ORCID Profile
0000-0003-2033-2793
Current Organisation
Nanyang Technological University
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Publisher: American Geophysical Union (AGU)
Date: 07-02-2021
DOI: 10.1029/2020GL090853
Abstract: P‐wave azimuthal anisotropic tomography reveals that the July 6, 2019 M w 7.1 Ridgecrest earthquake occurred in a region with clockwise crustal rotation. The rotation together with the sinistral slip on the Garlock Fault is a response to the northwest‐trending, dextral shear within the Eastern California Shear Zone due to the relative motion between the Pacific and North America Plates. The hypocentral area of the Ridgecrest mainshock is characterized by a sharp lateral velocity contrast which has a reversal in contrast polarity at about 5 km depth. We find high Vp/Vs ratio structures covering the rupture zones of the M w 6.4 foreshock and the M w 7.1 mainshock, which may indicate the existence of fluids in the fault zones. We speculate that fluids and crustal rotation may have played important mechanical roles in causing the 2019 Ridgecrest earthquake sequence.
Publisher: Seismological Society of America (SSA)
Date: 28-03-2022
DOI: 10.1785/0220210292
Abstract: Myanmar occupies a complex region in the active Indo-Burma subduction system. To illuminate the upper 10 km crustal structure of central Myanmar and obtain new insight into the subduction system, we jointly use P-wave polarizations and receiver functions (RFs) to construct a high-resolution VS profile based on a Bayesian Markov chain Monte Carlo approach. This obtained profile clearly delineates six tectonic units and their boundaries, including the Indo-Burman ranges (IBR), the IBR-fore-arc basin boundary, the fore-arc basin, the volcanic arc, the back-arc basin, and the Sunda plate. The Sunda plate has relatively higher upper crustal VS (& .0 km/s) and thinner sedimentary cover (∼1 km) compared with the Central Myanmar basin in the Burma plate. The fore-arc basin, containing thick sediments (& km), and the back-arc basin, with thinner sediments (∼1–6 km), are separated by a region with higher VS (∼3.0 km/s), which represents crystallized magma beneath the volcanic arc. A narrow zone of relatively high-VS (∼2.6–2.7 km/s) ophiolites is situated between the fore-arc basin and the IBR. We also find a narrow zone of high-VS (∼2.9 km/s) metamorphic rocks contained within the low-VS (≲2.3 km/s) IBR. This study suggests that the proposing joint inversion of two types of single-station measurements, that is, P-wave polarizations and RFs, can robustly and computationally efficiently image the shallow VS structure and provide a reliable uncertainty estimation.
Publisher: Wiley
Date: 19-12-2021
Publisher: Elsevier BV
Date: 05-2022
Publisher: Wiley
Date: 22-03-2022
Publisher: American Geophysical Union (AGU)
Date: 02-2022
DOI: 10.1029/2021JB023033
Abstract: The Moho discontinuity plays an important role in crustal growth and evolution. In this study, we delineate the Moho geometry in southern California by jointly using local Moho‐reflected waves PmP and teleseismic Moho‐converted waves Ps. To well constrain the Moho geometry, we have developed a two‐stage process to pick PmP waves and have created a reliable PmP travel time data set with a total of 10,192 picks. We have also extracted 38,648 high‐quality P‐wave receiver functions (RFs). The Moho depth is initially estimated via the common conversion point (CCP) stacking of RFs and then refined by inverting the PmP travel time data in a community velocity model (CVM‐H, version 15.1.1). The newly built Moho geometry is generally consistent with the California Moho Model version 1.0 (CMM‐1.0), that is, a shallow Moho beneath the Salton Trough (23 km), a uniformly shallow Moho beneath the Mojave Desert and the Basin and Range ( km), and a sliver of deep Moho under the western Peninsular Ranges, the eastern Transverse Ranges, and the western Sierra Nevada ( km). However, our Moho model reveals some new features different from the CMM–1.0, such as a deep Moho (∼34 km) beneath the northern end of the central and western Transverse Ranges, consistent with the observation of deep seismicities due to a thick brittle crust there. We also find a gradual transition from the lower crust to the uppermost mantle beneath the western Peninsular Ranges, leading to the rareness of pickable PmP waves as well as weak Moho‐converted signals there.
Publisher: American Geophysical Union (AGU)
Date: 06-2022
DOI: 10.1029/2021JB023582
Abstract: The magma plumbing in the lower crust beneath the Coso volcanic field (CVF) remains controversial, largely because of the absence of high‐resolution lower crustal velocity models. For the first time, we develop a high‐resolution crustal P‐wave velocity model for the Coso‐Ridgecrest region by jointly inverting 137,992 first P and 8,636 PmP travel‐time data using an eikonal equation‐based seismic reflection tomography method. More than half of the PmP travel times are picked from earthquakes after the 2019 M w 7.1 Ridgecrest earthquake. Such abundant PmP travel times significantly improve the resolution of the lower crust. Our final velocity model reveals a prominent low‐velocity body sitting right beneath the CVF at 5–20 km depths, which we interpret as a rhyolite magma reservoir that supplies heat flux to the hot springs and also feeds the volcanic activities at Coso. We find that the upper‐middle crustal low‐velocity body dips southwards into the lower crust, extending to regions beneath the Indian Wells Valley and the Garlock Fault at depth greater than 20 km. We ascribe the lower crustal low‐velocity body (more than 4% Vp reduction) to a basaltic magma reservoir that connects the melts in the uppermost mantle with the eruptible rhyolitic reservoir at shallower depths. The basaltic magma reservoir constitutes an important part of a continuous N‐S elongated crustal magma plumbing system beneath the CVF, formed as a combined result of local extension, faulting, and stress distribution.
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