Chapter 16 Flashcards
What is an Earthquake?
A trembling or shaking of the ground caused by the sudden release of energy stored in the rocks beneath the earth’s surface.
WHat is a focus when it comes to an earth quake?
The point within the earth where seismic waves first originate.
What is an epicenter?
The point on earth’s surface directly above the focus of an earthquake.
What are body waves?
Seismic waves that travel through earths interior.
What is a p Wave?
A compressional wave in which rock vibrates parallel to the direction of wave propagation. Think of the slinky analogy.
What is an s Wave or a secondary wave?
A seismic wave propagated by a shearing motion, which causes rock to vibrate perpendicular to the direction of wave propagation. THink of the rope analogy not the slinky.
What are Love Waves?
they are an as wave but they move side to side rather than up and down.
What is a Rayleigh Wave?
A type of surface seismic wave that behaves like a rolling ocean wave adn causes the ground to move in an elliptical path.
What is a seismometer?
An instrument used to measure seismic waves.
What is a travel-time curve.
A plot of seismic wave arrival times against distance.
What is an earthquakes intensity?
A measure of an earthquakes size by its effect on people and buildings.
What is the modified Mercalli scale?
Scale expressing intensities of earthquakes in roman numbers ranging from I to XII
What is the Richter Scale?
A numerical scale of earthquake magnitudes.
What is a seismograph?
The recording device for a seismometer.
WHat is a seismogram?
The paper record of earth vibrations.
What is the Moment Magnitude?
An earthquake magnitude calculated from the strength of the rock, surface area of the fault rupture, and the amount of rock displacement along the fault.
What is liquifaction?
When water saturated soil or sediment turns from a solid to a liquid as a result of earthquake shaking.
What is a Foreshock?
Small quakes that precede a main shock.
What is a Tsunami?
Huge ocean wave produced by displacement of sea floor; also called seismic sea wave.
What is a Benioff Zone?
Distinct earthquake zone that begins at an oceanic trench and slopes landward and downward into earth at an angle of about 30 to 60 degrees.
What types of earthquakes occur at divergent plate boundaries?
Shallow and low magnitude.
were are transform faults found?
On the ocean floor.
What is a precursor
A slight change in the rock next to a fault before the rock breaks or moves due to an earthquake.
What are microseisms?
Small tremors caused by small cracks opening within rock. Usually these are precursors to earthquakes.
What is Paleoseismology?
digging a trench across the fault zone to examine sedimentary layers that have been offset and discovering the recurrence period of that fault.
What are seismic gaps?
A gap where earthquakes have not accrued for a long time.
