What causes an earthquake? Why are some earthquakes stronger than others? Why do certain earthquakes cause so much damage? How do we prepare for an earthquake? Case we earthquake-proof our buildings? Why was the Boxing day tsunami in 2004 one of the worst disasters ever? All of this and more in this unit!
The lessons covered in this unit are: 9. Earthquakes 10. Earthquake measurements 11. Earthquake effects 12. Resisting earthquakes 13. Case study: Kobe (Japan) earthquake, 1995. 14. Case study: Indian Ocean tsunami, 2004. |
9. EARTHQUAKES
🡺 I can label the various features of a cross-section diagram of a volcano, including; crater, secondary or parasitic cone, lava tube, magma chamber and side vents.
🡺 I can list the main characteristics of composite cone, acid and basic lava volcanoes. An earthquake is the shaking and vibration of the Earth's crust due to movement of the Earth's plates. Earthquakes can happen along any type of plate boundary. Earthquakes occur when tension is released from inside the crust. Plates do not always move smoothly alongside each other and sometimes get stuck. When this happens, pressure builds up. When this pressure is eventually released, an earthquake tends to occur.
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Geo-check!
1. Add the words from below to the diagram.
2. What does the word ‘seismic’ mean? 3. Watch the video Bill Nye, the Science Guy S04E04 Earthquakes (on the right) and fill in the following statements.
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10. EARTHQUAKE MEASUREMENTS
🡺 I know about the use of the seismograph to measure the strength of an earthquake.
🡺 I can explain the Richter Scale to calculate the magnitude and relative effects of an earthquake. Seismologists are scientist who study earthquakes and seismic waves. The power of an earthquake is measured using a seismometer. A seismometer detects the vibrations caused by an earthquake. It plots these vibrations on a seismograph. The energy, or magnitude, of an earthquake is measured using the Richter scale. The Richter scale is numbered 0-10 and is a logarithmic scale. This means that for each increase of 1 on the Richter Scale, the magnitude increases by 10. Earthquakes measuring just 1 or 2 on the scale are very common and can happen every day in places like San Francisco. These earthquakes are so small that people cannot feel them; they can only be picked up by a seismometer. Earthquakes measuring around 7 or 8 on the Richter scale can be devastating. The earthquake in China's south-western Sichuan province in May 2008 measured 7.8 on the Richter scale. Why are some earthquakes more serious than others?
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Geo-check!
1. The table to the right shows the magnitude of earthquakes according to the Richter Scale. For each magnitude, the strength, damage and frequency are shown.
a. The damage column entries are listed below. Write them on the table here.
b. What do you notice about the frequency of earthquakes on this scale? 2. Compare these three earthquake events (on the right) and their data and answer the questions below.
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11. EARTHQUAKE EFFECTS
🡺 I can list the measures that can be taken in order to reduce the damaging effects of an earthquake.
Earthquakes can destroy settlements and kill many people. Aftershocks can cause even more damage to an area. Primary effects - those that occur immediately as the earthquake happens
Secondary effects - the subsequent effects of the quake, and can be even more devastating than the primary ones
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Geo-check!
1. Below are primary and secondary effects. Highlight the primary effects.
- Buildings collapse
- Mains water cut off
- Roads and railways damaged
- People killed or injured
- Cracks open in the ground
- Electricity cut off
- Tsunamis
- People homeless
- Lack of food
- Fires from gas leaks
- Disease: due to lack of clean water
- Mains water cut off
2. In the image above there are several primary effects. Choose four of the primary effects. For each primary effect, write down FOUR secondary effects that may be caused by this effect.
3. This is part of an article written by Maltese seismologists in 2015.
ROCKING THE ISLANDS
“A major earthquake hit Malta in 1693. At an estimated magnitude of 7.4, it struck about 170 km away, devastating south-eastern Sicily, destroying buildings and killing almost two thirds of Catania’s population. Historical documents record damage in Malta. Mdina’s cathedral needed to be rebuilt. While some might think that an earthquake of similar intensity is rare and would probably not happen again, research suggests that earthquakes of this strength strike every few hundred years in the area.
For many, Malta is considered as an earthquake-free region and even the 1693 earthquake is regarded as a ‘Sicilian’ event. Many of the earthquakes felt in Malta originate beneath Greece, along the Hellenic arc (more than 500 km away), but earthquakes even closer than 50 km away do occur too.
Dr Pauline Galea, who lectures at the Department of Physics and coordinates the Seismic Monitoring and Research Unit (SMRU) at the University of Malta, explains that the nearby seismic activity is no surprise. ‘In the last decade alone over 170 earthquakes have occurred within a 100 km radius around Malta.’
a. Did you learn anything new about tectonic activity in Malta? What did you learn?
b. Is Malta an earthquake-free region? Why / why not?
c. Find the Richter Scale and list the effects of a 7.4 earthquake.
d. Imagine the 1693 earthquake happens today. Describe what its effects would be on the Maltese Archipelago. Describe at least three effects for each below:
- Social impacts (people hurt, fear, broken houses, diseases, standard of living …)
- Economic impact (business, transport, jobs, costs, insurances, tourism, farming …)
- Environmental impacts (animals, vegetation, pollution, cultural or old buildings...)
12. RESISTING EARTHQUAKES
🡺 I can list the measures that can be taken in order to reduce the damaging effects of an earthquake.
Prediction Prediction involves using seismometers to monitor Earth tremors. Experts know where earthquakes are likely to happen. However, it is very difficult to predict when they will happen. Protection Many areas prone to earthquake hazards now use building codes. Any new building or adjustment to existing buildings must be carried out to strict guidelines to help protect people from future earthquake hazards. Protection involves constructing buildings so that they are safe to live in and will not collapse. Some examples of building improvements are:
Preparation In earthquake-prone countries, hospitals, emergency services and residents practice for an earthquake. They have drills in all public buildings so that people know what to do in the event of an earthquake. This helps to reduce the impact and increases their chance of survival. |
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Geo-check!
1. You are given the task of putting together an emergency kits for the school. Several kits will be placed around the school. Here are some items you can use:
Fire Extinguisher / First Aid Kit / Transmitter / Mobile Phone
Canned Food / Plastic Bucket / Torch / Television
Dried Food / Spare Clothes / Board Games /
Matches / Candles / Blankets / Wind-Up Radio
Can Opener / Spade / Small Tent / Toothpaste
Tools / Dust Mask / Batteries / Toilet Paper
Disinfectant / Swiss Army Knife / Battery-Operated Radio 10 Litres of Bottled Water / Water Purifying Tablets / Camping Gas and Cooker
a. What 10 things would you choose for your emergency kit? Explain your choices.
b. Would you change any of the 10 items if you had to prepare an emergency kit for your house? Why?
2. Imagine you are the mayor of a city in an earthquake zone. Explain, and give reasons, to what you would do in these following situations.
Fire Extinguisher / First Aid Kit / Transmitter / Mobile Phone
Canned Food / Plastic Bucket / Torch / Television
Dried Food / Spare Clothes / Board Games /
Matches / Candles / Blankets / Wind-Up Radio
Can Opener / Spade / Small Tent / Toothpaste
Tools / Dust Mask / Batteries / Toilet Paper
Disinfectant / Swiss Army Knife / Battery-Operated Radio 10 Litres of Bottled Water / Water Purifying Tablets / Camping Gas and Cooker
a. What 10 things would you choose for your emergency kit? Explain your choices.
b. Would you change any of the 10 items if you had to prepare an emergency kit for your house? Why?
2. Imagine you are the mayor of a city in an earthquake zone. Explain, and give reasons, to what you would do in these following situations.
- Residents in your city just felt very small tremors – what do you do?
- An earthquake is happening – what do you do?
- The earthquake has damaged a few buildings in the city centre, however houses in the poorer areas have been knocked down and people may be inside them – what do you do?
- A few days have passed. Emergency services are working on getting everything back to normal – what do you do?
- How would you protect your city buildings for the next earthquake?
- How would you protect your residents for the next earthquake?
- What else would you do before the next earthquake hits?
13. CASE STUDY: KOBE (JAPAN) EARTHQUAKE, 1995.
🡺 I can identify the location of Kobe on a map of Japan that includes the position of the plate margins involved.
🡺 I can explain the causes of the earthquake. 🡺 I can describe the course of events as well as the primary and secondary effects of the earthquake. Why did it happen? Kobe is on a minor fault, which lies at a destructive plate margin. The Philippines plate is forced under the Eurasian Plate. When did it happen?
Primary effects
Secondary effects
What happened months after the earthquake?
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Geo-check!
13.1 On the satellite image of Japan, find the following:
2. Highlight the correct causes of the Kobe earthquake of 1995.
Japan is found on a constructive plate margin.
OR Japan is located on a destructive plate margin.
The Kobe earthquake was caused by the Philippines Plate being forced downwards and below the Eurasian Plate.
OR The Kobe earthquake was caused by the Eurasian Plate moving beneath the Philippines Plate.
The Philippines plate (oceanic crust) is heavier than the Eurasian plate (continental crust).
OR The Philippines plate (oceanic crust) is lighter than the Eurasian plate (continental crust).
The Philippines plate is forced downwards to form a subduction zone.
OR When the plates collide, a mid-ocean ridge is formed.
3. Read the personal extracts about the Kobe earthquake. Then describe the impacts of the earthquake in these sections:
Kobe policeman
I quickly got into my car after the tremor and went out to assess the extent of the damage. As I approached the poorer industrial area of the city, I could see fires blazing on every corner. Entire rows of wooden houses had been razed to the ground – presumably with everyone inside. I came across one distraught man amid the ruins and managed, with the help of some other people, to pull the body of his son-in-law from the rubble.
Elderly inhabitant of Kobe, 2 days after the earthquake.
My wife and I quickly collected a few belongings before we had to flee from our house which was on fire. We didn’t even have time to change out of our pyjamas. Our car was in flames so we had to leave it behind. There seemed to be nowhere to go so we ended up in this children’s playground with dozens of other people from our district. We have kept warm around a large fire we built using furniture we found nearby. I have seen no sniffer dogs and almost no cranes or diggers. The odd helicopter flies over, but these are mainly from television stations.
News reporter
Walking through the damange, there is a chill silence broken only by the sirens of the rescue vehicles. The only lighs are the headlight of vehicles caught in bumper-to-bumper traffic hame both ways as people try to leave the city or get into it to see if their homes still stand. Emergency medical aid convoys carry medical supplies. One convoy is led by a dozen Japanese army trucks, each towing a water tank, but they are unable to move because of the congection. The surface of the road is cracked every 10meters and all the traffic lights are out of order.
Mother awaiting news of her daughter who lives in central Kobe
We saw on TV that the train station and supermarket next to her house had completely burnt down but we haven’t been able to contact her. The trains aren’t running because of derailments and the roads are jammed. People are being warned not to travel because some of the highways have collapsed and many buildings are about to fall down. We are just sitting and waiting.
Civil engineer working for Kobe District Authority, speaking two weeks after the earthquake.
There would have been much greater loss of life if out tough regulation did not insist that every new building must incorporate devices to counteract the effects of the earthquakes our modern skyscrapers withstood the quake well. They are designed to sway in the strong winds generated by typhons in this region, and this helped. Unfortunately, many smaller buildings collapsed because they were too low to sway and damage was severe among houses built before regulations came in during the 1960s. Our traditional buildings in Kobe are mainly made of wood and many of these became delay fire traps after the earthquake. A key question that remains is: why did so many highways and railways collapse?
4. List all the primary and secondary effects of the Kobe earthquake of 1995.
- Japan
- The capital city of Japan
- The towns of Osaka and Kobe
- The epicentre of the quake: Osaka Bay
- The plate boundaries
- The three plates involved: Eurasian plate, Philippines Plate and Pacific Plate
- Draw arrows to show movement of plates
2. Highlight the correct causes of the Kobe earthquake of 1995.
Japan is found on a constructive plate margin.
OR Japan is located on a destructive plate margin.
The Kobe earthquake was caused by the Philippines Plate being forced downwards and below the Eurasian Plate.
OR The Kobe earthquake was caused by the Eurasian Plate moving beneath the Philippines Plate.
The Philippines plate (oceanic crust) is heavier than the Eurasian plate (continental crust).
OR The Philippines plate (oceanic crust) is lighter than the Eurasian plate (continental crust).
The Philippines plate is forced downwards to form a subduction zone.
OR When the plates collide, a mid-ocean ridge is formed.
3. Read the personal extracts about the Kobe earthquake. Then describe the impacts of the earthquake in these sections:
- Impact of the earthquake on transport
- Impact of the earthquake buildings and industry
- Impact of the earthquake people
Kobe policeman
I quickly got into my car after the tremor and went out to assess the extent of the damage. As I approached the poorer industrial area of the city, I could see fires blazing on every corner. Entire rows of wooden houses had been razed to the ground – presumably with everyone inside. I came across one distraught man amid the ruins and managed, with the help of some other people, to pull the body of his son-in-law from the rubble.
Elderly inhabitant of Kobe, 2 days after the earthquake.
My wife and I quickly collected a few belongings before we had to flee from our house which was on fire. We didn’t even have time to change out of our pyjamas. Our car was in flames so we had to leave it behind. There seemed to be nowhere to go so we ended up in this children’s playground with dozens of other people from our district. We have kept warm around a large fire we built using furniture we found nearby. I have seen no sniffer dogs and almost no cranes or diggers. The odd helicopter flies over, but these are mainly from television stations.
News reporter
Walking through the damange, there is a chill silence broken only by the sirens of the rescue vehicles. The only lighs are the headlight of vehicles caught in bumper-to-bumper traffic hame both ways as people try to leave the city or get into it to see if their homes still stand. Emergency medical aid convoys carry medical supplies. One convoy is led by a dozen Japanese army trucks, each towing a water tank, but they are unable to move because of the congection. The surface of the road is cracked every 10meters and all the traffic lights are out of order.
Mother awaiting news of her daughter who lives in central Kobe
We saw on TV that the train station and supermarket next to her house had completely burnt down but we haven’t been able to contact her. The trains aren’t running because of derailments and the roads are jammed. People are being warned not to travel because some of the highways have collapsed and many buildings are about to fall down. We are just sitting and waiting.
Civil engineer working for Kobe District Authority, speaking two weeks after the earthquake.
There would have been much greater loss of life if out tough regulation did not insist that every new building must incorporate devices to counteract the effects of the earthquakes our modern skyscrapers withstood the quake well. They are designed to sway in the strong winds generated by typhons in this region, and this helped. Unfortunately, many smaller buildings collapsed because they were too low to sway and damage was severe among houses built before regulations came in during the 1960s. Our traditional buildings in Kobe are mainly made of wood and many of these became delay fire traps after the earthquake. A key question that remains is: why did so many highways and railways collapse?
4. List all the primary and secondary effects of the Kobe earthquake of 1995.
14. CASE STUDY: INDIAN OCEAN TSUNAMI, 2004.
🡺 I can locate on a world map the epicentre and the worst affected places of the tsunami.
🡺 I can explain the causes of the earthquake and tsunami. 🡺 I can describe the course of events and the effects of the tsunami. Why did it happen? This was on a destructive plate boundary between Indo-Australian Plate subducting beneath the Burma Plate at 6cm/year. The earthquake caused the Indian Ocean tsunami that affected 13 countries.
Why was this tsunami was devastating?
Social impacts
Economic impacts
Environmental impacts
Responses to the tsunami Immediate responses
Secondary responses
Short-term responses
Long-term responses
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Geo-check!
1. Place the following labels in the correct place on the diagram to explain the causes of the earthquake and the tsunami.
2. On the map of the Indian Ocean:
3. What is a tsunami? 4. Briefly describe what happened on December 26, 2004 in the Indian Ocean. 5. What were the causes for the earthquake and tsunami on the 26th December 2004? 6. Write about some of the destructive effects of this earthquake. 7. Explain THREE reasons this tsunami was so devastating. |