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SE5-001
10:50
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11:10
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DEVELOPMENT OF THE TAIWAN SEISMOGENIC SORUCE MOEDEL FOR SEISMIC HAZARD USING SSHAC LEVEL 3 METHODOLOGY
The purpose of this project is applying probabilistic seismic hazard analysis (PSHA) to specific sites based on a Senior Seismic Hazard Analysis Committee (SSHAC) Level 3 process for constructing the model of Seismic Source Characterization (SSC). We, the SSC team, integrated the data, methods, interpretations, alternative models and point of view from expertise in public meetings with invited experts to evaluate the center, body and range (CBR) of the technically defensible interpretations (TDI) for capturing the epistemic and aleatory uncertainties of parameters in SSC model for PSHA. For simplicity, we consider the single parameter of the maximum earthquake magnitude for a fault. However, the complete characterization of uncertainty will be referred to the “center, body, and range”. In this case, “center” can be thought of as the median of the maximum magnitude, “range” can be thought of as the extreme upper and lower estimates of the maximum magnitude limits, and “body” can be thought of as the shape of the distribution of potential maximum magnitudes within that range. Three seismic sources have been considered in SSC model, fault source, areal source and subduction zone interface, based on distribution of geological structures, seismicity and tectonic frame. Constructing geometrical model and activity model of fault source, subduction zone interface and areal source with parameters will help the SSC team to evaluate where the maximum magnitude located and it’s return period may generate a significant impact for specific site. However, limited geological and geophysical data forced the evaluation for the geometry and activity of faults with high uncertainty range. To drop down the uncertainty range, in near future, a conducted project for key data collection and related investigation is necessary.
Bor-Shouh Huang, Kuan-Yu Chen, Andrew, T. S. Lin, Kevin Clahan, Chin Tung Cheng, Chin Hsun Yeh, Yi Ping Chen, Ying Ping Kuo, Yu Wen Chang, Hsun Jen Liu, Yan Ru Chang, Chih Wei Chang, Chiun Lin Wu
aleatory, areal source, epistemic, fault source, Maximum Magnitude, PSHA, SSC, SSHAC level 3, subduction zone interface, uncertainty
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SE5-006
11:10
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11:30
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THE SEISMOGENIC STRUCTURE SOURCE MODEL OF TEM: ACHIEVEMENTS AND FUTURE CHALLENGES
As one of the most tectonically active areas in the world, the island of Taiwan is characterized by frequent seismic activities and numerous active faults. As a result, one of the most crucial tasks for Earth scientists in Taiwan is to understand, assess, and mitigate future seismic hazards of the island. To achieve this, models of earthquake hazard, risk, and related social and economic impact need to be established through multidisciplinary collaborations, and the very first step toward this would be to construct a complete seismogenic structure database for Taiwan. One such database has been constructed in the past several years based on reviews of existing active structure databases and new information for structures that have not been thoroughly analyzed before. For example, the Central Geological Survey of Taiwan has published a comprehensive database of active faults in Taiwan, including all of the historically ruptured faults. Many other active structures, such as blind faults or folds that can be identified from geomorphic or structural analysis, have also been reported in several previous investigations. On the basis of such information, a preliminary version of this database has been released and published in 2016. This preliminary database includes primarily on-land structures, but has not included offshore structures that may also pose significant seismic hazards. Therefore, we have been working on updating the seismogenic structure database in the effort to obtain sufficient data for offshore structures. In addition, based on historical earthquake events, we have been working on proposing earthquake scenarios that involve ruptures of multiple structures, or only partial segments of a given seismogenic structure. These new additions and considerations, however, also created new challenges for the construction of the database. For example, many parameters, especially the long-term slip rates, of the offshore structures are extremely difficult to determine. The proposed frequency of multi-structure or segmented rupture events would also significantly influence the recurrence interval calculation. Although such seismogenic structure database would undoubtedly provide significant constraints for the calculations of seismic hazards in Taiwan, we suggest that the issues and challenges we identified will constitute the next most important questions to be solved for future seismic hazard assessment studies.
J. Bruce H. Shyu
active fault, seismic hazard, seismogenic structure, Taiwan Earthquake Model (TEM)
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SE5-016
11:30
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11:45
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TAIWAN OFFSHORE SEISMOGENIC FAULTS
Since 1999 Chi-chi earthquake, the authorities have concentrated on seismogenic faults mapping, especially on offshore area. The amounts of data and results were dispersed on various institute individually. We integrated and consolidated the data have been investigated and collected, the results have been published in past two decades to establish the database for evaluating the parameters of Taiwan offshore seismiogenic faults. Currently, 15 Taiwan offshore seismogenic faults have been mapped, which includes 1. Binhai fault zone, 2. E fault, 3. Aoti offshore fault 4. I fault, 5. Okinawa fault, 6. Ryukyu strike slip fault, 7. Ryukyu trench, 8.Taitung Canyon fault, 9. North Luzon strike slip fault, 10. North Luzon back thrust fault 11 East Hengchun fault, 12. West Hengchun offshore structure, 13. Splay fault, 14.Manila trench, 15.Continental shelf fault.Parameters of seismogenic faults present their geometry and activity. Rupture length, rupture depth, strike, dipping angle and dipping direction are included as geometry parameters; slip rate, Maximum Magnitude and return period represent the activity. Due to limited geological and geophysical data for offshore seismogenic faults, we are forced to evaluated the geometry and activity of faults with high uncertainty range. We anticipate more geological and geophysical survey will be further conducted to collect more data for narrowing down the uncertainty range of geometry and activity parameters for Taiwan offshore faults.
冠宇 陳
Binhai fault zone, Manila trench, Return Period, Ryukyu trench, Splay fault
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SE5-002
11:45
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12:05
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METHODOLOGY OF DEVELOPING A GROUND MOTION LOGIC TREE FOR SITE-SPECIFIC PROBABILISTIC SEISMIC HAZARD ANALYSIS IN TAIWAN
In this study, we propose a methodology to develop a ground motion logic tree including median and sigma models for conducting the site-specific probabilistic seismic hazard analysis in Taiwan. A comprehensive ground motion dataset is compiled first including Taiwan and global ground motion records. Several ground motion prediction equations are selected as seed models with several suggested criteria to make sure they are all technically defensive for predicting the ground motion intensity of the target site in Taiwan. Several representative models are developed by using the common form approach in companion with Sammon’s map visualization technique to construct the logic tree branches of the median model to capture the center, body, range of the ground motion median intensity. Several kinds of statistics describing the fitness of the representative models to several selected ground motion datasets are evaluated to better assign the weights of median models in logic tree objectively. Some other key ground motion characteristics such as hanging wall effect, listric fault effect and edge effect were also evaluated and considered in the logic tree of median model. Single-station-sigma in consist of event-to-event variability (Tau) and record-to-record variability (PhiSS) of the ground motion intensity are evaluated and considered in the logic tree of sigma model. The proposed methodology is useful to develop a ground motion logic tree for conducting the site-specific probabilistic seismic hazard analysis in Taiwan.
Kuo-Liang Wen, Taiwan SSHAC Level 3 Project Team
ground motion characteristics, Ground Motion Prediction Equation, logic tree, probability seismic hazard analysis, single station sigma, Taiwan
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SE5-003
12:05
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12:25
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AN INTEGRATED SYSTEM FOR SHARING INFORMATION ON NATIONAL SEISMIC HAZARD MAPS FOR JAPAN AND ITS APPLICATION TO SEISMIC RISK ASSESSMENT
The National Seismic Hazard Maps for Japan are issued by a governmental organization, the headquarters for earthquake research promotion of Japan, to estimate strong motions caused by earthquakes that could occur in the future and show the estimated results on the maps. The National Seismic Hazard Maps for Japan consists of two types of maps that are different in nature: the probabilistic seismic hazard maps and the scenario earthquake-shaking maps for specified seismic source faults. The probabilistic seismic hazard maps are based on the PSHA that combines long-term evaluations of earthquake occurrence and strong motion evaluation. An integrated system of Japan seismic hazard information station (J-SHIS) has been developed for sharing the seismic hazard information. The system manages various data in an integrated manner, including provide detail seismic hazard information and site amplification models with a 250m mesh resolution, and the deep subsurface velocity structure models. The system is also capable of providing these data in a user-friendly manner by showing them over background maps. This J-SHIS system is a web mapping system based on open source software that allows public users to easily view various data by Internet browsers. As a consequence of continuous national seismic hazard assessment for Japan in the 15-years sustainable mission, the national seismic risk assessment on building damage in Japan is conducted based on an accumulated result of the National Seismic Hazard Maps for Japan. We construct a sets of seismic risk assessment database in a mesh-base of 250m, consists of number of building, building structure with attributes, building age, and population accommodation.
Hiroyuki Fujiwara, Nobuyuki Morikawa, Hiromitsu Nakamura, Takahiro Maeda, Shinichi Kawai, Ken Xiansheng Hao
J-SHIS, probabilistic seismic hazard, seismic risk, strong-motion
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