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Your Excellent Questions On Earthquakes

Today marks the 25th anniversary of the magnitude 6.9 Loma Prieta earthquake which rocked California’s San Francisco Bay Area on October 17, 1989. To commemorate the anniversary and raise awareness about resilience against earthquakes, Dr. Robert Muir-Wood, RMS chief research officer, and Dr. Patricia Grossi, RMS senior director of global earthquake modeling, hosted a Reddit Science AMA (Ask Me Anything). They discussed a number of topics; participants expressed curiosity not just for routine details like the best immediate action in the event of a quake, but also what fault lines are at risk and the finer points of earthquake insurance. Here are just a few of the subjects they tackled in a conversation that generated close to 200 comments by Thursday afternoon – you can also read the entire Reddit thread. Is the Bay Area is better prepared [now] than for the Loma Prieta quake? What role have you (or other scientists) played in planning? Grossi: There’s been a lot of work by PG&E, BART, and other agencies to mitigate earthquake risk – as well as the new span of the Bay Bridge. In addition, the California Earthquake Authority has been encouraging mitigation – and have mitigation incentives if you retrofit your home to withstand earthquake ground shaking. Scientists can help by creating strategic plans or perform cost-benefit analyses for mitigation/retrofit. Is there a link between fracking and earthquakes? Muir-Wood: The term ‘earthquake’ can cover an enormous range of sizes of energy release. Fracking may sometimes trigger small shallow earthquakes or tremors. One day there might be a bigger earthquake nearby and people will argue over whether it was linked to the fracking. The link, however, will remain tenuous. Am I being overcharged for earthquake insurance? I was charged $1,500 a year with a 15 percent deductible. Grossi: Premiums associated with the coverage seem high (as generally double premiums here in California). However, they are based on price-based pricing. The coverage is meant to be a ‘minimum’ coverage – and provide protection for the worst-case scenario. Is Tokyo due for another big earthquake? Muir-Wood: The Big One happened beneath Tokyo in 1923, and before that a similar Big One (not quite on the same fault) occurred in 1703. The 1923 earthquake is not so likely to come around again. However, there was a M7 earthquake in 1855 that occurred right under Tokyo and may be the type of damaging earthquake we can expect. It could do a lot of damage.   Was there anything we missed you wanted to discuss? Please let us know in the comments. …