Chapter 2: Earthquakes

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S waves

seismic waves that vibrate from side to side as well as up and down. This one is very destructive

3 steps to protect urself from eq's

DROP,COVER,HOLD

Geologists can determine eq risk by locating where ___ are active and where ___ eq's have occured

Faults, Past

Seismic waves carry energy from an earthquake away from the ____, through the Earth's ___, and across the surface

Focus, interior

Reverse Fault

Same structure as a normal fault but moves in opposite direction. Compression causes this to form

Over millions of years, the force of plate movement can change a flat plain into landforms such as anticlines,____, folded mtns,___-____, and plateaus

Synclines, Fault-block mtns

GPS satellites

Used to locate great points on Earth's surface with precision

Laser-Ranging Devices

Uses a laser beam to detect horizontal fault movments

Creep Meters

Uses a wire stretched across a fault to measure horizontal movement of the ground

Syncline

A fold in a rock that bends down to form a valley

Anticline

A fold in rock that bends upward into an arch

Stress

A force that acts on rock to change its shape or volume

Plateau

A large area of flat land elevated high above sea level. Some form when forces in Earth's crust push up large, flat block of rock

Magnitude

A number that geologists assign to an earthquake based on eq's size

Richter Scale

A rating of an eq's magnitude based on the size of the eq's seismic waves

Moment Magnitude Scale

A rating system that estimates the total energy released by an eq.

Aftershock

An eq that occurs after a larger eq in the same area

Seismograph

An instrument that records and measures seismic waves

Base isolate building

Designed to reduce the amount of energy that reaches the building during an eq and rests on springs or shocking absorbing rubber pads

Mercalli Scale

Developed to rate eq's according to their level of damage at a given place

Tiltmeters

Measures tilting or raising of the ground

Surface waves

Move more slowly than P and S waves, but produce severe ground movements

Most faults occur along plate boundaries, where the forces of plate motion push or pull the crust so much. There are three main types of faults:_____,______,______

Normal, Strike-Slip, and Reverse Faults

Liquefaction

Occurs when an eq's violent shaking suddenly turns loose, soft soil into liquid mud, create cracks

Tension

Pulls on crust, stretching rock so it becomes thinner in the middle

Geologists use ___ ___ to locate an eq's epicenter

Seismic waves

P waves

Seismic waves that compress and expand the ground like an accordion, a lot faster

Fact:

Seismographs and fault-monitoring devices provide data used to map faults and detect changes along faults.

Causes of eq damage???

Shaking, Liquefaction, Aftershocks, and Tsunamis

Compression

Squeezes rock until it folds or breaks

Shearing

Stress that pushes a mass of rock in two opposite directions

Normal Faults

Tension in Earth's crust pulls rock apart, causing this. There is a top block and a bottom block

_____,shearing, and compression work over millions of years ago to change the shape and ___ of rock.

Tension, volume

Focus

The area beneath Earth's surface where rock that is under stress breaks, triggering an earthquake

Hanging wall

The block of rock that lies above

Footwall

The block of rock that lies below

Friction

The force that opposes the motion of one surface as it moves across another surface

Seismogram

The pattern of lines/the record of an eq's seismic waves produced by a seismograph

Epicenter

The point on the surface directly above the focus

Strike-slip Fault

The rocks on either side slip past each other sideways, with little up or down motion. Shearing creates this fault

Earthquake

The shaking and trembling that results from the rock movment of rock beneath Earth's surface

Tsunami

The water displaced by the eq may form a large wave

Geologists have developed instruments to measure changes in elevation, ____ of the land surface, and ground _____ along faults

Tilting, movements


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