An international team of scientists just finished probing the depths of the Pacific Ocean offshore of Alaska and British Columbia, to better understand the Queen Charlotte-Fairweather Fault. During the past century, the 700-mile-long fault has generated at least half a dozen major earthquakes, and future shocks threaten coastal communities in both the United States and Canada. (more…)
New Zealand’s geologic hazards agency reported this week an ongoing, “silent” earthquake that began in January is still going strong. Though it is releasing the energy equivalent of a 7.0 earthquake, New Zealanders can’t feel it because its energy is being released over a long period of time, therefore slow, rather than a few short seconds.
These so-called “slow slip events” are common at subduction zone faults – where an oceanic plate meets a continental plate and dives beneath it. They also occur on continents along strike-slip faults like California’s San Andreas, where two plates move horizontally in opposite directions. Occurring close to the surface, in the upper 3-5 kilometers (km) of the fault, this slow, silent movement is referred to as “creep events.” (more…)
Join the Great ShakeOut on October 18, 2012, to prepare
The Central Virginia Seismic Zone, it’s called, and it sometimes shakes everything in sight.
As long ago as 1774, people in central Virginia felt small earthquakes and suffered damage from intermittent larger ones. A magnitude 4.8 quake happened in 1875.
Then last year, on August 23, 2011, a magnitude 5.8 quake hit the same region. Several aftershocks, ranging up to magnitude 4.5, occurred after the main tremor.
Will there be another such quake in the mid-Atlantic region? (more…)
It’s been a decade since a swarm of relatively mild earthquakes shook up parts of Spokane. Now, armed with the right tools, scientists want to find out what was at fault.
“It was always something not as well understood as we thought it should be,” said Douglas Gibbons, a University of Washington researcher in Earth and space sciences, who is guiding installation of strong-motion sensors as part of a project called NetQuakes.
NetQuakes will install a half-dozen seismometers in the Spokane area by the end of June, mostly in volunteers’ homes, to help improve understanding of what lies beneath the city. (more…)
*Geologists learn how earthquakes change the landscape — down to a few inches*
Geologists have a new tool to study how earthquakes change the landscape–down to a few inches. It’s giving scientists insights into how earthquake faults behave.
In this week’s issue of the journal Science, a team of scientists from the United States, Mexico and China reports the most comprehensive before-and-after picture yet of an earthquake zone, using data from the magnitude 7.2 event that struck near Mexicali, Mexico, in April 2010. (more…)
*Samples of rock, sediment from beneath the sea-floor help explain quakes like Japan’s*
New samples of rock and sediment from the depths of the eastern Pacific Ocean may help explain the cause of large, destructive earthquakes similar to the Tohoku Earthquake that struck Japan in mid-March.
Nearly 1,500 meters (almost one mile) of sediment cores collected from the ocean floor off the coast of Costa Rica reveal detailed records of some two million years of tectonic activity along a seismic plate boundary. (more…)
The fault initially thought to have triggered January’s devastating earthquake in Haiti is likely still under considerable strain and continues to pose a significant seismic hazard, according to a study published online in Nature Geoscience Sunday.
U.S. Geological Survey geologist Carol Prentice led a team of scientists to Haiti immediately after the earthquake to search for traces of ground rupture and to investigate the geology and paleoseismology of the area. (more…)
