Earthquakes and Tsunamis

Earthquakes

sudden slip along a fault (a break in the crust of the Earth)

Stress

the force that gets applied to rocks and can cause them to deform or rupture, leading to earthquakes.

Tensional

pulling/stretching rocks apart

Compressional

squeezing rocks together

Shear

distorts rocks

Strain

the deformation that’s observed as a result of stress

Faulting

process of fault rupture

Footwall

block below the fault plane

Hanging wall

blow above the fault plane

Normal Fault

hanging wall moves down relative to footwall

Reverse Fault

hanging wall moves up relative to footwall

Strike-slip Fault

crust moves in horizontal direction (left/right)

Epicenter

the location of the earthquake on surface above rupture

Focus (hypocenter)

point of initial breaking or rupturing

Seismic Waves

caused by a release of strain energy from rupture of a fault

P Waves

primary waves that move faster with a push/pull motion. can move through solid, liquid, and gas

S Waves

secondary waves that move slower with an up/down motion. can only travel through solids.

Tectonic Creep

gradual movement like slight curves that can slowly damage roads, side walks, and building foundations

Divergent Seismicity

narrow earthquake belt along mid-ocean ridges (low to moderate energy)

Convergent Seismicity

largest and most active earthquakes that occur at subduction zones

Transform Seismicity

strike-form faulting results in shallow earthquakes

Seismometer

used to measure earthquakes

Subsidence

sinking, settling, or lowering of parts of the crust of the earth

Liquefaction

loosely packed, water-logged sediments at or near ground surface lose their strength in response to earthquakes

Tsunamis are triggered by:

earthquakes, underwater landslides, volcano flank collapse, submarine volcanic explosion, or asteroid impact

Local Tsunami

travels to land

Distant Tsunami

travels out to sea

Runup Maps

areas that are most likely to be vulnerable and later show the levels which the water traveled to.