Tectonic hazards

Question 1

what is accretion wedge

Answer 1

-the accumulation of material at the point of subduction

Question 2

what is aseismic building

Answer 2

buildings designed to withstand or minimise destruction during an earthquake

Question 3

what is the asthenosphere

Answer 3

the upper mantle layer of the earth . its semi molten and approximately 200km wide

Question 4

what is ash

Answer 4

fine particles and dust ejected during an eruption , which can remain airborne as clouds or accumulate on the ground

Question 5

what is the continental crust

Answer 5

crust that forms the continents of the lithosphere , on average 35km thick

Question 6

what is continental drift

Answer 6

the movement of tectonic plates , due to varying weights of crust . it was originally though convection currents moved plates but now slab pull is though of as the primary driving force.

Question 7

what is Degg’s model

Answer 7

model shows that a hazard becomes a disaster if it affects a vulnerable population.

Question 8

what is the epicentre

Answer 8

the point on the surface , directly above the earth quakes origin

Question 9

what is the focus

Answer 9

the place in the crust where the pressure / seismic energy is released

Question 10

what is the hazard mitigation cycle

Answer 10

the sequence of governance of a natural hazard: monitoring and prediction, mitigation, preparedness.

Question 11

what is a hot spot

Answer 11

volcanoes found away from the plate boundary , due to magma plume closer to the surface.

Question 12

what is Jokulhaup

Answer 12

a sudden glacial flood caused by a glacier on top of or near a volcano melting due to heat from the eruption

Question 13

what is a lahar

Answer 13

a flow of mud and debris

Question 14

what is the lithosphere

Answer 14

the upper crust of the earth.

Question 15

what is a love wave

Answer 15

a surface earthquake wave with horizontal displacement

Question 16

what is a mid ocean ridge

Answer 16

Partin oceanic plates at a constructive plate boundary creates a ridge , with new land at the base of the oceanic valley

Question 17

what is the oceanic crust

Answer 17

crust, usually thinner than continental crust , that forms the sea floor . it is on average 7km thick

Question 18

what is paleomagnetism

Answer 18

the alternating polarisation of new land created.
as magma cools, the magnetic elements within will align with the earths magnetic field , which can alternate over thousands of years.

Question 19

what is the park model

Answer 19

a model describing the decline and recovery of a country over time, following a natural disaster

Question 20

what are primary waves

Answer 20

an earthquake wave causing compressions within the body of the rock

Question 21

what is pyroclastic flow

Answer 21

a mixture of gases and rock fragments , at high temperatures travelling at rapid speeds.

Question 22

what is a Rayleigh wave

Answer 22

a surface earthquake wave causing both horizontal vertical displacement

Question 23

what is a Richter scale

Answer 23

a logarithmic measure of earthquakes intensity.

Question 24

what is a secondary wave

Answer 24

an earthquake wave causing vertical displacement within the body of rock

Question 25

what is a seismic wave

Answer 25

the energy relesed during an earthquake in the forms of primary , secondary , love and Rayleigh waves

Question 26

what is slab pull

Answer 26

the force contributing to the movement of tectonic plates . slab pull is due to the weight of the plate.

Question 27

what is subduction

Answer 27

oceanic plate is forced below continental plate , due to the oceanic plate being more dense than the continental plate.

Question 28

what is a tsunami

Answer 28

initial vertical water displacement creates waves, with large destructive power.

Question 29

what is the volcanic explosivity index

Answer 29

a measure of magnitude of a volcanos eruption

Question 30

what is the wadati-benioff zone

Answer 30

a region of the subducting plate , most affected by pressure and friction, where most destructive margin earthquakes originate

Question 31

what is a destructive plate boundary

Answer 31

Continental and oceanic:
● Denser oceanic plate subducts below
the continental.
● The plate subducting leaves a deep
ocean trench.
● Built up pressure from the melting
plate cause explosive volcanoes
bursting through the continental plate

Question 32

what is a constructive boundary

Answer 32

Oceanic and oceanic:
● Magma rises in between the gap left by
the two plates separating, forming
new land when it cools.
● Less explosive underwater volcanoes
formed as magma rises.
● New land forming on the ocean floor by
lava filling the gaps is known as sea
floor spreading (as the floor spreads
and gets wider).
Continental to continental:
● Any land in the middle of the separation
is forced apart, causing a rift valley.
● Volcanoes form where the magma
rises.
● Eventually the gap will most likely fill
with water and separate completely
from the main island.

Question 33

what is ridge push

Answer 33

The slope created when plates move apart has
gravity acting upon it as it is at a higher
elevation. Gravity pushes the plates further
away, widening the gap (as this movement is
influenced by gravity, it is known as
gravitational sliding).

Question 34

what plate boundary does earthquakes occur at

Answer 34

The most powerful earthquakes occur at destructive and conservative
boundaries

Question 35

what plate boundary does Tsunami occur at

Answer 35

occur at destructive
boundaries

Question 36

what plate boundary does Volcanic hazards occur at

Answer 36

The world’s active volcanoes are found at constructive and destructive plate
boundaries, and at hotspots

Question 37

what is the equation for risk

Answer 37

Risk = hazard x vulnerability / capacity to cope

Question 38

what is the PAR model

Answer 38

Root causes - dynamic pressures - unsafe conditions- disaster( risk - hazard x vulnerability) - natural hazard

Question 39

what are the steps to the park’s model

Answer 39

step 1 - Relief ( hours-day)
Immediate local response ,foreign aid
step 2- Rehabilitation ( days or weeks )
Services ,Temporary shelters ,hospitals set up Food and water
step 3-Reconstruction ( weeks - years)
Restoring , Infrastructure , future event