Testing the limits of virtual deep seismic sounding via new crustal thickness estimates of the Australian continent

Abstract

We apply virtual deep seismic sounding (VDSS) to data collected from both permanent and temporary seismic stations in Australia with the goal of examining (i) the resilience of the method to the presence of complex lithospheric structure, and (ii) the effectiveness of different approaches for estimating bulk crustal properties (namely thickness and Vp). Data from the permanent WRAB in the Northern Territory station is ideal for benchmarking VDSS (large number and favourable distribution of recorded earthquakes), with the results from several approaches agreeing on a thickness of 40-42 km. Application of VDSS to data from the temporary BILBY array, a linear distribution of broadband stations that traverses central Australia, shows that strong Moho reflections can be retrieved with as few as two earthquakes even at the transition between crustal blocks of different character and in the presence of thick sedimentary basins. Crustal thickness varies between 36-54 km and compare well with the reflectivity character of nearby deep seismic reflection lines. Furthermore, we find that off-line estimates of crustal thickness, calculated by binning the source regions according to back-azimuth, produce estimates of crustal thickness that are consistent with the regional geology. Overall, we find that VDSS is a powerful technique for estimating crustal thickness and velocity due to its insensitivity to complex short-wavelength structure and requirement of a small number earthquakes to produce a stable result. However, not all schemes tested for extracting bulk crustal properties appear to be robust and stringent data quality checking is still required during implementation.

Constraining Crustal Properties With Bayesian Joint Inversion of Vertical and Radial Teleseismic P‐Wave Coda Autocorrelations

“…We also image such a Moho offset from station BL09 to stations BL08 and BL07. This is also consistent with results obtained with the virtual deep seismic sounding method (Thompson et al., 2019). Since our approach relies on the 1‐D Earth assumption, any existing crustal‐scale fault cannot be clearly imaged when creating a pseudo 2‐D profile by interpolation of the 1‐D structures.…”

“…Recently, several studies have discussed the crustal structure of central Australia using either passive seismic data recorded by the stations along the BILBY experiment (Sippl, 2016; Thompson et al., 2019), or deep seismic reflection data. Geoscience Australia conducted several deep seismic sounding profiles with 20 s recording time across Australia (Kennett & Saygin, 2015; Kennett et al., 2016) to better map the crustal structure and geodynamic evolution of the major geological provinces of Australia.…”

Crustal Structure of the UAE‐Oman Mountain Range and Arabian Rifted Passive Margin: New Constraints From Active and Passive Seismic Methods

“…This allowed us to account for all seismic events within the SsPmp epicentral distance limits, regardless of their focal depths. Therefore, we calculate the angle necessary to rotate the vertical and radial component traces into pseudo-S component using the ak135 (see Thompson et al, 2019;Yu et al, 2013). These are then deconvolved from the vertical and radial component VDSS traces using an extended-time multitaper approach (10 s sliding window, 75% window overall, 3 Slepian tapers; Helffrich, 2006 (i.e., no ringing or unwarranted oscillatory signal); iii) evidence of a prominent pulse associated with the SsPmp arrival time, and those corresponding to the precursory Sp and reverberatory SsPmsPmp phases.…”

Crustal structure of the UAE-Oman mountain range and Arabian rifted passive margin: new constraints from active and passive seismic methods

“…This allowed us to account for all seismic events within the SsPmp epicentral distance limits, regardless of their focal depths. Therefore, we calculate the angle necessary to rotate the vertical and radial component traces into pseudo-S component using the ak135 (see Thompson et al, 2019;Yu et al, 2013). These are then deconvolved from the vertical and radial component VDSS traces using an extended-time multitaper approach (10 s sliding window, 75% window overall, 3 Slepian tapers; Helffrich, 2006).…”