Crustal deformation during earthquake cycles

The Nicoya Peninsula locates directly above the subduction zone interface where the Cocos and Caribbean Plates converge at a rate of approximately 8 cm/yr. The peninsula’s unique location and the presence of a dense operating GPS and seismic network have made it a prime region to study strain accumulation and release at a subduction zone. The Nicoya Peninsula, Costa Rica, was struck by a long-anticipated and gap-filling MW 7.6 earthquake in 2012. To better determine the location and size of locked patches and compare them to the ruptured and slow-slipping regions, we present an interseismic coupling model by integrating both InSAR and GPS data. Even though measuring the deformation on the subduction zone using InSAR is challenging, our study shows InSAR data can be used to recover small, long wavelength deformation signals with refined resolution when integrated with GPS observations. The spatial correlation between the distribution of coupling and the locations of slow slip events and low-frequency events suggests that fluid and frictional heterogeneities may be the two main factors influencing coupling variations on the Nicoya, Costa Rica subduction zone.

Xue, L., S. Schwartz, Z. Liu, and L. Feng (2015), Interseismic megathrust coupling beneath the Nicoya Peninsula, Costa Rica, from the joint inversion of InSAR and GPS data. J. Geophys. Res. Solid Earth, 120, 3707–3722. doi: 10.1002/2014JB011844.