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New evidence showing that very large earthquakes can trigger an increase in activity at nearby volcanoes has been uncovered by Oxford University scientists.
An analysis of records in southern Chile has shown that up to four times as many volcanic eruptions occur during the year following very large earthquakes than in other years. This 'volcanic surge' can affect volcanoes up to at least 500 km away from an earthquake's epicentre.
A report of the work will be published in the journal Earth and Planetary Science Letters.
Previously, scientists had identified a few cases where volcanic eruptions follow very large earthquakes - but up until now it had been difficult to show statistically that such earthquakes may be the cause of an increase in eruptions, rather than the events just being a coincidence.


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Very large earthquakes can trigger an increase in activity at nearby volcanoes according to a new study.
The controversial findings come from an analysis of records in southern Chile.
It showed that up to four times as many volcanic eruptions occurred during the year following very large earthquakes than did so in other years.

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Scientists find evidence of tsunamis on Indian Ocean shores long before 2004
A quarter-million people were killed when a tsunami inundated Indian Ocean coastlines the day after Christmas in 2004. Now scientists have found evidence that the event was not a first-time occurrence.

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When an earthquake occurs, rocks at a fault line slip or rupture, and a portion of Earths crust physically moves. That releases energy, and two types of seismic waves radiate outward from the earthquake through Earths interior and along its surface. Compression waves (p-waves) alternately compress and release rocks in the direction the waves are moving. Shear waves (s-waves) move rocks perpendicularly to the direction the waves are moving. Compression and shear waves travel through the earth at different speeds. With seismic measurements of these waves, we can locate an earthquakes source.

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Although measurement techniques surrounding earthquakes have improved enormously over the last few decades, it has remained very difficult to measure changes in the crust that could enable earthquake prediction. Now, scientists have measured interesting changes in the speed of seismic waves that preceded two small earthquakes by 10 and 2 hours. These measurements, published in the 10 July issue of Nature, are an encouraging sign that hold promise for the field of earthquake prediction.

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Internet traffic counters used to measure web hits could rival dedicated seismological equipment as a way of detecting earthquakes.

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Satellite-based earthquake warning system
Nasa scientists have said they could be on the verge of a breakthrough in their efforts to forecast earthquakes.
Researchers say they have found a close link between electrical disturbances on the edge of our atmosphere and impending quakes on the ground below.

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Big Quakes Spark Jolts Worldwide
Until 1992, when California's magnitude-7.3 Landers earthquake set off small jolts as far away as Yellowstone National Park, scientists did not believe large earthquakes sparked smaller tremors at distant locations. Now, a definitive study shows large earthquakes routinely trigger smaller jolts worldwide, including on the opposite side of the planet and in areas not prone to quakes.

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In October, Japan launched its nationwide system to warn people about strong earthquakes before they hit. But the system underestimated the strength of last weeks quake near the nations west coast

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A French researcher has revealed that serpentine, a type of rock that coats the top of many tectonic plates, appears to play a significant role in the production and propagation of earthquakes.
Nadege Hilairet of the University of Lyon located in Lyon, France, worked with colleagues in France and the US, and studied the physical properties of the rock layer.
The researchers performed experiments to describe the deformation of a common form of serpentine at high pressures and temperatures.
They say that the rock is unusually soft, a feature that may help understand why it is often so highly deformed.
The softness of serpentinised fault surfaces in subduction zones, where one tectonic plate sinks beneath another, makes them slippery, encouraging subduction.
In some cases, it also arrests the propagation of earthquakes.

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