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Structural Controls on Induced Earthquake Sequence’s Growth and Slip Behavior

Description: 

To examine how the fault structures within Oklahoma control induced earthquake behavior, we examine both 3D seismic data and seismogenic faults. We utilize the LArge-n Seismic Survey in Oklahoma (LASSO), a dense nodal array with >1800 sensors, to characterize multiple small (<1 km in length) seismogenic faults. The identified faults’ orientations are then compared to the local stress field to determine how their behavior is affected by how well oriented they are in the stress field for failure. The seismogenic faults earthquakes temporal behavior indicates that optimally oriented are driven more often by event-event triggering, while non-optimally oriented faults are driven more often by fluid diffusion. These faults structural behavior mimics what is observed in faults characterized in nearby 3D seismic data and could either represent small isolated faults or small segments of larger complex immature faults. The immature fault structures indicated by both the seismogenic faults and 3D seismic not only affect seismogenic sequence development, but also the slip of larger events that occur on them. To confirm this, we compare slip distributions between low (Oklahoma) and high deformation regions (California). The low deformation regions have more prominent and well separated slip patches, which is a behavior indicative of immature faults. This behavior does not change if the event was induced or not. These observations suggest that the initial underlying stress distribution, strength and orientation of induced faults in low deformation regions are the primary controlling factors of the slip distribution, while the major driving forces of sequence development such as pore pressure perturbations or earthquake interactions play a secondary role.

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

Type: Oral

Date: 5/1/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Colin

Student Presenter: No

Invited Presentation: Yes

Authors