chapter 8-2, 3 Flashcards
(17 cards)
what are seismic waves?
vibrations that race out from focus in all directions
describe the two types of waves
body waves - carry energy away from the focus through earth’s interior to surface
surface waves - travel at the surface
describe P waves (primary waves)
particles in rock move back and forth in the same direction the wave is moving. Particles compress and stretch apart. Travels through solid, liquids, and gas
describe S waves (secondary waves)
particles in rocks move at right angles to the direction of the wave. Travels only through solid.
describe surface waves
they travel outward from the epicenter on the surface of the earth. Elliptical motion, most destruction
what is a seismograph and a seismogram?
seismograph - an instrument that measures seismic waves
seismogram - paper record of seismic waves
what is intensity and magnitude?
intensity is the measure of amount shaking and magnitude is the measure of size of seismic wave
describe the 3 types of scales
the richter scale: familiar but outdated or measuring magnitude, based on height
The moment magnitude scale: using factors and seismographic data, most widely used
Modified mercalli scale: used to rate earthquake intensity in terms of earthquake effects at different locations, shows areas affected by different levels of shaking
what is seismic shaking?
ground vibrations by seismic waves, can jolt/twist structures
what is liquefaction?
when wet soil that is solid most of the time acts more like a liquid when shaken
what is a landslide?
earthquakes cause loose rock and soil on slopes to move
what is a mudflow?
areas where water content of soil is high, earthquake starts
what is a tsunami?
seismic sea waves; when an earthquake occurs under the ocean, causes abrupt movements of the ocean floor, powerful waves travel to surface
what are the two types of evidence about earth’s interior?
Direct evidence from rock samples
Indirect evidence from seismic waves
describe the crust!
solid thin outer layer
Oceanic crust: crust beneath the ocean, dark rock fine texture
Continental crust: light colored with coarse texture
describe the core!
layer beneath the mantle, extends to center of earth, heavier so gravity pulls to center
As you descend, the earth gets WARMER and pressure INCREASES
describe the order of the layers of the earth
Crust → lithosphere → asthenosphere (upper mantle)→ lower mantle → outer core → inner core
