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A tsunami saved the Greek village of Potidaea from Persian invaders in winter 479 BC, a German study said Thursday, warning that the area remains prone to earthquakes.

New geological evidence suggests that the region could still face tsunami events like the one that drowned hundreds of Persian invaders as they lay siege to the ancient Greek village many centuries ago, according to Klaus Reicherter of Aachen University in Germany and his colleagues.

 

Sediment on the northern Greek peninsula where Potidaea, and its modern counterpart Nea Potidea, is located showed signs of massive marine events, such as large waves, the study said.

And excavations in the suburbs of the nearby ancient city of Mende uncovered a high-energy level dating back to the fifth century BC that contained far older sea shells likely plucked from the ocean bed and tossed about during a tsunami.

The event was previously described by Greek historian Herodotus.

Reicherter said the study’s findings suggested that the Thermaic Gulf where the peninsula is located — a densely populated area that is also a tourist destination — should be included in Greece’s tsunami-prone regions.

He was due to present his research Thursday at the annual meeting of the Seismological Society of America in San Diego, California. [AFP]

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7.4 quake shakes Mexico, 100s of homes damaged
A strong 7.4-magnitude earthquake hit southern Mexico on Tuesday, damaging some 800 homes near the epicenter and swaying tall buildings and spreading fear and panic hundreds of miles away in the capital of Mexico City.

One of the strongest to shake Mexico since the deadly 1985 temblor that killed thousands in Mexico City, Tuesday’s earthquake hit hardest in the border area of southern Oaxaca and Guerrero states. In Guerrero, officials confirmed that some 800 homes had been damaged, with another 60 having collapsed.

Long after the shaking at noon local time (18:02 GMT), there were still no reports of death, even after a less powerful, magnitude-5.1 aftershock was felt in the capital and several other aftershocks near the epicenter in a mountainous rural region. Interior Secretary Alejandro Poire said late Tuesday night that nine people were injured in Oaxaca and two in Mexico City, but no one had died.

Guerrero Gov. Angel Aguirre, who is from Ometepec, was headed there to survey the damage and ordered emergency crews and civil protection to the area to help with the damage. The state did not say how many were displaced.

In Mexico City, frightened workers and residents poured into the streets of the capital. Telephone service was down in the city and throughout the area where the quake was felt and some neighborhoods were without power, according to Mexico City Mayor Marcelo Ebrard, who set up a hotline for people to report damage.

A pedestrian bridge collapsed on an empty transit bus.

About 40 passengers were stranded for a short time on the Mexico City airport air train, but later released. The airport closed for a time but officials said there was no runway damage and they resumed operations.

Mexico City, built on a lakebed, was badly damaged in 1985 when a quake killed at least 10,000 people. That quake was originally measured at 8.1, but is now put by the U.S. Geological Survey at 8.0. In past years, Guerrero has suffered several severe earthquakes, including a 7.9 in 1957 which killed an estimated 68 people, and a 7.4 in 1995 which left three dead.

Tuesday’s quake was the strongest shaking felt in the capital since a magnitude-6.5 earthquake struck also in Guerrero in December. Officials said at least three people died in Guerrero, but there were no reports of widespread damage.

A magnitude-8.0 quake near Manzanillo on Mexico’s central Pacific coast killed 51 people in 1995 and a magintude-7.5 quake killed at least 20 people in the southern state of Oaxaca in 1999.

In Huajuapan, Guerrero, near the epicenter, hotel manager Marco Antonio Estrada also reported shaken-up guests but no major damage. He said it was longest and strongest he ever felt. People ran out of their homes and cars.

The U.S. Geological Survey set the preliminary magnitude of the first quake at 7.4 and said the epicenter was 11 miles underground. The survey set the aftershock at 5.1.

Seismologists and civil protection officials said there didn’t appear to be heavy damage or casualties because of where and how the earthquake hit.

There were reports of damaged buildings but none collapsed on the Oaxaca side of the border, said civil protection spokeswoman Cynthia Tovar said. Authorities believed that the absence of tall buildings in the area is one reason.

Another factor may be the high frequency of earthquakes in the region, said USGS seismologist Susan Hoover.

There have been 15 earthquakes of magnitude 7 or stronger since 1973 within 310 miles (500 kilometers) of Tuesday’s quake. Weaker buildings collapse with each quake, leaving a cadre of stronger ones that can withstand the shaking.

“Another factor to consider is how tested an area has been,” Hoover said.

Also limiting damage was that much less energy was released in Tuesday’s quake than in 1985.

Victor Hugo Espindola Castro, a seismologist with Mexico’s national service, said the difference was of a three-to-one margin.

“Many of the buildings that were damaged in 1985 were poorly constructed and from that came the new building regulations, so that now buildings are stronger,” he said.

March 21, 2012
Associated Press

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More than 200 people were killed and hundreds more feared dead on Monday after an earthquake struck parts of southeast Turkey, where rescue teams worked through the night to try to free survivors crying for help from under rubble.
Survivors and emergency service workers searched frantically through mounds of smashed concrete and other debris with shovels and their bare hands after the 7.2 magnitude quake toppled buildings and some roads on Sunday.
Interior Minister Idris Naim Sahin said the quake had killed 120 people in the town and 100 more in the city of Van, some 100 km (60 miles) further south. The toll was expected to rise.
Sahin, who is overseeing emergency operations in Ercis, said 1,090 people had been wounded while hundreds more were unaccounted for.
Rescue efforts were hampered by power outages after the quake brought down power cables to towns and villages across much of the barren Anatolian steppe near the Iranian border.
As dawn broke the scale of devastation was clear.
Prime Minister Tayyip Erdogan said there were an unknown number of people unaccounted for under the collapsed buildings of the stricken towns, and he feared the worst for villagers living in outlying rural areas, who had yet to be reached.
“Because the buildings are made of adobe, they are more vulnerable to quakes. I must say that almost all buildings in such villages are destroyed,” Erdogan told a televised news conference in Van on Monday shortly after midnight.
More than 100 aftershocks have jolted the region in the hours since the quake struck for around 25 seconds at 1041 GMT (6:41 a.m. EDT) on Sunday.
U.N Secretary General Ban Ki-moon said he was deeply saddened by the loss of life and devastation. “He expresses his heartfelt sympathies to the government and people of Turkey at this time of loss and suffering,” the United Nations said in a statement.
In Van, a bustling and ancient city on a lake ringed by snow-capped mountains and with a population of one million, cranes shifted rubble off a collapsed six-storey apartment block where bystanders said 70 people were trapped.
Erdogan visited Ercis earlier by helicopter to assess first hand the scale of the disaster. With 55 buildings flattened, including a student dormitory, the level of destruction in Ercis, a town of 100,000, was greater than in Van.
“We don’t know how many people are in the ruins of collapsed buildings, it would be wrong to give a number,” he said.
Newspapers said trauma had been piled on trauma in southeast Turkey. Kurdish militants killed 24 Turkish soldiers in an attack last week in Hakkari, south of Van.
“Homeland of Pain. Yesterday terrorism, today earthquake,” said Radikal newspaper.
The Red Crescent said a team of about 100 expert personnel had arrived at the earthquake zone to coordinate operations. Some 4,000 tents and 11,000 blankets, stoves and food were being distributed to help fight off the cold.
At Van airport, a large Turkish Airlines cargo plane was offloading aid materials, which military vehicles were waiting to transport to the quake zone.
A tent city was being set up at the Ercis sports stadium. Access to the region was made more difficult as the earthquake caused the partial collapse of the main road between Van and Ercis, broadcaster CNN Turk reported.
Soldiers were deployed in Ercis to help rescuers and digging machines had also arrived to help. There was a constant wail of ambulance sirens ferrying the injured to hospitals.
Dogan news agency reported that 24 people were pulled from the rubble alive in the two hours after midnight.
One nurse told CNN Turk news channel the town’s hospital was so badly damaged that staff were treating injured in the garden, and bodies were being left outside the building,
After visiting the quake zone, Erdogan returned to Ankara, where he is expected to chair a cabinet meeting to discuss the response to the disaster.
He said Turkey was able to meet the challenge itself, but thanked countries offering help, including Armenia and Israel, two governments that have strained relations with Ankara.

October 24, 2011
Reuters

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The devastating 2004 Indonesian tsunami, with its death toll of as many as 250,000 people, was caused by the first magnitude-9.0 earthquake since 1967. A succession of smaller but still destructive tremors in Haiti, Chile, and New Zealand — surpassed by this year’s magnitude-9.0 quake in Japan — has some researchers wondering whether the number of large earthquakes is on the rise.

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June 13 2011
Short Review

Christchurch was hit with aftershocks on June 13, as a series of tremors rocked New Zealand’s second- biggest city.

According to the RMS Reactions Catastrophe Centre, a 5.2 (body wave) magnitude earthquake struck at 01:00 UTC, and was followed by a stronger 6.0 (moment) magnitude earthquake within an hour and a half.

A further earthquake, of 4.6 (body wave) magnitude, struck at 02:40 UTC. According to reports, this resulted in a temporary closure of the airport followed by power outage to up to 56,000 users in addition to flooding and liquefaction.

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The largest earthquake in Japanese records hit the East coast of Japan Friday the 11 of March. The large magnitude of the earthquake (~8.9 Mw), its location offshore of the coast and its depth of 14km, triggered a destructive tsunami with waves up to 10m.
The main peculiarity of this this catastrophic event which has damaged most of the eastern coast of Japan leaving the country in need of foreign aid, is that it was preceded by several fore-shocks of large magnitudes up to 7.1 Mw. Such behaviour was not seen in previous hazardous earthquakes like Chile (9.3 Mw), Haiti (6.2Mw) or New Zealand (7.1 and 6.3 Mw)

For more information on this severe natural catastrophe go to:

  • USGSSeismological information and real time data
  • JMALocal scientific information
  • BBCLatest news and some technical notes
  • CNN: Latest news
  • Red Cross: For humanitarian aid

8.9 Earthquake / Tsunami Strikes Japan

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An earthquake of magnitude 7.2 has shaken the border between Pakistan and Afghanistan today at 01:23:26 AM local time according to the USGS.

For more scientific and general information about this event please go to the
USGS webpage.

This is not the first large or damaging earthquake which has happened in that zone. Below there is a list of historical earthquakes collected from the International Seismological Centre since 1964.

Author Date – Time Lon Lat Depth Value Type
1979-01-16 09:50:06 33.956 59.531 9.7 6.7 MS
1979-11-14 02:21:18 34.029 59.806 3.0 6.7 MS
1979-11-27 17:10:33 34.082 59.795 9.0 7.3 MS
1979-12-07 09:23:55 34.139 59.918 0.0 6.1 MS
1993-01-27 10:27:04 32.084 60.090 21.0 4.8 MS
1994-02-23 08:02:04 30.806 60.569 6.0 6.1 MS
1994-02-26 02:31:11 30.849 60.555 9.4 5.9 MS
1997-05-10 07:57:29 33.878 59.823 6.7 7.0 MS
1997-05-13 11:42:25 33.462 59.888 37.0 3.9 MS
1997-06-16 03:00:10 33.302 60.208 55.2 4.4 MS
1997-06-20 12:57:36 32.327 60.024 34.8 5.4 MS
1998-04-10 15:00:53 32.454 60.086 33.0 5.7 MS
1999-11-08 21:37:20 35.715 61.246 10.0 5.2 MS
2001-10-08 01:17:16 32.899 60.276 27.0 4.4 MS
2003-07-03 14:59:27 35.575 60.850 2.1 4.9 MS
2004-07-14 14:36:02 35.014 61.891 14.8 3.6 MS

This is the map of the events shown above

Global positioning Afghanistan-Pakistan border

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The World-Wide Earthquake Locator aims to provide up-to-date information and detailed dynamic maps of earthquakes across the world within a maximum of 24 hours of their occurence. This web site also includes a database of past earthquakes, an animation of the past month’s earthquakes, and statistical earthquake prediction.

The World-Wide Earthquake Locator was originally developed by Bruce Gittings of the School of GeoScience at the University of Edinburgh in 1995 and it became an early illustration of a real-time Geographical Information System which makes use the internet World-Wide Web and the internet to map dynamic phenomena.

The Locator takes data from the National Earthquake Information Center (NEIC), part of the US Geological Survey, based in Golden, Colorado (USA). This data provides basic information about the location of recent earthquakes and their strength within hours of the events taking place

The World Earthquake locator

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The 2010 Canterbury earthquake (also known as the Christchurch earthquake) was a 7.1 magnitude earthquake which struck the South Island of New Zealand at 4:35 am on 4 September 2010 local time (16:35 3 September UTC)

The quake caused widespread damage and several power outages, particularly in the city of Christchurch. Two residents were seriously injured, one by a collapsing chimney and a second by flying glass. One person died of a heart attack suffered during the quake, although this could not be directly linked to the earthquake. Mass fatalities were avoided partly due to New Zealand’s strict building codes, although this was also aided by the quake occurring during the night when most people were asleep at home

The earthquake’s epicentre was 40 kilometres (25 mi) west of Christchurch, near the town of Darfield. The hypocentre was at a shallow depth of 10 km. A foreshock of roughly magnitude 5.8 hit five seconds before the main quake, and strong aftershocks have been reported, up to magnitude 5.4. The initial quake lasted about 40 seconds, and was felt widely across the South Island, and in the North Island as far north as New Plymouth. As the epicentre was on land away from the coast, no tsunami occurred

(from wikipedia)

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earthquake disaster reliefEarthquake questions are raised whenever an event has happened, or one predicted.

Earthquakes have enthralled both young and old, from the “great San Francisco” earthquake of 1906, or the tsunami of 2007, to the latest headlines from Haiti and Chile.

The word “earthquake” is generally used to refer to any event caused naturally or by man that creates seismic (shaking) waves generated at geological fault lines but also by volcanic activity and man-made mine blasts and nuclear experiments.

This initial rupture is called the hypocenter. If you throw a rock into a lake, the waves ripple outwards from where the rock entered the water, getting weaker and weaker the farther from the center. This ground level center, in earthquake terms, is called the epicenter which is directly about the hypocenter.

During an earthquake, typically the first seismic wave is a compression wave, which is fast moving and hits with a sudden thump. They are followed a few seconds later by a second kind of seismic wave, a transverse wave, and cause the rocking, swaying, and shaking motions. Quakes are often preceded by foreshocks, or followed by aftershocks, which can be quite damaging and dangerous. They can occur hours or even days before or after the actual earthquake itself.

The size of earthquakes is usually measured using the “Richter” scale (Charles Richter developed this in the 1920s at the California Institute of Technology). It compares the heights of the seismic waves out from the epicenter and quantifies the amount of seismic energy by assigning a single number.

Following is a list of Richter scale numbers with related explanations of their power and an estimate of occurrence (source Wikipedia):

  • 2.0 Richter Magnitude: Micro earthquakes, not felt. Approximately 8,000 a day.
  • 2.0-2.9 Richter Magnitude: Usually not felt, but recorded. About 1,000 a day
  • 3.0-3.9 Richter Magnitude: Often felt, but infrequently cause damage. 49,000 a year.
  • 4.0-4.9 Richter Magnitude: Noticeable shaking of indoor items, rattling noises but little likelihood of significant damage. 6,200 a year.
  • 5.0-5.9 Richter Magnitude: Can cause major damage to poorly-constructed buildings over restricted regions (unlikely to cause more than slight damage to well-designed buildings). 800 a year.
  • 6.0-6.9 Richter Magnitude: Destructive in areas up to about 100 miles across in populated areas. 120 a year.
  • 7.0-7.9 Richter Magnitude: Usually cause serious damage over larger areas. 18 a year.
  • 8.0-8.9 Richter Magnitude: Can cause very serious damage in areas several hundred miles across. 1 a year.
  • 9.0-9.9 Richter Magnitude: Devastating in areas several thousand miles across. 1 per 20 years.
  • 10.0+ Richter Magnitude: Of epic proportions. Never recorded.

Here are some well-known earthquakes, and their approximate Richter scale magnitudes:

  • 0.5 Magnitude Equals The Power Of A Large Hand Grenade (approx.)
  • 3.5 Magnitude Chernobyl Nuclear Disaster, 1986
  • 6.9 Magnitude San Francisco Bay Area Earthquake (CA, USA), 1989
  • 8.0 Magnitude San Francisco Earthquake (CA, USA), 1906
  • 8.5 Magnitude Sumatra Earthquake (Indonesia), 2007
  • 9.5 Magnitude Valdivia Earthquake (Chile), 1960 (251 ZJ in this case)
  • 10.0 Magnitude Never Recorded

This site will address other questions and answers about earthquakes.

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