Earthquake Activity in Northern Cascadia Subduction Zone Off Vancouver Island Revealed by Ocean-Bottom Seismograph Observations.

Obana, K., Scherwath, M., Yamamoto, Y., Kodaira, S., Wang, K., Spence, G., Riedel, Michael and Kao, H. (2015) Earthquake Activity in Northern Cascadia Subduction Zone Off Vancouver Island Revealed by Ocean-Bottom Seismograph Observations. Bulletin of the Seismological Society of America, 105 (1). pp. 489-495. DOI 10.1785/0120140095.

[img] Text
Obana.pdf - Published Version
Restricted to Registered users only

Download (732Kb) | Contact

Supplementary data:

Abstract

Offshore seismicity at the Cascadia margin is poorly constrained because nearly all previous recordings of earthquakes were made using land‐based networks. We conducted earthquake monitoring off Vancouver Island in northern Cascadia using ocean‐bottom seismographs. Our results show that most of the offshore seismicity is concentrated along the Nootka fault zone. Otherwise seismicity is extremely low, with no earthquakes located along the shallow, seismogenic part of the megathrust. The lack of interplate seismicity may indicate complete healing and locking of the megathrust over three centuries after the great earthquake of 1700 and a somewhat lower degree of structure heterogeneity, such as subducting seamounts. Events along the Nootka fault zone occur over a 10–15 km depth range. This wide distribution and the previously reported overall moment release rate suggest that a significant part of deformation of this fault zone is aseismic. Several earthquakes beneath the continental shelf may be related to faults dividing tectonic terrains within the overriding plate.

Document Type: Article
Additional Information: Data and Resources: Seismograms used in this study were collected with Ocean-Bottom Seismographs of Japan Agency for Marine- Earth and Science (JAMSTEC) and onshore routine stations operated by the Canadian Hazard Information Service, Natural Resources Canada, as a part of Canadian National Seismograph Network (CNSN). Hypocenter catalog and seismograms of CNSN can be accessed at http://www.earthquakescanada .nrcan.gc.ca (last accessed February 2014). Figures were made using the Generic Mapping Tools version 4.5.9 (https://www .soest.hawaii.edu/gmt/; last accessed October 2014).
Keywords: Cascadia margin ; earthquake activity ; seismicity
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1785/0120140095
ISSN: 0037-1106
Date Deposited: 05 Oct 2015 07:45
Last Modified: 05 Oct 2015 07:46
URI: http://oceanrep.geomar.de/id/eprint/29904

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...