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Fault Reactivation During Induced Seismicity Sequences in Southern Kansas

Description: 

Using machine learning enhanced catalogs, it is possible to study the evolution of earthquake sequences in great detail owing to the significant decrease in magnitude of completeness compared to routine catalogs. We use the enhanced catalog of Park et al. (The Seismic Record, 2022) for Oklahoma and Southern Kansas to examine the spatial and temporal evolution of seismicity on individual faults in southern Kansas. In the Park et al. study it was found that individual faults commonly activate multiple times. To better understand the nature of reactivation we refine the hypocentral locations using the slope of the cross spectrum to measure sub-sample differences in travel time between highly correlated events. We obtain precise relative locations for earthquakes occurring along individual fault structures with an accuracy of 10-20 m. Along one isolated, 2.5 km-long fault we find approximately 10% of the events are “true” repeaters (>50% overlap in rupture area). Interevent times vary widely, between a few hours and several months with no clear trend with magnitude. Repeating earthquakes concentrate along the central portion of the fault indicating that the same portion of the fault slipped more than once during the sequence. Of note, the largest repeaters in the sequence, ML 3.2 and 3.1 occurred shortly after the fault became seismically active and just 3 days apart. This raises the question of the re-failure mechanism. Further investigations will be needed to determine the role of aseismic slip (potentially revealed by small repeaters), stress interaction and/or progressive weakening from rising pore pressure as the re-triggering mechanism.

Session: Induced Earthquakes: Source Characteristics, Mechanisms, Stress Field Modeling and Hazards - II

Type: Oral

Date: 5/1/2024

Presentation Time: 11:30 AM (local time)

Presenting Author: Rosamiel

Student Presenter: Yes

Invited Presentation: 

Authors