Earthquakes Flashcards
ring of fire
The Ring of Fire is a region around much of the rim of the Pacific Ocean where many volcanic eruptions and earthquakes occur. The Ring of Fire is a horseshoe-shaped belt about 40,000 km long and up to about 500 km wide
strike-slip fault
a fault in which rock strata are displaced mainly in a horizontal direction, parallel to the line of the fault.
normal fault
Normal, or Dip-slip, faults are inclined fractures where the blocks have mostly shifted vertically. If the rock mass above an inclined fault moves down, the fault is termed normal, whereas if the rock above the fault moves up, the fault is termed a Reverse fault.
reverse fault
In a reverse fault, the block above the fault moves up relative to the block below the fault. This fault motion is caused by compressional forces and results in shortening. … Other names: thrust fault, reverse-slip fault or compressional fault. Examples: Rocky Mountains, Himalayas.
P-waves
A P wave, or compressional wave, is a seismic body wave that shakes the ground back and forth in the same direction and the opposite direction as the direction the wave is moving.
S-waves
Secondary waves, or S-waves, are seismic waves produced by an earthquake. … S-waves are lateral waves that move side to side as a sine wave perpendicular to the direction of the wave. They are the second seismic wave to be felt or recorded during an earthquake, after the conveniently named primary wave.
epicenter
the point on the earth’s surface vertically above the focus of an earthquake.
focus
the point of origin of an earthquake.
Richter magnitude scale
The Richter magnitude scale, also known as the local magnitude (M) scale, assigns a number to quantify the amount of seismic energy released by an earthquake. It is a base-10 logarithmic scale. Micro earthquakes, not felt. Generally not felt, but recorded.
explosive volcano
In volcanology, an explosive eruption is a volcanic eruption of the most violent type. … Such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such that expelled lava violently froths into volcanic ash when pressure is suddenly lowered at the vent.
nonexplosive volcano
Nonexplosive eruptions are the most common type of volcanic eruptions. These eruptions produce relatively calm flows of lava in huge amounts. B. Vast areas of the Earth’s surface, including much of the sea floor and the Northwestern United States, are covered with lava form nonexplosive eruptions.
Krakatoa
a volcanic island in Indonesia, in the Sunda Strait between Java and Sumatra: partially destroyed by its eruption in 1883, the greatest in recorded history.
