Fault Failure in Oklahoma Is Anything but Simple

Date: 4/25/2019

Time: 06:00 PM

Room: Fifth Avenue

Seismicity in Oklahoma is primarily driven by wastewater injection, but where does the influence of wastewater end and the natural processes of fault failure take over? In order to answer this question, we construct finite fault models for 3 earthquakes in the region. They are of a M 4.1 earthquake that occurred near Guthrie, OK in April 2015, the M 5.0 Cushing earthquake that occurred in November 2016, and the M 5.1 Fairview earthquake that occurred in February 2016. Previous works on the Guthrie event and the Fairview event show that both events exhibit rupture complexity with more than two subevents (López-Comino and Cesca, 2018; Wu et al., 2018, AGU). A previous finite-fault slip model with ground motion records of the Cushing event shows rather complex rupture history (Ji & Archuleta, 2017, EGU). The finite fault model obtained for the Guthrie event supports these findings. It shows a small slip patch occurring at the hypocenter location, which then triggers 0.4s later a 500m wide and 2000m long slip patch 0.5 km to the SE. This slip patch is composed of a number of small high slip (0.08 m) patches that represent the slip for each subevent observed in previous works. In this study, we take advantage of the abundance of clustered events around each mainshock, and apply multiscale slip inversion to resolve details of the beginning stage of the rupture, assess how fault rupture propagates along the faults, and if there is any relationship between pressure propagation direction and rupture direction. In addition, we compare our source complexity to the source complexity from a recently compiled global dataset, to assess if the intraplate setting with low tectonic strain rate influences rupture complexity. Finally, we will assess whether rupture complexity influences aftershock distributions and activation of different fault segments, as well as ground motion distributions. These results will allow for the improved understanding of earthquake rupture, aftershock activity and improve our ability to assess the seismic hazard for similar failures in the future.

Presenting Author: Colin N. Pennington

Authors