Case Study of The Kobe earthquake.

Case Study: The Kobe earthquake

This assessment is about the Kobe earthquake in Japan and the effects of it. Kobe is on the island of Honshu in Japan. The earthquake was called the Great Hanshin Earthquake. An earthquake struck the city of Kobe on 17 January 1995 at 5:46am. The epicentre was on the northern part of Awaji Island (N34.36 E135.02). It depth was 16 kilometres below the earth's surface. The force of the earthquake was 7.3 on the Richter scale, 6 and 7 on the Japanese scale in different areas (Due to a review by the Meteorological Agency on April 23, 2001, magnitude was adjusted from 7.2). The ground motion was vertical and horizontal shaking occurring simultaneously.

Three crustal plates meet near to the coast of Japan. Close to Kobe, the bigger oceanic Philippines Plate is disappearing underneath the smaller continental Eurasian Plate. The Japanese islands have been formed from the molten magma released by the melting Philippines Plate. Earthquakes are quite common in Japan and happen because of the friction resulting from the two plates colliding along this destructive margin. Seismic shockwaves travelled from Awaji Island (the epicentre) along the Nojima Fault to the cities of Kobe and Osaka. The tectonic plates right next to Japan are the Pacific plate, the Eurasian plate and the Philippine Sea plate. Below is a picture of what direction the plates are going:

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The immediate effects of the earthquake include the collapse of buildings, bridges and roads due to the shaking of the crust. Many of the older, wooden houses completely collapsed. During the 20-second earthquake, the ground moved up to 50 centimetres horizontally and up to 1 metre vertically. The immediate effects caused some of the deaths. The secondary effects include the fires that broke out all over the city of Kobe, the congestion and chaos on the roads, the closure of businesses and the problem of homelessness. Many more people died in the fires that followed the earthquake. Fire, triggered by broken gas pipes and sparks from severed electrical cables, caused a huge amount of damage, destroying at least 7,500 wooden homes. Often firemen could not reach them because roads were blocked. And often they ran out of water because water mains had burst. The blocked streets made rescue difficult too. Thousands of victims were left in the cold without food, water or shelter, waiting for help. Office blocks built in the 1960's of steel and concrete frequently collapsed in the middle so that a whole floor was crushed but the rooms above and below remained intact. Modern buildings, designed to be earthquake proof, did quite well on the whole and suffered little damage.

The Statistics of the earthquake below shows a table of the victims:

The names at the top of the table correspond to the different areas in Kobe. This table shows that even an advance country can have major disasters and result in major losses. It also shows that the emergency services where on patrol during that day and that night. The next table below shows the amount of houses that had fully collapsed (houses whose damage to supporting structures (walls, pillars, beams, roof, stairs) amounts to more than 50% of the current value of the house) and that had half collapsed (houses whose damage to supporting structures (walls, pillars, beams, roof, stairs) amounts to between 20 - 50% of the current value of the house).

The table on the previous page at the bottom shows the amount of houses collapsed and the amount of houses burned. There was around 4 600 deaths, 15 000 injured, 75 000 buildings in ruins, 55 000 buildings badly damaged (including many schools) and roads and railways were torn apart. The cost was around £200 billion.

The main reasons for the high death toll was that the buildings were too old and couldn’t stand that size of earthquake. The emergency services kept getting blocked by telegraph poles, trees and buildings. They are both important reasons because the emergency services couldn’t get to the places they were meant to be and the old buildings crush people to death.

Leigh Clements