* Astronomy

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RE: Earthquake

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A new mystery faces scientists who study stresses that trigger earthquakes both large or small: Even the rise and fall of the ocean's tides are strong enough to trigger pulses of underground tremors that periodically send seismic faults slowly slipping beneath the northwest coast, quake researchers have found.
The scientists, led by a young researcher who will soon join the U.S. Geological Survey in Menlo Park, came upon their puzzling discovery after installing highly sensitive seismic detectors on the Olympic Peninsula in Washington and across Vancouver Island in British Columbia. Readings from the detectors revealed that twice a day when it's high tide, the strength of the faint tremors increases, and twice a day at low tide, those underground tremors grow fainter.

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Jerry Magloughlin will present a paper about unusual fossil earthquakes and the ancient faults that produced them at the 2007 Geological Society of America's annual meeting at the Colorado Convention Centre in Denver on Oct. 27-31.
A Colorado State researcher is studying Earth's ancient earthquakes, or fossil earthquakes, to get a better understanding of how and why earthquakes happen.
Geologist Jerry Magloughlin is studying the rocks that form where earthquakes actually happen. By studying these unique fossil earthquakes, scientists can learn about how and why faults slip and produce earthquakes.
These fossils are the only well-accepted evidence proving that an area was affected by ancient earthquakes. Magloughlin unearthed some of these rocks in Northern Colorado's Poudre Canyon.

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Science on a Sphere: Plate Tectonics and Paleo Animation

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The Early Earth and Plate Tectonics

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Japans earthquake warning system went online on Monday. This system monitors for earthquake vibrations and if they are detected it broadcasts a signal. This signal gives some people (depending upon location) a few extra seconds of warnings so that life-saving actions can be taken.

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More than 30 earthquakes have occurred in and around Ohio since 2002, spurring the Ohio Department of Natural Resources (ODNR) Division of Geological Survey to publish an updated map that pinpoints the location and approximate magnitude of these recent seismic incidents. The revised map also includes new information about historic earthquakes in the region.
More than 200 earthquakes with a magnitude of 2.0 or greater have occurred in the Ohio region since 1776. While it may seem like earthquakes are occurring more frequently in recent years, ODNRs Ohio Seismic Network attributes this perceived change to improved technology and communication among people who experience the earthquakes.
The new map, which includes all of Ohios recorded earthquakes, shows a concentration of earthquake epicenters in two areas of the state: western Ohio in the vicinity of Shelby County, and along the Lake Erie coast in Lake County at Painesville. Users can apply information from the map to determine earthquake insurance rates, construction strength determinations for bridges and buildings, and to research deep-earth structures such as hidden faults.

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Experts Find Positives For NZ After Big Quake In Peru
Earthquake experts who have returned from studying the after-effects of last months big quake in Peru found a number of positives for New Zealand, and some puzzles as well.
The six-person New Zealand Society of Earthquake Engineering team, who were sponsored by the Earthquake Commission, spent a week inspecting the damage from the magnitude 8 quake that occurred 150km south of Lima on 15 August.

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Reto Meier has created a Google Map layer that plots in near-real-time the felt areas for selected earthquakes. Earthquakes that have occurred in the last 24 hours are marked with a red circle and those that have occurred during the previous two days as a yellow circle.

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High-speed ruptures travelling along straight fault lines could explain why some earthquakes are more destructive than others, according to an Oxford University scientist. In this weeks Science, Professor Shamita Das suggests that ruptures in the Earths surface moving at 6km per second could make future earthquakes along Californias San Andreas fault much more destructive than current models predict.
Professor Das compared data from the 1906 California earthquake with data from a similar earthquake that occurred in 2001 in Kunlunshan, Tibet. The comparison suggests that, in both, the long straight portions of the fault enabled ruptures to travel twice as fast as the original shear wave travelling through the rock. Such super-shear waves were once thought to be impossible but could now explain why similar magnitudes of earthquake can cause much greater devastation in some areas than others.

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