table of contents forces in earth’s crust earthquakes and seismic waves monitoring earthquakes...
TRANSCRIPT
Table of Contents
Forces in Earth’s Crust
Earthquakes and Seismic Waves
Monitoring Earthquakes
Earthquakes
Stress in Earth’s CrustStress can push, pull, or squeeze rock in Earth’s crust. Three kinds of stress can occur in the crust.
Forces in Earth’s Crust
Forces in Earth’s Crust
FaultsThe three main types of faults are defined by the direction in which rock moves along the fault.
Forces in Earth’s Crust
The low angle of a thrust fault allows rock in the hanging wall to be pushed great distances. For example, over millions of years, rock along the Lewis thrust fault in Glacier National Park has moved 80 kilometers.
Forces in Earth’s Crust
Anticlines and SynclinesCompression can cause folds in the crust. Two types of folding are anticlines, which arch up, and synclines, which dip down.
Forces in Earth’s Crust
Tension and Normal FaultsWhat are the hanging wall and the two footwalls in diagram A? What is the new position of the hanging wall after movement occurs in diagram B?
Forces in Earth’s Crust
Tension and Normal FaultsAs tension forces pull the crust apart, two normal faults can form a fault-block mountain range.
Forces in Earth’s Crust
The Kaibab PlateauLook at the sequence of drawings. In your own words, describe what happens in the last two diagrams.
Earthquakes and Seismic Waves
Earthquakes start below the surface of the Earth. An earthquake's seismic waves carry energy up toward the surface and down through the interior.
Earthquakes and Seismic Waves
Seismic WavesThe diagram shows how seismic waves traveled during an earthquake along the Denali fault.
Earthquakes and Seismic Waves
P, S, and Surface WavesEarthquakes release stored energy as seismic waves.
Earthquakes and Seismic Waves
Modified Mercalli ScaleThe Modified Mercalli scale uses Roman numerals to rate the damage and shaking at any given location, usually close to the earthquake.
Earthquakes and Seismic Waves
Earthquake MagnitudeThe table gives the moment magnitudes of some recent earthquakes.
Earthquakes and Seismic Waves
Seismic Wave SpeedsSeismographs at five observation stations recorded the arrival times of the P and S waves produced by an earthquake. These data were used to draw the graph.
Earthquakes and Seismic Waves
An Earthquake’s EpicenterThe map shows how to find the epicenter of an earthquake using data from three seismographic stations.
Seismic Data From the USArray ProjectIn 2004, scientists in the USArray project placed 400 seismographs across the western United States. Every month, 18 seismographs are picked up and moved east, “leapfrogging” the other seismographs.
Monitoring Earthquakes
Monitoring Earthquakes
Recording Seismic WavesIn a simple seismograph, a pen attached to a suspended weight records an earthquake’s seismic waves.
Monitoring Earthquakes
SeismogramsWhen an earthquake’s seismic waves reach a simple seismograph, the seismograph’s drum vibrates. The vibrations are recorded by the seismograph’s pen, producing a seismogram.
Monitoring Earthquakes
Earthquake RiskThe map shows areas where serious earthquakes are likely to occur, based on the location of past earthquakes across the United States.
Monitoring Earthquakes
Earthquakes Around the WorldEarthquakes are closely linked to plate tectonics. The map shows where past earthquakes have occurred in relation to plate boundaries.