earthquakes and tsunamis: science and society Flashcards
what is an earthquake?
dislocation of land, plates slides against each other, with energy spreading from focus, hypocentre, along the fault plane.
how many detectable earthquakes are there each year?
500,000.
what is the hypocentre?
originate of the earthquake, the focus underground.
what is the epicentre?
directly above the focus on surface, it’s the area that starts the earthquake on the surface.
what does the earthquake release?
seismic waves. wavefronts are like waves in the ground coming away from the earthquake hypocentre. the plates suddenly move and slip or fracture which causes the earthquake due to the release of energy.
what earthquake happened in 2018?
Lombok
how many people died in Lombok 2018?
563 people.
what was the magnitude of Lombok 2018?
6.9
where do earthquakes occur? (3)
ring of fire, in the pacific.
alpide- spain towards india. due to the movement of the tectonic crust.
mid-Atlantic ridge- in between north American plate and Eurasian plate and African plate.
what percentage of earthquakes take place in ring of fire?
80%
what is a normal fault?
2 blocks are pulling away from one another
what is a reverse fault?
2 blocks of earth are moving towrds eachother (tsunami)
what is a strike fault?
2 block move horizontally opposite each other.
what happens when there is an normal and a reverse?
there is a change in height in one or both of the blocks of the earth.
what is a large amplitude?
when the epicentre is very close, but the earthquake is far away and very large.
what are the major hazards of earthquakes?
building collapses, loss of life due to buildings
landslides, liquefaction
fire- electical and gas lines
tsunamis, not tidal waves.
when was the kathmandu disaster?
2015
how many people died in Kathmandu?
8,600
what magnitude was kathmandu?
8.1
what was gorka magnitude?
7.8
how many people died in Gorka?
8800
what was the policy made in 1994?
development plans-national building code project in Nepal. earthquake resistant buildings.
what happens in an underwater earthquake?
seismic sea waves that are caused by a major displacement of oceans. 2 mantles being forces together, oceanic plates move between the mantle. as it builds, distortion occurs between 2 plates. increasing the stress and enhances the bulge. when the release happens, pressure releases and lifts column of water above the fault.
what earthquake happened in 2004?
Sumatra. 9.1, 225000 died.
what is NOAA?
tsunami mitigation
what are NOAA 3 approaches?
computer model to show worst-case scenaros
education
sophisticated detection sustem. DART system. Depp-ocean assessment and reporting of tsunamis.
what needs to be taken into consideration when deciding where to put a hospital in prone earthquake areas?
the income of the population nearby, the risk of earthquake hazards, the average distance between hospitals being more than 4 km, low shaking amplification, coastal areas, population density, liquefaction.
what can be learned from L’Aquila’s article 2013?
scientific and politician stances are different. public needs to know that science is unknown, cannot predict the random movement of the earth. a more systematic approach was needed in risk communication.
