tectonic hazards: earthquakes

Faulting

Slow due to friction, stressed rocks along the fault, rocks rupture and are displaced when stress exceeds the strength of the rocks

Stress

Force that results from plate tectonic movements : tensional, compressional and shearing forces

Strain

Change in shape or location of the rocks due to stress

Normal dip slip fault

Hanging wall moves relative to the footwall

Reverse dip slip

Hangning wall moves up relative to footwall

Low angle thrust fault

hanging wall moves up relative to footwall

Same movement as a reverse fault just at a shallower angle

Strike slip

Crust either side of fault moves horizontally (laterally) in opposing directions

Body waves

Primary and secondary waves.

Travel through the interior of the earth

Arrive before surface waves

Have a higher frequency (shorter wavelength) than surface waves