Mainshock Event-Term Calibration Using Temporal Portable Seismic Network Recorded Aftershocks

Date: 4/26/2019

Time: 06:00 PM

Room: Grand Ballroom

We investigate the possibility of the mainshock event-term calibration using aftershock events observed in more densely located velocimeters. An intensity map for a specific event provides a vital role to analyze the damage status, but it requires seismic records as well as understanding of ground motion distribution and site amplification effects. The map is generated using a local GMPE, regional site characterization, and ground motion observations. Herein, the median of local GMPE is modified by the mean trend of ground motion records to incorporate event-specific ground motion distribution trend, called event-term correction. The modification is effective if abundant seismic records are available especially in close distance to the source within which usually the severe damage is observed, but unfortunately the seismic stations are sparse due to high maintenance and installation cost.

The 2017 M5.4 Pohang earthquake struck south-east part of South Korea which damaged regional society. The mainshock ground motion was recorded by semi-permanent seismic stations maintained by Korea Meteorological Administration (KMA) and Korea Institute of Geoscience and Mineral Resources, and aftershock ground motions in adjacent to damaged regions were recorded by temporal portable velocimeters installed after the mainshock in addition to the permanent stations by KMA. Since the portable stations are relatively densely located near the source, they give an opportunity to calibrate the event-term more precisely in near-source distance. In this study, we seek to find the possibility of the adjustment of the mainshock event-term calibration using the aftershock event-terms. This example will provide a framework estimating more precise seismic intensity map of the mainshock from aftershock events observed in more densely located seismic stations.

Presenting Author: Dong Youp Kwak

Authors