Chapter 19 Earthquakes

amplitude

of the largest seismic weave.

focus

point of the initial fault rupture where an earthquake originates that usually lies at least several kilometers beneath earth surface.

soil liquefaction

process associated with seismic vibrations that occur in areas of sand that is nearly saturated resulting in the ground behaving a liquid.

Strain

The deformation of materials in response to stress.

seismogram

The record produced by a seismometer is called seismogram.

Seismic waves

The vibration of the ground produced during an earthquakes.

Plastic deformation

When stress build up past. Certain called the elastic limit rocks underg.

Modified Mercalli scale

Which rates the types of damage and other effect of an earthquakes as noted by observed during and after its occurrence.

tsunami

a large ocean wave generated by vertical motions of the seafloor during an earthquake.

seismic gaps.

are sections located along faults that are known to be active but which have not experience significant earthquakes for a long period of time.

secondary waves

called S-Waves are named with respect to their arrival times

Richter scale

devised by a geologist named Charles Richter is a numerical rating system that measures the energy of the largest seismic waves.

Moment Magnitude scale

is a rating scale that measures the energy released by a an earthquake taking into account the size of the fault rupture the amount of movements along the fault and the rocks stiffness.

Fault

Is any fracture or system of fractures along which earth move.

Elastic deformation

Is caused when a material is compressed, bent, or stretched.

Stress

Is the total force acting on crustal rock per unit of area.

Epicenter

Surface waves originates from the epicenter and spread out.

Seismometers

some seismometers consist of a rotating drum covered with a sheet of paper a pen or other such recording tool and a mass such as a pendulum.

primary waves

squeeze and push rocks in the direction along which waves are traveling.

Magnitude

that are produced during an earthquake.