Plate Tectonics KQ2

Question 1

Shield volcanoes

Answer 1

Gently sloping sides, broad summit
Low-silica lava
Gas escapes easily, not explosive
Divergent boundaries (magma can rise directly from mantle)
Mount Washington, USA

Question 2

Stratovolcanos

Answer 2

Steeper at the top, gentler at the bottom
High-silica lava
Trapped gas, build up of pressure, explosive
Eruption of pyroclasts
Mount Pinatubo, Philippines

Question 3

Population density

Answer 3

2008 earthquake of magnitude 7.8 in Sichuan Province (densely populated due to fertile soil) killed almost 80 000 people
2001 earthquake of magnitude 7.8 in Kunlun (sparsely populated) reported no deaths at all

Question 4

Level of preparedness

Answer 4

In Japan, buildings are build with high levels of technology such that they withstand shaking, and there are regular earthquake drills to prepare people to respond to earthquakes
In Haiti, buildings are badly constructed and people do not care about earthquake drills

Question 5

Distance from epicentre

Answer 5

During the earthquake in Christchurch, New Zealand, 2011, the epicentre was in a town 10km away from the city centre. The city suffered more damages than areas further away from the city

Question 6

Time of occurrence

Answer 6

Although the 7.8 magnitude earthquake in Tangshan, China, 1976, lasted only 14-16s, it killed over 240 000 people as it occured at 3.42am when people were sleeping

Question 7

Type of soil

Answer 7

In Christchurch, New Zealand, liquefaction caused roads to be caked with mud, obstructing fire engines and ambulances from saving people

Question 8

Fertile soil

Answer 8

Volcanic soils of Java and Bali support the cultivation of crops such as tea, coffee, and rice

Question 9

Precious stones and minerals

Answer 9

Old volcanic rocks in Kimberly, South Africa, is one of the world’s richest sources of diamond

Question 10

Tourism

Answer 10

People may choose to visit volcanoes such at Mount Fuji, Japan, with the breathtaking scenery and tourist facilities in the area

Question 11

Geothermal energy

Answer 11

Over 70% of homes in Iceland are heated by volcanic steam due to the large numbers of volcanoes in the country

Question 12

Massive destruction by volcanic materials

Answer 12

Eruption of Kilauea, Hawaii, 2023, has destroyed many homes and highways

Question 13

Disruption of services

Answer 13

Earthquake in Kobe, Japan, 1995 damaged pipes and transmission lines, disrupting electricity, gas, and water supply to about a million of Kobe’s 1.4 million residents

Question 14

Landslides

Answer 14

7.8 magnitude earthquake in Nepal, 2015, triggered over 10 000 landslides, blocking rivers damaged houses, roads, and infrastructure across the country

Question 15

Destruction of properties and infrastructure

Answer 15

Earthquake in Tōhoku, Japan, 2011, caused a tsunami travelling up to 10km inland, resulting in the total cost of repair being US$300 billion

Question 16

Loss of lives

Answer 16

7.0 magnitude earthquake in Haiti, 2010, resulted in 300 000 deaths

Question 17

Tsunamis (formation)

Answer 17

Formation starts when seismic energy form an undersea earthquake forces out a mass of sea water
Waves may start at a height of less than 1m, with wavelengths of 100 to 150km, at speeds of 800km/h which may pass undetected
On reaching shallower water, greater friction slows the waves and forces them to increase in height
Upon impact, the tsunami waves could be travelling at 30 to 50km/h, and may reach heights of about 15m

Question 18

Tsunamis (example)

Answer 18

9.2 magnitude earthquake in the Indian Ocean in 2004 triggered a tsunami causing damage to coastal communities in 12 countries