Empirical Earthquake Scaling Relationships Derived from Geodetic Slip Distributions

Session: Earthquake Source Parameters: Theory, Observations and Interpretations [Poster]
Type: Poster
Date: 4/30/2020
Time: 08:00 AM
Room: Ballroom
Description: 

Empirical earthquake scaling relationships describe expected relations between moment magnitude and spatial descriptors of the earthquake rupture (along‐strike length, down‐dip width, rupture area, and peak and mean slip). Most existing scaling relationships are derived from seismological observations (aftershock distributions or teleseismic finite fault models). Given that these methods may be biased by incorrect assumptions or inversion regularization issues, they may similarly bias expected scaling relationships. Earthquake slip distributions derived from geodetic observations provide an independent means to verify and explore earthquake scaling relationships. Here, we present earthquake scaling relationships derived from a database of 111 geodetically derived slip distributions from 73 different earthquakes ranging in magnitude from M_w 5.3 to 9.1. We find that our scaling relationships differ from existing scaling relationships, and that the source of this difference stems from the data source as opposed to a bias in our approaches for extracting spatial descriptors. One important difference is that our scaling relationships predict smaller fault area for a given magnitude earthquake than seismologically-determined scaling relationships. Geodetic slip distributions are likely contaminated with varying degrees of postseismic afterslip, so a smaller predicted fault area strongly suggests that existing earthquake scaling relationships overpredict fault area. We also find differences in scaling of along-strike length, down-dip width, and peak and mean slip. These differences are more complex and magnitude dependent.

Presenting Author: Clayton Brengman

Authors