Renewed Epicentral Distribution of Low Frequency Marsquakes by Varying‐Parameter Polarization Analysis of InSight Data

Abstract

Abstract Accurate information about marsquake locations is crucial for understanding the tectonic activity, subsurface structures, and dynamics of Mars. We designed a varying‐parameter scheme for polarization analysis to determine the back‐azimuths of marsquakes. For two Martian meteorite impact events with ground‐truth locations known from orbital images, our scheme yields back‐azimuths that are ∼5° and ∼14° closer to the true values than those reported previously, demonstrating our method's advantages in constraining back‐azimuths. We applied this method to determine the back‐azimuths of 44 Low Frequency marsquakes and 39 were reliably relocated. Nearly half of these marsquakes occur in Cerberus Fossae, while the rest are broadly distributed, including along the dichotomy boundary and within the northern lowlands and southern highlands. Although further studies are required to understand the mechanisms of these marsquakes, the widespread seismicity implies that present‐day Mars, especially the ancient southern highlands, is more tectonically active than previously thought.

Keywords

• marsquake
• relocation
• back‐azimuth
• polarization analysis
• InSight