Earthquake Hazards
Earthquake hazards include any physical phenomenon associated with an earthquake that may produce adverse effects on human activities. While the terms "hazard" and "risk" are commonly used as synonyms, scientists think of them as two separate concepts. Hazards are the natural phenomena that might impact a region, regardless of whether there is anyone around to experience them. Risk refers to what we stand to lose when the hazard occurs; it is the intersection of hazard and the human lives and societies that are threatened. Risk can be measured in dollars or fatalities. Hazard is generally measured in more physical units: energy, shaking strength, depth of water inundation, etc.
Earthquake hazards include:
Ground motion: shaking of the Earth due to passing seismic waves
The nature and severity of ground motion is also affected by local geological conditions, otherwise known as site effects
Surface ruptures: ground offset occurring when an earthquake rupture reaches the surface
Tsunamis: large waves that can inundate coastlines caused by seafloor uplift, underwater landslides, etc.
Liquefaction: when waterlogged soils lose their strength and stiffness during shaking
Landslides: ground movement such as rockfalls or mudflows triggered by shaking
Flooding due to tsunamis or infrastructure damage
Fires due to infrastructure damage.