Earthquake Risk in Indonesia

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1 過去の火災事例 MM I TTSS UU I SSUU MMI I TTOO MMOO I NN SSUURR AA NN CC EE GG RR OOUUPP INTTEERRI I ISSK AASSI IAA PPTTEE LLTTD... Earthquake Risk in Indonesia October 2009 In Indonesia, the Sumatra Earthquake of magnitude 7.6 struck at 17:16 local time on September 30, The fatalities are still on the rise. Another tremor registering a magnitude 7.0 also struck Java Island on September 2 and claimed 72 lives. This edition describes the outline of the earthquake risk and notable earthquakes in Indonesia, and it introduces useful web pages to get information on the earthquake. 1.Earthquake Risk in Indonesia (1) Geological Condition of Indonesia Indonesia is an archipelagic country expanding 5,125 kilometers from east to west and 1,760 kilometers from north to south (about 5.1 times the size of Japan). Indonesia's total land area is 1,919,317 square kilometers. It encompasses as many as 18,000 islands, only 6,000 of which are inhabited. There are five main islands; Sumatra, Java where the capital Jakarta is located, Kalimantan (formerly Borneo), Sulawesi (formerly Celebes) and Irian Jaya (formerly Irian Barat or West New Guinea). There are two major archipelagos; Nusa Tenggara (also known as the Lesser Sunda Islands) and the Maluku Islands (or the Moluccas). Kalimantan is shared with Malaysia and Brunei, and Irian Jaya shares the island of New Guinea with Papua New Guinea. Equator More than half of population is concentrated in Java Island, Kalimantan and Irian Jaya are thinly-populated. (Population Density in Indonesia, Reference :United Nations, OCHA) 1/6

2 Geographers have conventionally grouped Sumatra, Java, Kalimantan and Sulawesi in the Greater Sunda Islands. These islands, except Sulawesi, lie on the Sunda Shelf-an extension of the Malay Peninsula and the Southeast Asian mainland. Irian Jaya is, on the other hand, on the Sahul Shelf where Australia also lies. Sea depths in the Sunda and Sahul shelves are average 200 meters or less. Between these two shelves lie Sulawesi, Nusa Tenggara, and the Maluku Islands reach 4,500 meters in depth. Sea depth of Java Trench (Sunda Trench) stretching 2,600km from the western part of Sumatra to the south of Java Island is 7,100m at the deepest point. 作成者 :Maximilian Dörrbecker (2) Earthquake Risk in Indonesia Indonesia and the surrounding regions are the one of the most seismically active areas on the earth. In the south, there is Sunda volcano belts extending 3,000km east to west, which is the result of subduction of the Australia Plate beneath the Eurasia Plate in the north. In the volcanic belt in the north east of Sulawesi, small plates are stretching from south to north direction and showing complex and dynamic activities. In the western part of Java Trench (or Sunda Trench), plate moves by 6cm per year where are 5cm in the eastern part. In some years, about 10cm of plate movement is observed near Irian Jaya. (Volcano Belt in Indonesia, Reference: National Disaster Management Agency, Indonesia) There are a lot of active and dormant volcanoes making up a part of the Pacific ring of fire in Indonesia, and 76 eruptions are recorded in history. (Reference:U.S Geological Survey) 2/6

3 (Reference: United Nations, OCHA. The numbers indicate locations of notable earthquakes hereinafter) The above indicates earthquake intensity in Indonesia. There are many active faults around Indonesia as well as the active plates and volcanic activities, which makes Indonesia geologically prone to earthquake. 2. Notable Earthquakes struck Indonesia (1) Earthquake History Following is the list of the notable earthquakes of magnitude 6 or higher and caused fatalities in the past. Date Epicenter Disaster Area Magnitude Fatalities Jan 20, 1917 Bali Bali Island Unknown 1,500 Jan 24, 1965 Sanana East of Sulawesi Jun 25, 1976 Papua New Guinea 7.1 5,000 Dec 12, 1992 Flores South of Sulawesi 7.8 2,500 Jun 4, 2000 Southern Sumatra Sumatra Oct 10, 2002 Irian Jaya New Guinea Nov 2, 2002 Northern Sumatra Sumatra May 26, 2003 Halmahera Sulawesi Feb 5, 2004 Irian Jaya New Guinea Nov 11, 2004 Kepulauan Alor North east of Sulawesi Nov 26, 2004 Papua New Guinea Dec 26, 2004 Sumatra-Andaman Islands Sumatra ,898 Mar 28, 2005 Northern Sumatra Sumatra 8.6 1,313 Mar 14, 2006 Seram Java May 26, 2006 Java East of Java 6.3 5,749 Jul 17, 2006 South of Java Java Jan 21, 2007 Molucca Sea East of Sulawesi Mar 6, 2007 Southern Sumatra Sumatra /6

4 Sep 12, 2007 Southern Sumatra Sumatra Nov 25, 2007 Sumbawa Region East of Java Feb 20, 2008 Simeulue Sumatra Nov16, 2008 Minahasa, Sulawesi Sulawesi Jan 3, 2009 North Coast of Papua New Guinea Sep 2, 2009 Java Java Sep 30, 2009 Sumatra Sumatra 7.6 More than 1,100 (As of Oct 2 nd ) The bold-faced earthquakes are referred to hereinafter. The chronological table shows that the great earthquakes have occurred and killed people in the entire region of Indonesia except Kalimantan. (2) Outlines of Recent Earthquakes 1 Sumatra-Andaman Islands (2006) The 2004 Indian Ocean Earthquake which occurred off the north-west coast of Sumatra at 7:58on December 26 hit the whole Indian Ocean and caused huge tidal waves. It killed more than 220,000 people and injured more than 130,000 people. This is the second largest earthquake and tsunami since 1900 followed by the Chili Earthquake on May 22, The damage was widespread in the Asian countries such as Malaysia, Thailand, Myanmar, India, Sri Lanka, and Maldives as well as Indonesia reaching as far as Somalia in Africa. The earthquake is classified as a fault-plate boundary earthquake. It is believed that the plate repeated dip-slip three times from south at the focus, and it continued for 6-7 minutes. Though there are several views on the epicentral area, it seems to be as long as 1,000km~ 1,600km. According an observational data, shift of fault (plate boundary) which slid during the main shock ranged from about 400km north-south and 150km east-west, and expected range of displacement was about 20m at a maximum. 2 Java (2006) The Java Earthquake, which occurred in the east of Java Island at 5:54 on May 26, 2006 near Jogjakarta City, was an inland shallow earthquake with a focal-depth of 12km. Active fault stretching north to south of the middle of the island is considered to have triggered the seismic movement. It claimed more than 5,000 lives and injured more than 20,000 people. 3 Java (2009)/ South of Java (2006) The 2009 West Java Earthquake occurred in the west of Java Island at 14:55 on September 2, The focus-depth of the earthquake was 46km. The impact was felt in Jakarta, the capital of Indonesia, and there were many people evacuated from the office buildings. The shaking in the earthquake triggered landslides, which produced numerous causalities and caused further damages. Epicenter of the earthquake is near to the epicenter of the past earthquake in July, 2006 which killed 730 people. 4 Sumatra (2009) The Sumatra Earthquake occurred off the coast of Padang City at the center of Sumatra Island at 17:16 on September 30, The focus-depth of the earthquake was 81km. The seismic movement was felt as far as Malaysia, Singapore and Thailand. More than 2,650 houses were damaged and many people were buried under collapsed buildings. Despite the struggle to rescue the trapped people, the number of the casualties is on the rise. 4/6

5 3. Disaster Prevention Scheme in Indonesia Indonesian disaster prevention scheme was reviewed after the Sumatra Earthquake in December, 2004, and National Action Plan for Disaster was established ( ). Disaster Prevention Act 24 was drawn up in April, 2007 and BNPB (Badan Nasional Penanggulangan Bencana, or National Disaster Management Agency in English), which coordinates comprehensive disaster preventive measures, was set up in BNPB is organized by chief, Steering Committee, and Executive Body. The Steering Committee makes disaster preventive recommendations to the chief of BNPB. It consists of staff and specialists from 10 government agencies including national police and armed forces. Executive Body, on the other hand, deals with preventive measures, emergency responses and restoration strategy after disasters. Regional Disaster Management Agencies have been established at 33 districts, provinces and municipals nationwide. 4. How to Get Information on Earthquakes in Indonesia Here is some useful websites in collecting information on earthquakes in Indonesia. (1) USGS: U.S. Geological Survey, Earthquake Hazard Program (English) URL: Earthquakes listed in Latest Earthquakes are displayed on the map in the order of time of occurrence. Information is kept updated. (2) BNPB: Badan Nasional Penanggulangan Bencana (Indonesian) (English Name: National Disaster Management Agency) URL: The latest information is posted in the front page. Gempa bumi means earthquake in Indonesian. (3) ADRC: Asian Disaster Reduction Center (English, Japanese) URL: Disaster information in Asia in Japanese is also available. Reference:United Nations OCHA: Office for the Coordination of Humanitarian Affairs USGS: U.S. Geological Survey, Earthquake Hazard Program BNPB: Badan Nasional Penanggulangan Bencana, National Disaster Management Agency, Indonesia ADRC: Asian Disaster Reduction Center 5/6

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