Interseismic Strain Rate Evolution From InSAR Prior to the 2021 Mw 7.4
Maduo Earthquake
Abstract
Interseismic deformation and strain rates derived from Global Navigation
Satellite Systems (GNSS) or Interferometric Synthetic Aperture Radar
(InSAR) data are often used to assess earthquake potential. InSAR
measurements require GNSS data to put results into a geodetic reference
frame, posing an issue in regions with limited GNSS data. Deformation
rates are assumed to be indicative of long-term strain accumulation, and
the evolution of strain rate throughout the interseismic period is
poorly studied. We observe the interseismic period prior to the 2021 Mw
7.4 Maduo Earthquake. Using InSAR, we derive eastward velocities and
maximum shear strain rate for three independent time windows to observe
the temporal evolution of strain rate over time, whilst minimising the
influence of near-field GNSS data. We find that strain rate peaks
several years before the earthquake, contrary to recent studies showing
acceleration of strain rate before large earthquakes, which has
implications for earthquake hazard models globally.