Thèses sur le sujet « Stress triggering »

The aim of this PhD work is to study how earthquakes could favour new eruptions, focusing the attention on earthquake-induced static effects in three different case sites. As a first case site, I studied how earthquake-induced crustal dilatation could trigger new eruptions at mud volcanoes in Azerbaijan. Particular attention was then devoted to contribute to the understanding of how earthquake-induced magma pathway unclamping could favour new volcanic activity along the Alaska-Aleutian and Chilean volcanic arcs, where 9 seismic events with Mw ≥ 8 occurred in the last century. Regarding mud volcanoes, I studied the effects of two earthquakes of Mw 6.18 and 6.08 occurred in the Caspian Sea on November 25, 2000 close to Baku city, Azerbaijan. A total of 33 eruptions occurred at 24 mud volcanoes within a maximum distance of 108 km from the epicentres in the five years following the earthquakes. Results show that crustal dilatation might have triggered only 7 eruptions at a maximum distance of about 60 km from the epicentres and within 3 years. Dynamic rather than static strain is thus likely to have been the dominating “promoting” factor because it affected all the studied unrested volcanoes and its magnitude was much larger. Regarding magmatic volcanoes, the entire dataset includes a total of 51 eruptions following 9 large earthquakes (Mw ≥ 8); 33 represent first new eruptions occurred at each single volcano. Comparison of the eruption rate before and after each earthquake suggests that 26 out of the 33 first new eruptions have a positive relation with the studied earthquakes; 13 out of 26 represent awakening events, which are first new eruptions occurred at volcanoes with not-continuous eruptive activity that had no eruptions in the five years before the earthquake. I followed a novel approach that resolves the earthquake-induced static stress change normal to the magma pathway of each volcano instead of considering the general crustal volume. I also considered other parameters that may contribute to control eruptions, such as magma composition and viscosity, magma chamber depth and local tectonic settings. The sensitivity analysis performed for the 2010 Chile earthquake shows that the N-S- and NE-SW-striking magma pathways suffered a larger unclamping in comparison with those striking NW-SE and E-W. Magma pathway parallel or subparallel to the strike of modelled faults suffered the highest unclamping, and this was also evident in the Alaska-Aleutian arc. Magma pathway geometry controls the magnitude of the static stress change induced by large earthquakes, with differences of up to 8 times among magma-feeding planes of different orientation at the same volcano. This range of diverse values is larger for the volcanoes closer to the epicentre. The possible error in the estimate of magma chamber depth has a minimum effect on the results since the sensitivity analysis shows that the range of stress changes with depth is about 1.5 orders of magnitude smaller than the range linked to variations in the magma pathway strike. Result suggest that unclamping effect promoted eruptions that occurred at not-continuously erupting volcanoes (Type B) in a range of 157-543 km, while awakening under unclamping occurred in a range of 157-353 km. Regarding the time-gap, unclamping promoted eruptions at Type B volcanoes and awakening in a time window of 2 days-3 years. In the studied cases, it was also noted that unclamping enhanced eruptions preferentially at volcanoes with a deep magma chamber (> 5 km). Regarding the role of magma pathway geometry, results suggest that 4 awakening events occurred along magma pathways parallel or subparallel to the σHmax, and they are always under unclamping. Eleven awakening events occurred along magma pathways that have an angle from 40° to 90° respect to the σHmax, thus unclamping favoured 8 of these events. Finally, based on the results from this work, I suggest that earthquake-induced stress change can favour magma rise by imparting stress field modifications of the deviatoric stress acting on magma pathway in a percentage up to 5-10 %, increasing the efficiency of magma rise and consequent dyke intrusion also where the tectonic regime doesn’t favour magma rise (e.g. in the older and thicker crust in Chile under contractional tectonics).

Temporally and spatially clustered earthquake sequences along plate boundary zones indicate that patterns of seismicity may be influenced by earthquake-induced stress changes. Many studies invoke Coulomb stress change (CSC) as one possible geo-mechanical mechanism to explain stress interactions between earthquakes, their aftershocks, or large subsequent earthquakes; however, few address the statistical robustness of CSC triggering beyond spatial correlations. To address this, I evaluate the accuracy of CSC predictions in subduction zones where Earth’s largest earthquakes occur and generate voluminous and diverse aftershock sequences. A series of synthetic tests are implemented to investigate the accuracy of inferred stress changes predicted by slip distributions inverted from suites of geodetic observations (InSAR, GPS, seafloor geodetic observations) that are increasingly available for subduction zone earthquakes. Through these tests, I determine that inferred stress changes are accurately predicted at distances greater than a critical distance from modeled slip that is most dependent on earthquake magnitude and the proximity of observations to the earthquake itself. This methodology is then applied to the 2010 Mw 8.8 Maule, Chile earthquake sequence to identify aftershocks that may be used to perform statistically robust tests of CSC triggering; however, only 13 aftershocks from a population of 475 events occurred where confidence in CSC predictions is deemed to be high. The inferred CSC for these events exhibit large uncertainties owing to nodal plane uncertainties assigned to the aftershock mechanisms. Additionally, tests of multiple published slip distributions result in inconsistent stress change predictions resolved for the 13 candidate aftershocks. While these results suggest that CSC imparted by subduction megathrust earthquakes largely cannot be resolved with slip distributions inverted from terrestrial geodetic observations alone, the synthetic tests suggest that dramatic improvements can be made through the inclusion of near-source geodetic observations from seafloor geodetic networks. Furthermore, CSC uncertainties will likely improve with detailed earthquake moment tensor catalogs generated from dense regional seismic networks.

Candida albicans is an important opportunistic fungal pathogen which causes life threatening systemic diseases in immunocompromised people. An important virulence attribute of C. albicans is morphological plasticity. Yeasts engulfed by macrophages can transition to a hyphal filamentous morphology which either induce pyroptosis or rupture the phagosomal membrane of the macrophage and evade the toxic reactive oxygen species (ROS) generated by the NADPH oxidase complex of the phagocyte. Recent studies revealed that ROS causes cell cycle arrest resulting in hyperpolarised bud formation in C. albicans. Moreover, the ability of this pathogen to mount robust transcriptional responses to ROS is an essential pre-requisite for hyphal filament formation following phagocytosis. Thus, it was hypothesised that macrophage-derived reactive oxygen species (ROS) can inhibit C. albicans growth, which is more pronounced in ROS-sensitive mutants resulting in impaired filament formation following phagocytosis. Hence, the aim of this study was to decipher why C. albicans responses to ROS are important for filament formation in the phagolysosomal environment of the macrophage. In vitro, it was examined whether hydrogen peroxide (H2O2)-treatment could inhibit serum-induced hyphae formation and whether this was more pronounced in cells lacking the key Cap1 oxidative-stress responsive transcription factor, and its regulators Ybp1 and Gpx3. The results showed that exposure to H2O2 inhibited serum-induced hyphae formation. In addition, the inhibition of filament formation was more sustained in the cap1Δ, ybp1Δ and gpx3Δ mutant cells compared to the wild-type strain. A concurrent analysis of cell survival indicated that the mutant cells displayed a longer H2O2-induced growth arrest compared to wild-type cells. Hence, to identify regulators of hyperpolarised bud formation and, determine if ROS-resistance is a global requirement for filament formation following phagocytosis, a library of transcription factor mutants was screened for sensitivity to different forms of ROS. The most sensitive mutants; cap1Δ, efg1Δ, skn7Δ, ndt80Δ, and gzf3Δ were examined for ability to survive and form filaments following phagocytosis using confocal video microscopy. Only cap1Δ and efg1Δ cells failed to form filaments following phagocytosis. However, the three remaining mutants effectively formed filaments inside the phagosomal environment. Collectively, these data show that whilst Cap1 is essential for filament formation inside the macrophage, wild-type levels of oxidative stress resistance are not a necessary pre-requisite for this morphological switch following phagocytosis.

Ever since the great financial crisis of 2008 regulators have pushed toward more resilient banks, resulting in more demanding regulation and an increase of regulator’s insight and power. Through the revision of the BASEL framework, Contingent Convertible Bonds were introduced in 2010 as a part of regulatory capital and has since then grown increasingly popular. However, these instruments have never been tested in a stressed European financial system. Hence, there is no genuine information of how these instruments would behave. Neither have there been any published efforts in testing this through simulation, to the best of my knowledge. Using a temporally disaggregated augmentation of the EBA 2016 stress test, I simulate how the financial system would be affected by triggering the CoCos. Studying the implications of both low and high trigger instruments. Results indicate that there are low risks for a systemic fallout and showcases some notable differences as a result of CoCo design and type of trigger.

Orientador: Sérgio Roberto de Lucca
Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
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Resumo: O trabalho em saúde tem sido destacado no meio internacional, devido ao alto nível de adoecimento dos trabalhadores. No Brasil, a Estratégia Saúde da Família configura-se uma reorientação do modelo assistencial de saúde na qual uma equipe multiprofissional acompanha a situação de saúde e promove ações a um número de famílias, dentro de um território. As condições em que estes profissionais vivenciam o seu trabalho podem ser desencadeantes de sofrimento mental, causando o estresse. O agente comunitário de saúde é um dos atores centrais no processo de trabalho em saúde do modelo de atenção à saúde brasileiro. Na cidade de Parnaíba/PI, esses trabalhadores parecem estar expostos a situações de desgaste físico e/ou emocional durante o exercício de suas funções. Isto percebido pelo pesquisador na sua rotina de trabalho no Núcleo de Apoio ao Saúde da Família do município, trouxe o interesse e motivação para realização da pesquisa. Com o objetivo de compreender os fatores psicossociais desencadeadores de estresse no trabalho na percepção dos agentes comunitários, optou-se realizar um estudo epidemiológico de corte transversal. Utilizando-se uma abordagem quanti e qualitativa, buscou-se aplicar um questionário de avaliação de estresse com toda a população pesquisada, além de se realizar um grupo focal para se esclarecer os resultados encontrados. Da amostra final, a sua maioria era de mulheres (73,2%), com idade acima dos 30 anos (74,3%), com formação técnica (26,2%) e pós-graduação (24,4%) e com tempo de exercício na profissão e no SUS superior aos 14 anos. O território do Distrito III (31,55%) foi o mais representado no estudo. Como principais dimensões psicossociais encontradas temos as relacionadas aos relacionamentos, às mudanças e ao controle. As narrativas do grupo focal revelaram que: os agentes entendem bem o cargo que ocupam; o apoio da chefia ocorre menos que o dos colegas; há atribuições excessivas somadas à violência no ambiente de trabalho; a autonomia do agente é limitada ainda à técnica; as carências do serviço e a falta de comunicação prévia promovem descontentamento dos profissionais e da comunidade. A dimensão mais destacada foi a de relacionamentos, pois vínculos estabelecidos com a comunidade a equipe e a gestão municipal não são tão valorizados podendo ser quebrados. Acredita-se que um trabalho mais organizado e pautado na humanização possa trazer espaços de trabalho mais saudáveis, evitando-se o adoecimento e, até mesmo, o Burnout
Abstract: Health work has been featured in the international environment due to the high level of illness of workers. In Brazil, the Family Health Strategy sets up a reorientation of the health care model in which a multidisciplinary team monitors the health status and promotes actions to a number of families within a territory. The conditions under which these professionals have their work may trigger mental suffering causing stress. The Community Health Worker is one of the central actors in the work process in health care to the Brazilian model. In Parnaíba/PI, these workers seem to be exposed to situations of physical and/or emotional stress during the performance of their duties. This perceived by the researcher in his work routine at the municipal Support Center for the Family Health, brought the interest and motivation for the research. In order to understand the psychosocial factors triggering at stress at work in the perception of Community Health Worker, it was decided to conduct an epidemiological cross-sectional study. Using a quantitative and qualitative approach, we attempted to apply a stress assessment questionnaire with all the research population, in addition to conducting a focus group to clarify the results. The final sample, the majority were women (73.2%), over the age of 30 years (74.3%), with technical training (26.2%) and graduate (24.4%) and exercise time in profession and in SUS higher to 14 years. The territory of the Third District (31.55%) was the most represented in the study. The main founded psychosocial dimensions was related to relationships, changes and control. The narratives of the focus group revealed that: workers understand well the position they hold; the support of the head is less than that of colleagues; there excessive assignment added to violence in the workplace; the agent's autonomy is still limited to the technique; the needs of the service and the lack of prior notification promote discontent among professionals and the community. The most prominent was the dimension of relationships beacause the links established with the community, staff and municipal management are not as valued and can be broken. It is believed that a more organized work and guided by the humanization can bring healthier workspaces, avoiding the illness and even the Burnout
Mestrado
Epidemiologia
Mestre em Saude Coletiva

For the most recent and correct article, please click here: http://ascelibrary.org/doi/abs/10.1061/9780784412787.086 This study examines the use of performance-based approaches in liquefaction hazard analysis. Two new methods of performance-based liquefaction initiation analysis are proposed which use the works of Juang et al. (2012) and Boulanger and Idriss (2012). Further advances are made by incorporating the performance-based magnitude scaling factors as proposed by Cetin et al. (2012). Using these new equations a comparative study is made between the three methods. Further comparisons are made between the performance-based approaches and the more widely used deterministic approaches. The comparisons reveal that on average for the 11 sites used in this study, the performance-based approaches tend to be slightly less conservative than deterministic approaches overall, with large differences possible for some locations in the country. They also reveal that the newer performance-based approaches are generally less conservative than the approach proposed by Kramer and Mayfield (2007). Some cases where this relationship does not hold true and the new relationships are more conservative are outlined.

Volcanic activity, and the resultant deposits and structures at the Earth's surface, are the outcome of the inner workings of underground magmatic plumbing systems. These systems, essentially, consist of magma reservoirs which supply magma to the surface through volcanic conduits feeding volcanic eruptions. The mechanics and structure of plumbing systems remain largely unknown due to the obvious challenges involved in inferring volcanic processes occurring underground from observations at the surface. Nevertheless, volcanologists are beginning to gain a deeper understanding of the workings and architecture of magmatic plumbing systems from geophysical observations on active volcanoes, as well as from geological studies of the erosional remnants of ancient volcanic systems. In this work, I explore the relationship between the structure and mechanics of shallow plumbing systems and the volcanic eruptions these systems produce. I attempt to contribute to the understanding of this complex relationship by linking geological and geophysical observations of an eroded basaltic subvolcanic system, and the eruptive and tectonic activity of an active volcano, with mathematical models of magma ascent and stress transfer. The remarkable exposures of the Carmel outcrop intrusions, near the San Rafael swell, southeast Utah, U. S. A., allow detailed geological and geophysical observations of the roots of volcanic conduits that emerge from a subhorizontal magma feeder reservoir. These observations reveal a new mechanism for magma ascent and eruption triggering through gravitational instabilities created from an underlying feeding sill, and shed light on the mechanics of sill emplacement. Geophysical and geological observations of the 1999 and xii 1992 eruptions of the Cerro Negro volcano, Nicaragua, are used to explore the coupling between changes in the stress field and the triggering of volcanic eruptions, and magma ascent through the shallow crust. Modeling results of stress transfer and conduit flow highlight the importance of the surrounding stress field and geometry of the volcanic conduits that comprise shallow plumbing systems.

碩士
國立臺灣大學
分子與細胞生物學研究所
98
The annexin family is ubiquitous proteins capable of binding to membrane with their C-terminal annexin repeats in a Ca2+-dependent manner. The variances of N-terminal of each annexin member contribute to their wide variety of functions including vesicle trafficking, signaling, cell division, growth regulation and apoptosis. Their differentially expressions in distinct tumors are considered as biomarkers and may imply the participation in tumorgenesis. Our previous study showed that annexin A4, a member of annexin family, was overexpressed in both gastric tumor tissues and host cancer cells infected by Helicobacter pylori (H. pylori). Meanwhile, the production of IL-8, an indicator of infection, decreased after annexin A4 knockdown. To investigate the role of annexin A4 in gastric cancer cells, proteomics and network analysis were performed. 36 differentially expressed proteins and a network analysis related to protein folding were identified using Ingenuity Pathway Analysis software. Furthermore, we found ER stress pathway which may increase cell migration ability was very important in annexin A4-overexpressed cells. Therefore, we used western blotting, wound healing assay, cell migration ability assay to elucidate the expression levels of proteins involved in the response to ER stress and migration ability in annexin A4-overexpressed gastric cancer cells. Here, we show that annexin A4 overexpression not only increases ER stress related protein expression and migration ability but also activates two transcription factors, Nuclear factor kappa B (NF-kB) and c-myc, and triggers Akt phosphorylation. These changes might lead to a substantial rise in the expression of the eukaryotic initiation factor 4E (eIF4E) gene, ultimately promoting the migratory ability of gastric cancer cells. The phenomenon was reversed by treating cells with ER stress signaling inhibitor, 8-(N,N-Diethylamino)-octyl-3,4,5-trimethoxybenzoate (TMB-8). Our results demonstrated a plausible mechanism to explain the phenomena that migratory ability increased in annexin A4-overexpressed gastric cancer cells. Eventually, these findings provide useful information in gastric cancer therapy.

碩士
中山醫學大學
生化暨生物科技研究所
93
Oxidative damage to DNA via reactive oxygen species（ROS）is considered to play a crucial role in cell aging, tumorigenesis and cancer. Under exposure to environment of high oxidative stress, cells are predisposed to DNA structure damage, cell senescence and tumorigenesis. To prevent oxidative damage, cells therefore, evolve mechanisms involving in the activation of tumor suppress proteins, cell cycle control and DNA damage repair for the maintenance of DNA integrity. However, there are few data discussed about the cellular response under exposure of transient oxidative stress. The aim of this study was to clarify the possible mechanisms against oxidative injuring in different cell lines. Various cell lines, including a kidney cell line HEK 293 and breast cancer cell lines MCF-7, HCC1937 and HCC1937 (BRCA1), were enrolled, and all of them were treated with different concentrations of H2O2. Several techniques, including Comet assay, Flow cytometry, DNA fragmentation, Western blotting and Enzyme activity assay were used to analysis the physiological alternations of these cell lines. After the H2O2 treatment, we found that HEK 293 cells is the most sensitive to oxidative stress, showing of the largest moment tail among these four cell lines. In addition, up-regulated expression of Chk 1, p53 and phosphorylated-p53 proteins will correlated with down-regulation of A- and B1- cyclins in HEK 293 cells, resulting in the cell cycle arrested in G2/M stage. On the other hand, either p53 positive or p53 negative, p21 were apparently expressed in MCF-7, HCC1937 and HCC1937 (BRCA1) cells. Interestingly, these breast tumor cell lines showed an increasing trend of accumulation of cells in SubG1 phase after to high dosage of H2O2 treatment. Catalase activity will be forced to enhance after exposure to environment of high oxidative stress among these cell lines. In this study, we established a cell model with the temporal oxidative stress for the mimic of real oxidative stress surrounding that cells met with. We were able to define a real physiological status of cells under exposure to oxidative substance. The susceptibilities to oxidative injury were also ascribed to different genetic profiles of tumor suppressor gene. Therefore, the molecular mechanisms of cell cycle arrest for the potential benefit in triggering oxidative DNA damage repair were dependent upon the tissue- and genetic specificities. In conclusion, these findings may reassure the mechanisms of tumor suppressor gene against oxidative damage but also provide the functional role of the scavengers and cell cycle regulation in the response of oxidative stress.

碩士
國立中正大學
地震研究所暨應用地球物理研究所
97
We analyze the coseismic slip of Taitung earthquake on April 1st, 2006 by using isochron waveform inversion method to derive slip distribution on the rupture plane. The hypocenter of Taitung earthquake (ML=6.2) was located 7 km north of the Beinan strong motion site with depth of 7.2km. Waveforms of this earthquake recorded by Taiwan strong motion instrumentation program (TSMIP) of Central Weather Bureau, are bandpass filtered from 0.25 to 0.80Hz for simulation. We compare the original and the synthetic waveforms cross correlation which are chosen from strong motion sites. The optimal fitness, which is defined by the cross correlation between the observed and synthetic waveforms, indicates that the most likely model rupture for Taitung earthquake is characterize by strike-slip motion with maximum slips distributed to the south of the hypocenter on the rupture plane . To understand the mechanism of nucleation of Taitung earthquake, we calculate the static stress transfer between Chengkung earthquake in December, 2003 and Taitung earthquake. We find that the static stress transfer of Chengkung earthquake could enhance the Coulomb failure stress change (ΔCFS) at hypocenter of Taitung earthquake. Similarly, Taitung earthquake were able to elevate the static stress at the site of a thrust event with ML=6.0 offshore of Taitung occurred 15 days after the Taitung earthquake. This finding implies that stress transfer did occur between Central Range and Coastal Range fault system. Several similar results also have been reported around the world. These observations suggests that stress transfer and probable earthquake triggering between a strike-slip and a thrust fault systems at oblique convergent plate boundaries may be a common phenomenon.

博士
中山醫學大學
醫學研究所
103
Objective：Malic acid (MA) has been commonly used in cosmetic products, but the safety reports in skin are sparse. In this study, we investigated the biological and molecular effects of MA in human keratinocyte cell lines (HaCaT). Methods and Materials：HaCaT cells and normal human epidermal keratinocytes (NHEKs) were treated with MA at different concentrations (10 mM, 12.5 mM, 15 mM, 17.5 mM and 20 mM) for various time periods. Cell viability and cell cycle were analyzed by using flow cytometry. The molecular mechanisms of anti-proliferation through cell cycle arrest and apoptosis were investigated in HaCaT cells by phase-contrast microscope, flow cytometry, DAPI stain, DNA fragmentation, Seahorse XF 24, and Western blot. Results：The data showed that MA induced DNA damage and apoptosis based on the observations of DAPI staining, DNA fragmentation, and sub-G1 phase in HaCaT cells. Flow cytometric assays also showed that MA increased the production of mitochondrial superoxide (mito-SOX) but decreased the mitochondrial membrane potential. Analysis of bioenergetics function with the XF 24 analyzer Seahorse extracellular flux analyzer demonstrated that oxygen consumption rate (OCR) was significantly decreased whereas extracellular acidification rate (ECAR) was increased in MA-treated keratinocytes. The occurrence of apoptosis was proved by the increased expressions of FasL, Fas, Bax, Bid, caspases-3, -8, -9, cytochrome c, and the declined expressions of Bcl-2, PARP. MA also induced endoplasmic reticulum stress associated protein expression such as GRP78, GADD153, and ATF6α. Conclusion and Suggestion：We demonstrated that MA had anti-proliferative effect in HaCaT cell through the inhibition of cell cycle progression at G0/G1, and the induction of programmed cell death through endoplasmic reticulum stress- and mitochondria-dependent pathways. Our investigation highlights to consumers and physicians the potential risks of malic acid and other alpha-hydroxy acids which may be contained in cosmetic products.

The goal of this Ph.D. Thesis is to show and discuss implications of the main aspects of different governing laws in the description of all phases of seismogenic processes: nucleation, dynamic propagation and energy release, healing, arrest and mutual interactions between faults. This has been done by implementing or developing numerical codes and algorithms able to solve, in various dimensionalities, the fully dynamic, spontaneous problem. The next stage of the research project in which this work is inserted is to try to infer some constitutive details from real events, in order to discriminate between different models.
Istituto Nazionale di Geofisica e Vulcanologia - Sezione di Bologna Univertsita' degli Studi di Bologna - Dipartimento di Fisica
Published
open

碩士
國立成功大學
水利及海洋工程學系碩博士班
91
Taiwan has highly steep topography, broken geological conditions, concentrated rainstorms, and over developed hillsides, and these have frequently resulted debris-flow hazards. After a severe earthquake of 7.3 Richard scale at Central Taiwan on November 21, 1999, a large amount of loose soils on hillsides largely increase debris-flow occurrence frequency and magnitude , especially in Central Taiwan. Therefore, it is important to develop accurate debris-flow forecast or warning systems for reducingthe lose of human lives and properties. Three basic conditions for debris-flow occurrence are the abundant loose soils, the steep slope, and the large amount of water. For a specified watershed of a debris-flow gully, the changes of the topographical and geological conditions as well as the loose soil conditions in a period of normal time are negligible compared with the change of rainfall. Taiwan has heavy and concentrated rainfall, so occurrences of debris flows in Taiwan are always closely related with rainfall characteristics. If one can analyze the rainfall and its tendency, it is possible to predict debris flow occurrence potential based on the rainfall condition. Even though the effective rainfall intensity and the effective accumulated rainfall as well as other rainfall factors have been used to be rainfall indexes for debris flow prediction in Taiwan, there are still large rooms to be improved according to practical application experiences. This paper collects various rainfall-based debrisflow occurrence models, compares the differences and the suitability of the models, and then proposes an improved method for the prediction/warning of debris-flow occurrence. The common rainfall parameters used in debris-flow warning models are the rainfall intensity I, rainfall duration T, accumulated rainfall R and previous accumulated rainfall P. Based on the four rainfall parameters, debris-flow occurrence warning models could be classified into five categories: I-R model, I-T model, R-T model, I-P model and others. It has been found that there is inconsistent in defining a rainfall event used in analyzing debris-flow initiation. There are about four difference definitions of a rainfall event used by previous debris-flow investigators. Four kinds of rainfall-event definitions have been used and compared to analyze the rainfall parameters. The results show that different rainfall-event definitions would result different rainfall parameters, and their differences are very large. The paper proposed another two methods to define a rainfall event that would be more suitable for analyzing debris-flow initiation. The rainfall parameters obtained by the proposed method are also compared with that obtained by the present method used by the Soil and Water Conservation Bureau (SWCB), Council of Agriculture in Taiwan This paper also proposes a probability-based debris flow rainfall warning model.