Earthquakes Chapter 6
Seismogram
the record made by a seismograph
strike-slip fault
the rocks on either side of the fault slip past each other sideways, with little up or down motion
fault
A break in the earth's crust
Richter scale
A scale that rates an earthquake's magnitude based on the size of its seismic waves.
Mercalli scale
A scale that rates earthquakes according to their intensity and how much damage they cause at a particular place
convergent boundary
A tectonic plate boundary where two plates collide, come together, or crash into each other.
S waves (secondary waves)
Are produced when material moves either vertically or horizontally and travel only within the uppermost layers of Earth.
Seismograph
Instrument used to measure horizontal or vertical motion during an earthquake.
magnitude
Measure of the energy released during an earthquake
Epicenter
Point on Earth's surface directly above an earthquake's focus
tension
Stress that stretches rock so that it becomes thinner in the middle
Intensity
The amount of energy per second carried through a unit area by a wave.
divergent boundary
The boundary between two tectonic plates that are moving away from each other
Compression
The part of a longitudinal wave where the particles of the medium are close together.
focus
The point beneath Earth's surface where rock breaks under stress and causes an earthquake
reverse fault
a fault in which the hanging wall moves up relative to the footwall
P waves
a seismic wave that causes particles of rock to move in a back-and-forth direction
surface waves
a type of seismic wave that forms when P waves and S waves reach Earth's surface
dip-slip fault
blocks move parallel to the dip of the fault
normal fault
break in rock caused by tension forces, where rock above the fault surface moves down relative to the rock below the fault surface
Seismoscope
important scientific instrument used to detect earthquakes