Last modified: 2016-05-03
Abstract
Due to the fast plate motions, there have been frequent high seismic activities in Taiwan. According to history records, the most destructive earthquakes in Taiwan were mainly caused by inland active faults. The Central Geological Survey (CGS) of Taiwan has been publishing active fault maps in Taiwan since 1998. It has 33 active faults in the 2012 active fault map.
After the Chi-Chi earthquake, CGS launched a series of projects to investigate the details to better understand each active fault in Taiwan. We gathered these collected data for developing active fault parameters, and referred to certain experiences from Japan and United States to establish a methodology for earthquake probability assessment via active faults.
The first step is to collect the fault parameters, which include fault geometry (length, rupture depth, and dip), segmentation, and slip rate. We calculated the characteristic earthquake magnitude of each fault by its rupture area. Empirical source scaling equations (e.g., Wells and Coppersmith, 1994; Yen and Ma, 2011) were used for this purpose.
Every possible case considered, we needed to divide fault segment to establish a rupture model. A fault rupture model is a weighted combination of the rupture cases of a fault. The long-term slip rate data can be applied in characteristic earthquake model to obtain the recurrence interval. The gathered data were integrated as a fault parameter table for the following work.
We calculated the recurrence interval of earthquake by characteristic earthquake model.
Finally, we used appropriate “probability model” to estimate the 30, 50 and 100 year conditional probability of earthquakes.
Our research is to calculate the earthquake probability of the 33 active faults in Taiwan. The parameters of active faults are important information which can be applied in the following seismic hazard analysis and seismic simulation.
If the parameters of an active fault are not clear when collecting data, we will suggest the Central Geologic Survey a more detailed investigation for this fault. We also might suggest that a fault with high earthquake probability should be monitored constantly and to be paid more attention to prevent and mitigate the earthquake disaster.
Keywords
References
Cheng, C. T., 2002: Uncertainty analysis and de-aggregation of seismic hazard in Taiwan. Ph.D. Dissertation, Institute of Geophysics, National Central University, Chung-Li, Taiwan (in Chinese).
Cheng, C. T., S. J. Chiou, C. T. Lee, Y. B. Tsai, 2007: Study on probabilistic seismic hazard maps of Taiwan after Chi-Chi earthquake. Journal of GeoEngineering, 2, 19–28.
Cheng, C. T., P. S. Hsieh, P. S. Lin, Y. T. Yen and C. H. Chan, 2015: Probability seismic hazard mapping of Taiwan. Encyclopedia of Earthquake Engineering, 1-25.
Edward H. Field, Glenn P. Biasi, Peter Bird, Timothy E. Dawson, Karen R. Felzer, David D. Jackson, Kaj M. Johnson, Thomas H. Jordan, Christopher Madden, Andrew J. Michael, Kevin R. Milner, Morgan T. Page, Tom Parsons, Peter M. Powers, Bruce E. Shaw, Wayne R. Thatcher, Ray J. Weldon, II, and Yuehua Zeng (Working Group on California Earthquake Probabilities), 2013: The Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3). USGS Open-File Report 2013–1165, 115 pp.
Ellsworth, W. L., M. V. Matthews, R. M. Nadeau, S. P. Nishenko, P. A. Reasenberg and R. W. Simpson, 1999: A physically-based earthquake recurrence model for estimation of long-term earthquake probabilities. U. S. Geological Survey, Open-File Report 99-522, 22 pp.
Headquarters for Earthquake Research Promotion (HERP), 2014: The National Seismic Hazard Maps for Japan 2014 version.
Working Group on California Earthquake Probabilities 2003 (WGCEP 2003), 2003: Earthquake probabilities in the San Francisco Bay region: 2002-2031. USGS Open-File Report 03-214, 234 pp.
Working Group on California Earthquake Probabilities 2007 (WGCEP 2007), 2008: The uniform California earthquake rupture forecast, Version 2. USGS Open-File Report 07-1437, 96 pp.
Wells, D. L. and K .J. Coppersmith, 1994: New empirical relationships among magnitude, rupture length, rupture width, rupture area, and surface displacement. Bull. Seismo. Soc. Am., 84, 974-1002.
Yen, Y. T. and K. F. Ma, 2011: Source-Scaling Relationship for M 4.6–8.9 Earthquakes, Specifically for Earthquakes in the Collision Zone of Taiwan. Bull. Seismo. Soc. Am., 101(2), 464–481, doi: 10.1785/0120100046.
Youngs, R. R. and K. J. Coppersmith, 1985: Implications of fault slip rates and earthquake recurrence models to probabilistic seismic hazard estimates. Bull. Seismo. Soc. Am., 75, 939-964.