Monday, January 6, 2014

New theory explains earthquake lights - Spiegel Online

earthquake may be associated with specific phenomena of light, – and thereby sometimes even announce. This earthquake lights can sometimes occur weeks away from the epicenter of an earthquake before the earthquakes and hundreds of kilometers, such as North American geoscientists in the journal “Seismological Research Letters” report. In this they try to explain the controversial among researchers for a long time phenomenon physically.

The team led by Robert Thériault by the Ministry of Natural Resources of the Canadian province of Québec evaluated 65 cases of earthquake lights out since the year 1600, which are particularly well documented. This includes four events in Germany: Three of them are from the middle of the 18 Century in Karlsruhe, Aachen and Düren, the fourth case occurred in the late evening of 16 November 1911 at Ebingen on the Swabian Alb.

Of the earthquake lights near Ebingen witness a total of 110 reports, sometimes even more than a hundred kilometers from the epicenter of the quake of magnitude 5.8. Two eyewitnesses saw immediately before the quake a lightning rise from the ground, which was in the air to a ball of light and disappeared after a few seconds direction Ebingen.

distortions could carry electric charge

footage from Peru confirm the puzzling phenomenon: An earthquake measuring 8.0 in Pisco, a surveillance camera recorded several flashes of light. Analyzes showed, the researcher said later that the luminous phenomena coincided with the seismic vibrations. The 65 evaluated earthquake reached thicknesses from 3.6 to 9.2.

The lights appeared almost always before or during the tremors on, very rarely after that. Was unusual, especially in areas where the continental plates is particularly common shone. Interior zones – although there occur only five percent of all earthquakes

an important requirement of the phenomenon, the researchers hold deep, steeply dipping faults. These were associated with 97 percent of the evaluated lights. The researchers proposed: under high mechanical tension electric charge builds up and increases along this steep breaks to the surface, where it charges the air molecules. At subduction zones, where tectonic plates dive under each other, this will not happen, however, apparently because the distortions are not steep enough.

lights remain enigmatic

the devastating earthquake in 2009 in L’Aquila, Italy, the lights gave a resident apparently even the ability to save his family. The man brought according to the researchers before the main quake his family out of the house to the outside, after he had seen the lights. “This is one of the few documented reports that earthquake lights someone moving to action,” says Thériault. “Together with other hints that change before seismic activity, earthquake lights could one day help predict major quakes.”

Torsten Dahm from the German Research Centre for Geosciences (GFZ) speaks of an interesting model for the phenomenon. However, the presented explanation based only on a small data set of 65 earthquakes, of which the majority originated from the period before 1900 and was accordingly poorly documented. “If that were the data basis even smaller,” says Dahm.

In addition, the study could not explain why lights stayed away for most earthquakes. So also with two subsequent earthquakes in the Swabian Alb: So shocked in 1943 and 1978, more earthquakes the region, which were as strong as the Ebinger quake of 1911. Lights were evidently not documented.

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