Stress Drop Estimates of Deep Earthquakes Based on Empirical Green’s Function Analysis

Date: 4/26/2019

Time: 06:00 PM

Room: Grand Ballroom

Stress drop is a critical source parameter indicating stress release during an earthquake. It is a fundamental question whether deep earthquakes exhibit similar source processes as shallow earthquakes though, we lack a comprehensive understanding of stress drop for deep earthquakes owing to insufficient dataset. Here we aim to better understand the source processes of deep earthquakes with accurate stress drop estimations and will investigate whether stress drops of deep (> 400 km) earthquakes are much larger than those of shallow earthquakes due to the increase of shear strength with depth.

To obtain the stress drop pattern of deep earthquakes, we estimate their corner frequencies using the spectral ratios based on empirical Green’s functions(eGfs). Our analysis uses both P waves and S waves recorded by global and regional seismic stations and assumes Brune’s spectral model. We have identified more than 100 pairs of master events and their eGfs occurred since 2000. Each pair meets the criteria of magnitude difference larger than 0.5 and hypocentral distance within 50 km. Our preliminary corner frequency estimates for Mw6.0 - Mw8.2 deep earthquakes lead to similar stress drop ranges to shallow earthquakes of 0.03 - 30MPa and 0.01 - 10Mpa from S and P wave analysis, respectively. We will further investigate the uncertainty in the corner frequency estimates and the spatial variation of stress drop of deep earthquakes.

Presenting Author: Meichen Liu

Authors