Variation of Earthquake Nucleation Length of Injection-induced Seismicity Under the (Aging) Rate and State Friction Law
Description:
Earthquake nucleation length, a critical length characterizing the transition from the quasi-static propagation to the rapid dynamic rupture process of the nucleation zone, is reported to reduce with the elevated loading rate. Recently, laboratory injection experiments showed that injection can also be regarded as a kind of “loading” condition and high-rate injection would reduce the nucleation length of injection-induced seismicity. Motivated by this, in this study, we systematically explored the variation of the nucleation length of injection-induced seismicity under various conditions (different hydraulic diffusivity and injection rate) with the 2D and 3D injection-induced seismic simulations based on the (aging) rate and state friction law. Interestingly, similar to previous work, nucleation regimes of injection-induced seismicity can also be classified into two regimes based on the value of Ω (Ω = Vθ/Dc, i.e. the ratio of the weakening to healing rates) in the center of the nucleation zone. When Ω ≫ 1, or, in the “no-healing” regime, nucleation length seems to be smaller for seismic events associated with higher injection rate or lower hydraulic diffusivity. However, its evolution would be different when the value of Ω is close to 1. When Ω ≅1, or, in the “constant weakening” regime, nucleation length is affected by how long the state of the fault stays in this regime. In our study, the nucleation length is smaller for seismic events related to higher hydraulic diffusivity, and shows no correlation with increasing injection rate (but still smaller than the theoretical upper limit derived based on the fracture energy balance theory). Our study shows the similarity between injection-induced seismicity and natural earthquakes in the nucleation process and preliminarily explains the underlying reason for the variation in nucleation length of the injection-induced seismicity.
Session: Understanding and Managing Induced Seismicity [Poster]
Type: Poster
Date: 4/19/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Xinyu Tan
Student Presenter: Yes
Invited Presentation:
Authors
Xinyu Tan Presenting Author Corresponding Author xy.tan@mail.utoronto.ca University of Toronto |
Semechah K. Y. Lui semechah.lui@utoronto.ca University of Toronto |
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Variation of Earthquake Nucleation Length of Injection-induced Seismicity Under the (Aging) Rate and State Friction Law
Category
Understanding and Managing Induced Seismicity