Squeezing · compression

Reverse Fault

When the brittle crust is compressed, it shortens and thickens as the hanging wall is pushed up the fault relative to the footwall.

Video coming soon

Legend

HW: hanging wall, the block above the fault

FW: footwall, the block below the fault

Epicenter: the point on the ground directly above the focus

Focus (hypocenter): location on the fault where the rupture initiates

Small black arrows: how the blocks move relative to each other

Triangles: reverse or thrust fault, on the hanging wall (indicating the uplifted block)

Large blue arrows: compressional stress acting on the crust

Fault plane (pink)

Rupture surface: the part of the fault that slipped

Rupture front, spreading out from the focus

Fault slip magnitude arrows: blue (most slip) to yellow (least)

Road

Aqueduct (concrete channel)

Railroad

Power line

Electrical arcing where the power line snaps

Flooding from the broken aqueduct

House: a wood-frame home, flexible enough to sway and ride out the shaking

Brick building: three stories of unreinforced brick and masonry, brittle, so it collapses into rubble during strong shaking

Industrial complex: built right across the fault, so the rupture tears it in half and the bays beside the break collapse

Leeper's Awesome 2016 Tacoma

Passenger train: a diesel engine pulling three passenger cars

The hanging wall moves up along the dip of the fault.

Compressional stress. The crust is being shortened and thickened.

As the rupture spreads, every part of the fault that slips generates seismic energy that radiates out from the fault surface as seismic waves.

Hills and mountain ranges that grow a little with each earthquake.

1980 El Asnam, Algeria, M7.3 · 2008 Wenchuan, China, M7.9 (reverse with some strike-slip)

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