Earthquake rupture below the brittle-ductile transition in continental lithospheric mantle

Earthquakes deep in the continental lithosphere are rare and hard to interpret in our current understanding of temperature control on brittle failure. The recent lithospheric mantle earthquake with a moment magnitude of 4.8 at a depth of ~75 km in the Wyoming Craton was exceptionally well recorded a...

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Bibliographic Details
Published in:Science Advances
Main Authors: Prieto, German A., Froment, Berenice, Yu, Chunquan, Poli, Piero, Abercrombie, Rachel
Format: Article in Journal/Newspaper
Language:English
Published: AMER ASSOC ADVANCEMENT SCIENCE 2017
Subjects:
Science & technology
Multidisciplinary sciences
Intraplate earthquakes
Source parameters
Discontinuities
Reassessment
Inversion
Spectra
Stress
Craton
Tibet
Continental lithosphere
Directivity
Earthquake sources
Lithosphere
Rheology
Rupture mechanics
Seismological Facilities for the Advancement of Geoscience and EarthScope
Online Access:https://hdl.handle.net/2144/37782
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000397044000035&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=6e74115fe3da270499c3d65c9b17d654
https://doi.org/10.1126/sciadv.1602642
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Summary:Earthquakes deep in the continental lithosphere are rare and hard to interpret in our current understanding of temperature control on brittle failure. The recent lithospheric mantle earthquake with a moment magnitude of 4.8 at a depth of ~75 km in the Wyoming Craton was exceptionally well recorded and thus enabled us to probe the cause of these unusual earthquakes. On the basis of complete earthquake energy balance estimates using broadband waveforms and temperature estimates using surface heat flow and shear wave velocities, we argue that this earthquake occurred in response to ductile deformation at temperatures above 750°C. The high stress drop, low rupture velocity, and low radiation efficiency are all consistent with a dissipative mechanism. Our results imply that earthquake nucleation in the lithospheric mantle is not exclusively limited to the brittle regime; weakening mechanisms in the ductile regime can allow earthquakes to initiate and propagate. This finding has significant implications for understanding deep earthquake rupture mechanics and rheology of the continental lithosphere. G.A.P. and P.P. was supported by the NSF (grant EAR-1521534). Incorporated Research Institutions for Seismology (IRIS) Data Services were funded through the Seismological Facilities for the Advancement of Geoscience and EarthScope proposal under the NSF cooperative agreement (EAR-1261681). (EAR-1521534 - NSF; EAR-1261681 - Seismological Facilities for the Advancement of Geoscience and EarthScope proposal under the NSF cooperative agreement) Published version

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