Update for November 2, 2011:
In Oklahoma, earthquakes could be a result of “fracking”, natural gas extraction. Story: here.
Info from The US Geological Survey about earthquakes is here.
Gives dates, magnitude, and info for recent summer 2011 Virginia and Colorado earthquakes.
August, 2011, Earthquake analysis: Did fracking (gas and oil extraction) cause the Virginia earthquake?
August 23, 2011 update:Earthquake in Virginia was felt on Long Island. Comments and video from people in Smithtown, Long Island, NY, USA about feeling the first earthquake there in 30 years.
2011 update: A commission in Arkansas, studying a series of earthquakes, believes that gas drilling is connected to increased earthquake activity in Arkansas. Story at the Daily Mail UK: here.
Why earthquakes in CA?: Background information on drilling and concerns related to the Easter Earthquake in California: here.
Update on April 14, 2010: A New York Times report of earthquake in China: here.
Update on April 4, 2010: Earthquakes hit Pacific Coast of the US and Mexico on Easter Sunday. Story at CNN: here.
Update on March 8, 2010: See Turkey earthquake notes at bottom
KW: Ian was just saying that it seems like there are more earthquakes in the world than usual. What do all these earthquakes mean? For me, in addition to my empathy for Haiti and Chile, a desire to help, and some apathy caused by the overwhelming nature of it all, I know I have questions about if the pattern of earthquakes has a reason, and if the pattern of earthquake devastation should cause a certain, pro-active response.
Don’t have all the answers yet. But, I did find a good article in the Wall Street Journal (of all places) which seems to explain the nitty gritty details about what is happening with the plates in the earth to cause these earthquakes. And, the article also notes that some very human causes — like megacities and poverty — actually affect the outcomes, death, and consequent drama of the quakes. I think it is interesting that the last big earthquake near that same fault line in Chile was observed and reported on by Charles Darwin in 1835.
The Darwin connection reminds me how important it is to have enlightened people concerned with science and nature, including folks who write about those topics on various levels. It brings to mind for me the wonderful, scientific roamings and ramblings* of Georgiana, The Duchess of Devonshire, in the 1800′s, and the scientific travels and studies of Isabella Bird in the 1900′s (as brought to my attention by the play Top Girls.)
(excerpt from) The Wall Street Journal
Why Bigger Quake Sows Less Damage
By Gautam Naik, AP / March 1, 2010
Scientists Say Recent Temblors Are Unrelated; Underwater Topography May Explain Where Tsunami Wreaked Havoc
A tsunami caused by the 8.8-magnitude earthquake flooded much of Pelluhue, a town of roughly 1,000 people about 200 miles southwest of Chile’s capital of Santiago.
Three massive earthquakes have struck in less than two months, raising the questions: Are they related, and are we living in a time of more and bigger temblors?
The Chile earthquake, 8.8 on the Richter scale, was by far the largest. But a little noticed 7.0 quake struck near Japan’s Ryukyu islands just a few hours earlier, triggering its own tsunami warnings.
The Jan. 12 temblor in Haiti was also 7.0, about 500 times less powerful than the Chile quake, though it appears to have killed many more people. That prompts yet another question: Why did a much larger quake cause much less destruction?
Scientists say the three recent earthquakes probably aren’t related, mainly because they occurred at such great distances from one another.
To be sure, the back-to-back quakes in Japan and Chile both occurred along the notorious “ring of fire,” a 25,000-mile zone of constant seismic and volcanic activity encircling the Pacific Ocean that accounts for 95% of the world’s quakes. But the Chile and Japan quakes are separated by about 10,000 miles, so, seismologists say, they are probably unconnected.
Earthquakes are caused by friction between tectonic plates, which are essentially shards of the earth’s crust. They slip-slide past each other, very slowly but inexorably. Sometimes they get stuck, then jerk forward again, producing a quake.
The Haiti quake was caused by different regional plates than the Chile and Ryukyu temblors.
The Chile earthquake occurred at the boundary between the Nazca and South American tectonic plates, according to the United States Geological Survey…
The last big earthquake near this point on the faultline occurred in 1835—when Charles Darwin was sailing nearby—and had an estimated 8.5 magnitude. Since then, the plates at this location have been trying to move past each other, but have been locked in place. Over the ensuing 175 years, the stresses and strains gradually built up.
Despite the spate of recent temblors, the frequency of quakes has not increased…
What makes modern quakes particularly devastating are megacities located near seismically active zones. “Earthquakes don’t kill people, buildings kill people,” says David Wald of the National Earthquake Information Center of the USGS.
That is especially true in poorer countries where many buildings are shoddily designed and constructed from weak materials, or they simply fail to meet basic building standards. That was the case in Haiti, where the death toll is estimated to exceed 220,000—much greater than what is thought to have occurred in Chile, even though the Haiti quake was far less powerful…
But the danger hasn’t abated in Chile. Some 100 aftershocks were recorded in Chile of magnitude 5 or larger, according to the NEIC…
Write to journalist Gautam Naik at gautam dot naik at wsj dot com
*For Georgiana’s studies as an amateur chemist and mineralogist, see Georgiana Duchess of Devonshire by Amanda Foreman. For more about Georgiana, or to comment on her life, see my blog “Georgiana Circle: Women Healing History”
Update: Some info and assurances about the Turkey earthquake:
Excerpt from a Houston Chron/AP story:
…Earthquakes are frequent in Turkey, much of which lies on top of two main fault lines. In 1999, two powerful earthquakes struck northwestern Turkey, killing about 18,000 people.
The Elazig quake followed deadly temblors in Haiti and Chile, but Bernard Doft, the seismologist for the Royal Netherlands Meteorological Institute in Utrecht, said there was no direct connection between the three.
“These events are too far apart to be of direct influence to each other,” he said.
Richard Luckett, a seismologist from the British Geological Survey, said there has not been a spike in global seismic activity.
“If there was a big increase in the number of magnitude 6.0s in the past decade we would know it because we would see it in the statistics,” Luckett said. “We haven’t seen an increase in 7.0s either.”
He said scientists often see strong quakes but they don’t get reported because the damage or death toll is minimal.
“The point is that earthquakes are common and always have been,” he said…
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