Earthquakes and Volcanoes: Causes, Types, and Impacts
Earthquakes: Causes and Effects
Earthquakes occur when tension is released from inside the Earth’s crust. Tectonic 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.
- Magma rises through cracks or weaknesses in the Earth’s crust. Pressure builds up inside the Earth.
- When this pressure is released, e.g. as a result of plate movement, magma explodes to the surface causing a volcanic eruption.
- The lava from the eruption cools to form new crust.
Types of Volcanoes
Strato-volcanoes: Erupt with great violence, causing much death and destruction. They usually occur in mountain regions where great pressure can build up beneath the ground.
Shield volcanoes: Much flatter than strato-volcanoes, and are less violent, dramatic, and damaging. This is because they are created where there is no great build-up of pressure, so they erupt more often.
Volcano Classification
- Active
- Dormant
- Extinct
Volcanoes: Positive and Negative Impacts
Positive:
- Attractive for tourists
- Minerals
- Light ash falls add nutrients to soil
- Used for geothermal power
Negative:
- Kills people and wildlife
- Destroys farms
- Ash can cause problems for aircraft
- Destroys cities
Earthquakes: Positive and Negative Impacts
Positive:
- Underground minerals may be brought nearer to the surface
- Landform development
- Scientists study earthquakes
Negative:
- Destroys buildings/roads
- Creates tsunamis
Opportunities and Risk Reduction
Volcanoes Opportunities:
Increasing the population in some cities. Volcanic soils are fertile and are responsible for prosperous vineyards and farms. They can provide energy for thermal areas and hot springs.
Reducing the Impact of Volcanoes:
- Prepare an evacuation kit/plan.
- Predictions of eruptions are becoming more accurate; volcanoes give signs before a major eruption.
Reducing the Impact of Earthquakes:
- Construct buildings that are capable of withstanding strong movements.
Coastal Hazards and Opportunities
Advantages:
Coasts offer many opportunities for the people who live there. In many areas, the land is flat or gently sloping, making it ideal for farming and the building of settlements and communications such as roads.
Disadvantages:
Living on the coast may sometimes be hazardous, as storms may cause damage to property and loss of life. Also, lowland areas close to the sea may be at risk from tsunamis, so people have to protect their homes. Hurricanes and severe storms also pose a threat.
Volcano Case Study: Indonesia
Indonesia’s 15,000 islands stretch eastwards across the Pacific Ocean, linking southern Asia to the northern seas off Australia. Java and Sumatra are the main two islands, and most volcanoes in the region are found on the western coast of Sumatra. Spreading along the Pacific Ocean’s Ring of Fire, Indonesia has more volcanoes than any other nation, which makes it a hazardous place to live. More than 3.5 million people live within 10 km of one of the region’s 130 volcanoes and, being many islands, it is difficult to get away if a volcano erupts.
Although Mount Merapi in the east of Java erupted in late 2010, killing 350 people, Mount Sinabung to the north of Sumatra was dormant for over 400 years until it also erupted in late August 2010. On this occasion, there were warnings for people to move away from danger. This was also the case when it erupted in September 2013. The eruptions continued for several months, but in February 2014 vast quantities of rock, toxic gas, and ash exploded out of the crater and onto nearby villages and farms. This time at least 16 people were killed; the first time the volcano has been known to claim lives.