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Moment-Rate Spectra, Source Scaling and Spectral Fall-Off in the Korean Peninsula Using the Coda Calibration Tool (2.0

Description: 

We applied the Coda Calibration Tool (CCT) to local and regional broadband data across the Korean peninsula and Yellow Sea region with the goal of obtaining stable moment-rate source spectra. The 2016 Gyeongju and 2017 Pohang sequences allowed us to compute stable coda spectral ratios that were used as reference events, an integral step in the CCT calibration methodology. We are able to measure single-station M_w for events as small as ~2.0, compare earthquake source scaling with other independent methods, and study the spectral characteristics of shallow induced events as well as man-made sources over the past 20 years. Another important focus of this study was the spectral fall-off. While source scaling studies must account for the inherent trade-offs between site, source and path effects, the empirical Green’s function (eGf) approaches, and their variants, have been attractive because common path and site terms cancel. Source complexity and a priori assumptions can bias eGf results so we plan to address these following challenges in this study, namely: 1) The spectral models used to fit the data must assume a spectral fall-off which are also a topic of active debate; 2) Potential issues with source directivity of either or both events which might bias the results; 3) Source complexity that can create spectral holes and peaks as reported in a number of finite-fault inversions; 4) Finally, the assumption of an eGf stress drop can, in theory, bias both the small magnitude corner frequencies and subsequent interpretation of the overall source scaling.

Session: Understanding and Quantifying the Variability in Earthquake Source Parameter Measurements [Poster Session]

Type: Poster

Date: 5/3/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Kevin

Student Presenter: No

Invited Presentation: