Earthquakes

Question 1

what is the focus/hypocentre?

Answer 1

the spot under the surface of the ground where the earthquake happens

Question 2

what is the epicentre?

Answer 2

the spot on the surface directly above the focus

Question 3

what are P waves?

Answer 3

these are the fastest waves and reach the surface first, they are high frequency and travel through the mantle and core to opposite sides of the earth, they travel at between 4 and 7km/second

Question 4

what are S waves?

Answer 4

these are half as fast as P waves and are second to reach the surface, they are high intensity waves that shake side to side through the crust and mantle only, they travel at between 2 and 5km/second

Question 5

what are Love waves?

Answer 5

these are the slowest waves and cause the most damage, they are surface waves and travel between 2 and 3km/second

Question 6

what are Rayleigh waves?

Answer 6

these radiate out from the epicentre in low frequency, rolling motions, these travel between 2 and 3km/second

Question 7

what is the Richter scale?

Answer 7

it was developed in the 1930s and it uses a logarithm to mathematically determine the magnitude of earthquakes, each increase in the scale is 30 times more

Question 8

what is the Movement Magnitude Scale?

Answer 8

developed in the 1970s, it is more effective for large earthquakes

Question 9

what is the Modified Mercalli Scale?

Answer 9

it measures the intensity of the earthquake event and its impacts

Question 10

how can earthquakes cause landslides?

Answer 10

earthquakes cause loose rocks and soil on slopes to move, often these landslides can cause more destruction and loss of life than the initial quake

Question 11

how can earthquakes cause mudflows?

Answer 11

in areas where the water content of the soil is high, an earthquake can trigger a mudflow where the mixture of mud and water slides downhill

Question 12

how can earthquakes cause tsunamis?

Answer 12

they are caused by ocean floor earthquakes, submarine volcanic eruptions and landslides

Question 13

what are the possible signs of an earthquake?

Answer 13

• microquakes before the main tremor
• bulging of the ground
• decreasing radon gas concentrations in groundwater
• raised groundwater levels
• electrical and magnetic changes within local rocks
• increased argon gas content in the soil
• curious animal behaviour

Question 14

how are earthquakes predicted?

Answer 14

it is very difficult and regions at risk can be identified through plate tectonics, fault lines can be monitored and local magnetic fields measured

Question 15

how are earthquakes prevented?

Answer 15

it is almost impossible to prevent but there has been studies to stop plates sliding past each other

Question 16

how can you be protected against earthquakes?

Answer 16

it means preparing for the event by modifying the human and built environments in order to decrease vulnerability

Question 17

what is the Federal Emergency Management Agency?

Answer 17

they plan to promote understanding of earthquakes and their efforts, they work better to identify earthquake risk, to improve earthquake resistant design and construction techniques, and to encourage the use of earthquake safe policies

Question 18

how is education helpful for earthquakes?

Answer 18

this is the main way that loss of life can be minimised, instructions are issued in how to prepare for events including securing homes and assembling earthquake kits

Question 19

how can structures be made hazard resistant?

Answer 19

by putting a large concrete weight on top of the buildings which will move in the opposite direction to the force of the earthquake, putting large rubber shock absorbers in the foundations, and by adding cross-bracing to the structure to hold it together

Question 20

how can fires be prevented?

Answer 20

smart meters have been developed that can cut off the gas if an earthquake of sufficient magnitude occurs

Question 21

how can the emergency services help?

Answer 21

heavy lifting gear needs to be available and many people should be given first aid training

Question 22

how can insurance help?

Answer 22

in richer areas, people are urged to take out insurance to cover their losses, the only problem being is that it is very expensive

Question 23

how can aid help?

Answer 23

most aid to poorer countries has generally been to help in the few days after the event, providing medical services, tents, water purification equipment, and search and rescue

Question 24

how can tsunamis be protected against?

Answer 24

they cannot be entirely predicted even if the location and magnitude is known, certain automated systems can be installed to give warnings
regions with a high tsunami risk use warnings to warn the population before the waves reach the land

Question 25

what happened in the Haiti 2010 earthquake?

Answer 25

• initial shock duration less than 1 minute
• epicentre 15 miles from city centre
• shallow focus 13km deep
• on the north american/caribbean plate boundary
• population 9.8 million
• 48% urban population
• life expectancy is 62 years
• magnitude 7.0

Question 26

what were the primary impacts of Haiti 2010?

Answer 26

• 300,000 people killed
• 1.5 million left homeless
• 1 in 3 buildings collapsed
• severe soil erosion and landslides
• shoreline moving back and forth

Question 27

what were the secondary impacts of Haiti 2010?

Answer 27

• small businesses collapsed

- rapid spread of diseases like cholera

Question 28

what were the primary responses of Haiti 2010?

Answer 28

• disaster management around the world
• poor infrastructure and building improvements
• homeless people in over 1100 camps
• emergency surgeries on life-saving operations
• 16,000 UN troops
• the US military took control of the airport
• UNDP helped fund and rescue survivors
• bottled water and purification tablets for 250,000 people

Question 29

what were the secondary responses of Haiti 2010?

Answer 29

• $11.5 billion in aid, reconstruction completed by 2020
• hospitals, schools and government buildings rebuilt
• economic activity moved away from earthquake prone areas

Question 30

what happened in the Japan 2011 earthquake?

Answer 30

• duration was 5 minutes
• 100km off the coast, 6km deep
• on the pacific and north american plate boundary fault line
• 6m high tsunami
• magnitude 9.0

Question 31

what were the primary impacts of Japan 2011?

Answer 31

• extensive flooding up to 15m inland
• over 18,000 people were dead or missing
• 500,000 made homeless
• $100 trillion economic cost
• japan moved a further 3m out to sea
• flooded an area of 500km2

Question 32

what were the secondary impacts of Japan 2011?

Answer 32

• after two weeks there were over 700 more aftershocks

- explosions and radiation leaks at fukushima nuclear plant

Question 33

what were the primary responses of Japan 2011?

Answer 33

• helicopter crews pick up survivors
• offers of aid from countries such as uk and china
• 100,000 soldiers were mobilised to help control it all
• exclusion zone set up around the nuclear plant
• the uk sent 63 search and rescue specialists and dogs

Question 34

what were the secondary responses of Japan 2011?

Answer 34

• in 2013 there was an upgrade to the tsunami warning system
• the government set up the reconstruction design council to plan a long term growth in tohoku
• future contingency planning took place