earthquakes reflection 3- faults and mechanisms

what are the types of faults?

normal, reverse, transform

earthquake causes:

tectonic movement along faults, volcanic eruption, explosions, impacts

fault

fracture in crust along which there has been movement and displacement

rupture is where

epicenter/focus is determined

fault orientation

how fault surface is oriented: vertically or horizontally

strike

orientation of an imaginary horizontal line on a fault

footwall

piece of rock on underneath side

hanging wall

above side

compression

pushing toward fault

tension/extension

pulling away from fault

shearing

horizontal movement parallel to fault

normal fault

vertical or near vertical movement, dip slip, tensional stress, common in divergent margins, hanging wall moves down, footwall moves up

reverse and thrust faults

fault blocks pushed together, compressional stress, common in convergent margins, hanging wall moves up, footwall moves down

reverse fault

high angle. builds mountains, weaker earthquakes

thrust fault

low angle, subduction zones, bigger earthquakes

blind thrust fault

does not rupture surface, may hide active fault, covered by topography/sediment

transform or strike slip

crust blocks slide past each other horizontally, shear stress, common along transform boundaries

sinistral

left lateral, opposite block of land at fault moves left

dextral

right lateral, opposite block of land at fault moves right

oblique fault

combination of horizontal and vertical movement