Lead supervisor: Nicholas Rawlinson, Earth Sciences
Co-supervisor: Sergei Lebedev, Earth Sciences
Brief summary:
The goal of this project is to image the seismic structure beneath Borneo in order to constrain fundamental properties of its lithosphere, including crustal thickness, depth extent of the mantle lithosphere, and the presence of major anomalies associated with recent tectonic events.
Importance of the area of research concerned:
Indonesia lies at the tectonic boundary between the Australian and Eurasian plates, where it is subject to large and destructive earthquakes that frequently result in significant loss of life and widespread damage to buildings and infrastructure. While the main Sunda Arc separating the Australian and Eurasian plates has been intensively studied, this is less true of the large islands which occupy the backarc region, including Borneo, the third largest Island in the world. Despite its size, even its first-order structure has been poorly constrained by passive seismic methods, due largely to a paucity of data. As a result, basic information about the lithosphere, including crustal thickness and thickness of the underlying mantle lithosphere is poorly known, let alone velocity changes that may be associated with recent tectonic events such as subduction termination and slab break-off. The absence of these basic constraints has lead to differing interpretations on the nature of dynamic topography in the region, and uncertainty as to whether southeast Asia is characterized by a very thin lithosphere, as sometimes inferred from global seismic models.
Project summary :
The aim of the project is to jointly invert ambient noise and regional earthquake surface wave dispersion data together with receiver functions in order to constrain seismic structure across the full thickness of the lithosphere beneath Borneo. Data from temporary and permanent stations in Indonesia and Malaysia will be utilised for this purpose. Due to the irregular distribution of stations, an adaptive parameterisation approach will be adopted via a transdimensional tomography scheme, which is also well suited to the inversion of multiple data types. It may also be feasible to include local and regional earthquake traveltimes, which will need to be extracted from the continuous records. Conversion of the seismic velocities to temperature will allow lithosphere thickness to be constrained, and converted teleseismic phases can also be used to help understand the nature of the LAB.
What will the student do?:
The student will assemble and groom a high quality dataset comprising various seismic data types collected in Borneo from temporary arrays deployed in northern Borneo, Sarawak and Kalimantan. While transdimensional tomography is expected to be the main imaging tool applied to this data, the student may wish to investigate machine learning methods to aid both data processing and inversion. This project would best suit a student with solid computational skills and a willingness to investigate novel methods of seismic tomography. They would also interact with local partners in Indonesia on interpreting the results and writing up papers.
References - references should provide further reading about the project:
Zenonos, A., De Siena, L., Widiyantoro, S. & Rawlinson, N. (2020). Direct inversion of S-P differential arrival times for Vp/Vs ratio in SE Asia. Journal of Geophysical Research, vol 125, e2019JB019152.
Zenonos, A., De Siena, L. D., Widiyantoro, S. & Rawlinson, N. (2019). P and S wave travel time tomography of the SE Asia-Australia collision zone, Physics of the Earth and Planetary Interiors, vol 293, 106267.
Wehner, D., Blom, N., Rawlinson, N., Daryono, , Böhm, C., Miller, M. S., et al. (2022). SASSY21: A 3-D seismic structural model of the lithosphere and underlying mantle beneath Southeast Asia from multi-scale adjoint waveform tomography. Journal of Geophysical Research: Solid Earth, 127, e2021JB022930.
Applying
You can find out about applying for this project on the Department of Earth Sciences page.