Comprehensive macroseismic analyses for probabilistic seismic hazard assessment in intraplate regions

• Main Author: Han, Jeongmin
• Other Authors: Fenton, Clark
• Published: Imperial College London 2016
• Subjects: 551.22
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.700698

In low to moderate seismicity intraplate regions, earthquake engineers and engineering seismologists face challenges dealing with the considerable level of uncertainty in the estimation of magnitude recurrence parameters and maximum magnitude estimation for probabilistic seismic hazard assessment (PSHA). This is largely due to the lack of strong ground motion records, short and incomplete earthquake catalogue, and extremely long recurrence intervals between large magnitude events. This puts additional importance of finding reliable estimates of earthquake source parameters for historical and early instrumental records which often have greater impact on hazard results than short span of instrumental records. This thesis explores the presence of regional differences within stable continental regions (SCRs) as well as a degree of regional variability with respect to the global average SCR using isoseismal area data. This is accomplished by careful collection and processing of isoseismal areas from the global stable continental regions, and by developing felt area-to-magnitude relationships through a uniform regression framework of Johnston (1996b). By comparing with existing relationships, the applicability of the newly developed felt area-to-magnitude relationships is evaluated. Analyses of focal depth distribution, and their correspondence with the Moho depth and the surface heat flow are investigated for the Korean peninsula, as a case study region. Macroseismic attenuation parameters for the Kövesligethy (1906) attenuation model are derived from a newly compiled, comprehensive macroseismic intensity database in order to determine macroseismic focal depths. The influence of using different types of macroseismic data and regional earthquake data on the macroseismic attenuation parameters is also investigated. Finally, a suite of three intensity attenuation models, each using a different functional form, is derived for the Korean peninsula, and the sensitivity of the model results to different regression techniques and functional regression forms is evaluated. The newly derived intensity attenuation model is used to estimate earthquake magnitude and epicentral location through the bootstrap resampling technique of Bakun and Wentworth (1997).