by analyzing ULF electromagnetic signals.
30
Wu, Tsung-Yu, and 吳宗祐. "Seismo-Ionospheric Precursor in the GIM TEC associated with the 24 August 2014 M6.0 South Napa Earthquake." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/86636397525952332708.
Повний текст джерелаАнотація:
碩士國立中央大學
太空科學研究所
104
This study examines seismo-ionospheric precursors (SIPs) in the global ionosphere map (GIM) of the total electron content (TEC) associated with the 24 August 2014 M6.0 South Napa earthquake. We separate analysis of GIM to three parts including statistical, temporal and spatial analysis. Extract 52 M≧5.0 earthquake during 1 January 2000 to 23 August 2014 to do z-test. Z-test result indicates that there are significantly TEC decreasing (negative anomaly) 2-4 days before earthquake during 02:00-04:00UT. The temporal SIP in the GIM TEC around the epicenter significantly decreasing at 02:00UT on 22 August. Spatial SIP in the GIM TEC indicate that negative anomaly only happen around the epicenter during 02:00-12:00UT on 22 August. Check spatial gradient of GIM TEC and find that there are negative anomaly of eastward gradient during 16:00-24:00UT on 19 August. Both of spatial analysis show the result that SIP was triggered 2-5 days before the South Napa earthquake. Model simulation is further carried out to reproduce the SIP in the GIM before the earthquake. Results indicate that the westward electric field generated over the epicenter area during the earthquake preparation period might be essential.
31
Yao, Chiao-Chun, and 姚喬鈞. "Application of b- and z- values statistics upon the precursor study, cases of the larger earthquake of Taiwan." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/48234784136340736468.
Повний текст джерелаАнотація:
碩士國立臺灣海洋大學
應用地球科學研究所
94
Abstract We took advantage of the seismic catalog compiled by the Central Weather Bureau for studying the possible seismicity precursor before the large earthquakes for the Taiwan area. Seismic data adopted from 1990 to 2005, with the criteria of seismic magnitude larger than 5.0 and focal depth less than 40 km, were applied to conclude the relationship between the precursory period prior to the occurrence of large crustal earthquake. The seismicity sampling spaces were defined with the radii of 20 and 50 kilometers, respectively to estimate the near-field and large field seismicity change. The other search the area where high earthquake probability near main earthquake for the calculation of z value. Along the seismic time sequence, the sudden drop of b and z values were considered as the index of moment reflecting seismicity change corresponding to the coming large event. The duration between this moment and the main shock was defined as the possible precursory time (denoted as △t) for the large earthquake. We compared each precursory time with the magnitude, focal mechanisms and spatial and temporal distributions of these main. In general, △t was larger at the eastern part than the western Taiwan. △t obtained form z value were increasing with time from 0.22 to 0.32 years. However, △t focused within the range of 0.12 to 0.15 years for the larger earthquakes. The comparison with the varied focal mechanisms showed that △t seemed nothing with the different rupture process. It's observed that the seismic frequency was obvious increasing for the period just prior to the large earthquake. Our study illustrated that the b and z statistics can detect such an increasing of seismicity rate. The duration between the moment of obvious variation of the two values and main earthquake is within the range of 0.12 to 0.2 years. The standard deviation of △t obtained form high earthquake probability less then obtained form the radii of 20 and 50 kilometers.