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Flashcards in Tectonics Part 2 Deck (20):

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

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


What is Pyroclastic flow?

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.


Describe ash fall?

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.


What is a gas eruption?

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


What is a lahar?

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


What is a Jokulhlaup

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


How do tsunamis occur?

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


Describe the characteristics of tsunamis?

High wave heights
High speeds
Long wavelengths


Why do some tectonic hazards develop into disasters?

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

The location is a factor

Level of development



What does risk=

Risk=hazard x vulnerability
Capacity to cope


How can communities be more resilient?

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


What are the root causes of vulnerability?

Low access to resources

Limited influence in decision making

Poor governance and a weak economic system


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

Lack of education, training and investment

Rapid population change and urbanisation


What are unsafe conditions due to?

Poor construction standards

Unsafe infrastructure


Lack of social safety net


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

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


Why is comparing impacts of tectonic hazards between countries difficult

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


Why is there a weak relationship between magnitude and death toll

-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


What hazard characteristics present the highest risk?

High magnitude, low frequency events

Rapid onset events with low spatial predictability

Regional areal extent


Why are countries with lower HDIs more vulnerable?

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


What are the factors increasing risk?

Very young or very old population

Population growth

Urbanisation and urban sprawl

Ageing inadequate infrastructure