March 11th, 2011

Earthquake Strikes off Northeastern Japan

Posted at 11:59 AM ET

japan-earthquake-smallA powerful earthquake struck off the coast of northeastern Japan at 05:46:23 UTC (14:46:23 local time) on March 11, causing severe shaking near the epicenter region and triggering a massive tsunami, according to reports. The U.S. Geological Survey (USGS) said the earthquake measured 8.9Mw while the Japanese Meteorological Agency said it recorded a magnitude of 8.4. The USGS added that the quake was located 130 kilometers (80 miles) east of Sendai and 373 kilometers (230 miles) northeast of Tokyo, at a depth of 24 kilometers (15 miles). This is the fifth most powerful earthquake since 1900 and the largest in Japanese recorded history, according to reports. At least 40 aftershocks have hit the region since the main earthquake, the most powerful at 7.1Mw.

Reports from coastal gauges indicate that a tsunami was generated with official wave measurements ranging from 0.9 meters (3 feet) and 2.8 meters (9 feet) along Japan’s eastern coast. There have been unconfirmed reports in the local media that waves of 10 meters (33 feet) high hit Sendai City, severely damaging the city’s port before sweeping far inland. The tsunami waves have reportedly caused widespread damage in the prefectures of Miyagi and Fukushima, with massive surges of debris-filled water sweeping away buildings, cars and ships. At around 13:00 UTC (03:00 local time), tsunami waves reaching a height of up to 0.7 meters (2.3 feet) struck Hawaii, but no major damage was reported. The Pacific Tsunami Warning Center currently has a tsunami warning in effect for dozens of other Pacific countries, including Russia, Indonesia, the Philippines, Taiwan, Australia, New Zealand, Chile, Canada, Alaska and the entire U.S. West Coast. Coastal areas in several of these countries have been evacuated ahead of the tsunami’s expected arrival.


Hazard data illustrated in the CAT-i map was taken from i-aXs®, Guy Carpenter’s web-based risk management platform. i-aXs users can view impacted areas on any map as well as see how their portfolios were affected. Please contact your broker or GC Analytics (SM)  representative for assistance or go to for further information.

The USGS said around 59 million people live in areas impacted by a Modified Mercalli Intensity (MMI) of V or higher (nearly 30 million people were subjected to shaking of intensity MMI VII). The cities of Sendai, Chiba, Funabashi, Matsudo, Ichikawa, Utsunomiya and Mito experienced intensity VII on the MMI scale, equivalent to very strong shaking with the potential for moderate to heavy building damage, the USGS said. The capital of Tokyo (population of more than 8 million), meanwhile, was hit by MMI intensity of VI, strong shaking that can cause light to moderate structural damage.

Officials say the death toll currently stands at 110, but this is expected to rise with up to 300 people reportedly killed in the coastal city of Sendai and hundreds more missing. No official insured loss estimates have been released as of yet. Dozens of towns and cities along the 2,100 kilometer (1,300 miles) stretch of Japan’s eastern shore were violently shaken by the earthquake. Early reports indicate that the earthquake and tsunami severely damaged residential and commercial properties across the region. Prime Minister Naoto Kan said the earthquake has caused “tremendous damage over a wide area”. Local media reported that farmland around Sendai was submerged by muddy water and the waves pushed debris across the runway of the city’s airport. Other towns and cities in the region reported severe tsunami damage. Dozens of fires were also ignited in northern prefectures of Fukushima, Sendai, Iwate and Ibaraki, according to local media. A large section of the town of Kesennuma was burning hours after the earthquake and fires have been reported in the center of Sendai, prompting officials to evacuate some 70,000 people.

The earthquake also ignited fires at nuclear and oil operations in the region, including a blaze that is reportedly burning in the turbine building of the Onagawa nuclear plant in Miyagi Prefecture. The government also ordered thousands of residents near a nuclear power facility in Onahama City to move away from the plant. Prime Minister Kan said there had been no radiation leaks and appealed for calm. The U.N.’s nuclear agency said four nuclear power plants had shut down safely. Elsewhere, a massive blaze at the Cosmo oil refinery in Ichihara City (Chiba Prefecture) is reportedly engulfing storage tanks and Japan’s largest oil refiner has suspended refinery operations in Sendai, Kashima and Negashi. Manufacturing operations have also been affected, with plants in and around Sendai particularly badly hit. Several car manufacturers, including Toyota and Nissan, have suspended production following the earthquake while operations at some electronic firms have been indefinitely shutdown.

Infrastructure, including roads, bridges, ports, trains, airports, utilities and communication networks, was also badly disrupted. In Iwate Prefecture, officials said roads were badly damaged by the tsunami waves while transport links in Sendai were cut due to damaged road, bridges and railways. Bullet train services to northern Japan were halted and rapid transit in Tokyo was suspended, stranding many workers in the city center. Some structural damage has also been reported in Tokyo after high rise buildings were violently shaken by the earthquake. About four million properties in the capital suffered power outages and a large fire has reportedly broken out in the Odaiba district of the city. Hundreds of flights were cancelled after both airports in Tokyo (Narita Airport and Haneda Airport) were closed immediately after the earthquake, although reports say Haneda has now reopened.

The 8.9Mw earthquake is the latest in a series of quakes to hit offshore of northeastern Honshu over the last couple of days. A 7.2Mw earthquake struck off the same coast on March 9 and was followed a day later by a 6.3Mw quake. The March 11 event is the fifth most powerful earthquake since 1900 and the strongest in Japanese recorded history, according to the USGS. Japan is accustomed to powerful earthquakes and the country’s worst previous event occurred in 1923 when around 143,000 people were killed by an 8.3 magnitude earthquake, according to reports. A 7.2 Mw earthquake hit Kobe City in 1995, killing 6,400 people. Despite economic losses of around USD100 billion from the Kobe event, insured losses were approximately USD6 billion. According to Axco, there is low penetration of commercial earthquake insurance in Japan.

Table 1: Estimated Population Exposed to Significant Earthquake Shaking

Estimated MMI

Estimated Population Exposure

Perceived Shaking






Very strong







Sources: USGS, WSI, Reuters News, Associated News, Agence France Presse, CNN News, BBC News

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Guy Carpenter publishes CAT-i reports for major natural catastrophes worldwide. These reports cover catastrophes including worldwide tropical cyclones, earthquakes, major UK and European floods and any other natural event that is likely to incur a significant loss to the (re)insurance industry. Please email if you wish to be added to the free email distribution list.

Guy Carpenter compiles RISK-i reports for major technological or man-made events worldwide. These reports cover risks to property, transport and life including explosions, fires, crashes, engineering disasters and terrorist attacks that are likely to incur a significant loss to the (re)insurance industry. Please email if you wish to be added to the free email distribution list.

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