Natural Hazards
Programme 1: Earthquake

Aims

To describe the earthquake that hit Kobe in 1995
To explain the causes of the earthquake
To illustrate the effects and consequences
To investigate why so much loss of life and damage occurred
To explore the relationship between the earthquake hazard and the effect on human activity
To evaluate what lessons have been learnt and how the effects of such a hazard could be reduced in the future

00.00–01.29 Dramatic opening shots of the Kobe Earthquake and opening titles
01.20–01.55 A huge earthquake strikes Kobe, Japan at 5.46am on 17 January 1995 – the costliest natural disaster in history
01.56–04.00 The fire's impact on the residents and fire and rescue services
04.01–04.57 The causes of the earthquake – The Theory of Plate Tectonics
04.58–06.10 The geography of Kobe's urban area and why there was so much damage
06.11–07.29 An explanation of liquefaction and its impact
07.30–09.18 Why some structures survived – a suspension bridge and a hotel
09.19–11.53 Reducing the risks of damage in the reconstruction of Kobe and the impact on the lives of the people
11.54–13.16 The rebirth of Kobe; recording the roots of the disaster and helping people to come to terms with their experiences
13.17–13.54 The lessons learnt from the Kobe earthquake – buildings; roads; services; training
13.55–end Credits

Curriculum Relevance

Hazards created by tectonic activity and the effects and responses to earthquakes
Characteristic features at tectonic plate boundaries and the effects of movement
A case study of one earthquake and its management

Background

What are earthquakes?
Earthquakes are sudden movements or jolts of the outer layer of the Earth, called the crust. The crust is made up of solid rock and is between 30-70 kilometres thick. The shockwaves that result from these jolts are called earthquakes.

Why do we get earthquakes?
The earth's crust is like a broken eggshell and the individual pieces of the 'shell' are called plates. However, the plates are gigantic slabs of the earth's crust. This is called The Theory of Plate Tectonics. The boundaries between these plates are lines of weakness in the crust, and the rocks are put under great pressure as the plates move against each other. Where the plates are moving apart the boundary is called a constructive plate boundary and new crust is formed in the form of molten rock (magma). Where plates are pushing together one plate may be forced under another and the crust is destroyed. This is known as a destructive plate boundary. Sometimes plates just slide past each other and no crust is created or destroyed – called conservative plate boundaries. Earthquakes usually occur at destructive plate boundaries or where plates are sliding past each other. Three plates meet near to the coast of Japan (the Eurasian Plate, the Pacific Plate and the Philippine Sea Plate). Close to Kobe, the Philippine Sea Plate sinks beneath the Eurasian Plate at a rate of about 10 centimetres per year. Earthquakes happen here because of the friction resulting from the two plates colliding along this destructive margin. The point at which the earthquake originated in the earth's crust is called the focus. Shockwaves travel from the focus to a point directly above it on the surface called the epicentre. The greatest amount of damage generally occurs near the epicentre and Kobe was near the epicentre of the earthquake in 1995.

How do we measure earthquakes?
When an earthquake takes place the jolts in the plate boundaries cause the earth to shake and the resulting vibrations are called shockwaves. The force of the shockwaves is measured using an instrument called a seismograph. A seismograph records a continuous line on a graph. During an earthquake the lines go up and down. The stronger the earthquake the wider the vertical movement of the line. The duration of the earthquake is shown by the horizontal length of vibrations on the graph. The readings on the graph are interpreted using the Richter Scale. The Richter Scale measures the magnitude or intensity of the earthquake using a scale that goes from 0-9. Each level on the scale is ten times greater that the one below it. Levels 0-3 can usually only be detected on an instrument. At level 9 the ground can be seen to shake and gaps open up. What were the effects of the Kobe Earthquake?

Primary Effects
The Kobe earthquake of 17 January 1995 recorded a magnitude of 7.3 on the Richter Scale and it lasted 20 seconds. Kobe is a densely populated area with about 10 million inhabitants. 6,500 were killed; 30,000 injured; 300,000 made homeless and £75 billion of damage was caused to roads, houses, factories and the infrastructure (gas, water, electricity, telecommunications, sewage).

Secondary Effects
Fires broke out all over the city; there was chaos on the roads; businesses closed; there were massive problems of homelessness. More people died in the fires that followed the earthquake and the problems were made worse by the aftershocks which numbered over 1,300.

Why was there so much destruction of buildings?
As a result of the shortage of land for building much of the industry was concentrated on reclaimed land in the port area. Here the land was not as stable and the strong ground movements caused a phenomenon called liquefaction which led to severe damage. The shaking of the ground during an earthquake can cause the underground layers of sediment to turn to a loose semi-liquid mass (similar to wet sand on a beach). This is liquefaction and the ground becomes very unstable. Any construction built on material like this will collapse unless special foundations have been put in place.

Activities

1. Below is a list of 25 major earthquakes (7.0 and over on the Richter Scale) that have taken place since 1965:

Date	Place	Latitude	Longitude	Magnitude of Earthquake
4 February 1965	Bat Island, Alaska	51ºN	178ºW	8.7
31 May 1970	Peru	9ºS	78ºW	7.9
31 July 1970	Colombia	1ºS	7ºW	8.0
4 February 1975	Haicheng, China	40ºN	122ºE	7.0
4 February 1976	Guatemala	15ºN	89ºW	7.5
27 July 1976	Tangshan, China	39ºN	117ºE	7.5
8 November 1980	Gorda Plate, California	41ºN	124ºW	7.2
8 November 1980	Gorda Plate, California	41ºN	124ºW	7.2
19 September 1985	Michoacan, Mexico	18ºN	102ºW	8.0
7 May 1986	Andreanof Isle, Alaska	51ºN	174ºW	8.0
30 November 1987	Gulf of Alaska	58ºN	142ºW	7.9
17 August 1991	Honeydew, California	41ºN	125ºW	7.1
25 April 1992	Cape Mendocino, California	40ºN	124ºW	7.2
2 September 1992	Nicaragua	11ºN	87ºW	7.7
9 June 1994	Bolivia	13ºS	67ºW	8.2
17 January 1995	Kobe, Japan	34ºN	135ºE	7.3
17 August 1997	Izmit, Turkey	40ºN	30ºE	7.6
17 July 1998	New Guinea	3ºS	142ºE	7.0
20 September 1999	Chr-Chi, Taiwan	24ºN	121ºE	7.7
16 October 1999	Hector Mine, California	34ºN	116ºW	7.2
12 November 1999	Duzce, Turkey	41ºN	31ºE	7.2
16 November 2000	Papua New Guinea	4ºS	152ºE	8.0
13 January 2001	El Salvador	4ºN	88ºW	7.7
26 January 2001	Gujarat, India	23ºN	70ºE	7.7
23 June 2001	Coastal Peru	16ºS	73ºW	8.4
3 November 2002	Denali Park, Alaska	63ºN	147ºW	7.9

The world map below shows the location of the tectonic plates, their boundaries and the directions in which they are moving.

Mark on the map the locations of the earthquakes
Describe and explain the relationship between the locations of the earthquakes and the tectonic plates.

2. Using the background information above and the television programme:

Make a list of the effects of the earthquake on the infrastructure and people of Kobe.
Working in small discussion groups, imagine that your team has been given the responsibility for organising the rescue and restructuring of the city.

What would be your priorities?
What resources would be required?
A disaster on this scale would need help from all over the world. What would you ask for and who would you ask?
Present your findings in a diagram under the following headings - Effects of the Earthquake; Resources Required; Rescue/Support Agencies.

3. The following is a personal perspective of the Kobe Earthquake written by Adam Crewe, an earthquake engineer working for the Earthquake Engineering Research Centre. His account with pictures can be seen by visiting

The Kobe Earthquake 17/1/95

A Personal Perspective (at 20/2/95) by Adam Crewe

'The earthquake that hit Kobe on 17th January caused severe damage to the city and the surrounding areas. Hundreds of buildings collapsed, roads cracked, bridges were destroyed, there were several landslips, and water, power and telephone lines were severed. As part of an EFFIT team I visited the city a few days after the earthquake.

I had thought that all the news reports had prepared me for the extent of the damage but only when I was standing in the midst of 10,000m² of ashes and twisted metal did the scale of the disaster really hit me. So many people died and the cost of rebuilding is so large, an estimated £200 billion, because only the most recent buildings in the city had been designed to withstand earthquakes.

The structures designed to modern Japanese codes all performed very well with minimal damage, but this only seemed to highlight the deficiencies in the older buildings. Much of the research in the EERC is aimed at improving current design practices and it was gratifying to see that the research we are doing is slowly improving our ability to design for earthquakes.

However, this earthquake still caused many dramatic failures that show we have a long way to go before we can be really confident in our ability to overcome nature. For example, the port of Kobe is built on man-made islands and cracks in the quays up to six feet deep have now rendered these facilities useless.

Inland, in the centre of town, the supports for a railway bridge have fractured in a very unusual way, and many buildings in the city have been so badly damaged that they will have to be demolished over the next few weeks.

But even with so much damage still around them the Japanese are starting to recover and are rebuilding their lives and city and I was constantly amazed at the resilience of the people and the speed at which order was being restored to the city.'

Using this account and the background information write a TV report covering the disaster. Describe what happened and explain why the earthquake happened. Try to present your report from the viewpoint of an individual caught up in this disaster.

Links

This web page contains links to other websites that are neither controlled nor maintained by Channel 4 Television. Channel 4 Television is not responsible for the content of these sites and does not necessarily endorse the material on them.

http://volcano.und.nodak.edu
An introduction to plate tectonics – Level: teachers

www.kie.berkeley.edu/ned/data/E01-980211-001/full.html
The Richter Scale – Level: teachers

www.ask.co.uk/
A full description and explanation of the Kobe earthquake and its impact (contains photographs) – Level: teachers and pupils

www.ask.co.uk/
A report on the Kobe Earthquake, 17 January 1995 – Level: teachers and students

www.ask.co.uk
The impact of the Kobe earthquake – Level: teachers