Tecotnic Flashcards
(29 cards)
What’s a constructive (divergent) plate margin
Plates move away
What’s a destructive (convergent) plate margin
Plates move together and collide if both continental. Oceanic subduction if continental and oceanic vied on subduction if both oceanic
Where are volcanoes found
Active volcanoes are found at constructive/destructive and at hotspots
Volcanoes: What happens a constructive plate margin
Magma is less dense than plate so rises above it (similar to ridges)
Volcanoes: what happens at a destructive plate margin
Subduction causes me,ting of oceanic plate, allowing magma to rise and form a volcano
What does the shape of the volcano give?
It will determine its destructive ability (e.g composite cone are usually more destructive than shield)
What do primary and secondary hazards include in a volcano?
Primary: include lava flows, phreatic (steam) eruptions and pyroclastic flow carry hot ash and rock
Secondary:
Involve water in form of Lahars and jokuhlaups
What’s an earthquake
They are most powerful at conservative and destructive
Earthquake: what happens at a constructive plate margin
Plates move at different speeds building, building up pressure until plates crack, causing fault lines and releasing seismic waves
Earthquake: what happens at a conservative plate margin
Locked fault between plates building up pressure and suddenly releasing seismic waves
What is a natural hazard caused by?
Either climatic (meteorological) or land (geophysical) processes
What is a hazard
Potential threat to human life and property
Where does a geophysical hazard happen
Near plate boundaries
Where do earthquakes happen
Happen in the middle of plates (intra-plate) caused by pre existing weakness that reachuate and produce seismic waves
Where are volcanic hotspots (e.g ring of fire) found?
Found in the middle of plates
Found on earths crust and upper mantle where’s there’s high temperature from upswelling and hot molten material from the core
What is the role of development and governance on impacts
People remain vulnerable to disasters risks due to inequality such as education, health care and income
Urbanisation and population growth means that more people are vulnerable increasing the amount of poverty
In Japan they prepare for hazards
Having public infrastructure, housing, food supplies and health care can lower the impacts In a disaster
Poor governance means that the hazard is more likely to turn into a disaster
Governance is seen as the root cause and critical n the case of a hazard/disaster
What is the Richter scale and what does it measure?
It measures magnitude and uses the arrival times of P and S waves
What is the moment magnitude scale and what does it measure?
It uses the energy released and the movement produced by shock waves to calculate magnitude
What can earthquake intensity be measured by?
The Mercalli scale- this takes into account the damage
What are volcanic eruptions measured by
Volcanic explosivity index- uses the amount of energy released and the type of eruption to calculate a value
Definition of disaster
When a hazard affects human weathering
Definition of vulnerability
How susceptible a population is to damage caused by a hazard
-capacity to cope of how resilient the population is can affect how well it can recover
Definition of risk
He livelihood of humans being affected by a hazard
This is calculated by the hazard risk equation
(Hazard x vulnerability divided by capacity to cope)
Risks of disasters
It increases as the severity/frequency of the hazard increases as well as vulnerability.
However for a worse risk- capacity to cope will decrease along with everything else
Qatar- 0.1% has lowest risk
Phillipeans- 27.5% highest risk
Even if a country doesn’t have a major hazard- they can still be a risk because of their capacity to cope
