Global Distribution of Hazards and Earth's Structure

What is a hazard?

• A potential threat to human life and property

• A type of rock

• A weather pattern

• A tectonic plate

A natural hazard can be either hydro-meteorological or geophysical.

• True

• False

Geophysical hazards occur near plate boundaries.

• True

• False

What is the main cause of earthquakes near the middle of plates (intra-plate)?

• Plates have pre-existing weaknesses which become reactivated, forming seismic waves.

• Volcanic eruptions at plate boundaries.

• Tidal forces from the moon and sun.

• Movement of magma beneath ocean ridges.

What is a volcanic hotspot?

• A place where two plates collide

• A localised area of the lithosphere with unusually high temperature due to upwelling of hot molten material from the core

• A mountain range

• A type of earthquake

What does OFZ (Oceanic Fracture Zone) refer to?

• A belt of activity through the oceans and along the mid-ocean ridges through Africa, the Red Sea, the Dead Sea.

• A type of oceanic current found only in the Pacific Ocean.

• A deep-sea trench located near the Mariana Islands.

• A volcanic island chain in the Atlantic Ocean.

Since 1960, the total number of recorded hazards has:

• Increased

• Decreased

• Stayed the same

The number of fatalities from hazards has decreased, but there are some spikes during mega disasters.

• True

• False

List the four sections of the Earth as described in the text.

• Crust, Mantle, Outer Core, Inner Core

• Crust, Lithosphere, Asthenosphere, Core

• Mantle, Lithosphere, Hydrosphere, Core

• Crust, Biosphere, Atmosphere, Core

What is the thickness of the oceanic crust?

• Only 7km thick

• About 70km thick

• Around 30km thick

• Nearly 100km thick