A Transient in Surface Motions Dominated by Deep Afterslip Subsequent to a Shallow Supershear Earthquake

A Transient in Surface Motions Dominated by Deep Afterslip Subsequent to a Shallow Supershear Earthquake: The 2018 M_w7.5 Palu Case

Nijholt, N. (TU Delft Astrodynamics & Space Missions; TU Delft Physical and Space Geodesy)
Simons, W.J.F. (TU Delft Astrodynamics & Space Missions)
Efendi, J. (Geospatial Information Agency)
Sarsito, D. A. (Institute of Technology Bandung)
Riva, R.E.M. (TU Delft Physical and Space Geodesy)

2021

The 2018 (Formula presented.) Palu earthquake is a remarkable strike-slip event due to its nature as a shallow supershear fault rupture across several segments and a destructive tsunami that followed coseismic deformation. GPS offsets in the wake of the 2018 earthquake display a transient in the surface motions of northwest Sulawesi. A Bayesian approach identifies (predominantly aseismic) deep afterslip on and below the coseismic rupture plane as the dominant physical mechanism causing the cumulative, postseismic, surface displacements whereas viscous relaxation of the lower crust and poro-elastic rebound contribute negligibly. We confirm a correlation between shallow supershear rupture and postseismic surface transients with afterslip activity in the zone below an interseismically locked fault plane where the slip rate tapers from zero to creeping.

afterslip
Bayesian inference
GPS
postseismic deformation
strike-slip fault
Sulawesi

http://resolver.tudelft.nl/uuid:4798aaa4-bf4b-46e3-84e2-de4183fdc794

https://doi.org/10.1029/2020GC009491

1525-2027

G3: Geochemistry, Geophysics, Geosystems: an electronic journal of the earth sciences, 22 (4)

Institutional Repository

journal article

© 2021 N. Nijholt, W.J.F. Simons, J. Efendi, D. A. Sarsito, R.E.M. Riva