Skip to main content
U.S. flag

An official website of the United States government

Subduction megathrust heterogeneity characterized from 3D seismic data

April 20, 2020

Megathrust roughness and structural complexity are thought to be controls on earthquake slip at subduction zones because they result in heterogeneity in shear strength and resolved stress. However, because active megathrust faults are difficult to observe, the causes and scales of complexity are largely unknown. Here we measured the in situ properties of the megathrust of the Middle America subduction zone in a three-dimensional seismic reflection volume to determine how fault properties vary. We quantify spatial variability in the megathrust roughness, overburden and rock physical properties. Heterogeneity in the megathrust roughness exists at length scales of a few kilometres because the megathrust is dissected by active lower-plate normal faults, which offset the megathrust and renewed fault roughness. Spatial variations in the rock physical properties at the plate interface are characterized by correlation length scales of hundreds of metres. Frontal prism taper, historical seismicity and the variation in earthquake stress drop values local to the megathrust are all affected by the heterogeneity at these length scales. Both geometric and rheological complexities may therefore control the mechanical behaviour of the subduction plate interface, which includes earthquake rupture characteristics.

Publication Year 2020
Title Subduction megathrust heterogeneity characterized from 3D seismic data
DOI 10.1038/s41561-020-0562-9
Authors James D. Kirkpatrick, Joel H. Edwards, Alessandro Verdecchia, Jared W. Kluesner, Rebecca M. Harrington, Eli Silver
Publication Type Article
Publication Subtype Journal Article
Series Title Nature Geoscience
Index ID 70210970
Record Source USGS Publications Warehouse
USGS Organization Pacific Coastal and Marine Science Center