It all happened on the morning of January the 17th 1995, the second most populated and industrialized city in one of the biggest economies of the world, was struck by a powerful earthquake causing thousands of injuries and hundreds of deaths. It was a disaster waiting to happen. Situated in the south-central region of Japan, Kobe was the second largest city in Japan people and industrial-wise, after Tokyo. It was the biggest earthquake to hit Japan, after the great Kanto earthquake of 1923, where around 140,000 people were killed, most after the impact.
The strong shock occurred across the fault that runs through the city of Kobe, and the Awaji island. The earthquake lasted for around 20 seconds, with around 5,500 deaths resulting from it. The number of injuries reached about 35,000 in total, and nearly 180,000 buildings were said to have collapsed. The damage was recorded over a radius of 100 km from the epicentre. The earthquake also hit the cities of Osaka and Kyoto. The economic loss was worse than anything. It was the largest ever to be lost directly from a natural disaster.
Directly from the shaking itself, around 13 trillion yen worth of damage was caused. This is around i??100 billion and before, the loss of life, production, and business interruptions. The Destruction The amount of destruction left by the earthquake was enormous. Around one in every five building collapsed. A further eighty thousand were badly damaged. The fires that followed the earthquake were even worse, causing more damage. The Kobe businesses district was made of many buildings around 6 to 12 stories high, and these were all structurally damaged.
Most collapses were towards the north, which was evidently the result of a long-period velocity pulse perpendicular to the fault. Around 4% of Japan’s industry is located in the area of the severe ground shaking in and around Kobe. Most of the industry is located near ports next to the softer soils, causing the damage to be even more extensive. All types of industrial buildings, equipment, and equipment systems; fire protection systems; racks; and inventory were destroyed by the earthquake directly and by the following fires.
Industries affected include shipbuilding, steel plants, breweries, pharmaceutical firms, computer component manufacturing plants, and consumer goods production facilities. One of the most disturbing aspects of the earthquake was the damage to the city’s transport system. Two highway services in Osaka and Kobe were badly damaged and partially collapsed. The Hanshin and Wangan expressways were collapsed on one side, failed welds at splices of longitudinal bars were also observed by earthquake experts. Many other bridges collapsed as well.
The 252 meter long, Nishinomiya bridge near the port, this caused many cables that were tied to the bride to collapse. Railways were also a problem. Elevated railroad structures and railway stations were particularly hit hard. Three main lines the JR West, Hankyu, and Hanshin run through the Kobe-Osaka transportation corridor, on elevated structures and embankments. All the lines had elevated structure and embankment failures, overpass collapses, distorted rails, and other severe damage. A large number of cars were damaged, and some fell onto city streets.
Several stations and several kilometers of reinforced concrete elevated structures were destroyed, and numerous spans collapsed. The Rokkomichi Station of the JR West line was virtually destroyed. The Shinkansen, better known, as the bullet train had most of its path in the Kobe area through two long tunnels under Rokko Mountain. At the east portal of the tunnel, the line is carried on an elevated viaduct for a length of 3 kilometers, this viaduct was severely damaged, with a number of the longer spans collapsing.
These collapses were caused by failure of the supporting concrete columns. Damage to underground facilities, such as mines, tunnels, or subways, is generally quite rare in earthquakes. An unusual example of severe damage to this type of facility occurred in the Kobe subway system, a two-track line running under central Kobe, which was built by cut-and-cover methods. The double track is carried through a concrete tube 9 meters wide by 6. 4 meters high, which widens to 17 meters at the stations.
The tube has about 5 meters of overburden, which is supported by 0. 4-meter-thick walls and roof slabs. The walls and roof slab are supported midspan (between the tracks) by a series of 5-meter-tall, 1. 0-meter-long by 0. 4-meter-wide reinforced concrete columns. Kansai International Airport was only recently completed in 1994 on a human-made island southeast of the epicenter. Itami is the former international airport for Osaka and now handles much of the domestic traffic. It lies east of the heavily damaged area.
Neither airport was significantly damaged, but neither was located in an area that had severe ground motion. Electricty in the area was completely. Blackouts did not occur, in part because of the earthquake’s location. All of the power generating stations continued normal operation. But, 1 million customers were without power for a few hours following the event. More than 4,700 restoration crews from Kansai Electric, contractors, and six other electric utilities successfully restored the system within a few days.
The Kobe area had a water system designed to be operable after earthquakes. There are approximately 30 reservoirs supplying water to the Kobe area through a gravity-fed system. Of these, 22 reservoirs had automatic emergency shutdown valves and multiple storage tanks. In the event of an earthquake, these valves are designed to automatically shut off water flow out of half of the reservoir tanks. All 22 valves tripped and worked correctly. This enabled 30,000 cubic meters of water (8 million gallons) to be stored in reserve in the reservoirs equipped with automatic shutdown valves.
Extensive ground settlement and other failures caused underground water pipelines to be severely damaged in the earthquake, with approximately 2,000 breaks resulting in lack of service in Kobe. The massive damage to the water transmission lines caused the tanks without automatic shutoff valves to drain in the first 1 to 8 hours after the earthquake. By the time the fires had started, much of the unreserved water had already drained from the system. With the transmission lines destroyed, the reserve water was also unavailable for fire fighting. Large fires followed the earthquake.
The risks are particularly high in Japan because of high population densities; very narrow streets and alleys, which cannot act as fire breaks; numerous old wood-frame smaller commercial and residential buildings mixed in the commercial zones of towns; unanchored or unprotected gas storage tanks or heaters; and a mix of collapse-prone old buildings in all built-up areas. The Ashiya Fire Department reported 11 fires on the day. Nine of these were before 7:30 a. m. Distribution of the fires was along an east-west line about 1 kilometer wide centered on National Route 2. The total burned area for the 11 fires was about 4,400 square meters.