Japan is positioned on the margin of the Eurasian Plate. Where these plates meet it is known as a subduction zone, where effectively one plate slides under the other. Along these subduction zones there are both deep and shallow earthquakes that occur due to the compressive forces against the meeting of the plates. Kobe lies in a region where the Philippine Sea Plate is thrust under the Eurasian Plate (See picture below)
At Osaka Bay there is a fault called the Median Tectonic Line (MTL), and it was sudden movement along this fault that triggered the earthquake that hit Kobe.
The earthquake happened early morning 5:45am JST January 17 1995, the epicentre was at Akachi. It was 7.2 on the Richter scale; this earthquake was a national catastrophe. Kobe has 1.5 million residents and is the worlds 6th largest city and port.
Impacts of the Earthquake :
Surface Fault Rupture: It was noticed that along the fault that there was a maximum vertical displacement of 1.2m with a right-lateral slip of 2.1m. The surface fault rupture was found to stretch over 60km from the Kobe-Nishinomiya area to the Akashi Strait. The earthquake also had a shaking intensity of X to XI on the Mercalli scale and had a maximum horizontal acceleration of 0.84g.
Liquefaction: This is the result of water saturated sands found in soil being disturbed by intense shaking. This leads to buildings collapsing and for sand to ‘explode’ onto the surface to create ‘sand volcanoes’ and ‘boils’. In Kobe the effects of liquefaction were felt primarily along the waterfront although the effects were found as far as 3km inland. Parts of Kobe were built on reclaimed land as well as artificial islands. These were constructed using various sands as well as decomposed granite. Due to the nature of these materials it is made very easy for liquefaction to take place if it was not compacted well enough.
Lateral spreading was found to be responsible for the lateral ground movement of 2-3m in the region resulting in structural damage especially to the port side buildings and walls. The damage inflicted by this resulted in the majority of the port shutting down
Violent shaking of the earth and buildings for 20 seconds
1320 aftershocks were recorded, of which 150 were felt by people
Over 5500 people killed and 35000 injured
Nearly 7500 houses were destroyed by fired which rages out of control for several days.
Gas mains fractured, electricity cut off, many fires started. 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.
Water mains broken so no water reaching houses.
200,000 buildings collapsed, leaving 300,000 homeless
130km of bullet train network was closed, and the Hanshin Highway was completely closed when a 1km stretch of the elevated highway collapsed. This made the job of the emergency service very difficult
Transport was disrupted for weeks afterwards
Older houses worst hit, new earthquake proof building survived better. Heavy cost of rebuilding, which takes years to complete.
Water and food shortages, so army brought supplies to people living in schools.
Total damage was estimated at almost 10000 billion Japanese Yen (£64 billion). All this damage was the result of just 20 seconds of earthquake.
Monitoring and Management
1,100 shelters included community centers, schools, and other available and undamaged public buildings were set up and used for those who had lost their own homes. Due to facilities and shelters being too few there was severe crowding causing sanitation problems and increased risk of communicable disease. Indeed, two weeks after the earthquake, reports of influenza and pneumonia were common.
Food, water for drinking and sanitation, blankets, and warm clothing were in short supply for at least the first few days after the earthquake.
By Friday, January 20, both official and volunteer efforts to supply the basic needs of the impacted area were becoming increasingly evident. Corporations and other non-governmental organizations donated goods, and transportation was provided by both business and government vehicles. In some cases, normal production schedules and processes were modified to assist in the relief effort. They were also supported by encouragement and aid from friends across Japan and throughout the world, Co-op Kobe was able to take immediate action as an organization rooted in the community. Even though many of the executives and staff members of Co-op Kobe were disaster victims themselves, they rushed to stores in order to provide suffering residents with food and commodities. Co-op Kobe also mobilized its trucks, which ordinarily deliver merchandise to HAN groups, to provide relief aid to all corners of the disaster-struck area.
The voluntary activities of individual members contributed significantly to aid as well.
Another example of closer co-operation is the campaign that solicited signatures from individuals demanding a “Nationwide Security System for Natural Disasters.” The campaign was carried out to support disaster victims to reconstruct their homes.
Hyogo Prefecture and Kobe City adopted restoration plans that complemented national policies, prioritizing projects that would stabilize the economy and attract new businesses. 17 restoration promotion districts were initially established. At least $50 billion was invested by Japan’s national government to rebuild public facilities and infrastructure. Public projects generally had 50% funding from the national government, and 50% funding from the cities or government.
High-level citywide plans for major centres, trunk roads, and parks were developed, identifying sites for large-scale re-housing and redevelopment projects. Local street and park plans were reviewed with neighbourhood residents through the machizukuri (town building) committees either formed or pre-existing in damaged areas. Two key recovery tools used were land readjustment and urban redevelopment
Land readjustment projects were established in heavily damaged areas where plans called for the shifting of property rights and boundaries to allow for future road widening projects, open spaces and other public facilities. National funds covered construction costs for these kinds of public infrastructure, but not for housing reconstruction in these areas.
Urban redevelopment projects involved the total purchase of properties in a damaged area. In Kobe, previously established redevelopment plans, with locations targeted for housing, commercial, office complexes, and new roads, helped guide reconstruction decisions. Some of these redevelopment project areas have been highly successful, with new housing being sold at a premium price.
Kobe City’s Emergency Three-Year Plan for Housing Reconstruction (released months after the earthquake) called for the construction of 82,000 units. When the plan was issued, an estimated 10,000 units were already under construction and considered in the plan count. Repair and reconstruction needs far exceeded individual resources for rebuilding. More than 30,000 businesses and households were rebuilt with grants and loans, backed by various government agencies.
Action to avoid future problems
The best materials to build with in order to withstand the earthquake would be concrete and steel.
Preparedness and emergency response is often the most affordable thing to do. Efforts are needed to:
* Continue and increase support for emergency awareness and response, at all levels, public and private.
* Encourage development of innovative techniques for improved response such as automated, rapid post-event damage assessment and decision-making using geographic information system-based tools.
* Investigate enhanced response through development of citizen cadres for disaster assistance.
Overall and since the 1995 earthquake there seems to have been no problems with buildings collapsing and other problems due to earthquakes, this suggests that the management and action that the people of Kobe, Japan made was successful.