Repeating earthquake behavior due to fluid circulation through tough-biem simulation.

Hideo Aochi (1) , Farid Smaï (1) , Jonny Rutqvist (2)

1 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
2 LBNL - Lawrence Berkeley National Laboratory [Berkeley]

We carry out TOUGH-BIEM simulations for modeling fault slip behavior triggered by fluid circulation in a geothermal context. The TOUGH2 code is used for modeling the pore pressure evolution within a fault and then a boundary integral equation method is applied for simulating fault slip, including aseismic slip on the entire fault plane and fast slip on seismogenic asperities. It is assumed that Coulomb friction and a slip-strengthening-then-weakening friction govern the fault slip. The pore pressure change due to injection is increasing logarithmically (fast at the beginning and later slow) so that the induced aseismic slip is fast at the beginning and slows down later. The fault slip on the asperities are periodic, and its recurrence depends on the previous aseismic slip in surrounding fault areas. When the two asperities are separated, their behavior is independent. When they are close each other, the recurrence timing of each asperity is disturbed. This feature is consistent with repeating earthquakes observed associated with geothermal stimulation experiments. The configuration of this study is simple for our demonstration, but the combination of TOUGH2-BIEM simulation would allow for studies of complex seismic fault behavior in different geological applications of fluid injections.

Domaines: Géophysique [physics.geo-ph]

Hideo Aochi, Farid Smaï, Jonny Rutqvist. Repeating earthquake behavior due to fluid circulation through tough-biem simulation.. TOUGH Symposium 2018, Oct 2018, Berkeley, CA, United States. ⟨hal-01823547⟩