Tectonic Processes and Hazards

Question 1

Tectonic Hazards

Answer 1

a result of lithospheric plate movement causing earthquakes and/or volcanoes which lead to the potential loss of life and the built environment

Question 2

Oceanic Crust

Answer 2

denser rock types (basaltic) and is created at divergent/constructive plate boundaries

Question 3

Continental Crust

Answer 3

less dense rock types (granitic) and is created at convergent/destructive plate boundaries

Question 4

Crust

Answer 4

0-100km thick

Question 5

Mantle

Answer 5

around 2800km thick, solid but acts like viscous liquid due to some minerals being near melting point, contains variety of oxides (O, Si, Mg)

Question 6

Outer Core

Answer 6

around 2300km thick, 4400C liquid (because less pressure), Fe and Ni give Earth’s magnetic field

Question 7

Inner Core

Answer 7

around 1220km thick (radius), 6000C, solid, Fe and Ni

Question 8

Benioff Zone

Answer 8

Zone where one plate subducts another, creating massive and deep earthquakes due to the friction/pressure build up. Can create fold mountains (continental-continental)

Question 9

Seafloor Spreading and Palaeomagnetism

Answer 9

Minerals in newly formed oceanic plates cool down and align themselves with the Earth’s magnetic polarity. These flips can be seen as the rocks (plates) move away from each other (diverge)

Question 10

Intra-Plate Volcanism

Answer 10

a mantle plume (abnormally hot rock) rises from the mantle and creates a hotspot on the crust. The plume is stationary and the crust moves, so the magma heats the rock and melts and thins it, causing the volcanism eg. ICeland, Hawaii

Question 11

Convection Currents

Answer 11

heat produced by the decay of radioactive elements in the Earth’s crust heat the lower part of the mantle, which creates convection currents. These hot liquid magma currents rise into the asthenosphere where they move in cells- circular in motion, carrying the plates’ motion

Question 12

Slab Pull

Answer 12

newly formed oceanic crust at mid-oceanic ridges become denser as they cool, so they sink under their own weight into the magma below them, therefore dragging the rest of plate consequently causing plate movement

Question 13

Fault

Answer 13

line in the crust along which a fracture of breakage will occur

Question 14

Focus/Hypocentre

Answer 14

where the earthquake actually occurs in the ground and gives off seismic energy

Question 15

Epicentre

Answer 15

the focus point on the surface

Question 16

P Waves

Answer 16

Primary/Pressure- fastest, travel longitudinal. Reach surface first, cause least damage, travels through both solids and liquids

Question 17

S Waves

Answer 17

Secondary- slower, 60% of P Wave speed, only travels through solids, moves perpendicular to movement

Question 18

L Waves

Answer 18

Love/Surface- slowest, last to reach surface, causes most damage as it shakes ground side-to-side, longer and focuses all energy on the surface

Question 19

Liquefaction

Answer 19

when structure of a loose, saturated snad/soil loses strength, seismic activity shakes the water and forces it up making the sand/soil lose structural integrity

Question 20

Pyroclastic Flow

Answer 20

tephra (volcanic ejecta in general eg. ash, rock, gas) that flows downhill quickly (100km/h), very hot (1000C)

eg. Mt Pinatubo, Philippines 1991

Question 21

Lahar

Answer 21

water and ash and mud, violent mudflow that can reach far distances, consists of pyroclastic material

eg. Nevado del Ruiz, Colombia 1985

Question 22

Hazard

Answer 22

event that has potential to cause loss of life or destruction of the built environment

Question 23

Disaster

Answer 23

when the hazard isn’t managed well, inability to cope.

UN definition: when the hazard causes 10+ deaths

Question 24

Vulnerability

Answer 24

factors that lead to an increased chance loss of life and destruction

Question 25

Threshold for Resilience

Answer 25

in essence, the ability to “bounce back” after a disaster, eg. regain stability economically, environmentally, politically, socially

Question 26

Risk Equation

Answer 26

Risk (R) = Hazard (H) x Vulnerability (V) / Capacity to Cope (C)
i.e. Risk- likelihood
Hazard- magnitude, scale, duration
Vulnerability- governance, wealth, land-use zoning

Question 27

Administrative Governance

Answer 27

policy implementation, eg. building codes/land-use zoning, monitoring vulnerability on a local scale

Question 28

Economic Governance

Answer 28

management of economy, relates to jobs, poverty, equality

Question 29

Political Governance

Answer 29

deals with third party organisations, includes the aid from other countries (search and rescue, food/water, resources)

Question 30

Multiple Hazard Zones

Answer 30

regions of the world that suffer from a range of hazards (meteorological, climatic and geomorphic)

eg. Philippines