The major earthquake that struck Kōbe, Japan, in 1995 showed that, despite a long and generally successful tradition of earthquake preparedness, the Japanese were not as well prepared to handle a quake of such magnitude as they had believed.
Kōbe, Japan’s sixth-largest city and third-largest seaport, is located along Ōsaka Bay on the nation’s main island of Honshū. At 5:46
When the earthquake struck, the strong seismic motion followed the Nojima fault and the neighboring Suma and Suwayama faults, which dip to a depth of 20 kilometers underneath the city of Kōbe in the direction of the Rokko Mountains to the north. These faults are part of a very active and complex system produced because Japan lies at the intersection of the Pacific, Philippine, and Eurasian tectonic plates. At this triple junction, the Philippine Sea plate is sliding beneath the Eurasian plate at a rate of 4 centimeters (about 1.6 inches) per year in a process called subduction.
The effects of the earthquake were dramatic. Changes of elevation took place that reached 1.3 meters (about 4.3 feet), lateral displacements of 3 meters (9.8 feet) occurred, ground subsidence reached 3 meters in the Kōbe harbor, and average ground elevation increased by 26 centimeters (10 inches) over a rupture of 6 kilometers (3.7 miles). The shaking lasted only about twenty seconds, but it resulted in the deaths of at least 5,000 people (estimates range from 5,378 to 6,433) and injuries to approximately 30,000 more.
Part of the Hanshin Expressway in Nishinomiya lies on its side after the powerful Kōbe earthquake.
The area that surrounds Ōsaka Bay is covered by young, unconsolidated alluvial sediment and soft mud. These sediments do not stand up well to ground motion triggered by an earthquake. Fill was also used to extend Kōbe’s urban areas and its harbor along the shore ringing Ōsaka Bay. Unconsolidated fill, soft mud, and alluvial deposits, particularly when saturated with water, amplify an earthquake’s shaking and can produce severe ground failure in a geologic process called liquefaction. During liquefaction, the strength of the soils decreases and the ability of these materials to support bridge and building foundations is so diminished that buildings constructed on it lose their support, with catastrophic results. Most of the loss of life in Kōbe was associated with the failure of human-made structures. In the prefecture of Hyōgo, more than 100,000 buildings were damaged. Many buildings were tilted and collapsed in the streets, interrupting traffic. Altogether, some 1.3 million people were left homeless by the quake.
Although the Ōsaka Gas Company stopped the delivery of gas immediately when the quake began, the rupture of gas mains started fires, the deadliest of which took place in a shoe factory in a very densely populated neighborhood. With the streets gridlocked and many of the underground water storage tanks empty, the fire spread quickly to the fragile wooden homes in the low-income area nearby. Many people fleeing the fires were killed when heavy roof tiles—used to protect traditional houses from typhoons—fell on them.
Eight commuter trains were derailed by the earthquake because of damage to the metallic and concrete frames of viaducts and the collapse of electric poles on the railroad tracks. No one was killed in these derailments, but many injuries were reported. A great deal of damage was concentrated along Kōbe’s Hanshin Expressway, where 20-meter (66-foot) supporting piers broke and 500 meters (1,640 feet) of the elevated road fell on its side, catapulting cars and trucks to the ground. Many other viaducts and bridges collapsed in the area as well.
In addition, most of the piers, storehouses, and cranes in Kōbe harbor were destroyed. Out of 186 harbor berths, only 9 were operational after the earthquake; the rest were so badly damaged that it took twenty-six months and $5 billion to restore them. In all, property damage from the quake was estimated to be in excess of $100 billion.
The damage and deaths caused by the Kōbe earthquake, which occurred almost five decades after the previous major earthquake in Japan, shook the confidence of Japanese authorities, who had believed that their broad experience with earthquakes had led to efficient and dependable preparations for such events.
Given these shortcomings, after the Kōbe earthquake Japan modified the required specifications for the seismic design of new buildings, highway bridges, overpasses, and railroad tracks. In addition to enhancing overall construction quality, prefecture and local governments examined the problems that occurred in rescue and relief efforts in the hours following the seismic disaster: traffic congestion, water shortages, and deficiencies in preparedness and response systems. To enable quick response to the basic needs of the population in the event of an earthquake, all Japanese schools began storing food and other emergency supplies. Before the Kōbe earthquake, Japan had no system in place for the military to respond to nonmilitary emergencies; such a system was created after the quake, and an emergency communication system and a response plan were also put in place. In addition, bureaucratic regulations that might hamper relief efforts (such as the quarantine laws that kept European search-and-rescue dogs caged at customs buildings following the Kōbe quake instead of deployed around the city) were examined and revised.
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Clancy, Gregory. Earthquake Nation: The Cultural Politics of Japanese Seismicity, 1868-1939. Berkeley: University of California Press, 2006. Discusses the Nobi and Tokyo earthquakes and their consequences for Japan. -
Coburn, Andrew, and Robin Spence. Earthquake Protection. 2d ed. New York: John Wiley & Sons, 2002. An architect and an engineer provide an integrated account of the effects of earthquakes. Emphasizes the relationships among structural damage, human behavior, socioeconomic factors, and casualty patterns. -
Hough, Susan Elizabeth. Earthshaking Science: What We Know (and Don’t Know) About Earthquakes. Princeton, N.J.: Princeton University Press, 2002. Good source of basic information about earthquakes. Includes suggestions for further reading. -
Özerdem, Alpaslan, and Tim Jacoby. Disaster Management and Civil Society: Earthquake Relief in Japan, Turkey, and India. New York: I. B. Tauris, 2006. Focuses on the rescue efforts made in the critical first few hours after a quake in the three earthquake-plagued nations discussed. -
Stein, Seth, and Michael Wysession. An Introduction to Seismology, Earthquakes, and Earth Structure. Malden, Mass.: Blackwell, 2003. Textbook aimed at advanced college undergraduates and beginning graduate students presents comprehensive information about earthquakes and plate tectonics. Includes many illustrations.
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