Earthquake Clustering in Southcentral Utah

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

Southcentral Utah is characterized by assemblages of late Cenozoic volcanics and faulting, areas of high heat flux, shallow contours of low resistivity, and is known to experience sequences of small magnitude, shallow earthquakes. The aim of this study is to define and characterize earthquake sequences in order to assess the influence of fluids in the upper crust on earthquake generation in this area. Towards this, we compiled a catalog of 2119 events from 1981 to 2018, derived from (i) the University of Utah Seismograph Stations catalog (UUSS; 1950 earthquakes), and (ii) temporary nodal geophone deployments (July 2016-October 2017; 166 earthquakes). To improve the accuracy of interevent distances, which are used to determine earthquake clusters, we relocate the earthquake catalog using a double difference technique and differential times from the catalog data. Earthquake sequences are defined by applying spatiotemporal criteria which include seismicity rate, distance from a cluster’s centroid, interevent time, and interevent distance based on the nearest neighbor approach. To discriminate earthquake clusters into mainshock-aftershock sequences and earthquake swarms, we examine for each earthquake sequence the magnitude-frequency distribution, the aftershock decay, the skewness and kurtosis of the moment release history, interevent times, and the difference in magnitude between the two largest earthquakes. Preliminary results show that earthquakes form several clusters within the study area.

Presenting Author: Amy S. Record

Authors