Challenges of Natural hazards KO

Question 1

The Crust

Answer 1

Varies in thickness (5-10km) beneath the ocean. Made up of several large plates

Question 2

The Mantle

Answer 2

Widest layer (2900km thick). The heat and pressure means the rock is in a liquid state that is in a state of convection

Question 3

The inner and outer core

Answer 3

Hottest section (5000 degrees). Mostly made of iron and nickel and is 4x denser than the crust. Inner section is solid whereas outer layer is liquid

Question 4

Ash cloud

Answer 4

Small pieces of pulverised rock and glass which are thrown into the atmosphere

Question 5

Gas

Answer 5

Sulphur dioxide, water vapour and carbon dioxide come out of the volcano

Question 6

Lahar

Answer 6

A volcanic mudflow which usually runs down a valley side on the volcano

Question 7

Pyroclastic flow

Answer 7

A fast moving current of super-heated gas and ash (1000oC). They travel at 450mph

Question 8

Volcanic bomb

Answer 8

A thick (viscous) lava fragment that is ejected from the volcano

Question 9

Warning signs of earthquakes

Answer 9

. Small earthquakes are caused as magma rises up
. Temperature around the volcano rises as activity increases
. When a volcano is close to erupting, it releases gases

Question 10

Monitoring techniques (Earthquakes)

Answer 10

. Seismometer’s are used to detect earthquakes
. Thermal imaging and satellite cameras can be used to detect heat around a volcano
. Gas samples may be taken and chemical sensors used to measure Sulphur levels

Question 11

Preparation for volcanic eruptions

Answer 11

. Creating an exclusion zone around the volcano
. Being ready and able to evacuate residents
. Having an emergency supply of basic provisions, such as food
. Trained emergency services and a good communication system

Question 12

Predicting earthquakes

Answer 12

.Satellite surveying (tracks changes in the earth’s surface)​

.Laser reflector (surveys movement across fault lines)​

.Radon gas sensor (radon gas is released when plates move so this finds that)​

.Seismometer ​

.Water table level (water levels fluctuate before an earthquake).​

.Scientists also use seismic records to predict when the next event will occur.​

Question 13

Protection against earthquakes

Answer 13

. Building earthquake-resistant buildings​
. Raising public awareness ​
. Improving earthquake prediction​

Question 14

Convection currents

Answer 14

. Radioactive decay of some of the elements in the core and mantle generate a lot of heat
. When lower parts of the mantle molten rock (Magma) heat up they become less dense and slowly rise
. As they move towards the top they cool down, become more dense and slowly sink
. These circular movements of semi-molten rock are convection currents
. Convection currents create drag on the base of the tectonic plates and this causes them to move

Question 15

Causes of Nepal Earthquake

Answer 15

. On a destructive plate margin, involving the Indo-Australian & Eurasian plates.​
. Magnitude 7.9 earthquake
. About 50 miles from the capital Kathmandu
. Very shallow focus of 15km deep

Question 16

Effects of the Nepal Earthquake

Answer 16

9000 people died , 20,000 injured. 8 million people affected​

250,000 homes collapsed or were damaged. 3 Million left homeless.​

Landslides and avalanches caused flooding and further deaths​

Question 17

Management / response to Nepal Earthquake

Answer 17

Individuals tried to recover people. ​

Many countries responded with appeals or rescue teams.​

Heavily relied on international aid. ​

98% of rubble remained after 6 months.

Question 18

Destructive plate margin

Answer 18

When the denser plate subducts beneath the other, friction causes it to melt and become molten magma. The magma forces its ways up to the surface to form a volcano. This margin is also responsible for devastating earthquakes

Question 19

Constructive plate margin

Answer 19

Here two plates are moving apart causing new magma to reach the surface through the gap. Volcanoes formed along this crack cause a submarine mountain range such as those in the Mid Atlantic Ridge

Question 20

Conservative plate margin

Answer 20

A conservative plate boundary occurs where plates slide past each other in opposite directions, or in the same direction but at different speeds. This is responsible for earthquakes such as the ones happening along the San Andreas Fault, USA

Question 21

Causes of Earthquakes

Answer 21

. Earthquakes are caused when two plates
become locked causing friction to build up. . From this stress, the pressure will eventually be released, triggering the plates to move into a new position.
. This movement causes energy in the form of seismic waves, to travel from the focus towards the epicenter.
. As a result, the crust vibrates triggering an earthquake

Question 22

What is the Epicenter

Answer 22

The point directly above the focus, where the seismic waves reach first, is called the EPICENTRE

Question 23

What are Seismic waves

Answer 23

SEISMIC WAVES (energy waves) travel out from the focus

Question 24

What is the Focus

Answer 24

The point at which pressure is released is called the FOCUS

Question 25

Causes of the Chile earthquake

Answer 25

The Nazca plate and South American plate move towards each other on a destructive plate margin​

The magnitude 8.8 earthquake struck just off the coast of Chile, It was followed by a series of smaller aftershocks

Question 26

Effects of the Chile earthquake

Answer 26

500 deaths, 12,000 injured.​

800,000 people affected.​

220,000 homes, 4500 schools destroyed.​

Port of Talcahuanao and Santiago airport badly damaged.​

Landslides cut communities off for days

Question 27

Management / responses to the Chile earthquakes

Answer 27

Emergency services acted swiftly​

International help was sent quickly.​

Temporary repairs were made to important highways within 24 hours​

Power and water restored to 90% of homes within 10 days​