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
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
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