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Abstract The upper mantle and transition zone beneath Antarctica and the surrounding oceans are among the poorest‐imaged regions of the Earth's interior. Over the last 15 years, several large broadband regional seismic arrays have been deployed, as have new permanent seismic stations. Using data from 297 Antarctic and 26 additional seismic stations south of ~40°S, we image the seismic structure of the upper mantle and transition zone using adjoint tomography. Over the course of 20 iterations, we utilize phase observations from three‐component seismograms containingP,S, Rayleigh, and Love waves, including reflections and overtones, generated by 270 earthquakes that occurred from 2001–2003 and 2007–2016. The new continental‐scale seismic model (ANT‐20) possesses regional‐scale resolution south of 60°S. In East Antarctica, thinner continental lithosphere is found beneath areas of Dronning Maud Land and Enderby‐Kemp Land. A continuous slow wave speed anomaly extends from the Balleny Islands through the western Ross Embayment and delineates areas of Cenozoic extension and volcanism that span both oceanic and continental regions. Slow wave speed anomalies are also imaged beneath Marie Byrd Land and along the Amundsen Sea Coast, extending to the Antarctic Peninsula. These anomalies are confined to the upper 200–250 km of the mantle, except in the vicinity of Marie Byrd Land where they extend into the transition zone and possibly deeper. Finally, slow wave speeds along the Amundsen Sea Coast link to deeper anomalies offshore, suggesting a possible connection with deeper mantle processes.
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P-Wave Arrival-Time Tomography of the Middle East Using ISC-EHB and Waveform Data
High-resolution seismic images are essential to gain insights into tectonic and geodynamical processes and assess seismic hazards. We constructed a P-wave model, MEPT (Middle East P-wave Travel-time), of the upper mantle beneath the Middle East and the surrounding region, which has a complex tectonic and geological history embodying various plate boundaries such as spreading ridges, subduction, suture zones, and strike-slip faults causing destructive earthquakes, specifically in Iran, Caucasus and Anatolia, and active volcanism. We use data from the ISC-EHB bulletin and onset-time readings of first-arrival P waves from waveforms recorded in the Arabian Peninsula. The additional onset-time readings from the regional waveform data significantly improve the resolution of the structure underneath the Arabian Peninsula, clearly indicating the boundary between the Arabian platform and the Arabian shield down to about 300 km depth, highlighted by slow and fast wavespeed perturbations in the upper mantle. Consistent with previous studies, we observe the Arabian-Eurasian collision, the Red Sea rifting, the Hellenic Arc, and low-velocity anomalies beneath the lithosphere of the Red Sea and the west of the Arabian shield. Our model supports the connection of the slow wavespeed anomalies in the lithosphere along the Red Sea to the Afar plume and shows evidence for smaller mantle upwellings underneath the Arabian plate and Jordan.
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- PAR ID:
- 10616235
- Publisher / Repository:
- McGill University
- Date Published:
- Journal Name:
- Seismica
- Volume:
- 4
- Issue:
- 1
- ISSN:
- 2816-9387
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.26443/seismica.v4i1.1349
