Geology 1 MT2: EQs

the sudden slip on a fault (release of elastic energy) and the resulting ground shaking and radiated seismic energy caused by the slip

• the first point on a fault that moves in an EQ
• the EQ originated at the hypocenter

the point on the earth's surface that is directly above the hypocenter

the portion of a fault that slips in an EQ

where the fault breaks the earth's surface

a fault that does not break the earth's surface

• 1. stresses (force/area) are applied to a fault
• 2. strain (deformation) accumulates in the vicinity of friction-locked faults
• 3. strain accumulation reaches a threshold and fault slips suddenly
• 4. rupture (slip) continues over some portion of the fault

• body waves - move through the earth's interior
• surface waves - through earth's surface

• p-wave: (primary wave)
• the first wave to arrive following an EQ
• propogate by alternately compressing/expanding material
• can move through solids, liquids, gases

• s-wave: (secondary wave)
• shear wave
• can only move through solids

Love wave: horizontal shearing of the earth's surface

Rayleigh wave: "rolling" of the earth's surface

depends on the time gap b/t p-waves and s-wave arrivals (∆ t)

• ∆ t = ts - tp
• [ts= s-wave arrival time, tp= p-wave arrival time]

D= (Vp x Vs) / (Vp - Vs) x ∆ t

the amplitude of the largest s-wave

• Find distance
• Measure amplitude and find log
• Find log A₀ from graph
• Find difference: M_L= logA - logA₀

oblique fault

fault creep