earthquakes Flashcards
types of hazards created
-ground shaking
-liquefaction
-landslides and avlanches
-tsunamis
ground shaking
vertical and horizontal
extend depends upon - magnitude and depth foucus
-distance from epicenter as energy decreases with distance
-geology - more unconsolidated rocks are damages more easily
liquifaction
if it hits an area with unconsolidated rock that has high liquid content the water can separate and make the ground act like a liquid
once the shaking stops it solidfies and is stuck in the ground again
example - christ church in 2011
landslides and avlanches
problem has been made worse by deforestation and there are no longer roots biniding together parts of the ground
landslides can also
-bloc rivers
-damage transport routs
-damage dams and upalnd areas
tusnamis
when underwater earthquake causes the sea bed to rise, this displaces the water above the waves, they have a low hight and a long wavelength
impacts -
death
illness
disease
lack of food and crops are dead
lack of infrastructure
the four places earthquakes occur?
-mid ocean ridges
-ocean trenches and island arcs
-collision zones
- constructive plate margins
primary waves (P waves)
fast travelling back and forth
can travell through liquid and soild
they get there first but dont cause extent of the damage
secondary waves (S waves)
half the speed of p waves
high frequancy
go through solid not liquid
surafce waves (L waves)
slowest and arrive last,low frequancy and large amplituide
containes rolling movemnet
causes signifacnt damage and fracturing of the ground
shallow focus earthquakes
0-70km deep
often brittel rock
low levels of energy releases but when there are high levels of energy the impact is massive and can cause most damage
deep focus earthwaukes
70km-700km deep
increasing depth leads to high pressure
very powerful howveer they have less of an effect on the surface
three ways to messure earthwuakes
richter scale
modified marcalli scale - imapct
movemnet magntuide scale - messures movemnet
why do people live in tectonicly active areas?
-fertail soil
- tourism
- geothermal power
-minrels
- percived level of risk
what reasons are countries not as prepared as they could be?
-lack of political commitment
- lack of recognition to the connection between disaster and risk
- inadequate investment, especially in poor countries with high venerability
earthquake warnings
-messuring mechanical movemnt of the earths crust by satalilite
electromagnetic phonoman
