Seismic Hazard Analysis of Aizawl, India with a Focus on Water System Fragilities

Abstract:

GeoHazards International (GHI) has partnered with the University of California, Berkeley in a joint Civil Engineering and Earth Science summer internship program to investigate geologic hazards. This year the focus was on Aizawl, the capital of India's Mizoram state, situated on a ridge in the Burma Ranges. Nearby sources have the potential for large (M > 7) earthquakes that would be devastating to the approximately 300,000 people living in the city. Earthquake induced landslides also threaten the population as well as the city’s lifelines. Fieldwork conducted in June 2015 identified hazards to vital water system components. The focus of this abstract is a review of the seismic hazards that affect Aizawl, with special attention paid to water system locations. To motivate action to reduce risk, GHI created an earthquake scenario describing effects of a M7 right-lateral strike-slip intraplate earthquake occurring 30 km below the city. We extended this analysis by exploring additional mapped faults as well as hypothetical blind reverse faults in terms of PGA, PGV, and PSA. Ground motions with hanging wall and directivity effects were also examined. Several attenuation relationships were used in order to assess the uncertainty in the ground motion parameters. Results were used to determine the likely seismic performance of water system components, and will be applied in future PSHA studies.