2014 Update of the United States National Seismic Hazard Maps
Note: This is day 25 of National Preparedness Month . Follow this year’s campaign on Twitter by searching for the #NatlPrep hash tag.
This month, as part of NPM15, I’ll be rerunning some edited and updated older preparedness essays, along with some new ones.
# 10,562
Last August, in USGS: Nearly Half Of U.S. Population Exposed to Potentially Damaging Earthquakes, we looked at the results of a new study – published in the journal Earthquake Spectra, that nearly doubles – to 143 million - the number of Americans who live or work in areas susceptible to potentially damaging ground shaking.
Of particular note, since research is still ongoing, this study didn’t consider earthquakes due to human activity – such as `Fracking’ - nor does it take into consideration the amplification of ground shaking due to soil type, which could exacerbate the effects of some earthquakes.
Add in non-seismically active regions along the Gulf and Atlantic coastlines that are susceptible to tsunamis generated from distant earthquakes (see #NatlPrep : Tsunami Awareness), and there is better than a 50-50 chance that you live somewhere that is at risk of some seismically induced disaster.
Although California, Alaska, and Hawaii are first thought of when it comes to U.S. earthquakes, there are three other major areas of concern (and a lot of second tier threats).
Perhaps best known is the New Madrid fault, which makes up the bull's-eye in the center of the nation on the seismic map above. Just over 200 years ago – when that area of the country was sparsely populated – this was the scene of 4 major quakes over a two year period. Today, millions of people live in – and much of the nation’s transportation crosses – this seismic hotspot (see USGS: New Madrid Simulation Shows Risks For Memphis & Little Rock).
Lesser known, but probably a bigger threat, is the Pacific Northwest, which 315 years ago saw an estimated M9.0 earthquake and massive tsunami, and is considered `overdue’ for another. Earlier this year, in OSU: Pragmatic Action - Not Fatalism - In Order To Survive The `Big One’, we looked at the growing concern over this highly populated area of the country.
Probably 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.
An earthquake of that size today, in the same area, it is estimated would produce:
- 45,000 injuries
- 9,000 hospitalizations
- 900 fatalities
- 200,000 displaced or homeless persons
- 20 billion dollars in Damage
But many other regions, including parts of Utah, Tennessee, Nevada, and Illinois are at substantial risk. Even New York City has fault lines running beneath it.
While the last significant quake occurred there in 1884, with a magnitude 5.2 off shore from Far Rockaway Beach, scientists believe a quake of that size is likely to occur every 100 years or so.
Areas that seldom see quakes, like New York City, generally don’t build structures with earthquakes in mind – meaning that a smaller magnitude quake there could be more damaging than a larger quake in Los Angeles.
And frankly, your odds aren’t much better if you live outside of the United States, as the map below attests. Literally billions of people live on, or near fault lines, including the inhabitants of half of the world’s supercities (urban areas with 2 million – 15 million inhabitants) see (UNDP: Supercities At Seismic Risk).
Seismically active areas of the world
Working to improve earthquake awareness, preparation, and safety is Shakeout.org, which promotes yearly earthquake drills and education around the country (see NPM13: A Whole Lotta Shakeouts Going On). If you live in or near one of these seismically active areas, I would encourage you to take part in these yearly drills.
Every home should have no less than a 72-hour supply of emergency food and water, for all of its occupants (including pets!).
Basic kit : NWS radio, First Aid Kit, Lanterns, Water & Food & cash
This is a bare minimum, here in the United States many agencies and organizations recommend that households work towards having a 10-day supply of food, water, and emergency supplies on hand.
In When 72 Hours Isn’t Enough, I highlighted a colorful, easy-to-follow, 100 page `survival guide’ released by Los Angeles County, that covers everything from earthquake and tsunami preparedness, to getting ready for a pandemic.
While admittedly California-threat specific, this useful guide may be downloaded here (6.5 Mbyte PDF).
Despite the abundant seismic risk to the nation (not to mention hurricanes, floods, tornadoes, blizzards, power outages, etc.), according to FEMA: 60% Of Americans Not Practicing For Disasters. Which means there are probably 100 million Americans living in seismically active zones who are not prepared for an earthquake.
My best advice: Don’t be one of them.
For more on earthquake risks, and preparedness, you may wish to revisit:
Dr. Lucy Jones: `Imagine America Without Los Angeles’
California Quakes : Concrete Concerns
Estimating The Economic Impact Of A San Andreas Quake
USGS/OGS Joint Statement On Increased Earthquake Threat To Oklahoma
