Finite Fault Inversion of Mw4.1 and its Implications for Induced
Earthquake Ruptures.
Abstract
To better quantify how injection, prior seismicity and fault properties
control rupture growth and propagation of induced earthquakes, we
perform finite-fault slip inversion on a $M_{w}$ 4.1 earthquake
that occurred in April 2015, which is the largest earthquake of an
induced sequence near Guthrie, Oklahoma. The slip inversion reveals a
complex rupture with multiple slip patches that are anti-correlated to
the cumulative slip distributions of prior seismicity. This indicates
that the $M_{w}$ 4.1 earthquake likely ruptured relatively strong
asperities, while earlier seismicity driven by pore pressure occurred in
weaker area. Compared to similar magnitude events in swarms from other
regions, intraplate earthquakes in Oklahoma have higher number of well
separated slip patches, indicating a difference in fault characteristics
between regions. These observations suggest that both pore pressure
perturbations, earthquake interactions, and fault characteristics
control rupture propagation in moderate size earthquakes in Oklahoma,
with the latter likely the dominant factor.