Geog

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Armenia, 7 December 1988

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This earthquake had a magnitude of Richter 7.0 and devastated large sections of the three Armenian cities of Spitak, Leninakan and Kirovokan. It appears to have resulted from a fault rupture on the southern side of the Caucasus mountains. As all of the
three cities were relatively close to the epicentre of the earthquake, serious damage was expected, not least because the area was not well prepared. The death toll is estimated at between 25 000 and 100 000. 80 per cent of the structures collapsed or
were seriously damaged in Leninakan; in Spitak all of the buildings were damaged; in Kirovakan damage was far less.

Loss of life and damage in Armenia appeared to have been disproportionate. A contributory factor was the soft sediments under Leninakan and Spitak but it was not the main one. Engineers summarised the situation:

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'The catastrophic earthquake that occurred on
December 7,1988 brought about heavy damage to most
buildings and structures in many cities and villages.
Our initial results reveal that most frame and nine-storey panel
buildings were completely destroyed. Stone buildings
with no anti-seismic measures collapsed.'

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Case Study – Japan Earthquake & Tsunami

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•A massive 9.0-magnitude earthquake struck Japan, Friday afternoon, on 11 March 2011 @ 0546 GMT
•The quake was centred 130 kilometres to the east of the prefecture’s capital, Sendai.
•A tsunami was sent crashing into the country’s north-eastern coast.
•It was originally reported at a magnitude of 7.9, but later was upgraded to 8.9 and then to a 9.0.
•It lasted 6 minutes
The Cause
•Japan is located on the east edge of the Eurasian Plate.
•The oceanic Pacific Plate subducts (sinks under) the Eurasian Plate.
•This plate margain is “destructive” – it is not a smooth process, friction is present and the plates stick.
•When the plates stick, tension builds up.

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Impact
•Japan was largely prepared for the earthquake and many buildings remained standing afterwards, but it was not prepared for the subsequent Tsunami.
•A tsunami warning extended to at least 50 nations and territories, as far away as South America.
•Damage was caused in Tokyo and many injuries in the north where the quake was centred
•The yen fell sharply but recouped most of its decline several hours later. Tokyo stocks fell.
•Local television showed smoke rising from a Tokyo port building, fire in the capital’s waterfront Odaiba district and an oil refinery ablaze in Ichihara, near Tokyo.
•A tsunami measured at anywhere from one meter to 7.3 meters hit at various places along the coast, while a 10-meter tsunami was seen at the port in Sendai, near the epicentre.
•Aftershocks were continuing, with one hitting magnitude 7.1, according to the USGS. Tall buildings swayed violently in central Tokyo as the aftershocks hit.Response
•A Tsunami warning was issued 3 minutes after the earthquake.
•Prime Minister Naoto Kan, who convened an emergency Cabinet meeting, urged the nation to be calm and said the government will do its utmost to minimize damage from the quake. He told a news conference a large amount of damage had occurred in the northern Tohoku region.
•A Meteorological Agency official appeared on TV urging those affected by the quake not to return home because of possible tsunamis.