Crustal Velocity Structure of the 2013 m7.5 Craig Earthquake Source Region With Joint Ocean-Bottom Seismometer and Streamer Tomography
Description:
Fault damage zones are regions of fractured rock that surround a fault’s main slip interface. Numerical studies show that the presence and depth exent of fault damage zones can influence rupture processes and large, pervasive damage zones may promote complex modes of slip. The Queen Charlotte Fault (QCF), located offshore of southeastern Alaska and western British Columbia, accommodates ~5 cm/yr of right-lateral strike-slip between the Pacific and North American plates along a highly localized fault trace. The QCF has generated several Mw >7 earthquakes in the last century, the most recent being the 2013 Mw 7.5 Craig earthquake. To better understand the structure and material properties of the QCF, including the presence and characteristics of a fault damage zone, we conducted first arrival traveltime tomography with crustal refractions recorded on an ultra-long offset marine seismic streamer and an array of 16 ocean bottom seismometers in the region of the Craig earthquake. Our high-resolution P-wave velocity model constrains the upper crustal structure across the QCF revealing multiple velocity anomalies through the upper seismogenic zone in the Craig earthquake region. A prominent low velocity anomaly lies west of the QCF in the Pacific plate crust, implying past damage in response to oblique collision and flexure. We see no indication of a pervasive damage zone surrounding the main slip interface of the QCF, as is reported in studies at oceanic transform faults that use similar methods. The highly localized nature and lack of an extensive damage zone at the QCF may contribute to large earthquakes.
Session: Structure, Seismicity and Dynamics of the Queen Charlotte-Fairweather Fault System [Poster Session]
Type: Poster
Date: 5/1/2024
Presentation Time: 08:00 AM (local time)
Presenting Author: Emma
Student Presenter: Yes
Invited Presentation:
Authors
Emma Martin Presenting Author Corresponding Author marti435@wwu.edu Western Washington University |
Andrew Gase gasea@wwu.edu Western Washington University |
Emily Roland rolande2@wwu.edu Western Washington University |
Lazaro Garza garzal2@wwu.edu Western Washington University |
Lindsay Lowe Worthington lworthington@unm.edu University of New Mexico |
Olumide Adedji oadedeji@unm.edu University of New Mexico |
Maureen Walton maureen.walton@nrlssc.navy.mil U.S. Naval Research Laboratory |
Mladen Nedimović mladen@Dal.Ca Dalhousie University |
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Crustal Velocity Structure of the 2013 m7.5 Craig Earthquake Source Region With Joint Ocean-Bottom Seismometer and Streamer Tomography
Category
Structure, Seismicity and Dynamics of the Queen Charlotte-Fairweather Fault System