Potential Volcano‐Tectonic Origins and Faulting Mechanisms of Three Low‐Frequency Marsquakes Detected by a Single InSight Seismometer

Abstract

AbstractUtilizing low‐frequency events reported by the Marsquake Service (MQS), we selected waveform data collected from the InSight mission to characterize the origins of three potential marsquakes. S0173a and S0235b were determined to originate near the Cerberus Fossae region. Our calculated backazimuths and epicentral distances were in agreement with those provided by the InSight team. The third event, S0325ab, likely originated southeast of the lander with an epicentral distance of 38.4°, uniquely placing it near the boundary between the Martian highlands and lowlands. We then estimated potential double‐couple faulting mechanisms associated with each of the marsquakes using the relative amplitudes and polarities of the P, SH, and SV waves, in a novel method. S0173a and S0173ab can be explained with a composite mechanism that begins as a thrust faulting, followed by an oblique normal‐faulting mechanism. Given the low level of seismicity on Mars, it is likely that these events did not occur independently but instead form a doublet resulting from a single origin. Though its weaker, S0325a and S0325ab could also represent a doublet that begins with E‐W extension and ends with N‐S extension. Our preferred explanation for S0235b is a single faulting mechanism representing vertical dip‐slip with a small normal‐faulting component. The strike of one fault plane aligns roughly with the exposed faults that represent the Cerberus Fossae. We propose that these diverse faulting mechanisms from different locations represent intra‐crustal deformation in the form of volcano‐tectonic quakes related to magmatic activity, including possible dike propagation in the lower crust.