Swaminathan Krishnan: Re-Creating the Great Fort Tejon Earthquake of 1857

On January 9, 1857, a large earthquake of magnitude 7.9 occurred on the San Andreas fault, with rupture initiating at Parkfield in central California and propagating in a southeasterly direction over a distance of more than 360 kilometers. Such a unilateral rupture produces significant directivity toward the San Fernando and Los Angeles basins. Indeed, newspaper reports of sloshing observed in the Los Angeles river point to large amplitude, long-period (2 to 8 seconds) and long-duration (1 to 2 minutes) shaking. There were no long-period structures in the Los Angeles region at the time. Now, the region has upwards of 650 long-period, 10-plus story buildings. What would happen if such an earthquake were to repeat today?

Using state-of-the-art computational tools in seismology and structural engineering, we have recreated such an event in a region-wide rupture-to-rafters simulation. This lecture details how such a unification of science and engineering can help us better prepare for the Big One.

Swaminathan Krishnan is Assistant Professor of Civil Engineering and Geophysics at Caltech.