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Aseismic Deformation During the 2014 M w 5.2 Karonga Earthquake, Malawi, From Satellite Interferometry and Earthquake Source Mechanisms
Author(s) -
Zheng Whyjay,
Oliva Sarah Jaye,
Ebinger Cynthia,
Pritchard Matthew E.
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl090930
Subject(s) - geology , seismology , aftershock , rift , slip (aerodynamics) , deformation (meteorology) , paleoseismology , tectonics , crust , interferometric synthetic aperture radar , geophysics , synthetic aperture radar , oceanography , physics , thermodynamics , remote sensing
Aseismic deformation has been suggested as a mechanism to release the accumulated strain in rifts. However, the fraction and the spatial distribution of the aseismic strain are poorly constrained during amagmatic episodes. Using Sentinel‐1 interferograms, we identify the surface deformation associated with the 2014 M w 5.2 Karonga earthquake, Malawi, and perform inversions for fault geometry. We also analyze aftershocks and find a variety of source mechanisms within short timescales. A significant discrepancy in the earthquake depth determined by geodesy (3–6 km) and seismology (11–13 km) exists, although both methods indicate M w 5.2. We propose that the surface deformation is caused by aseismic slip from a shallow depth. This vertical partitioning from seismic to aseismic strain is accommodated by intersecting dilatational faults in the shallow upper crust and sedimentary basin, highlighting the importance of considering aseismic deformation in active tectonics and time‐averaged strain patterns, even in rifts with little volcanism.