Western US seismicity shake-up
Embargo
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London: Wednesday 26 August 2015 18:00 (BST)
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Sydney: Thursday 27 August 2015 03:00 (AEST)
A potential explanation for the longstanding question of why certain earthquakes occur away
from tectonic plate boundaries is proposed in a paper published in this week’s Nature. The study
suggests that such intraplate earthquakes are linked to convection currents beneath the crust of
the Earth, as part of a process known as mantle flow.
In the western United States, intraplate earthquake activity is concentrated in a region running
north to south known as the intermountain belt. Thorsten Becker and colleagues use recent
models of mantle flow computed from seismic waves to predict the spatial distribution of seismic
activity in this belt. Their results show that changes in surface topography generated by the
movement, or convection, of material within the mantle — specifically, active mantle upwelling —
are likely to contribute to causing the earthquakes.
The study presents a way of analysing seismic data that can potentially be applied to other areas
affected by continental deformation. The results highlight the key role of mantle flow in shaping
surface topography, which in turn leads to deformation and earthquake activity within tectonic
plates, and couldhave important implications for the study of earthquakes and associated
hazards in these intraplate settings.
Article and author details
1. Western US intermountain seismicity caused by changes in
upper mantle flow
Corresponding Author
Thorsten Becker
University of Southern California, Los Angeles, California, United States
Email: twb@usc.edu, Tel: +1 213 740 8365
DOI
10.1038/nature14867
Online paper*
http://nature.com/articles/doi:10.1038/nature14867
* Please link to the article in online versions of your report (the URL will go live after the embargo ends).