Controls of Structural Complexity and Earthquake Rupture Process on Spatiotemporal Evolution of Induced Earthquake Sequences

Date: 4/26/2019

Time: 04:15 PM

Room: Cascade I

It is well known that most of the recent seismicity in Oklahoma are induced due to wastewater disposal and hydraulic fracturing. However, the control factors that control of the initiation and spatiotemporal evolution of individual earthquake sequences still remain unclear. In this study, we focus on a few well well-recorded earthquake sequences in Oklahoma, perform detailed analysis on the spatiotemporal evolution of seismicity and earthquake source parameters analysis, in order to understand the roles of geological structures and earthquake rupture processes on induced earthquake sequences. For the Guthrie sequence in central Oklahoma, we interpret a complex conjugate fault mesh network based on high-resolution earthquake catalog and focal mechanism solutions. Detailed source parameter analysis suggests that the sequence initiated along weaker fault patches in the central shallower portion of the fault. Rapid fault activation of a low stress drop region is accompanied with low b-value and high seismicity rate. Although the entire sequence exhibits diffusion-type spatial migration, embedded slow slip episodes and earthquake-to-earthquake triggering are identified for selected larger earthquakes. For the Cushing sequence, detailed relocation and focal mechanism solutions suggest predominanting NE- oriented right-lateral strike-slip faulting, and show diverse faulting types are found along the portion where the M5 mainshock occurred. The association betweencoincidence of mainshock occurrence and diverse faulting types suggestss that structural complexity may play a role in the rupture initiation process of larger mainshocks. Further analysis of source parameters of small earthquakes, and aeromagnetic datasets will unravel the roles of basement structure and earthquake rupture processes on the Cushing earthquake sequence.

Presenting Author: Xiaowei Chen

Authors