#14,166
One of the ideas driven home to me by writing this blog over the past 14 years is that all droughts - even good ones - eventually end.
- When Category 4 Hurricane Harvey battered and flooded east Texas in 2017, it ended an 11+ year drought in major (CAT 3+) land-falling hurricanes in the Continental United States.
- When a novel swine-origin H1N1 virus emerged in 2009, it ended a 40 year drought in flu pandemics.
A tactic that works wonderfully well until it doesn't anymore.While the threat of another great California earthquake remains easy fodder for disaster movies, California has been in an earthquake drought for over a century, and few can truly imagine the level of seismic activity that state saw in the 1800s.
Earlier this year, the SSA (Seismological Society of America) held their annual meeting, and a study was presented that concludes that California's recent lack of major quakes has no precedent in the past 1000 years.
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
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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.
The following SSA news article discusses these findings.
How to Explain California’s Recent Earthquake Hiatus?
25 April 2019–There have been no major ground rupturing earthquakes along California’s three highest slip rate faults—the San Andreas, the San Jacinto and the Hayward—in the past 100 years. At the 2019 SSA Annual Meeting, researchers discussed why this “hiatus” might exist, and what we might expect for California earthquakes over the next century.
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Researchers can’t predict when earthquake clusters may occur again, she adds, but if clustering is occurring, “it’s likely that we’re going to have a lot of earthquakes when they do start happening again.”
At the meeting, USGS seismologist Kate Scharer will also present results of a recent study published in the journal Seismological Research Letters on the unlikely nature of the California hiatus. The analysis by Scharer and her USGS colleague Glenn Biasi concludes that the current hiatus has no precedent in the last 1000 years of paleoseismic records along the three major faults.
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.”
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Yesterday's M6.4 earthquake in the Mojave desert - which has been followed by nearly 200 M2.5 aftershocks - is a not-so-gentle reminder that the ground beneath our feet isn't as secure as we'd like to believe.
Clusters of earthquakes - even moderately strong ones - are not uncommon, however, and most of the time they recede in intensity and frequency over a matter of a few weeks.Hopefully, this latest swarm will follow that path. But history tells us that one of these days - another great quake will strike the West Coast of the United States, and that cities like Los Angeles, San Francisco, and Seattle are all vulnerable to severe damage.
In 2013, in Dr. Lucy Jones: `Imagine America Without Los Angeles’, we looked at a presentation given at the annual meeting of the American Geophysical Union (held that year in San Francisco), that emphasized that should the `big one’ hit Southern California, we could literally `lose’ Los Angeles.
She warned that the damage could be far greater, and last much longer, than most people believe. While 99 out of 100 modern buildings might remain standing, the (often buried) infrastructure needed to provide water, electricity, internet connectivity, and natural gas – the lifeblood - to the region could be devastated (see CBS News report).In 2011 (see Estimating The Economic Impact Of A San Andreas Quake) we looked at a report from the U.S. Bureau of Labor Statistics that endeavored to gauge the crippling impact that a highly feasible (and long overdue) 7.8 magnitude Southern California earthquake would have on jobs and local businesses.
Download PDF file
A quake of this magnitude, they estimate, could affect 430,000 businesses and 4.5 million workers and deliver a devastating – and prolonged – blow to the local (and national) economy.
While huge death tolls are considered unlikely in this scenario, the untimely demise of thousands of unprepared businesses is all but assured.As a follow up story in the Los Angeles Times pointed out, it is imperative that local businesses prepare now for an inevitable quake. Else they risk not only their own economic future, but the futures of their employees and of the local economy.
Southland businesses urged to get ready for 'The Big One' -- a 7.8 earthquake
June 21, 2011 | 3:03 pm
As the USGS map at the top of this blog shows, it isn't just the West Coast at risk of a massive quake (see USGS: Nearly Half Of U.S. Population Exposed to Potentially Damaging Earthquakes).
- Three years ago FEMA and the U.S. government conducted a huge drill (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.
- Northern Alabama, Georgia and Eastern Tennessee - and even New York City and parts of New England - can experience infrequent, but strong temblors (see USGS: Eastern Earthquakes - Rare But Powerful).
Hopefully the Searles quake swarm will soon recede, but someday another major quake will strike the region. When that day comes, the advantage will go to individuals, families, and businesses who were already prepared.
If I lived in a seismic zone, and were not already well prepared, I'd be spending a good deal of time today reviewing my earthquake plan, and making sure I had as many bases covered as possible.For those living in California, the Governor's Office of Emergency Preparedness has an Earthquake Preparedness website set up with information on how best to prepare.
Whether you live in an earthquake zone, hurricane country, or tornado alley - every home should be at least minimally prepared to deal with one if it happens.So . . . if a disaster struck your region today, and the power went out, stores closed their doors, and water stopped flowing from your kitchen tap for the next 7 to 14 days . . . do you already have:
- A battery operated NWS Emergency Radio to find out what was going on, and to get vital instructions from emergency officials
- A decent first-aid kit, so that you can treat injuries
- Enough non-perishable food and water on hand to feed and hydrate your family (including pets) for the duration
- A way to provide light when the grid is down.
- A way to cook safely without electricity
- A way to purify or filter water
- A way to stay cool (fans) or warm when the power is out.
- A small supply of cash to use in case credit/debit machines are not working
- An emergency plan, including meeting places, emergency out-of-state contact numbers, a disaster buddy, and in case you must evacuate, a bug-out bag
- Spare supply of essential prescription medicines that you or your family may need
- A way to entertain yourself, or your kids, during a prolonged blackout
