Tag Archives: Earthquakes

Seismometer Puts Earthquakes Online at Kent School

First posted on the Earth Institute’s State of the Planet blog on Dec. 2, 2011

seismograph, Kent School, Connecticut

The latest station in the Lamont-Doherty Cooperative Seismographic Network, at the Kent School in Connecticut, in its new home. Photo: D. Funkhouser

A well-traveled seismometer sits tucked inside a concrete chamber behind the Kent School chapel in Northwest Connecticut, recording earthquakes. The latest event was on Nov. 28 – a minor shake of magnitude 2.0 just north of Medina, N.Y.

Scientists from the Lamont-Doherty Earth Observatory installed the seismograph at Kent in early November – the latest addition to the 40-year-old Lamont-Doherty Cooperative Seismographic Network, which tracks earthquakes around the Northeast. Scores of small earthquakes, mostly unfelt by people, send elastic waves coursing through the ground in the Northeast each year. They’re recorded by more than 40 stations operated by the network, and by other stations that make up a national grid of seismographic sensors.

Now and then comes a larger one – like the 5.8 quake centered in rural Virginia that shook up and down the East Coast. But large or small, they all add to our knowledge of the geology underlying our region, and eventually, perhaps, to a better understanding of the how and why of earthquakes.

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From Sendai to Rio: A Call for Action

First posted on the Earth Institute’s State of the Planet blog on April 13, 2012

Sendai, Japan 2011 tsunami

A house swept to sea by the 2011 tsunami that struck northern Japan. Photo: U.S. Navy

The people living on the northeast coast of Japan had learned to expect large earthquakes. But despite being one of the best-prepared nations, they were caught off-guard by the force of the March 11, 2011, earthquake and tsunami that devastated their coastline and led to the meltdown of reactors at the Fukushima nuclear power plant.

Many areas of the world are far less prepared, and the effects of major earthquakes, hurricanes and floods can be even more far-reaching than they have been in Japan. But there are measures we can take to lessen the impacts of such events. A worldwide effort is underway to improve resilience against the forces of nature, and to link that effort to sustainable economic development.

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Undersea Clues to Haiti’s Earthquake History

First published July 21, 2011, on the Earth Institute’s State of the Planet blog.

Mud core, Haiti

After an earthquake, heavier sand set loose in landslides settles first, while water is still sloshing around, forming recognizable patterns; thicker layers of mud settle on top in calmer waters over a longer time. This core was taken from the sea floor in the Canal de Sud, off the coast of Hispaniola. (McHugh et al., 2011)

For all of its violent destruction, the earthquake that struck Haiti on Jan. 12, 2010, hardly scratched the surface of the island. But scientists now say they have found some of the best clues to understanding the quake under water.

The deadly quake also shook loose an enormous amount of sediment, sending large volumes of earth sliding into the sea from the shore and also downslope from shallower to deeper portions of the Canal de Sud, adjacent to the southern prong of the island of Hispaniola. That caused water to slosh back and forth in the basin, like in a bathtub, and generated a small tsunami that killed several people.

The toll was miniscule compared to the hundreds of thousands believed to have been killed in and around Port-au-Prince. But the landslides bore important fruit for a team of scientists from Lamont-Doherty Earth Observatory and other institutions, including Queens College of the City University of New York, who came to study this part of the region immediately after the earthquake.

Within weeks of the disaster they were out on a research vessel studying the water column and drilling out long cylinders of mud and sand from deep in the Canal de Sud. They found that as some of the sediment unleashed in the landslides settled, it left patterns that reflected the water sloshing back and forth in the Canal de Sud. They were able to identify similar imprints further down in the sediment that were likely caused by landslides triggered by several previous quakes.

Their work, described in a paper published in the journal Geology, gives scientists another way to decode the seismic history of this and other regions, and to better assess the risks posed by future earthquakes.

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Japan’s Natural Hazards

Lamont-Doherty experts

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Japan’s earthquakes

First published on the Earth Institute and Lamont-Doherty web sites on March 30, 2011.

The Great Japan Earthquake: Where Did Scientists Go Wrong? from Earth Institute on Vimeo.

In the two and a half weeks since a massive earthquake struck Japan, scientists from the Lamont-Doherty Earth Observatory have been immersed in both studying the quake, and reaching out to the media and other organizations to explain what happened. Other Earth Institute experts have added their voices to the public conversation about natural hazards, preparedness and nuclear power.

Can we ever be prepared enough for such events? The Japanese were as experienced as any people on the planet when it comes to dealing with earthquakes. Yet they were caught off-guard by a once-in-a-thousand-year event. In a matter of hours, that same event washed ashore on the U.S. West Coast, a relatively minor reminder that we, too, may not always be ready when the power of natural forces takes charge.
The jolt in Japan stunned even scientists who’ve studied earthquakes all their lives. Chris Scholz, a Lamont-Doherty Earth Observatory professor with decades of experience looking at how earthquakes work, said he had thought a 9.0 magnitude quake like the one that struck near Sendai, Japan, was “impossible” in that area (see video). But it turns out the last comparable earthquake shook the same region in the year 869 and pushed a tsunami miles into the interior. Scientists were humbled by the realization that they simply had not looked back far enough to gauge the probability of such a huge event.

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