Earthquakes

Christopher Scholz is being awarded the Harry Fielding Reid Medal for his pioneering work in rock mechanics and his skill at communicating earthquake science. The Seismological Society of America cites Scholz’s wide range of contributions over a nearly 50-year career.

Rarely a day goes by without earthquakes shaking the Alaska Peninsula, a string of volcanoes curving off the Alaska mainland into the Pacific. Just off shore, two tectonic plates are converging: The Pacific plate is bending under the North American plate and pushing deep into the Earth. Along this subduction zone, scientists have noticed something unusual. Two adjacent sections that appear almost identical in large-scale characteristics—temperature, angle of subduction, age of the rocks—are exhibiting very different earthquake behaviors over short spans of just tens of kilometers. One section is highly active with small earthquakes; the other is more quiet but has large earthquakes every 50 to 75 years. To get a closer look, Lamont-Doherty Earth Observatory’s research ship, the R/V Marcus G. Langseth, ran seismic surveys to map the ocean floor and the earth beneath it.

Most earthquakes erupt suddenly from faults near Earth’s surface, and the big ones can topple cities. But miles below, rocks heated to the consistency of wax moving over thousands to millions of years may be the driving force behind some of these events.

A new study in the journal Nature provides fresh insight into deep-earth processes driving apart huge sections of the earth’s crust. The process, called rifting, mostly takes place on seabeds, but can be seen in a few places on land—nowhere more visibly than in the Afar region of northern Ethiopia. (See the slideshow below.) Here, earthquakes and volcanoes have rent the surface over some 30 million years, forming part of Africa’s Great Rift Valley. What causes this, and does it resemble the processes on the seafloor, as many geologists think?

Scientists from Columbia University’s Earth Institute will present important new studies at the Dec. 3-7 meeting of the American Geophysical Union, the world’s largest gathering of earth and space scientists. Below: a chronological guide. Most researchers are at our Lamont-Doherty Earth Observatory (LDEO).More info: http://fallmeeting.agu.org/2012/ Reporters may contact scientists directly at any time, or call press officers:

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.

Starting today, armchair explorers will be able to view parts of the deep ocean floors in far greater detail than ever before, thanks to a new synthesis of seafloor topography released through Google Earth. Developed by oceanographers at Columbia University’s Lamont-Doherty Earth Observatory from scientific data collected on research cruises, the new feature tightens resolution in covered areas from the former 1-kilometer grids to just 100 meters.

The largest recorded earthquake in Japan's history has triggered a series of events that have killed thousands, crushed and submerged cities, and left a financial toll from which it will take years for an already struggling economy to recover.

An earthquake with the following parameters has occurred:

Time: Wednesday, June 23, 2010 at 17:41:42 UTC, 13:41:42 EDT (1:42 PM in NY)

Location: 45.862 °N, 75.457 °W (Southern Ontario), approximately 53 KM (33 mi) NNE from Ottawa

Depth: 18 km (11.2 mi) set by location program

Magnitude 5.0

This week U.S. and Haitian scientists will start a 20-day research cruise off Haiti to address urgent questions about the workings of the great Jan. 12 earthquake, and the possibility of continuing threats. They hope to gather sonar images, sediments and other evidence from the seafloor that might reveal hidden structures...

That rumbling you feel is not necessarily a passing subway. New York City and the surrounding region gets a surprising number of small earthquakes, and a 2008 study from the region’s network of seismographs, run by Lamont-Doherty Earth Observatory, suggests that the risk of a damaging one is not negligible. This week, the federal government announced a major upgrade to that network.

Dec 10, 2007--Scientists from Columbia University’s Lamont-Doherty Earth Observatory will report this week on vital topics including new evidence of the effects of climate change; technologies to confront it; studies of eastern U.S. earthquake risk; and previously unseen inner workings of the deep polar ice caps.  The reports will be presented at the fall 2007 American Geophysical Union (AGU), the largest earth-sciences gathering in the world, Dec. 10-14 in San Francisco.

When the sea floor off the coast of Sumatra split on the morning of December 26, 2004, it took days to measure the full extent of the rupture. Recently, researchers at Columbia University's Lamont-Doherty Earth Observatory analyzed recordings of the underwater sound produced by the magnitude 9.3 earthquake.

Finding the epicenter of earthquakes has not changed in principle since the 1930s -- after closely examining seismograms from different widely-spaced listening stations, researchers decide on the arrival times of various seismic waves and calculate an approximation. In practice this can result in errors of several miles