1. Earthquake Hazards

3. Earthquakes can have a variety of harmful effects, some obvious, some more subtle.
Earthquakes of the same magnitude (size) can cause very different amounts of damage, depending on such variables as the:
Nature of the local geology
Whether the area affected is near the coast
Whether the terrain is steep or flat
Distance from the epicenter

4. Primary Effects
Release of energy caused by the sudden movement of tectonics plates
The energy is released as “seismic waves” (like ripples in a pond)
The offset between rocks on opposite sides of a fault can break power lines, pipelines, buildings, roads, bridges and other structures that cross the fault
Like ripples in a pond -

5. Primary Effects
Fault – an “active zone” boundary between tectonic plates
Focus – the exact location where tectonic plates suddenly move
Epicenter – the location on the surface of the earth directly above the FOCUS
Like ripples in a pond -

6. Like ripples in a pond -

7. Secondary Effects 1. Aftershocks:
Smaller earthquakes that occur after a main earthquake.
The main shock usually causes the most damage, but when aftershocks are many and are nearly as strong as the main shock, they may cause serious destruction.
2. Fire:
Power lines knocked down and natural gas lines may rupture due to an E.Q, fires often start after earthquakes
3. Landslides:
In mountainous regions subjected to earthquakes ground shaking may trigger landslides, rock and debris falls, and debris avalanches
4. Liquefaction:
When wet soil is shaken by an E.Q, the soil particles may be jarred apart, allowing water to seep b/w them. Causes the ground to become somewhat like quicksand.

8. Secondary Effects 4. Tsunamis
Giant ocean waves that rapidly travel across oceans, generated by earthquakes that occur beneath sea level and along coastal areas
Tsunami’s can cause damage thousands of kilometers away on the other side of the ocean
In the open ocean, the tsunamis are only broad swells on the watersurface
As they approach land, they develop into large breaking waves which can be over 15 m high and may travel at speeds of 1000 km/hr

9. Secondary Effects 4. Tsunamis
Indonesia, 2004
Japan, 2011

10. Tertiary Effects Changes in Ground Level
E.Q’s may cause both uplift and subsidence of the land surface, sometimes up to 15 meters!