2014 Update To The USGS Seismic Risk Map
Note: September is National Preparedness Month. Follow this year’s campaign on Twitter by searching for the #NatlPrep #BeReady or #PrepMonth hashtags.
This month, as part of #NPM21, I’ll be rerunning some updated preparedness essays, along with some new ones.
#16,170
In 2006 the USGS calculated that earthquakes posed a significant risk to 75 million Americans living in 39 States. Since then, populations have changed and/or shifted and ongoing research has uncovered new seismic risks (see USGS: Updated U.S. Seismic Risk Hazard Maps), providing geologists with a better understanding of the extent of ground shaking from these quakes.
A study, published in 2015 in the journal Earthquake Spectra, nearly doubled – to 143 million - the number of Americans who live or work in areas susceptible to potentially damaging ground shaking.
The New Madrid Seismic Zone (NMSZ), the Pacific Northwest (Cascadia fault), coastal South Carolina and even New York City and parts of New England are at risk of seeing significant seismic activity.
But of course, due to popular culture, everyone's first thought is California.
The Current Unlikely Earthquake Hiatus at California’s Transform Boundary Paleoseismic Sites
Glenn P. Biasi, Katherine M. Scharer
Seismological Research Letters (2019) 90 (3): 1168-1176.
https://doi.org/10.1785/0220180244
ABSTRACT
(Continue . . . )Paleoseismic and historical earthquake records used to quantify earthquake recurrence rates can also be used to test the likelihood of seismically quiescent periods. At principal paleoseismic sites in California on the San Andreas, San Jacinto, Elsinore, and Hayward faults, no ground‐rupturing earthquake has occurred in the last 100 yr, yet this interval is about three times the average interearthquake period for the ensemble of sites.
They agree that the next 100 years of California earthquakes along these faults could be a busy one. “If our work is correct,” Scharer and Biasi note, the next century isn’t going to be like the last one, but could more like the century that ended in 1918.”
While the `big one' in California (see Dr. Lucy Jones: `Imagine America Without Los Angeles’) is perhaps the most anticipated major disaster of all time, there are other areas in the continental United States equally ripe for a big quake.
FEMA and the U.S. government conducted a huge drill five years ago (see FEMA: Cascadia Rising 2016) involving 20,000 people from both the United States and Canada, in order to prepare for a catastrophic M9.0 quake & tsunami off the Pacific coast.
And in 2011 – during the bicentennial of the four great New Madrid earthquakes of 1811-12 – FEMA and other federal agencies mounted the largest National Level Exercise (NLE) to that date, revolving around a catastrophic earthquake occurring in the New Madrid Seismic Zone (NMSZ) that would involve eight Central U.S. States.
Perhaps least appreciated is the seismic history of South Carolina, which in 1886 was struck by an (Est. 7.3-7.6 magnitude) quake that devastated much of Charleston, South Carolina. Shaking was felt as far north as Boston, south to Cuba, and west as far as New Orleans.
- 45,000 injuries
- 9,000 hospitalizations
- 900 fatalities
- 200,000 displaced or homeless persons
- 20 billion dollars in Damage
Even if you don't live or work in the shake zone of one of the events, should a great quake strike any one of them, the economic and societal impacts could easily spread far beyond the damaged area.
A quake of that size could impact the transportation of food, the delivery of energy (power, gas, coal, etc.), the national power grid, and the nation's economy in ways we can only partially imagine.
While we can't prevent the next big quake from happening, we can prepare for it.
Working to improve earthquake awareness, preparation, and safety is Shakeout.org, which promotes yearly earthquake drills and education around the country (see A Whole Lotta Shakeouts Going On).
The third Thursday in October (Oct 28th in 2020) is International Shakeout Day, when dozens of states and countries practice earthquake safety. If you live in or near one of these seismically active areas, I strongly would urge you, your family, and your employees take part in these yearly drills.
But after the shaking stops, you'll have to find ways to cope with the aftermath.
While 72 hours is an admirable start, I wouldn't feel comfortable with it. Here in the United States many agencies and organizations recommend that households work towards having a 10-to-14 day supply of food, water, and emergency supplies on hand.
As the (above) graphic illustrates (see #NatlPrep: FEMA National Household Preparedness Survey), while we've seen some improvement over past few years, Americans still have a long way to go if we are to cultivate a culture of preparedness.