KI1.1: The global distribution of tectonic hazards can be explained by plate boundary and
other tectonic processes
a. The global distribution and causes of earthquakes, volcanic eruptions and tsunamis (1)
- The majority of tectonic activity occurs on the Pacific ring of fire (about 70% of all
earthquakes)
- They mainly occur at plate boundaries, but can occur as intra-plate earthquakes or
hotspot volcanoes
- The most powerful earthquakes are at convergent or conservative boundaries
- Volcanic eruptions only occur at convergent and divergent boundaries
- Convection currents cause the movement of plates, which causes tectonic activity
- Tsunamis can be caused by landslides, earthquakes or volcanoes
- The oceanic fracture zone (OFZ) - a belt of activity through the oceans along the mid-
ocean ridges, coming ashore in Africa, the Red Sea, the Dead Sea rift and California
- The continental fracture zone (CFZ) - a belt of activity following the mountain ranges
from Spain via the Alps, to the Middle East, the Himalayas to the East Indies and then
circumscribing the Pacific
Earthquake causes
- Earthquakes are caused by a sudden release of stored energy as 2 plates move past each
other
- Strain builds up over time between the plates, until it is suddenly released. This is ‘slip-
stick’ behaviour
- The energy radiates away from the focus
Tsunami causes
other tectonic processes
a. The global distribution and causes of earthquakes, volcanic eruptions and tsunamis (1)
- The majority of tectonic activity occurs on the Pacific ring of fire (about 70% of all
earthquakes)
- They mainly occur at plate boundaries, but can occur as intra-plate earthquakes or
hotspot volcanoes
- The most powerful earthquakes are at convergent or conservative boundaries
- Volcanic eruptions only occur at convergent and divergent boundaries
- Convection currents cause the movement of plates, which causes tectonic activity
- Tsunamis can be caused by landslides, earthquakes or volcanoes
- The oceanic fracture zone (OFZ) - a belt of activity through the oceans along the mid-
ocean ridges, coming ashore in Africa, the Red Sea, the Dead Sea rift and California
- The continental fracture zone (CFZ) - a belt of activity following the mountain ranges
from Spain via the Alps, to the Middle East, the Himalayas to the East Indies and then
circumscribing the Pacific
Earthquake causes
- Earthquakes are caused by a sudden release of stored energy as 2 plates move past each
other
- Strain builds up over time between the plates, until it is suddenly released. This is ‘slip-
stick’ behaviour
- The energy radiates away from the focus
Tsunami causes
