Seismic hazards

Earthquake - convection current causes stress on rocks, when there lots of friction pressure is released, resultng in intense shaking motion

Focus - point where pressure release occurs

Epicentre - point directly above focus on earths surface

Seismic waves - wave of energy generated by an earthquake, travels within earth / along surface

Tsunamis - giant sea waves generated by shallow focus (0-70km) 

Fault - crack in earth's crust- resulting from displacement. Occurs at plate boundaries.

Seismic gap - segment of an active fault which hasnt slipped in unusally long time

Effects of seismic waves:

Primary: ground rupture - visible breaking/displacement of earth's surface. Likely along line of a fault 

Secondary: liquefaction - saturated soils loose mechanical strength when shaken - fluid like

               landslide - slope failure as result of ground shaking

Richter scale - logarithmic scale (6 is 10x greater than 5) Measures energy measures magnitude/strength of earthquake

Moment magnitiude scale (MMS) - scaled 1-10, measures energy release

Mercalli scale - scaled 1-12, measures intensity of event & impact

Human induced earthquakes:

Fracking - pumping water/sand past water table into tight rock formations. causes micro-seismic events (-3 on Richter scale)

Retrofitting - earthquake proofing buildings - shock absorbers, cross bracing