Intro to country’s location: history of earthquakes in the country, why there’s a history of earthquakes in the country

KOBE EARTHQUAKE, JANUARY 1995


Where did it happen?
The focus of the earthquake was located 16 km beneath its epicenter, which was the northern end of Awaji Island, 20 km away from the city of Kobe, which had a population of 1.5 million at the time. This area is located right in the middle of the fault zone between the Pacific, the Eurasian and the Philippine tectonic plates.

Kobe is a bustling city in southern Japan. It’s one of Japan’s biggest ports and an important center of industry. Although earthquakes do shake Japan regularly, Kobe had not been hit with some big earthquake for quite some time, that is, until 17 January 1995, 5.46 a.m. in the morning.

Why did the earthquake happen here?
Three tectonic plates meet near to the coast of Japan. Close to Kobe, the denser oceanic Philippines Plate was being subducted beneath the lighter continental Eurasian Plate at a rate of about 10 centimetres per year.

The Japanese island arc was formed from the molten magma released by the melting Philippines Plate. Earthquakes are very common here and happen often because of the friction accumulated from the two plates colliding along this destructive margin. (In 1923, the Great Kanto Earthquake killed 140,000 people in this area. It was the deadliest quake to have hit Japan before Kobe.)

The great destruction which resulted from the 1995 Kobe Earthquake was due to the shallow depth of the focus which was only of about 16 km below the surface, and that the epicentre had occurred close to a very heavily populated area. Seismic shockwaves travelled from Awaji Island (the epicentre) along the Nojima Fault to the cities of Kobe and Osaka.

Collapse of infrastructure
The earthquake caused massive damage to all transport facilities. Several sections of motorway, many of which were built above the ground on tall concrete stilts, collapsed or toppled sideways. This resulted in making the Hanshin Expressway, the raised main road linking Kobe to Osaka, keel over on its side. Railway lines were buckled and many stations were damaged.

Worse still, a 130 km section of the 'bullet train' rail network had to be closed. At the port, cranes tilted or fell and out of 150 quays, 120, where ships were moored at, were destroyed. Port buildings and , cranes tilted or fell and out of 150 quays, 120, where ships were moored at, were destroyed. Port buildings and their contents were partly destroyed in many areas.

Damage by fire
Many of the older, wooden houses completely collapsed. Fires, triggered by gas leaks and sparks from severed electrical cables, caused even more damage, destroying at least 7,500 wooden homes. 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. Some 190,000 buildings in total were destroyed despite the fact that many were presumed earthquake-proof.

An additional obstacle hindering the reconstruction and repair operations was that most people in Kobe had no insurance due to the difficulties of insuring such an earthquake prone area.

Landslide
Buildings were left hanging over the head scrap of a landslide of decomposed bedrock that was set off by the earthquake. Several homes were buried and over 30 people got killed by landslide. At least 28 more people were killed by a landslide that occurred at Nishinomiya.


Sources:
www.Wikipedia.com (info.)
http://vathena.arc.nasa.gov/curric/land/kobe.html (pictures)
http://www.georesources.co.uk/kobehigh.htm (more info.)


Done By:
Sing Hau
Leslie
Kenneth
Leon
Barry

Earthquake

Kobe, Japan, January 1995

4. How do people adapt to earthquakes?
a. Planning
b. Hardware
- New infrastructure
- Strengthening existing infrastructure

c. Software

- Education
- Monitoring and warning system

Conclusion



















a. Planning

Most of the damage we associate with earthquakes involves human-built structures: people trapped by collapsed buildings or cut off from vital water or energy supplies.

Engineering the seismic safety of a structure involves the same considerations as any real estate venture—design, construction, and location, location, location.

The taller a structure, the more flexible it is. The more flexible it is, the less energy is required to keep it from toppling or collapsing when the earth's shaking makes it sway.

Of course, the materials a building is constructed from also determine its strength, and again, flexibility is important. Wood and steel have more give than stucco, unreinforced concrete, or masonry, and they are favored materials for building in fault zones.

Engineers must design in structures that can absorb the energy of the waves throughout the height of the building. Floors and walls can be constructed to transfer the shaking energy downward through the building and back to the ground. The joints between supportive parts of a building can be reinforced to tolerate being bent or misshapen by earthquake forces.














b. Hardware
- New infrastructure
- Strengthening existing infrastructure


Engineers think a magnitude 7 quake near San Francisco could damage this world-famous bridge. Retrofitting the Golden Gate is a $400 million project that includes putting the approaches to the bridge on base isolators, strengthening the connections between the sections of roadbed, and bracing the support towers. When the decade-long project is complete, the Golden Gate should be able to tolerate a magnitude 8.3 quake.



Some of the older freeway bridges had already undergone retrofitting, the process of adding features to a structure to strengthen it against the forces of earthquakes. All the overpasses that failed during the quake were still awaiting their retrofit.
Older overpasses are supported by vertical steel rods embedded in the concrete of the pillars holding up the highway. If these rods are bent by the pressure of the freeway rocking above them, they lose their strength and continue to bend outward. Ultimately, the pillar can collapse. The steel girders prevent these rods from bending too far outward, helping the pillar retain enough strength to support the freeway above it.
Along with adding steel girders, engineers can add size and weight to a bridge’s footings, and anchor the footings more securely into the ground. Thick cables hold sections of the freeway together and secure it to the support pillars.






Examples
San Francisco's TransAmerica pyramid is famous for its architecture. Diagonal trusses at its base protect it from both horizontal and vertical forces. ‘





d. Software

- Education
- Monitoring and warning system

Other ways to avoid disaster Even without being able to predict earthquakes, city planners and engineers can put warning systems in place that will save lives. One early warning scheme relies on the difference in travel time between waves created by an earthquake. The relatively mild primary (P) waves travel much faster than the more destructive secondary (S) waves. Sensors on buildings and other structures that detect the P waves can provide warning of the coming S waves. While that warning would arrive less than a minute before the S waves, that's enough time for automated systems to shut factories down, close bridges and freeway overpasses, or slow trains—all measures that could prevent disastrous consequences.
It is also possible to warn people of tsunamis, huge waves of water that overwhelm coastlines as a result of earthquakes that occur on the ocean floor. In December 2004, a massive earthquake occured off the coast of Sumatra, killing tens of thousands of people living in countries where there were no tsunami warning systems. The government of Indonesia is now developing a warning system to prevent a similar tragedy. Japan and the western United States have well-developed tsunami warning systems, should a quake occur offshore of those areas.
Scientists are hoping to learn much more about how earthquakes happen at the San Andreas Fault Observatory at Depth (or SAFOD for short). The SAFOD project involves boring a hole into the fault and putting equipment there. These instruments will watch the San Andreas from deep within it, sending back mountains of new data about the most mapped, drilled, prodded, and spied on fault on the planet. Yet even with an ever-increasing knowledge about the inner workings of the earth, scientists probably won't be able to tell us when the great fault will shimmy like it did in 1906. Perhaps the best they can do is help us better understand how to build for the next Big One.

Conclusion
We had no ways of stopping Earthquakes from happening.And we cannot prevent Earthquakes.
The only way is to safeguard the things we had and to damage control.
If we cannot oppose it then rather, flow with it.
There are several things and structures set up to prevent earthquakes.

Done by:
>Chenxi
>Jia Ni
>Kai Jie
>Edwin