Recent Trends in Earthquake Disaster Management in Japan
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QUARTERLY REVIEW No.19 / April 2006 7 Recent Trends in Earthquake Disaster Management in Japan KATSUTOSHI SUGANUMA General Unit major earthquake directly struck a large city in 1 Introduction Japan. With advances in construction technology and so on, it was widely believed that major Despite the fact that Japan and the seas destruction would not occur in the event of an around it account for only about 1 percent of the earthquake. Earth’s surface, approximately 10 percent of the The Great Hanshin-Awaji Earthquake, however, world’s earthquakes of magnitude 8.0 or greater caused the collapse of expressway overpasses and during the 20th century occurred in Japan or other damage that had been unanticipated and its vicinity, it shows Japan is one of the most not thought possible. earthquake-prone countries in the world. Japan is also a leader in earthquake disaster management. 2-1 Earthquakes with a seismic intensity of 6 Since the Great Hanshin-Awaji Earthquake of or greater occur in various parts of Japan January 1995, various technologies for earthquake The Niigata-ken-chuetsu Earthquake disaster management have been developed. occurred in October 2004. It was the first major In March 2005, the Central Disaster earthquake since the Great Hanshin-Awaji Management Council established an “Earthquake Earthquake with a maximum seismic intensity Disaster Management Reduction” that sets of 7 on the Japanese scale. In addition, the concrete goals for disaster mitigation by Fukuoka-ken Seiho-oki Earthquake occurred strategically and intensively promoting steps in March 2005 in northern Kyushu, a site of that include making housing and public little previous seismic activity. That earthquake facilities earthquake-resistant and tsunami registered a maximum seismic intensity of 6−. countermeasures. In addition, there is deep concern that a Tokai The strategy sets a clear goal of reducing Earthquake, a Tohnankai/Nankai Earthquake, or by half over the next 10 years the probable an earthquake centered under Tokyo could be deaths and economic damage from a Tokai imminent. Earthquake, which is possible at any time, or a The source regions of earthquakes and massive Tohnankai/Nankai Earthquake, which appears ocean trench earthquakes during the past 30 likely during the first half of the 21st century. years are depicted in Figure 1. We will now turn our attention to recent They have occurred throughout the country trends and future issues in earthquake disaster outside the probable source regions for a Tokai management in Japan. Earthquake, a Tohnankai/Nankai Earthquake or an earthquake directly under Tokyo. There are approximately 2,000 active 2 What has been learned from earthquake faults in Japan’s inland and coastal the Great Hanshin-Awaji areas. The Headquarters for Earthquake Research Earthquake and subsequent Promotion has selected 98 fault zones where a earthquakes major earthquake would cause serious social and From the Great Kanto Earthquake of 1923 until economic effects. It promotes research on active the Great Hanshin-Awaji Earthquake of 1995, no faults. 91 SCIENCE & TECHNOLOGY TRENDS QUARTERLY REVIEW No.19 / April 2006 There are about 2,000 confirmed active faults, a major earthquake immediately after the Great but several times that many unknown active Hanshin-Awaji Earthquake, but awareness of faults may also exist. A major earthquake could disaster preparedness has declined with the occur almost anywhere, not only in the Tokai passage of time. (See Figure 2.) and Tohnankai/Nankai regions or directly under In addition, as shown in Figure 3, Tokyo. people’s greatest concerns in the event of a major earthquake are fire and collapsing buildings, 2-2 Declining awareness of disaster preparedness followed by securing food and drinking water According to surveys of about 3,000 people in the aftermath, road and bridge damage and aged 20 and older carried out by the Cabinet congestion, and tsunamis, inundations, and Office of Japan regarding disaster prevention, a broken levees, and so on. high percentage took measures to prepare for The percentage that has secured furniture to Figure 1 : Source regions of earthquakes and massive ocean trench earthquakes during the past 30 years source : 2005 White Paper on Disaster Management [1] Figure 2 : Measures taken in preparation for a major earthquake (multiple responses) Unit: % Source: Prepared by the STFC from “Survey on Disaster Preparedness”, Cabinet Office, Government of Japan [2] 92 93 SCIENCE & TECHNOLOGY TRENDS QUARTERLY REVIEW No.19 / April 2006 prevent it from toppling or falling is also low, There were many dead and missing in past with respondents citing concern for appearance tsunamis such as that generated by the Meiji and lack of awareness of the need as reasons. Sanriku Earthquake of 1896, the Showa Sanriku Earthquake of 1933, and the Chile Earthquake of 2-3 Evacuation of residents 1960. The Pacific Plate subducts beneath the In the May 2003 earthquake offshore from continental plate in Offshore Sanriku. The Miyagi Prefecture, seismic intensity levels of 4 to Sanriku coastline is a ria coast, so it is considered 6− were registered along the Sanriku coast, but a tsunami-prone area where tsunamis tend to be no tsunami occurred. large. Figure 4 depicts the results of a survey on Figure 3 : Concerns in the event of a major earthquake (multiple responses) Unit: % Source: Prepared by the STFC from “Survey on Disaster Preparedness”, Cabinet Office, Government of Japan [2] Figure 4 : Evacuation behavior of residents of Kesennuma City during the 2003 Miyagi-ken-oki Earthquake Source: “Current conditions and issues in tsunami disaster management as seen in the evacuation behavior of residents: Awareness survey of Kesennuma City residents regarding the 2003 Miyagi-ken-oki Earthquake” [3] 92 93 SCIENCE & TECHNOLOGY TRENDS QUARTERLY REVIEW No.19 / April 2006 evacuation in an administrative area that includes In recent years, many people have been getting the tsunami danger zone in Kesennuma City, their earthquake and evacuation information Miyagi Prefecture. Three thousand six hundred from television, government, and other sources, questionnaires, about 30 percent of those sent, so disaster management measures that can be were returned. quickly translated into action without depending Referring to the earthquake, about 8 percent on receiving such information are an urgent task. evacuated, while 40 percent responded that they never intended to evacuate. Even in a 2-4 The effects of the new 1981 tsunami-prone area, few people evacuated earthquake-resistance design code voluntarily. Over 6,400 people died in the Great Furthermore, a September 2004 earthquake Hanshin-Awaji Earthquake. The cause of death with a hypocenter offshore from Tokaido in most cases was collapsed buildings or toppled registered a maximum seismic intensity of 5−. furniture. Within four to six minutes of the earthquake, the Figure 5 shows the relationship between the Japan Meteorological Agency issued a tsunami percentage of pre-1981 structures according to warning for 42 municipalities in Aichi, Mie, and block-by-block data collected from the City of Wakayama Prefectures. Twelve municipalities Kobe's property tax rolls, and the percentage of issued evacuation advisories, but few people all buildings completely destroyed based on a actually got out. survey by the City Planning Institute of Japan, and This area is one where tremendous so on. damage is feared in the event of a Tokai or The percentage of buildings damaged that Tohnankai/Nankai Earthquake, so promotion were built before 1981 was extremely high, of disaster preparedness there is considered demonstrating the effectiveness of the new particularly necessary. earthquake-resistance design code implemented Figure 5 : Block-by-block comparison of the percentage of all buildings completely destroyed and the percentage of buildings built before 1981 Source: Building Research Institute, “Damage to buildings from the Hyogo-ken-nanbu Earthquake and subsequent response” [4] 94 95 SCIENCE & TECHNOLOGY TRENDS QUARTERLY REVIEW No.19 / April 2006 in 1981. 2-5 Recovery and reconstruction following Of Japan’s approximately 47 million the Great Hanshin-Awaji Earthquake households, 17.5 million were built before 1982. Figure 6 depicts recovery and reconstruction Of these, an estimated 11.5 million are not following the Great Hanshin-Awaji Earthquake. sufficiently resistant to earthquakes. Recovery of lifelines and other urban functions Making homes and buildings earthquake-resistant was accomplished relatively quickly (electricity, is effective not only in terms of saving lives, but 6 days; telephones, 14 days; gas, 84 days; water, also in mitigating fire damage and the number 90 days; sewers, 93 days), but reconstruction of of fires, reducing the need for rescue and industry and housing took longer. first-aid activities related to collapsed structures, The Chuetsu Earthquake occurred after the and preventing impediments to recovery and floods of July 13 and the heavy rains of Typhoon reconstruction. No. 23 had loosened the ground, and aftershocks In addition, in the September 2003 Tokachi-oki continued for a long time afterwards. Earthquake, no damage was found at locations Immediately after the earthquake, some where measures such as equipment to prevent communities were cut off due to damaged roads. bridge collapses, soil stabilization to prevent Evacuation of victims was therefore difficult, liquefaction, and earthquake retrofitting of and delivery of emergency supplies and