thumbnail

From coseismic offsets to fault-block mountains

Proceedings of the National Academy of Sciences of the United States of America

By:
and ORCID iD
https://doi.org/10.1073/pnas.1711203114

Links

Abstract

In the Basin and Range extensional province of the western United States, coseismic offsets, under the influence of gravity, display predominantly subsidence of the basin side (fault hanging wall), with comparatively little or no uplift of the mountainside (fault footwall). A few decades later, geodetic measurements [GPS and interferometric synthetic aperture radar (InSAR)] show broad (∼100 km) aseismic uplift symmetrically spanning the fault zone. Finally, after millions of years and hundreds of fault offsets, the mountain blocks display large uplift and tilting over a breadth of only about 10 km. These sparse but robust observations pose a problem in that the coesismic uplifts of the footwall are small and inadequate to raise the mountain blocks. To address this paradox we develop finite-element models subjected to extensional and gravitational forces to study time-varying deformation associated with normal faulting. Stretching the model under gravity demonstrates that asymmetric slip via collapse of the hanging wall is a natural consequence of coseismic deformation. Focused flow in the upper mantle imposed by deformation of the lower crust localizes uplift, which is predicted to take place within one to two decades after each large earthquake. Thus, the best-preserved topographic signature of earthquakes is expected to occur early in the postseismic period.

Additional publication details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
From coseismic offsets to fault-block mountains
Series title:
Proceedings of the National Academy of Sciences of the United States of America
DOI:
10.1073/pnas.1711203114
Volume:
114
Issue:
37
Year Published:
2017
Language:
English
Publisher:
The National Academy of the Sciences
Contributing office(s):
Pacific Coastal and Marine Science Center
Description:
6 p.
First page:
9820
Last page:
9825