Tectonic Processes and Hazards Enquiry Question 1 - A Level Geography

Tectonic
Processes
and Hazards
Enquiry Question 1: Why are some locations more at risk from
tectonic hazards?

, 1.1 The global distribution of tectonic hazards can be explained by plate boundary and
other tectonic processes.
Tectonic hazards are earthquakes and volcanic eruptions. Also included under the heading
are secondary hazards, such as tsunamis.
Oceanic Fracture Zone (OFZ)
Constructive/Divergent Plate Boundary
Low risk of hazards - small population
Low magnitude earthquakes
Non-explosive eruptions




Continental Fracture Zone (CFZ)
Destructive/Convergent Plate Boundary
High risk of hazards - large population
High magnitude earthquakes
Explosive eruptions
Mountains inland = landslides


The global distribution of tectonic hazards is far from random. The main earthquake zones
occur along the plate boundaries, particularly convergent and conservative ones.
Occasionally, earthquakes occur in the middle of tectonic plates (intra-plate earthquakes).
There are about 500 active volcanoes around the world and a significant number of these
are located around the 'Ring of Fire' around the Pacific Ocean. Most volcanoes occur near
plate boundaries, but there are also hotspot volcanoes (eg: Hawaii).

, Tsunamis are caused by submarine shock waves generated by earthquakes or volcanic
eruptions, and have a wide global distribution. They are most commonly experienced
around the coastlines of the Pacific Ocean. Tsunamis are potentially more devastating
where a gently sloping continental shelf allows them to build to greater heights.


Oceanic C.
Continental C.

Upper-most Mantle

Upper Mantle


Lower Mantle
Moho
Discontinu
Outer Core ity
Gutenberg
Inner
Discontinu
Core
ity
Lehmann
Discontinu
ity