2004 Chuetsu Earthquake

2004 Chuetsu earthquake The Chuetsu Earthquakes (中越地震) began at 5:56 p.m. on Saturday, October 23, 2004 (0856 UT, same day). The Japan Meteorological Agency (JMA) has named it the Heisei 16 Niigata Prefecture Chuetsu Earthquake (平成 16 年新潟県中越地震) or The Mid Niigata Prefecture Earthquake of 2004.

EARTHQUAKE DETAILS The first quake struck the Chuetsu area of Niigata Prefecture, Japan with a reading of 7 on the Japanese shindo scale at Kawaguchi, Niigata. On the Richter scale, the moment magnitude of the earthquake is estimated at 6.9. (For comparison, the Great Hanshin earthquake, which devastated much of Kobe, measured 7 on the shindo scale, with a magnitude of 7.2.) The earthquake occurred at a depth of 15.8 km. The JMA gave the coordinates of the earthquake as 37.3° N 138.8° W. A second earthquake occurred at 6:12 p.m. (16 minutes after the first). This one, at a much shallower depth, also caused a shindo of 6+ and had a magnitude of 5.9. A third, at 6:34, had a shindo of 6−. At 7:46, another shindo 6− earthquake occurred. Intervening and subsequent earthquakes of lesser intensity also shook the region. During the first 66 hours, 15 earthquakes with intensities of shindo 5− or higher rocked the Chuetsu region. In a press release, the Geographical Survey Institute (GSI) of the Government of Japan published preliminary estimates that a fault having a length of 22 km and a width of 17 km moved approximately 1.4 m. This was the deadliest earthquake to strike Japan since the January 1995 Great Hanshin earthquake. Damage

Damaged road; photo taken in October, 2004, Ojiya As late as November 3, the 39th fatality attributable to the earthquakes occurred as perceptible aftershocks continued. Over 3,000 injuries were reported in Niigata Prefecture. Over one hundred thousand people fled their homes. The earthquakes caused houses to collapse in Ojiya and damaged thousands in the area.

For the first time in its history, a Shinkansen train derailed while in service. Eight out of ten cars of the Toki 325 (a 200 Series Shinkansen) derailed on the Joetsu Shinkansen line between Nagaoka Station in Nagaoka and Urasa Station in Yamato; no injuries were reported among the 155 passengers. Railbeds, bridges and tunnels were all affected. East Japan Railway Company stopped all trains in Niigata Prefecture, including the extensively damaged Joetsu Line, Shinetsu Main Line, Iiyama Line, Tadami Line and Echigo Line. Part of Nagaoka Station appeared ready to collapse as a result of an aftershock, but after a brief closure, the station reopened. The segment of the Joetsu Shinkansen between Echigo Yuzawa Station and Nagaoka Station closed. Buses transferred passengers between the two operating segments of the line: Tokyo Station–Echigo Yuzawa Station and Nagaoka Station–Niigata Station. On December 27, 2004, service resumed on all remaining parts of the Joetsu and Iiyama Lines reopened. On December 28, 2004, the Joetsu Shinkansen also reopened, the last to do so. Japan Highways closed all expressways in Niigata Prefecture. Closures affected the Kanetsu Expressway and the Hokuriku Expressway. As of November 4, the Kanetsu Expressway remained closed between Nagaoka Interchange and Koide Interchange. This segment reopened on November 5. Landslides and other problems forced closure of two national highways, Route 8 and Route 17, as well as several prefectural roads. This isolated several localities, including nearly the entire village of Yamakoshi, which was then a village in the district of Koshi but since merged with and became part of the city of Nagaoka. On July 22, 2005, the government lifted the nine-month-old evacuation order for 528 of the 690 affected households. The earthquakes also caused a landslide that partially buried three vehicles. A young boy was rescued from one of these vehicles, but his mother and sister perished. (Recent typhoons had waterlogged the soil, making landslides more likely.) The quake broke water mains. Extensive electric power, telephone (including cellular telephone) and Internet outages were reported. The cellular telephone system suffered from direct damage to relay stations, as well as depletion of battery back-up power supplies in as little as a day.

Background The shindo scale is a scale of intensity, like the Mercalli Intensity Scale. It provides information related to the severity of shaking at the earth's surface, where it affects structures. In contrast, the magnitude of the earthquake describes the energy released by the quake.

Niigata Prefecture is located in the Hokuriku region of Honshū, the largest island of Japan. The initial earthquake caused noticeable shaking across almost half of Honshū, including parts of the Tohoku, Hokuriku, Chubu, and Kantō regions. REFERENCE:From Wikipedia, the free encyclopedia(Redirected from 2004 Chuetsu Earthquake)

2004 Indian Ocean earthquake The 2004 Indian Ocean earthquake, known by the scientific community as the Sumatra-Andaman earthquake, [1] was a great undersea earthquake that occurred at 00:58:53 UTC (07:58:53 local time) December 26, 2004 with an epicentre off the west coast of Sumatra, Indonesia. The earthquake triggered a series of devastating tsunamis along the coasts of most landmasses bordering the Indian Ocean, killing large numbers of people and inundating coastal communities across South and Southeast Asia, including parts of Indonesia, Sri Lanka, India, and Thailand. Although initial estimates had put the worldwide death toll at over 275,000 with thousands of others missing, more recent analysis compiled by the United Nations lists a total of 229,866 people lost, including 186,983 dead and 42,883 missing.[2] The figure excludes 400 to 600 people who are believed to have perished in Myanmar which is more than that government's official figure of only 61 dead.[3] The catastrophe is one of the deadliest disasters in modern history. The disaster is known in Asia and in the international media as the Asian Tsunami, and also called the Boxing Day Tsunami in Australia, Canada, New Zealand, and the United Kingdom as it took place on Boxing Day. Coincidentally, the tsunami occurred exactly one year after the 2003 earthquake that devastated the southern Iranian city of Bam and exactly two years before the 2006 Hengchun earthquake. The magnitude of the earthquake was originally recorded as 9.0 on the Richter scale, but has been upgraded to between 9.1 and 9.3. At this magnitude, it is the second largest earthquake ever recorded on a seismograph. This earthquake was also reported to be the longest duration of faulting ever observed, lasting between 500(8.3 minutes) and 600(10 minutes)seconds, and it was large enough that it caused the entire planet to vibrate at least half an inch, or over a centimetre.[4] It also triggered earthquakes in other locations as far away as Alaska.[5] The earthquake originated in the Indian Ocean just north of Simeulue island, off the western coast of northern Sumatra. The resulting tsunami devastated the shores of Indonesia, Sri Lanka, India, Thailand and other countries with waves up to 30 m (100 ft). It caused serious damage and deaths as far as the east coast of Africa, with the farthest recorded death due to the tsunami occurring at Rooi Els in South Africa, 8,000 km (5,000 mi) away from the epicentre. In total, eight people in South Africa died due to abnormally high sea levels and waves.

The plight of the many affected people and countries prompted a widespread humanitarian response. In all, the worldwide community donated more than $7 billion (2004 US dollars) in humanitarian aid to those affected by the earthquake.

Earthquake characteristics

Epicentre of the earthquake, just north of Simeulue Island The earthquake was initially reported as moment magnitude, Mw 9.0 (note that this is not the so-called Richter scale or local magnitude scale, Ml, which is known to saturate at higher magnitudes.) In February 2005 scientists revised the estimate of the magnitude to Mw9.3.[6] Although the Pacific Tsunami Warning Center has accepted these new numbers, the United States Geological Survey has so far not changed its estimate of 9.1. The most recent studies in 2006 have obtained a magnitude of Mw 9.1 to 9.3. Dr. Hiroo Kanamori of the California Institute of Technology believes that Mw = 9.2 is a good representative value for the size of this great earthquake. Reference: EERI Publication 2006-06, page 14 [www.eeri.org] The hypocentre of the main earthquake was at 3.316°N, 95.854°E (3°19′N 95°51.24′E), approximately 160 km (100 mi) west of Sumatra, at a depth of 30 km (19 mi) below mean sea level (initially reported as 10 km). The earthquake itself (apart from the tsunami) was felt as far away as Bangladesh, India, Malaysia, Myanmar, Thailand, Singapore and the Maldives. Indonesia lies between the Pacific Ring of Fire along the north-eastern islands adjacent to and including New Guinea and the Alpide belt along the south and west from Sumatra, Java, Bali, Flores, and Timor. The December 2004 earthquake actually occurred within the Alpide belt. [citation needed]

Great earthquakes such as the Sumatra-Andaman event, which are invariably associated with megathrust events in subduction zones, have seismic moments that can account for a significant fraction of the global earthquake moment across century-scale time periods. The Sumatra-Andaman earthquake was the largest earthquake since 1964, and the second largest since the Kamchatka earthquake of October 16, 1737.

Of all the seismic moment released by earthquakes in the 100 years from 1906 through 2005, roughly one-eighth was due to the Sumatra-Andaman event. This quake, together with the Good Friday Earthquake (Alaska, 1964) and the Great Chilean Earthquake (1960), account for almost half of the total moment. The much smaller but still catastrophic 1906 San Francisco earthquake is included in the diagram at left for perspective. Mw denotes the magnitude of an earthquake on the moment magnitude scale. Since 1900 the only earthquakes recorded with a greater magnitude were the 1960 Great Chilean Earthquake (magnitude 9.5) and the 1964 Good Friday Earthquake in Prince William Sound (9.2). The only other recorded earthquake of magnitude 9.0 or greater was off Kamchatka, Russia, on November 4, 1952 (magnitude 9.0).[7] Each of these megathrust earthquakes also spawned tsunamis in the Pacific Ocean, but the death toll from these was significantly lower. The worst of these caused only a few thousand deaths, primarily because of the lower population density along the coasts near affected areas and the much greater distances to more populated coasts. Other very large megathrust earthquakes occurred in 1868 (Peru, Nazca Plate and South American Plate); 1827 (Colombia, Nazca Plate and South American Plate); 1812 (Venezuela, Caribbean Plate and South American Plate) and 1700 (Cascadia Earthquake, western U.S. and Canada, Juan de Fuca Plate and North American Plate). These are all believed to have been of greater than magnitude 9, but no accurate measurements were available at the time.

REFERENCE: From Wikipedia,

ADAMSON UNIVERISTY COLLEGE OF ENGINEERING CIVIL ENGINEERING DEPARTMENT

EARTHQUAKE ENGINEERING

Caliwatan, Michael F. Sibayan, Mark Joseph M.

Engr. Cris Lictaoa