There were nearly 5,500 deaths with about 35,000 injured people. Nearly 180,000 buildings were badly damaged or destroyed, and officials estimate that more than 300,000 people were homeless on the night of the earthquake.
The worst effected area was in the central part of Kobe, a region about 5km by 20km alongside the main docks and port area. This area is built on soft and easily moved rocks, especially the port itself, which is built on reclaimed ground. Here the ground actually melted and acted like thick soup, allowing buildings to collapse, resulting in the huge cranes in the harbour falling over into the sea.
When all the costs were added up, it made the “Hyogo-ken Nanbu” earthquake probably the most expensive natural disaster in modern history!
All this damage was the result of just 20 seconds of earthquake.
Transportation
The damage caused by the Kobe earthquake included destruction of roads and railways and things were made even more difficult because Kobe is situated on a strip of flat land between high mountains and the sea. A number of major expressways, rail lines, and bridges, some of very modern design, were severely damaged.
The famous high-speed railway link from the Japanese capital, Tokyo, and the whole of western Japan was cut in half when the bridges in Kobe fell down. The only other two rail links were also cut during the quake.
Like many large cities, Kobe had a raised motorway that allowed vehicles to travel around the city and out into neighbouring towns. As the shock waves passed under the supports holding up the motorway, the ground gave way and large sections of the road collapsed in three parts of the city. One section of the road that collapsed was over half a kilometre long!
The Port of Kobe, much of which was new, was devastated by widespread and severe liquefaction and/or permanent ground deformation, which destroyed more than 90% of the port's 187 berths and damaged or destroyed most large cranes. Shipping was be disrupted for many months, and some shipping business never returned to Kobe, resulting in significant losses to the local economy.
The only way to travel around the city was to use the smaller roads that were at ground level, but many were closed by either fallen debris from buildings or cracks and bumps caused by the ground moving. In some places sections of the roads and pavements had been pushed up over 10 cm from their original positions, making it impossible to drive vehicles along them.
Major Highways and Bridges
Elevated highways in Japan typically consist of single spans that have roller bearings at one end and are fixed at the other. To conserve valuable space, single-column, cantilever structures are common. Bearing widths on Kobe area expressways appeared to be inadequate in some instances. Column shearing revealed small reinforcing steel ties at relatively large spacing. Failed welds at splices of longitudinal bars were also observed.
Utilities and Services
Like most cities, services like water, gas, electricity and sewerage were provided through a network of underground pipes and cables. When the ground began to move, the more rigid pipes weren't able to move as well so they fractured. Almost three quarters of the water supply across the entire city was out of action, gas pipes leaked gas into the air, and sewers discharged their contents into the streets.
Electricity supplies were not all routed underground but that didn't save the supply from disruption. Much of the supply was transmitted around the city by 123cables on poles. As buildings collapsed and the ground shook, many of the poles also collapsed, cutting off the electricity supply not just to homes, but to police stations, hospitals and fire stations too.
During the earthquake, Kobe's water system sustained approximately 2,000 breaks. Generally, ground or building failure was the cause of the severe damage to Kobe's water systems. The resulting lack of water contributed significantly to the fire problem and was a major hardship on the population for several months. The gas system had major damage, generally caused by ground or building failure, which also contributed significantly to the fire problem.
Fires
The earthquake struck early in the morning and people who were not still in bed were just getting up and making breakfast. People were cooking meals at the very moment that their homes began to shake and collapse. Cookers, sparking electric wires and hot embers from fires very quickly started over 300 fires, especially among the remains of wooden buildings.
The collapse of the electricity and telephone systems made it almost impossible for people to let the fire teams know where they were needed, whilst the broken water pipes and blocked roads made it hard for fire teams to reach and put out fires.
Within the next day, teams of fire fighters had arrived from all over Japan, but despite this there were at least a dozen major fires that burned for up to two whole days before they were brought under control. Roughly 500 deaths were due to fires and almost 7,000 buildings were destroyed by fire alone. Luckily the weather was not good for fires, otherwise the damage would have been even greater!
Building Structure
The number of buildings destroyed by the earthquake exceeded 100,000, or approximately one in five buildings in the strongly shaken area. An additional 80,000 buildings were badly damaged. The large numbers of damaged traditional-style Japanese residences and small, traditional commercial buildings of three stories or less account for a great deal of the damage. In sections where these buildings were concentrated in the outlying areas of Kobe, entire blocks of collapsed buildings were common. The fires following the earthquake also destroyed several thousand buildings.
Differences in the Kobe and Northridge Earquakes
The Northbridge earthquake was a similar type of earthquake to Kobe in Los Angeles 1994. While there are more similarities than differences in structural performance in the Kobe and Northridge earthquakes, there are important differences that explain why the Kobe Earthquake was so much more damaging. Some of the lessons from these differences apply only to Japan; others apply to all areas of the world at risk from earthquakes.
The majority of deaths in Kobe occurred in the collapse of housing built using traditional Japanese methods. Traditional Japanese housing construction is based on a post-and-beam method with little lateral resistance. Increasing the problem is the practice of using thick mud and heavy tile for roofing, resulting in a structure with a very heavy roof and little resistance to the horizontal forces of earthquakes. U.S.-style frame housing with lightweight roofs is now coming into use in Japan and newer housing constructed using these methods had little or no damage from the earthquake.
Another significant difference between the Kobe area and the Northridge area is the quality of the soils. Because of a severe shortage of available land, much of modern urban Japan, including Tokyo, is built on the worst soil possible for earthquakes. Much of the newer construction in Kobe, particularly larger buildings, is built on very soft, recent alluvial soil and on recently constructed near-shore islands. Most of the serious damage to larger commercial and industrial buildings and infrastructure occurred in areas of soft soils and reclaimed land. The worst industrial damage occurred at or near the waterfront due to ground failures-melting, lateral spreading, and settlement.
Kobe earthquake Northridge earthquake
The Port of Kobe was an extreme example of the problems associated with poor soils in areas prone to earthquakes. The port is built almost entirely on fill. The engineering profession has tried hard to develop methods for strengthening filled areas to resist failures during earthquakes, but most of these methods have been put into practice without the benefit of being sufficiently tested in strong earthquakes. The results were decidedly mixed, but the failures costly most retaining walls along the port failed, and the related ground settlement pulled buildings and other structures apart.
Economic Effects
The effects of the Kobe earthquakes were a huge impact to small, as well as large businesses. The direct and indirect business losses outweighed the repair cost particularly with the transport and other lifeline failures. The overall economic impact and long term effects both influenced the speed of infrastructure and businesses were repaired.
It was said that between 95 billion and 147 billion dollars were lost to cause one of the biggest economical crash since the “Wall Street crash” in 1929. It made many people redundant and because nearly one third of the country was affected most of Japans trade broke down.
The life loss caused by the earthquake was the worst in Japan since the 1923 Great Kanto Earthquake, when about 140,000 people were killed, mostly by the post-earthquake conflagration. The economic loss from the 1995 earthquake may be the largest ever caused by a natural disaster in modern times. The direct damage caused by the shaking is estimated at over ¥13 trillion (about U.S.$147 billion). This does not include indirect economic effects from loss of life, business interruption, and loss of production
Social Effects
The most significant social impact was the massive loss of life. In addition more than 300,000 people’s houses had been severely damaged or destroyed in the earthquake, leaving many homeless with a hardship of space for temporal shelters. The water pipes had been destroyed and ruptured along with the shortage of many other essentials including food, and warmth. In response to this food was rationed and sheets and blankets were assigned to families.
Conclusion
Our experience with many past earthquakes in developed, industrial areas is that the media, particularly television, can present an exaggerated image of the damage by concentrating on the few spectacular collapses that occurred. The actual damage in Kobe and the surrounding region, however, was much worse than the media could convey, because it is very difficult to show more than local damage at one time. For example, images of the main 550-meter-long collapsed section of Kobe’s elevated Hanshin Expressway were ever-present throughout the media, but that collapse was only a small fraction of the losses to the area’s highway system.
