Mamun Miah

Mamun Miah (Photo credit: Kristine Wong)

With dozens of postdocs in residence at the Earth & Environmental Sciences Area (EESA), it can be challenging to stay up to date on the research they’re doing.

Now the “Meet Your Postdoc” series sponsored by the Area’s Energy Geosciences Division is making it a little easier to stay in the know.

The effort aims to raise the visibility of EESA’s postdocs by giving them the opportunity to present their work to their colleagues. Earlier this month, first-year postdoc Mamun Miah was among the four who spoke at the “Meet Your Postdoc” event about research spanning a range of topics in energy geosciences.

Growing up near Dhaka, the capital of Bangladesh, Miah discovered the importance of civil engineering at an early age.

“Bangladesh has been working to build the infrastructure that first world countries developed decades ago,” he said. “I wanted to learn how to build the structures of developed nations in our country.”

That interest prompted Miah to enroll in an engineering geology class as an undergraduate student at Bangladesh University of Engineering and Technology, where he became fascinated with how the structural design of buildings and other infrastructure are affected by earthquakes.

Miah first got the chance to pursue that kind of research as a Berkeley Lab intern in the summer of 2013 and 2014, when he was a doctoral student in structural engineering at the University of Mississippi. At EESA, he studied the occurrence of small-scale seismic incidents at The Geysers geothermal field north of San Francisco.

Diagram showing process to assess risk from an earthquake event

Diagram showing the step-by-step process to assess risk from an earthquake event in a region with an active fault. The bottom picture shows risk distribution in a color-coded map. Red-shaded areas are expected to experience the greatest impact. (Graphic courtesy David McCallen Research Group)

Since last summer, Miah has been working with David McCallen’s research group on a Department of Energy (DOE)-funded project that is developing regional scale earthquake simulation models aimed at reducing seismic risks and assessing hazards.

The maps and hazard assessments are produced from high performance computing simulations conducted at Berkeley Lab’s National Energy Research Scientific Computing Center (NERSC). They analyze how ground motion from a hypothetical but expected level of earthquake impacts steel structure buildings (between three to 40 stories high) and the surrounding region.

“No one has ever done earthquake risk mapping at this massive regional scale before because of the computational constraints,” Miah says. “By conducting advanced simulations, we have advantages over using only measured data, because actual earthquake ground motion data is still quite sparse and insufficient to develop a high fidelity picture of the regional variation of earthquake risk.”

At the postdoc event, he presented the results of an analysis he conducted involving a hypothetical 6.5 magnitude earthquake on a region of 30 x 40 km in dimension.

What he found was that risks to a building’s structural damage vary based on a specific site’s orientation to a fault (for example, whether it lies north or south of it)—not necessarily the distance from the fault itself.

“Our results show that peak ground velocity (PGV) is a better predictor of earthquake risks than peak ground acceleration (PGA) both near and far from the fault,” Miah said. “This is important, because when designing structures for seismic safety, structural engineers currently use PGA instead of PGV.”

Based on his research, he says, buildings and the communities surrounding them could be more effectively designed to protect against earthquake risks if engineers use PGV as the principal measure of earthquake risk.

The analyses—which will be presented at next year’s National Conference of Earthquake Engineering—will provide policymakers and authorities with information that could help them determine if they should retrofit existing buildings.

Right now, as part of a DOE Exascale Computing Project, McCallen’s research team is developing a map of the San Francisco Bay Area showing the locations which are most susceptible to risks from an earthquake originating at the Hayward fault. Miah is working on the structural analysis component of the project using NERSC’s high performance computational modeling.

“An earthquake on the Hayward fault is an expected incident in the Bay Area,” he said. “And since it could also be imminent, we hope that our work will have an impact in mitigating the risks.”

This is the first in a series profiling the work of EESA postdocs.