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Mapping b-Values Based on Background Seismicity in the Korean Peninsula

Description: 

The b value of the Gutenberg and Richter relationship, one of the parameters indicating seismicity, is crucial to seismic hazard assessments and understanding the stress state of regions of interest. We built b-value maps of the Korean Peninsula that belongs to an intraplate region to identify spatial and temporal variations in seismicity, based on the earthquake catalog (1998 to 2022) of the Korea Institute of Geoscience and Mineral Resources. Non-natural or dependent events typically produce high b-values; therefore, we attempted to eliminate non-natural events, such as quarry and mine explosions, by applying the daytime-to-nighttime ratio proposed by Wiemer and Baer (2000) to cataloged events with local magnitudes less than 2.5. We then declustered seismicity to obtain only independent events, by identifying dependent events, such as after- or foreshocks, using the window method proposed by Gardner and Knopoff (1974). The magnitude of completeness (M_c) for the determination of the b-value was estimated using the goodness-of-fit test proposed by Wiemer and Wyss (2000), and the b-value was calculated using the maximum likelihood method proposed by Aki (1965). We mapped the M_c and b-values at nodes generated by dividing the Korean Peninsula into grids of 0.1° × 0.1°. The b-value maps based on background seismicity in the Korean Peninsula showed characteristic temporal and spatial features. Here, we discuss the implications of the low b-values observed, especially around Baekryoeng Island, and examine the changes in b-values after the 2011 Tohoku and 2016 Gyeongju earthquakes.

Session: Tectonics and Seismicity of Stable Continental Interiors [Poster]

Type: Poster

Date: 4/19/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Seula Jung

Student Presenter: No

Invited Presentation: 

Authors