Study simulating pressures in mantle beneath the ocean floor shows that rocks can melt at depths up to 250 kilometers
Magma forms far deeper than geologists previously thought, according to new research results.
A team led by geologist Rajdeep Dasgupta of Rice University put very small samples of peridotite, rock derived from Earth’s mantle, under high pressures in a laboratory.
The scientists found that the rock can and does liquify, at least in small amounts, at pressures equivalent to those found as deep as 250 kilometers down in the mantle beneath the ocean floor. (more…)
Japan fisheries data provides a look at how the ocean is faring 18 months after the worst accidental release of radiation to the ocean in history
Japan’s “triple disaster,” as it has become known, began on March 11, 2011, and remains unprecedented in its scope and complexity. To understand the lingering effects and potential public health implications of that chain of events, scientists are turning to a diverse and widespread sentinel in the world’s ocean: fish.
Events on March 11 began with a magnitude 9.0 earthquake, the fourth largest ever recorded. The earthquake in turn spawned a massive 40-foot tsunami that inundated the northeast Japanese coast and resulted in an estimated 20,000 missing or dead. Finally, the wave caused catastrophic damage to the Fukushima Dai-ichi nuclear power plant, resulting in the largest accidental release of radiation to the ocean in history, 80 percent of which ended up in the Northwest Pacific Ocean. (more…)
There’s an old adage (with several variations) that California has four seasons: earthquake, fire, flood and drought. While Californians happily cede the title of Hurricane Capital of America to U.S. East and Gulf coasters, every once in a while, Mother Nature sends a reminder to Southern Californians that they are not completely immune to the whims of tropical cyclones. Typically, this takes the form of rainfall from the remnants of a tropical cyclone in the eastern Pacific, as happened recently when the remnants of Hurricane John brought rain and thunderstorms to parts of Southern California. But could a hurricane ever make landfall in Southern California?
The answer, as it turns out, is yes, and no. While there has never been a documented case of a hurricane making landfall in California, the Golden State has had its share of run-ins and close calls with tropical cyclones. In fact, California has been affected by at least a few tropical cyclones in every decade since 1900. Over that timeframe, three of those storms brought gale-force winds to California: an unnamed California tropical storm in 1939, Kathleen in 1976 and Nora in 1997. But the primary threat from California tropical cyclones isn’t winds or storm surge. It’s rainfall — sometimes torrential — which has led to flooding, damage and, occasionally, casualties. (more…)
While wave watching is a favorite pastime of beachgoers, few notice what is happening in the shallowest water. A closer look by two University of Colorado Boulder applied mathematicians has led to the discovery of interacting X- and Y-shaped ocean waves that may help explain why some tsunamis are able to wreak so much havoc.
Professor Mark Ablowitz and doctoral student Douglas Baldwin repeatedly observed such wave interactions in ankle-deep water at both Nuevo Vallarta, Mexico, and Venice Beach, Calif., in the Pacific Ocean — interactions that were thought to be very rare but which actually happen every day near low tide. There they saw single, straight waves interacting with each other to form X- and Y-shaped waves as well as more complex wave structures, all predicted by mathematical equations, said Ablowitz. (more…)
Delaware Geological Survey discovers evidence of past earthquakes
Delaware Geological Survey (DGS) scientists have uncovered hard proof of faults in northern Delaware, indicating the occurrence of earthquakes millions of years ago.
The geologic evidence turned up in sediment samples removed during a well-drilling project this summer from depths ranging 137 to 251 feet down in Smyrna and the Woodland Beach Wildlife Area.
“People have postulated that there are faults in this area,” DGS Senior Scientist Scott Andres said. “Now we have evidence of it.” (more…)
Long-forgotten coastal habitats reappeared, species unseen for years returned
The reappearance of long-forgotten habitats and the resurgence of species unseen for years may not be among the expected effects of a natural disaster.
Yet that’s exactly what researchers found in a study of the sandy beaches of south central Chile, after an 8.8-magnitude earthquake and devastating tsunami in 2010.
Their study also revealed a preview of the problems wrought by sea level rise–a major symptom of climate change. (more…)
PASADENA, Calif. – The space-based technology that lets GPS-equipped motorists constantly update their precise location will undergo a major test of its ability to rapidly pinpoint the location and magnitude of strong earthquakes across the western United States. Results from the new Real-time Earthquake Analysis for Disaster (READI) Mitigation Network soon could be used to assist prompt disaster response and more accurate tsunami warnings.
The new research network builds on decades of technology development supported by the National Science Foundation, the Department of Defense, NASA and the U.S. Geological Survey (USGS). The network uses real-time GPS measurements from nearly 500 stations throughout California, Oregon and Washington. When a large earthquake is detected, GPS data are used to automatically calculate its vital characteristics, including location, magnitude and details about the fault rupture.(more…)
