Yunyue Elita Li
Yunyue Elita Li joined the Department of Earth, Atmospheric, and Planetary Science at Purdue University as a Mary J. Elmore New Frontiers Associate Professor in Data Science in August 2021. Before that, she worked in the Department of Civil and Environmental Engineering at the National University of Singapore as an assistant professor since 2016. Elita did her postdoctoral research at the Massachusetts Institute of Technology, holding a joint position in the Earth Resources Laboratory and the Department of Mathematics. She received her PhD and M.S. degrees in Geophysics from Stanford University in 2014 and 2010, respectively. She obtained her B.S. degree in Information and Computational Science from China University of Petroleum, Beijing in 2008. Elita’s research group works on geophysical applications in urban environments for smart cities and sustainable developments. By integrating geophysical inversion techniques, ambient noise data analysis, and distributed sensor networks, her group focuses its research efforts on the development of non-invasive, high-resolution, and real-time systems to solve pressing challenges in space, water, security, and sustainability. Elita was the recipient of the J. Clarence Karcher Award from SEG in 2018 and was nominated as the SEG South & East Asia Honorary Lecturer for 2022.
2022 SEG Honorary Lecturer, South & East Asia
Listening to Singapore: Harvesting urban noise for space, water, and hazard mitigation
Today, more than half of the world's population lives in urban areas with a projected growth to over two-thirds in 2050. The city-state of Singapore faces the challenges of supporting a sustainable urban system with a growing population in a limited land, sea, and air space. The only direction to develop is toward the subsurface. Conventional geophysical methods are not applicable because of their disruptions to urban activities, a deteriorated performance due to strong anthropogenic interference, and unsatisfying spatial and temporal resolution. In this seminar, we present recent advances in passive sensing to harvest the urban noise from traffic, construction, and ocean waves with small, dense arrays. We design novel signal processing techniques that turn urban hum into rich information of the urban system, both above and below the surface. The resulting meter-scale spatial resolution and minute-scale temporal resolution are the cornerstones to meeting engineering demands in urban environments. We present newly-developed fiber sensing technology using existing dark fiber infrastructure that has the potential to enable a million-sensor system underneath each major city around the globe. Applications of these techniques in shallow bedrock mapping, deep aquifer identification, and near-surface monitoring for geohazards provide the opportunity for geophysicists to contribute directly to urban society in planning, managing, and monitoring its space, water, infrastructure, and other resources.
A recording of the lecture is available.
Biography Citation for the SEG 2018 J. Clarence Karcher Award 
by Arthur Cheng
I first met Elita at the end of August 2014 when she started her postdoctoral work at the Earth Resources Laboratory at the Massachusetts Institute of Technology (MIT), having graduated from Stanford. I learned then that she had turned down more lucrative job offers from the industry and wanted to stay in academics, and I invited her to apply for a position at the National University of Singapore (NUS). Her performance during the job interview was impressive because of her ability to explain highly technical content to engineers who had not heard of geophysics before. Subsequently, she was offered a position and joined NUS as an assistant professor in July 2016.
Elita's doctoral research was most recognized for her vision of tying various measurements and characterizations of the earth's subsurface through a well-defined common rock physics model. She designed an integrated inversion scheme that simultaneously honors geologic prior knowledge, seismic data, and rock physics models. In her thesis, she applied this inversion method to a Gulf of Mexico data set and obtained better vertical symmetry axis (VTI) models as well as better-focused seismic images. Her efforts in closing the loop from seismic imaging to earth model building were highly praised by the geophysical community. Her thesis work was highlighted by Sam Gray in his “Recent advances and road ahead” presentation at the 2014 SEG Annual Meeting. Her paper, “Integrated VTI model building with seismic, geological and rock physics data: Part I — Theory and synthetic examples,” won Honorable Mention for Best Paper in Geophysics in 2016. This framework is suitable in a multitude of applications in many industries and is truly translational.
During her postdoctoral research, Elita significantly broadened her horizons by working with Professor Laurent Demanet in the Department of Mathematics at MIT. To solve the fundamental problem of lacking low-frequency data for full-waveform inversion, she investigated the smooth nature of the phase function of an individual seismic event. This simple yet powerful formulation of an event separation problem enables frequency extrapolation beyond the recorded bandwidth. In particular, the extrapolated low frequencies could potentially solve the cycle-skipping problem that severely jeopardizes the practical applications of full-waveform inversion. Her presentation on “Extrapolated full-waveform inversion with synthesized low-frequency data” was ranked in the top 30 papers presented at the SEG Annual Meeting in 2016.
Having worked closely with Elita for the past two years since her arrival at NUS, I am constantly amazed by her broad interest in geophysical research and her ability to perform and to lead a research group. While she has continued innovations in seismic imaging and integrated model building, she has expanded her research from oil and gas to other applications, such as near-surface site investigation, deep underground characterization for water resources, and look-ahead while tunneling. We have grown the group from a three-person team to a 10-person team, working on research topics including seismic imaging and inversion, attenuation characterization, passive seismic monitoring, distributed acoustic sensing, rock physics modeling, and fracture characterization. With her guidance, leadership, and diligence, these research efforts with students and postdocs resulted in six submitted manuscripts to Geophysics and 14 submitted abstracts to the SEG Annual Meeting in 2017 and 2018. Once again, her presentation at the 2017 SEG Annual Meeting, “Anisotropic model building from logs in vertical wells,” was selected as one of the 39 best presentations at the meeting. She is without a doubt one of the best young scientists whom I have worked with over my long career, both at MIT and in private industry.
Elita has been very active in the Singapore geophysics community and within SEG. She organized two workshops in 2017 and 2018 to gather geoscientists in Southeast Asia for academic and industry discussion and to cultivate the geophysical mindset in Singapore. She helped start and is the faculty advisor of the new NUS SEG Student Chapter. She is representing SEG on OTC Asia and IPTC subcommittees and is presently serving on the SEG Publications Committee. In addition, she is on the organizing committee for the 5th International Workshop on Rock Physics to be held in Hong Kong in April 2019.
The J. Clarence Karcher Award is given in recognition of significant contributions to the science and technology of exploration geophysics by a young geophysicist of outstanding abilities. What Elita has achieved in her early career and her potential to achieve more makes her a well-deserved recipient of this award, and I am very fortunate to have her as my colleague.
- The Leading Edge Volume 37, Issue 11