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Observing Slow-Slip Fault-Activation Processes Using DAS

Description: 

Recent models have postulated that aseismic slip could play an important role in the initiation of injection-induced seismicity. Distributed fiber optic sensing, especially distributed acoustic sensing (DAS), is being increasingly used to monitor hydraulic fracturing operations. We show several examples of DAS-recorded M < 2 induced events that show near-field signatures of aseismic slip before or during seismic slip. In one example, we model and interpret a strain pattern observed using DAS at low frequency (< 1 Hz) to represent initial fault tensile opening followed by aseismic shear slip over several hours. In several other cases, low-frequency DAS data indicate aseismic fracture growth that correlates with measured pressure and/or temperature perturbations. In one such case, a M1.8 induced event occurred within the depth range of the aseismic slip, with a time lag of less than one day. Modelling of these signals using a modified displacement discontinuity method is providing new insights into the possible role of aseismic slip in earthquake nucleation following fluid injection.

Session: Understanding Earth Systems with Fiber-optic Cables

Type: Oral

Date: 4/19/2023

Presentation Time: 08:45 AM (local time)

Presenting Author: David W. Eaton

Student Presenter: No

Invited Presentation: 

Authors