Donnerstag, 27. September 2012

Massive Indian Ocean quakes may signal tectonic break-up

The past few years have been marked by numerous seismic events, some of dramatic magnitude; aside from the huge 9.1 temblor in Japan, the world was also shocked by the pair of massive earthquakes that rocked the Indian Ocean on 11 April 2012. However, as geophysicists warn, this may only be the beginning – the birth of a new plate boundary.

 

A pair of massive earthquakes

 

 

The undersea earthquakes measured magnitudes of 8.6 and 8.2 and triggered tsunamis throughout the Indian Ocean. The damage was somewhat smaller than what you’d expect, but now, researchers claim their effects may be more far-reaching than first believed. Basically, the earthquakes were caused by accumulated geologic stress breaking the Indo-Australian plate apart; when they took place, they released energy across numerous faults and unleashed aftershocks for almost a week afterwards.
Ever since the 1980s, researchers believed the Indo-Australian plate is breaking apart, but until now, there hasn’t really been any conclusive evidence to support those claims. The April 11 earthquakes represents the most spectacular example of the process in action, as Matthias Delescluse, a geophysicist at the Ecole Normale Supérieure in Paris explains: “it’s the clearest example of newly formed plate boundaries,” he says.

 

Plate tectonics

 

According to generally accepted theories, the internal stressing and deformation of the Indo-Australian plate began some 10 million years ago; while the plate moved northwards, the Indian part was stopped by the Eurasian plate and dove under the Himalayas, rising them. However, the Australian part forged ahead, creating the tension which is breaking the plate apart today.
Gregory Beroza, a seismologist at Stanford University in Palo Alto, California, is also a believer in this model:
“The 2004 and 2005 earthquakes by themselves would not have caused this other earthquake. There had to be other stresses”, he says.

 

Earthquakes and strike-slips

 

Most earthquakes form at the boundary of tectonic plates, as you can see from the second picture above; one plate drifts beneath the other, creating massive earthquakes – this is called subduction. However, this is not the only form of contact between plates: plates or portions of plates can also slip by each other, horizontally, resulting in what is called as ‘strike-slip’ earthquakes. Typically, these earthquakes are smaller and less dangerous (though dangerous as well).
However, the first of the two earthquakes defied all expectations, being the largest strike slip earthquake on record, and one of the biggest to occur away from any plate boundaries.
Another study drew some pretty interesting, but worrying conclusion: the earthquake was created by accumulated stress throughout the plate, and the release of this stress created one of the most complex fault patterns in the world – something you really don’t want to hear if you live in that area. Typically, an earthquake like this shakes along a single fault, or maybe two if it’s a really big one; but this one shook no less than four faults, one of which slipped more than 20 meters. While this pattern has been described partially in previous work, nobody has analyzed slip amounts in so much detail: Beroza says that Lay and his team “do a splendid job of picking apart this very important earthquake” in their paper.

Aftershocks

So not only was this earthquake unique due to its high magnitude and slip, its aftershocks are also special. In yet another study, researchers found that for the six days following the temblor, aftershocks with magnitudes bigger than 5.5 occurred 5 times more often than normal.
“Aftershocks are usually restricted to the immediate vicinity of a main shock,” says lead author Fred Pollitz, a geophysicist at the US Geological Survey in Menlo Park, California.
However, this changes the general belief of how soon and how close aftershocks can occur after earthquakes, raising the importance of this particular earthquake even more.
“Every earthquake is important to study, but this earthquake is rather unique,” says Hiroo Kanamori, a seismologist at the California Institute of Technology in Pasadena.

source: Scientific (zmescience)

Strong Earthquake Jolts Alaska's Aleutian Islands

Seismologists say a strong earthquake has jolted Alaska's sparsely populated western Aleutian islands.
There are no immediate reports of injury or damage from Wednesday's magnitude-6.9 earthquake. But the Alaska Earthquake Information Center says the quake was felt in the communities of Adak and Atka, more than 1,000 miles from Anchorage.
The quake struck at 3:39 p.m. Alaska Daylight Time, or 7:39 p.m. EDT, and was centered 71 miles southwest of Adak.
The Tsunami Warning Center in Palmer, Alaska, says there is no expectation that the quake will create a damaging tsunami.

Source: ABC-NEWS

Mittwoch, 26. September 2012

Magnitude 6.2 Earthquake strikes near Mexico's Baja Peninsula

WASHINGTON (Reuters) - A magnitude 6.3 earthquake struck near Mexico's Baja Peninsula on Tuesday, according to the U.S. Geological Survey.
The quake's epicentre was located 38 miles (61 km) north of La Paz, Mexico, and was offshore in the Gulf of California.
A magnitude 6 earthquake is capable of causing severe damage, but there were no immediate reports of injuries or deaths.

Copyright © 2012 Reuters

Samstag, 22. September 2012

M 5.1 - Strong Earthquake in Corinth (Greece)

Strong earthquake of magnitude 5.1 hit Corinthian prefecture of Greece.Tremors were felt in Corinth, Argos, Nafplio and many areas of Attica.
According to the US Geological Survey , the quake’s epicenter was located 4 km from Kiato and 86 km west of Athens .
Greece is continuously hit by number of strong earthquakes in the past few years, including major quakes on or near Crete, Rhodes , the Peloponnese, Karpathos, and elsewhere in Greece.

Mittwoch, 12. September 2012

Juskis Earthquakeprediction Calendar Week 38 (Global)

The current active period seems to reach its peak in the next week. That climax could be a heavy one. It is possible that this is the strongest earthquake of the year (so far: M 8.6). As a result, it might also be the most destructive.
Here is an overview:


Monday to Wednesday, September 17 to 19, 2012

The probability M 6,5+: 90% 
The probability M 7,0+: 70%
The probability M 8,0+: 40%
The probability M 9,0+: 10%

The probabilities can, like all predictions of large earthquakes,  still change significantly some days before. Therefore, these are only tendencies. On Saturday or Sunday, probably a correction follows in the form of an update.
For this prediction it is also important: Before and after the strong quake  it is possible that an earthquake between magnitude 6 and 7 occurs at an other place on earth. It should be magnitude 9, it may also be greater than 7.

Freitag, 7. September 2012

Juskis Earthquakeprediction

Calendar Week 37 (GLOBAL):

There is only one earthquake period but this one is a very heavy one! This earthquake could be stronger than the earthquakes of  El Salvador, Costa Rica, Phillipines and Sachalin.
The period is from 13 to 14 of September 2012 (Thursday and Friday)

Global:  
The probability M 6,5+: 85% 
The probability M 7,0+: 70%
The probability M 8,0+: 30%
The probability M 9,0+:   5%

Source: Juskis Earthquakeprediction


what happened in Costa Rica?? (video)


Earthquake in southwest China kills dozens

At least 43 people killed and 20,000 homes damaged as tremor hits Yunnan and Guizhou provinces, state media reports.

At least 43 people have been killed and 20,000 homes damaged by a series of earthquakes, one measuring 5.7 in magnitude, in southwestern China, local authorities and state media say.
The largest of the tremors struck the border between Yunnan and Guizhou provinces at about 11:00am local time (03:00 GMT) on Friday. The state-run Xinhua news agency said the earthquake hit the border area of Yiliang county of Yunnan and Weining county of Guizhou.
Zhang Junwei, a spokesperson from the Yunnan seismological bureau, said that the deaths all occurred in Yiliang, and that another 150 people were hurt.
The main tremor, which occurred at a depth of 14km, was followed by a series of aftershocks, the China Earthquake Networks Centre said. The earthquake was also felt in neighbouring Sichuan province.
Xinhua quoted an official with the Yunnan civil affairs department as saying more than 100,000 people had been evacuated in Yunnan.
Xinhua said the provincial government had sent work teams to the quake-hit area and the civil affairs department was shipping thousands of tents, blankets and coats to the area.
Al Jazeera's Marga Ortigas, reporting from Hong Kong, said that the military had been deployed to conduct search and rescue operations in the area.
The US Geological Survey put the magnitude of the largest quake at 5.6 and said it struck at a depth of 10km.
Buildings damaged
Television footage on state broadcaster CCTV showed hundreds of people gathered on the streets in the town of Yiliang, which appeared to have been worst hit, and streets strewn with fallen bricks and rocks.
Local residents described how people ran out of buildings screaming as the quake hit.
"I was walking on the street when I suddenly felt the ground shaking beneath me. People started rushing outside screaming, it still scares me to think of it now," posted one on Sina Weibo, a microblogging service similar to Twitter.
Photographs posted online showed streets strewn with rocks and bricks from damaged buildings.
Mobile phone services were down and regular phone lines disrupted in the area.
Xinhua said that so far no casualties had been reported in Guizhou, but that homes had been damaged or destroyed there.
"This is a very agricultural, rural area of southwestern China [and it is] also very mountainous and hilly," reported Al Jazeera's Ortigas. "The buildings in those areas and the construction is known to be quite poor."
Southwestern China is prone to earthquakes. In May 2008, an 8.0-magnitude tremor hit Sichuan province and parts of neighbouring Shaanxi and Gansu provinces, killing tens of thousands of people and flattening many areas.

 
Source:
Al Jazeera and agencies

Mittwoch, 5. September 2012

Powerful 7.6 quake hit Costa Rica, tsunami warning issued


SAN JOSE, Costa Rica | Wed Sep 5, 2012 11:34am EDT


(Reuters) - A powerful 7.6-magnitude earthquake rocked Costa Rica on Wednesday, rattling buildings and cutting power in some areas of the capital.
Residents of San Jose said electricity poles were rattling along the streets of San Jose and water flowed out of pools during the quake.
The quake's epicenter was in western Costa Rica about 140 km (87 miles) from San Jose, the U.S. Geological Survey (USGS) said, and it was felt as far away as Managua, the capital of neighboring Nicaragua.
The Pacific Tsunami Warning Center issued a warning for Pacific coastlines from Mexico to Chile.
The last major earthquake in Costa Rica was a 6.1 magnitude quake in 2009, which killed 40 people, according to the USGS.