Analysis of intraplate eathquake dynamics on the North West Shelf Australia: new strike slip focal mechanisms

Victoria Holloway, Myra Keep

Research output: Chapter in Book/Conference paperConference paper

Abstract

The recent 6.6 Mww magnitude earthquake on the North West Shelf of Australia (14 July 2019), and its dozens of aftershocks, including three of magnitude 5 and above, highlights the need to increase our understanding of earthquake causes and implications in this region. The North West Shelf hosts one of Australia’s most prolific seismic provinces, with over 650 earthquake events recorded since 1970, 170 of them this century alone. Data reduction for earthquake events usually includes epicentre and depth determination, but focal mechanisms, a crucial aspect of tectonic determinations, remain significantly under-represented in seismicity studies for this area. Historically, poor data quality is due to sparse station spacing and large distances between offshore events and seismic recording stations. Prior to this study, results from 1979 to present show only eight published focal mechanism determinations for earthquakes on the North West Shelf for events greater than magnitude 5mb/ML. All showed strike-slip focal mechanism solutions. This paper presents eight new focal mechanism determinations, derived from earthquake events in the Browse and Canning basins. All eight solutions indicate strike-slip focal mechanisms. Our new contribution doubles the available focal mechanism data set for the region, and concludes that with present-day stress orientations the north-western part of Australia is experiencing strike-slip stress conditions, supporting the results of previous seismic and geomorphological studies.
Original languageEnglish
Title of host publicationThe Sedimentary Basins of Western Australia V
Subtitle of host publicationProceedings of the Petroleum Exploration Society of Australia Symposium
Place of PublicationPerth, Australia
PublisherPetroleum Exploration Society of Australia
Number of pages15
Volume5
Publication statusPublished - 2019
EventWest Australian Basins Symposium 2019 - Perth, Australia
Duration: 2 Sep 20195 Sep 2019

Conference

ConferenceWest Australian Basins Symposium 2019
CountryAustralia
CityPerth
Period2/09/195/09/19

Fingerprint

focal mechanism
shelves
slip
earthquakes
earthquake event
canning
stations
depth determination
earthquake
data reduction
earthquake magnitude
earthquake epicenter
aftershock
data quality
analysis
seismicity
tectonics
spacing
recording
causes

Cite this

Holloway, V., & Keep, M. (2019). Analysis of intraplate eathquake dynamics on the North West Shelf Australia: new strike slip focal mechanisms. In The Sedimentary Basins of Western Australia V: Proceedings of the Petroleum Exploration Society of Australia Symposium (Vol. 5). Perth, Australia: Petroleum Exploration Society of Australia.
Holloway, Victoria ; Keep, Myra. / Analysis of intraplate eathquake dynamics on the North West Shelf Australia : new strike slip focal mechanisms. The Sedimentary Basins of Western Australia V: Proceedings of the Petroleum Exploration Society of Australia Symposium. Vol. 5 Perth, Australia : Petroleum Exploration Society of Australia, 2019.
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abstract = "The recent 6.6 Mww magnitude earthquake on the North West Shelf of Australia (14 July 2019), and its dozens of aftershocks, including three of magnitude 5 and above, highlights the need to increase our understanding of earthquake causes and implications in this region. The North West Shelf hosts one of Australia’s most prolific seismic provinces, with over 650 earthquake events recorded since 1970, 170 of them this century alone. Data reduction for earthquake events usually includes epicentre and depth determination, but focal mechanisms, a crucial aspect of tectonic determinations, remain significantly under-represented in seismicity studies for this area. Historically, poor data quality is due to sparse station spacing and large distances between offshore events and seismic recording stations. Prior to this study, results from 1979 to present show only eight published focal mechanism determinations for earthquakes on the North West Shelf for events greater than magnitude 5mb/ML. All showed strike-slip focal mechanism solutions. This paper presents eight new focal mechanism determinations, derived from earthquake events in the Browse and Canning basins. All eight solutions indicate strike-slip focal mechanisms. Our new contribution doubles the available focal mechanism data set for the region, and concludes that with present-day stress orientations the north-western part of Australia is experiencing strike-slip stress conditions, supporting the results of previous seismic and geomorphological studies.",
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Holloway, V & Keep, M 2019, Analysis of intraplate eathquake dynamics on the North West Shelf Australia: new strike slip focal mechanisms. in The Sedimentary Basins of Western Australia V: Proceedings of the Petroleum Exploration Society of Australia Symposium. vol. 5, Petroleum Exploration Society of Australia, Perth, Australia, West Australian Basins Symposium 2019, Perth, Australia, 2/09/19.

Analysis of intraplate eathquake dynamics on the North West Shelf Australia : new strike slip focal mechanisms. / Holloway, Victoria; Keep, Myra.

The Sedimentary Basins of Western Australia V: Proceedings of the Petroleum Exploration Society of Australia Symposium. Vol. 5 Perth, Australia : Petroleum Exploration Society of Australia, 2019.

Research output: Chapter in Book/Conference paperConference paper

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Holloway V, Keep M. Analysis of intraplate eathquake dynamics on the North West Shelf Australia: new strike slip focal mechanisms. In The Sedimentary Basins of Western Australia V: Proceedings of the Petroleum Exploration Society of Australia Symposium. Vol. 5. Perth, Australia: Petroleum Exploration Society of Australia. 2019