tectonic hazards Flashcards
which is denser - an oceanic plate or a continental plate?
the oceanic plates are denser
what causes the tectonic plates to move?
convection currents
which way are the plates moving at a constructive plate boundary?
they move apart - diverge
what is created at a constructive plate boundary?
volcanoes becuase magma forces its way through the gap
which way are the plates moving in a conservative plate margin?
they are sliding past each other
what is caused at a conservative plate margin and why?
earthquakes becuase the rocks have jagged edges so they snag when the two plates are sliding past each other - this causes friction and tension to build up
how are the plates moving in destructive plate boundaries?
the oceanic plate slides beneath the continental plate
what can be formed at a destuctive plate margin?
a volcano becuase the magma rises to the surface in cracks in the continental plate - very explosive volcanos
what are the primary effects of a volcanic eruption?
-damaged buildings
-deaths/suffocation
-crop and livestock deaths
what are the secondary effects of a volcanic eruption?
-loss of forests or farmland
-infratructure damage
-increased soil fertility
-economic damage
-volcanic winter (can cause famine as crops wont ripen)
-flooding and tsunamis (result of tectonic activity)
-lahars (mudflows)
what are some immidiate responses to volcanic eruptions?
-evacuation
-aid from NGOs and foreign govs
-temporary infrastucure created for evacuated people
what are some long term responses to volcanic eruptions?
-relocation
-government efforts to rebuild the local economy (eg tax breaks)
-rebuild infrastructure
at what boundaries can earthquakes happen?
all three!
define an earthquake
sudden or violent movements in the earths crust
what is a seismic wave?
the shock waves released from the focus
the most damage will be done at the places where the shock waves are strongest
what is the epicentre?
the point on the earths crust that is directly above the centre of the earthquake
what is the focus in an earthquake?
where the pressure is released underground and where the energy radiates out from
place with the strongest waves that cause the most destruction
what scale is used to measure earthqaukes?
the moment magnitude scale measures how much energy the quake releases
what are some immidiate responses to earthquakes?
-aid from charities
-temporary infrasructure like energy, electrisity, phone lines
-temporary housing
-rescue operations for trapped people and bodies
what are some longterm responses to earthquakes?
-improve preperation
-improve the local economy (gov. grants or encourage tourism)
-rebuild buildings and infrastructure
give some ways that we can reduce the impact of tectonic hazards
-using seisometers to monitor and detect the movements in the earth
-predicting them by looking at tectonic plate boundaries so we know where they could happen
what three signals can indicate a volcanic eruption?
-small earthquakes
-bulges
-gas emission
Give some ways that we can reduce the impact of tectonic hazards
-protection like earthquake proof buildings or automatic switches that turn off gas taps (in high income countries)
-protection like light roof materials and bamboo instead of metal support in walls (in low income countries)
-planning for evacuation systems
Give some reasons why people would live in a place with tectonic hazards?
-they have family in the area
-the land is fertile due to volcanic ash (good farming)
-good government that has plans for evacuation
-jobs
