High-frequency strong ground-motion simulation for the 2016 Mw 7.0 Kumamoto earthquake
Authors: Ojeda Javier , Arriola Sebastian , Flores Christian , Otarola Cristian , Ruiz Sergio 
Published: March 2021

&lt;p&gt;&lt;span&gt;&lt;span&gt;The 2016&amp;#160;&lt;/span&gt;&lt;span&gt;Kumamoto&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;earthquake&amp;#160;&lt;/span&gt;&lt;span&gt;Mw&lt;/span&gt;&lt;span&gt;&amp;#160;7.0 occurred in Japan&amp;#160;&lt;/span&gt;&lt;span&gt;reveal&lt;/span&gt;&lt;span&gt;&amp;#160;a multisegment shallow fault rupture that was&amp;#160;&lt;/span&gt;&lt;span&gt;well&lt;/span&gt;&lt;span&gt;&amp;#160;recorded by the&amp;#160;&lt;/span&gt;&lt;span&gt;KiK-net&lt;/span&gt;&lt;span&gt;&amp;#160;stations&lt;/span&gt;&lt;span&gt;&amp;#160;in accelerographs placed inside boreholes and on the&amp;#160;&lt;/span&gt;&lt;span&gt;surface&lt;/span&gt;&lt;span&gt;.&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&amp;#160;The&amp;#160;&lt;span&gt;numerous&lt;/span&gt;&amp;#160;damaged buildings due to this&amp;#160;&lt;span&gt;earthquake&lt;/span&gt;&amp;#160;&lt;span&gt;reflect&lt;/span&gt;&amp;#160;the critical implications for seismic hazard&amp;#160;&lt;span&gt;estimation&lt;/span&gt;&amp;#160;and&amp;#160;&lt;span&gt;improvement&lt;/span&gt;&amp;#160;of earthquake-resistant design for a shallower event.&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;span&gt;Here&lt;/span&gt;,&amp;#160;&lt;span&gt;we&lt;/span&gt;&amp;#160;&lt;span&gt;generate&lt;/span&gt;&amp;#160;synthetic&amp;#160;&lt;span&gt;accelerograms&lt;/span&gt;&amp;#160;at high frequencies&amp;#160;&lt;span&gt;implementing&lt;/span&gt;&amp;#160;a stochastic method that&amp;#160;&lt;span&gt;allow&lt;/span&gt;&amp;#160;us to&amp;#160;&lt;span&gt;simulate&lt;/span&gt;&amp;#160;horizontal and vertical strong ground-motion&amp;#160;&lt;span&gt;accelerograms&lt;/span&gt;&amp;#160;in azimuthal well-distributed stations.&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;span&gt;We&lt;/span&gt;&amp;#160;&lt;span&gt;included&lt;/span&gt;&amp;#160;multisegment finite fault geometries&amp;#160;&lt;span&gt;estimated&lt;/span&gt;&amp;#160;by independent authors as input for source model.&lt;/span&gt;&lt;span&gt;&lt;span&gt;&amp;#160;From&amp;#160;&lt;/span&gt;&lt;span&gt;each&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;sub-fault&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;we&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;calculated&lt;/span&gt;&lt;span&gt;&amp;#160;the&amp;#160;&lt;/span&gt;&lt;span&gt;incident&lt;/span&gt;&lt;span&gt;&amp;#160;and azimuthal angles&amp;#160;&lt;/span&gt;&lt;span&gt;arriving&lt;/span&gt;&lt;span&gt;&amp;#160;at&amp;#160;&lt;/span&gt;&lt;span&gt;each&lt;/span&gt;&lt;span&gt;&amp;#160;seismic station,&amp;#160;&lt;/span&gt;&lt;span&gt;we&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;determined&lt;/span&gt;&lt;span&gt;&amp;#160;free surface&amp;#160;&lt;/span&gt;&lt;span&gt;effect&lt;/span&gt;&lt;span&gt;, energy partition, radiation pattern and dynamic frequency corner for sources&amp;#160;&lt;/span&gt;&lt;span&gt;effect&lt;/span&gt;&lt;span&gt;.&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;Besides&lt;/span&gt;&lt;span&gt;,&amp;#160;&lt;/span&gt;&lt;span&gt;we&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;adopted&lt;/span&gt;&lt;span&gt;&amp;#160;region-specific&amp;#160;&lt;/span&gt;&lt;span&gt;attenuation&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;parameters&lt;/span&gt;&lt;span&gt;&amp;#160;such as geometrical spreading and anelastic&amp;#160;&lt;/span&gt;&lt;span&gt;attenuation&lt;/span&gt;&lt;span&gt;&amp;#160;for path&amp;#160;&lt;/span&gt;&lt;span&gt;effect&lt;/span&gt;&lt;span&gt;, and site&amp;#160;&lt;/span&gt;&lt;span&gt;effect&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;parameters&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;such as&lt;/span&gt;&lt;span&gt;&amp;#160;generic&amp;#160;&lt;/span&gt;&lt;span&gt;amplifications&lt;/span&gt;&lt;span&gt;, soil&amp;#160;&lt;/span&gt;&lt;span&gt;amplification&lt;/span&gt;&lt;span&gt;&amp;#160;transfer functions for body waves, and high-frequency&amp;#160;&lt;/span&gt;&lt;span&gt;attenuation&lt;/span&gt;&lt;span&gt;&amp;#160;kappa filter.&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;&amp;#160;Our&lt;/span&gt;&amp;#160;simulated acceleration&amp;#160;&lt;span&gt;time series&lt;/span&gt;&amp;#160;show similarities&amp;#160;&lt;span&gt;in&amp;#160;&lt;/span&gt;&lt;span&gt;time&lt;/span&gt;&amp;#160;and&amp;#160;&lt;span&gt;frequency&lt;/span&gt;&amp;#160;with the observed records in the&amp;#160;&lt;span&gt;frequency band&lt;/span&gt;&amp;#160;between&amp;#160;&lt;span&gt;1&lt;/span&gt;&amp;#160;&amp;#8211;&lt;/span&gt;&lt;span&gt;&amp;#160;10 Hz.&lt;/span&gt;&lt;span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;We&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;obtained&lt;/span&gt;&lt;span&gt;&amp;#160;a&amp;#160;&lt;/span&gt;&lt;span&gt;good&lt;/span&gt;&lt;span&gt;&amp;#160;agreement between peak ground accelerations for both&amp;#160;&lt;/span&gt;&lt;span&gt;horizontal&lt;/span&gt;&lt;span&gt;&amp;#160;and vertical&amp;#160;&lt;/span&gt;&lt;span&gt;components&lt;/span&gt;&lt;span&gt;, and&amp;#160;&lt;/span&gt;&lt;span&gt;we&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;reproduce&lt;/span&gt;&lt;span&gt;&amp;#160;the&amp;#160;&lt;/span&gt;&lt;span&gt;amplitude&lt;/span&gt;&lt;span&gt;&amp;#160;and&amp;#160;&lt;/span&gt;&lt;span&gt;attenuation&lt;/span&gt;&lt;span&gt;&amp;#160;trend for the&amp;#160;&lt;/span&gt;&lt;span&gt;horizontal&lt;/span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;component&lt;/span&gt;&lt;span&gt;&amp;#160;of the&amp;#160;&lt;/span&gt;&lt;span&gt;GMPE&lt;/span&gt;&lt;span&gt;&amp;#160;models&lt;/span&gt;&lt;span&gt;&amp;#160;in the&amp;#160;&lt;/span&gt;&lt;span&gt;region&lt;/span&gt;&lt;span&gt;.&lt;/span&gt;&lt;/span&gt;&lt;span&gt;&lt;span&gt;&amp;#160;&lt;/span&gt;&lt;span&gt;Finally&lt;/span&gt;&lt;span&gt;,&amp;#160;&lt;/span&gt;&lt;span&gt;we&lt;/span&gt;&lt;span&gt;&amp;#160;are capable to&amp;#160;&lt;/span&gt;&lt;span&gt;simulate&lt;/span&gt;&lt;span&gt;&amp;#160;the high-frequency band of engineering interest using physics-based&amp;#160;&lt;/span&gt;&lt;span&gt;parameters&lt;/span&gt;&lt;span&gt;&amp;#160;to&amp;#160;&lt;/span&gt;&lt;span&gt;improve&lt;/span&gt;&lt;span&gt;&amp;#160;our&amp;#160;&lt;/span&gt;&lt;span&gt;knowledge&lt;/span&gt;&lt;span&gt;&amp;#160;about the&amp;#160;&lt;/span&gt;&lt;span&gt;source&lt;/span&gt;&lt;span&gt;,&amp;#160;&lt;/span&gt;&lt;span&gt;path&lt;/span&gt;&lt;span&gt;, and site effect and their&amp;#160;&lt;/span&gt;&lt;span&gt;impact&lt;/span&gt;&lt;span&gt;&amp;#160;on a seismic hazard assessment in earthquake-prone regions.&lt;/span&gt;&lt;/span&gt;&lt;/p&gt;