Scientists are looking for reliable ways to predict earthquakes

January 4, 2013. 2,300 years ago hordes of mice, snakes and insects have left the Greek city Gelika in the Gulf of Corinth. "The night after the outcome of these creatures was earthquake, — Wrote the Roman writer Claudius Elian. — The city sank beneath the water, a huge wave flooded and Gelika ceased to exist. "

Since then, generations of scientists and folklorists have used an incredible number of methods in an attempt to predict earthquakes. Animal behavior, weather changes, gather — all were unreliable. (See Video home video footage and the science of earthquakes)

The aim is to predict earthquakes — just as we now predict the weather. Even a warning for a few minutes will be enough people to move away from walls or ceilings, which may collapse, or to nuclear power plants and other critical facilities were able to stop the process in anticipation of aftershocks. And if an accurate prediction can be done in a few days, you could plan the evacuation of residents, as well as now it is done before the hurricanes.

At first, the researchers turned to seismology as a tool for forecasting, hoping to identify the algorithms of previous events, which could be a sign of impending shift of the earth's crust. However, one can not with certainty distinguish between waves of energy that portend a strong earthquake, and the usual harmless excitement.

Thomas Jordan, head of the University of California Seismology Southern California Earthquake Center, said at the December meeting of the American Geophysical Union (AGU) in San Francisco that seismologists can not simply say "Yes" or "no" to the question of whether to wait for a major earthquake.

So some scientists have paid attention to other signals, such as electrical energy that can be associated with the processes occurring in the Earth's crust before the earthquake.

Underground lightning

According to one theory, shortly before the earthquake in the earth's surface there are "strange change", provoking strong electromagnetic emissions, said Tom Blair, an engineer on satellite communications and project officer QuakeFinder.

"These emissions are ambitious — Blair said at a meeting of AGU. — Approximately 100,000 amperes by an earthquake of magnitude 6.0 and about one million amperes at magnitude 7.0. It's like lightning, just under the ground. "

To measure these emissions, Bleier and his team have spent millions of dollars on accommodation magnetometers along geological fault lines in California, Peru, Taiwan and Greece. This apparatus is sensitive enough to capture the magnetic pulses of electric discharges up to 16 kilommetrov.

— On a typical day at the San Andreas fault [California] can detect up to 10 pulses per day. Rift is constantly moving, changing.

See also: Underground lightning earthquakes and volcanoes

According to Blair, before the earthquake background level of static electricity should increase dramatically. He claims that this is what he had seen shortly before the six earthquakes of magnitude 5.0 and 6.0, which he was able to observe.

"The number of pulses increased to 150-200 per day," — said Bleier. He added that the ripple begins to grow about 2 weeks before the earthquake, and then abruptly returned to baseline just shortly before the shift. "It is such an algorithm, and we were looking for," — said Blair.

False Alarms

But the magnetic pulses can cause a number of different reasons, ranging from non-earthquake processes in the Earth's crust, lightning, solar flares and electromagnetic interference from up to highway equipment, lawn mowers and even tractor engine from a nearby farm. And not only that may damage the operation of sensitive equipment. Blair recalled how once inside one of the vehicles climbed spiders, so I had to install the shields.

Bleier also noticed that the charged particles — ions formed from the ranks deep in the earth's crust as a result of moving to the surface. "So I had to add sensors positively and negatively charged ions," — he said.

As the rain can also cause spikes ion concentration, the team had Blair also add moisture sensors to prevent a possible cause for a false alarm.

Another Blair said that when the ions are released into the atmosphere, the positive and negative charges are neutralized. This causes the release of infrared radiation due to weather satellites which can fix the erroneous heating of the surface near the fault, while the ground-based weather stations do not. This can be seen with geostationary satellites.

— If these symptoms are present, we expect that there will be earthquake a magnitude greater than 5.0 in about two days.

Team Blair watched while an insufficient number of earthquakes to confidently assert that the algorithm is correct for all the earthquakes. "However, this algorithm is really quite interesting," — says Tom Bleier.

He believes that they have enough good clues for further work. Starting in January, his team plans to make predictions. "Instead of looking to the past, we intend to look into the future" — said Blair was optimistic.

Other scientists doing laboratory analyzes for the development of the theory of magnetic field. Robert Dahlgren, an electrical engineer from SETI Institute, spent 16 months together with other researchers, trying to squeeze the rocks under high pressure in order to determine whether they produce electric discharge.

He confirmed that the dry stone does produce an electrical discharge and voltage signals as a function of pressure. However, he did not record a bit compression stones wetted with brine, such as found at the depth of the earthquake's epicenter. Presumably because the brine leads to short circuit the electric discharge.

How will this affect predicting earthquakes? Dahlgren has no idea. "I'm just doing research," — he said. However, Dahlgren said that measured in the laboratory signals do generate a magnetic field under certain conditions.

This is a very painstaking research. "We need a year to make a sample impregnated with brine stone — said Dahlgren. — It's like a bear baby elephant. It will take a lot of time to get some results. "

Success — an infrequent visitor in the prediction of earthquakes.

Separating the wheat from the chaff

A few years ago, scientists thought that earthquakes can be predicted by the changes in the ionosphere — the upper layer of the atmosphere at an altitude of 300 km above the Earth's surface. It was assumed that the ions formed before the earthquake, can cause changes in the ionosphere.

But an analysis of five goes before earthquakes change the ionosphere showed that each of them could be caused by other reasons — in most cases the Sun.

"The impact of space physics, and not an earthquake," — said Jeremy Thomas, an expert on space plasma of Northwest Research Associates and Digipen Institute of Technology (Redmond, WA, USA). Thomas presented the study at a meeting of AGU.

In other words, changes in the ionosphere can be detected at a significant distance from the epicenter of the earthquake.

These failures do not mean that the prediction of earthquakes just quackery.

"This area is very promising," — said Michael Blenpayd, Executive Director National Council of earthquake prediction and assessment. Scientists estimate the validity of the council presented methods for predicting earthquakes and report back U.S. Geological Survey.

"A lot of people are working on the problem, explore it from different angles, trying to separate the wheat from the chaff — and find whether there is something else that we have not noticed. The key to success is that the problem involved and highly qualified experts and people from other professions, and people with no special scientific education, but which nevertheless can contribute. "

And this separation of grains from the chaff is the essence of the science of predicting earthquakes.

Translation: Anastasia Antoshkina
Source: National Geographic

Like this post? Please share to your friends: