Complex Source Process of the 2020 Caribbean Earthquake along the Oriente Transform Fault

Abstract:

The large strike-slip earthquake occurred in the Caribbean Sea on January 28, 2020. We inverted the globally observed teleseismic P-waveforms to construct a finite-fault model, by using the newly developed inversion framework to simultaneously resolve spatiotemporal evolution of fault geometry and slip. The model exhibits almost unilateral rupture propagation toward west from the epicenter at fast rupture speed exceeding the local shear-wave velocity along 300 km long within the Oriente transform fault. Our finite-fault model suggests that the 2020 Caribbean earthquake involved a geometric bend in the fault system associated with the bathymetric feature around the source region. The geometric complexity should be the key to trigger multiple rupture episodes and complex rupture evolution. The 2020 Caribbean earthquake exhibits hidden complexity of both the rupture process and fault geometry for the oceanic-transform fault earthquake, which has been through to have a linear fault system and a simple rupture evolution.