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Seismicity and Structure of SW Australia via the SWAN and Western Australia Seismic Networks

Description: 

The South-West region of Australia is the country’s most seismically active zone and has experienced ~20 M5+ events in the last 50 years, including the most damaging event in Australian history (1968 M6.8 Meckering). It is also privy to numerous seismic swarms, including a year-long event which began in early 2022, captured by the new SWAN network (2P, 2020-2023). As SW Australia is far from any plate boundary, there is no obvious explanation for the frequent shallow intra-continental earthquakes here which mostly occur within the Archean-aged Yilgarn Craton. This area has recently been examined by the 27 broadband stations (SWAN) as well as 130 stations across the ambitious new WA-Array rolling network (XO, 2022-2032) which has a linear array geometry with 40 km station spacing. Between 2020-2023 over 10,000 earthquakes have been located using a Machine Learning phase picker (e.g. EQTransformer, Mousavi et al. 2020), event associator (e.g. REAL, Zhang et al. 2019) and locator (e.g. NonLinLoc, Lomax et al. 2000). These events have been used to derive regional body wave velocity models, centroid moment tensors, and estimated Greens Functions between each station pair have also been used to create an ambient noise velocity model. Both models outline the Yilgarn Craton as well as the thick sedimentary deposits of the Perth Basin, west of the Darling Fault. We also imaged a distinct high-velocity fragment in the lower crust along the western margin of Yilgarn Craton, east of the Darling Fault, which may reflect the terrane accretion tectonics. At the time of writing, our results are being integrated with other geophysical and geological information, with the ultimate goal of unveiling the history of Yilgarn and the unusual intra-plate seismicity that has been observed across the oldest craton on Earth.

Session: Tectonics and Seismicity of Stable Continental Interiors - II

Type: Oral

Date: 5/3/2024

Presentation Time: 10:30 AM (local time)

Presenting Author: Robert

Student Presenter: No

Invited Presentation: 

Authors