Tectonics Part 2

Question 1

Describe what lava flow is and in what volcano type it occurs in?

Answer 1

Extensive areas of solidified lava which can extend several metres from volcanic vents if it’s basaltic and has a low viscosity. It happens in composite volcanoes and shield volcanoes

Question 2

What is Pyroclastic flow?

Answer 2

Large dense clouds of hot ash and gas at temperatures of up to 600. They can flow down the flanks of volcanoes and devastate large areas. It happens at composite volcanoes.

Question 3

Describe ash fall?

Answer 3

It is ash particles and larger tephra particles which blanket large areas in ash killing vegetation, collapsing buildings and poisoning water courses. It happens at composite volcanoes and constructive plate margin volcanoes.

Question 4

What is a gas eruption?

Answer 4

The eruption of carbon dioxide and sulphur dioxide which can poision people and animals in extreme cases

Question 5

What is a lahar?

Answer 5

Volcanic mudflows which happens mm when rainfall mobilises volcanic ash. They travel at high speed down river systems and cause major destruction.

Question 6

What is a Jokulhlaup

Answer 6

Devastating floods which occur when volcanoes erupt near glaciers and ice caps creating huge amounts of meltwater. They happen at constructive plate margin Volcanoes.

Question 7

How do tsunamis occur?

Answer 7

When a sub marine earthquake displaces the sea bed vertically as a result of movement along a fault line at a subduction zone. This motion displaces a large volume of water in the ocean water column which moved outward in all directions from the point of displacement. It moves as a vast bulge in open water

Question 8

Describe the characteristics of tsunamis?

Answer 8

High wave heights
High speeds
Long wavelengths

Question 9

Why do some tectonic hazards develop into disasters?

Answer 9

Vulnerability and resilience have an effect on whether it becomes a disaster

The location is a factor

Level of development

Governance

Question 10

What does risk=

Answer 10

Risk=hazard x vulnerability
________________
Capacity to cope

Question 11

How can communities be more resilient?

Answer 11

Emergency evacuation, rescue and relief systems in place.

They react by helping each other to reduce numbers affected

Hazard resistant design or land use planning have reduced the numbers at risk

Question 12

What are the root causes of vulnerability?

Answer 12

Low access to resources

Limited influence in decision making

Poor governance and a weak economic system

Question 13

What are the dynamic pressures in the pressure and release model?

Answer 13

Lack of education, training and investment

Rapid population change and urbanisation

Question 14

What are unsafe conditions due to?

Answer 14

Poor construction standards

Unsafe infrastructure

Poverty

Lack of social safety net

Question 15

What are the 3 different types of impacts from tectonic hazards?

Answer 15

Social: deaths, injury and sided health impacts including psychological ones

Economic: the loss of property, businesses, infrastructure and opportunity

Environmental: damage of destruction of physical systems, especially ecosystems

Question 16

Why is comparing impacts of tectonic hazards between countries difficult

Answer 16

Both the physical nature of the event and the social economic profiles of affected places are different

Question 17

Why is there a weak relationship between magnitude and death toll

Answer 17

• some earthquakes cause serious secondary impacts(landslides and tsunamis)
• earthquakes are worse in urban areas than in rural ones
• level of development and preparedness affects death toll
• isolated, hard to reach places can have higher death tolls because rescue and relief take longer

Question 18

What hazard characteristics present the highest risk?

Answer 18

High magnitude, low frequency events

Rapid onset events with low spatial predictability

Regional areal extent

Question 19

Why are countries with lower HDIs more vulnerable?

Answer 19

Many people lack basic needs even in normal times

Most houses are informally built(no hazard resilience)

Access to healthcare is poor so disease and illness is common

Education levels are lower, so hazard perception and risk awareness is low

Question 20

What are the factors increasing risk?

Answer 20

Very young or very old population

Population growth

Urbanisation and urban sprawl

Ageing inadequate infrastructure