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As a sseismologist, I specialize in exploring large datasets and using novel methods to explore planetary interiors. I have developed and applied innovative tools to scan planetary interiors, such as crustal and mantle structures. More information can be found on my Homepage.
3D Crustal Structure of the Yunnan, China Region Revealed by Adjoint Inversion of Frequency-dependent Traveltimes
3D Crustal Structure of the Yunnan, China Region Revealed by Adjoint Inversion of Frequency-dependent Traveltimes
We conduct a high-resolution seismic tomography for the crustal P and S-wave velocities of the Yunnan region in southwestern China. Waveforms recorded at 128 broadband stations from 131 regional earthquakes of moment magnitudes 3.9−5.5 occurring between 2009 and 2021 are used to obtain traveltime residuals by the cross-correlation between records and synthetics. Using the regional community velocity model SWChinaCVM‐1.0 as the initial model, we carry out a three-stage iterative adjoint tomography, progressing from the longer period band of 50–20 s to shorter-period bands of 30–10 s and 30–5 s. The final model, obtained after a total of 53 iterations, has vertically variable resolutions for both P and S waves: ~30 km for P wave and ~20 km for S wave in the shallow crust (5–10 km), and ~50 km and ~40 km for P and S waves in the lower crust. Our model shows general consistency in the spatial patterns of P- and S-wave velocity anomalies. However, different strengths of P- and S-wave anomalies result in complex spatial variation in the Vp/Vs ratio. Widespread low-velocity anomalies with high-Vp/Vs ratios in the mid and lower crust in the region suggest a mix of weak materials of the mid-lower crustal flow from under the Tibetan Plateau with hot materials of the upwelling from the deep mantle plume that led to the Emeishan Large Igneous Province. Localized velocity and Vp/Vs ratio anomalies also reveal that the Lijiang-Xiaojinhe Fault Zone appears to be confined in the upper crust, while the Anninghe-Zemuhe Fault Zone and the Xiaojiang Fault Zone are both whole-crust structures reaching the Moho interface. The Red River Fault Zone, also a whole-crust fault, marks the boundary between the Yangtze Craton on the northeast side, having lower P and S velocities and the Indo-China Block on the southwest side, having higher P and S velocities. The main fault zones, the decoupling between the crustal and uppermost mantle parts, and the wide-spreading weak mid-lower crustal materials mutually interact, all contributing to the tectonic evolution of the entire region.
Developing the first 3D velocity structure model for the Macquire Ridge Complex
Developing the first 3D velocity structure model for the Macquire Ridge Complex
By collaborating with researchers from University of Cambridge, California Institute of Technology, Nanyang Technological University, University of Maine, University of Tasmania and Woods Hole Oceanographic Institution, we develop the first 3D seismic velocity model for the lithosphere of the Macquire Ridge Complex (MRC). MRC evolved from a spreading mid-ocean ridge and is dominated by a transpressional plate boundary. This unique ridge is composed entirely of oceanic crust and upper mantle rocks and has the most significant underwater strike-slip events on the planet occurring in the region, and the grand question of the possibility of incipient subduction, studying the deep structures in this region will not only be beneficial to the tsunami disaster mitigation and prevention for the Australian coast but only contribute to the understanding of the evolution of the solid Earth.
This study is the first journal contribution from research on the waveform dataset recorded by a temporary network of ocean-bottom seismometers (OBSs) our team deployed in the Furious Fifties near Macquarie Island during 2020–2021. Our study uses full-waveform ambient noise tomography to develop a 3-D S-wave velocity model for the crust and uppermost mantle of the central Macquarie Ridge Complex. To date, attempts to use a model that includes a water layer to undertake full waveform tomography are rare. It is one of the pioneering full-waveform inversion papers that includes a water layer. It is also a pioneering attempt to study the 3-D S-wave velocity structure of the crust and uppermost mantle along the entire ~1500-km-long MRC.
Our analysis reveals prominent high S-wave velocity anomalies along the central Macquarie segment. These high S-wave velocity anomalies may suggest the presence and distribution of deep-seated upper mantle rock in the crust, indicating that the lithosphere in this region has not been substantially reworked during obduction and incorporation within an orogenic belt.
Developing the first Lg-wave attenuation model for the crust of the whole Australian continent
Developing the first Lg-wave attenuation model for the crust of the whole Australian continent
We use Lg-waves recorded on vertical components by seismic stations deployed across and around the Australian continent to construct a high-resolution seismic attenuation model for the entire Australian crust, across multiple frequency bands. This crustal attenuation model not only offers an innovative approach to simulating high-frequency ground motion generated by earthquakes anywhere on the Australian continent, which has significant meaning for the construction of low-rise buildings, but it also addresses a long-standing geological question regarding the existence of the Tasman Line—an important feature tied to the formation mechanisms of the Australian continent. Our new model reveals a clear boundary between the eastern and western parts of the Australian continent, thereby confirming the existence of the Tasman Line and providing valuable insights into the ongoing evolution of Australia in response to tectonic plate movements
Exploring the uppermost mantle structure of the Australian continent
Exploring the uppermost mantle structure of the Australian continent
We use a large dataset of Sn-wave traveltimes to perform a tomographic inversion of the 3D velocity structure in the uppermost mantle beneath the entire Australian continent. To address the challenge of inaccurate travel-time picking caused by the influence of P-coda waves, we develop and apply an innovative method for reliably identifying the onsets of Sn waves in this research. Based on this high-resolution S-wave velocity model, we identify several regions of extremely low wave speed along the entire eastern coastline, which may indicate remnants of a mantle plume in the uppermost mantle. These low-velocity anomalies are closely associated with the distribution of volcanoes along the coast, providing valuable insights into the geological evolution of the Australian continent.
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