Earthquake/Volcano Flashcards
fault
a break in a body of rock along which one block slides relative to another
ring of fire
an area where a large number of earthquakes and volcanic eruptions occur in the basin of the Pacific Ocean.
transform / strike-slip
Plate Boundaries are locations where two plates slide past one another
divergent / normal
is a linear feature that exists between two tectonic plates that are moving away from each other.
convergent / reverse
is a region of active deformation where two or more tectonic plates or fragments of the lithosphere are near the end of their life cycle.
P-waves
is one of the two main types of elastic body waves, called seismic waves in seismology, the first signal from an earthquake to arrive at a seismograph. It may be transmitted through gases, liquids, or solids.
S-waves
Traveling through the interior of the earth, body waves arrive before the surface waves emitted by an earthquake. These waves are of a higher frequency than surface waves.
epicenter
is the point on the earth’s surface vertically above the hypocenter (or focus), point in the crust where a seismic rupture begins.
focus
he location where the earthquake begins. The ground ruptures at this spot, then seismic waves radiate outward in all directions.
Richter scale
Because it is logarithmic, an earthquake rated as 5 is ten times as powerful as one rated as 4. An earthquake with a magnitude of 1 is detectable only by seismographs; one with a magnitude of 7 is a major earthquake. The Richter scale is named after the American seismologist Charles Francis Richter
explosive volcano
The most common type of volcanic eruption occurs when magma (the term for lava when it is below the Earth’s surface) is released from a volcanic vent. … In explosive eruptions, the fragmented rock may be accompanied by ash and gases; in effusive eruptions, degassing is common but ash is usually not.
nonexplosive volcano
Because the composition of magma is different in different volcanoes, the properties of the lava are different. In effusive eruptions, lava flows are relatively calm and do not explode out of the volcano.
Krakatoa
Tsunami deposits from major explosive eruptions; an example from the 1883 eruption of Krakatoa.” Geological Society of America
Yellowstone supervolcano
The last full-scale eruption of the Yellowstone Supervolcano, the Lava Creek eruption which happened approximately 640,000 years ago, ejected approximately 240 cubic miles
San Andreas fault
is a continental transform fault that extends roughly 1,200 kilometers through California. It forms the tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip
Mid-oceanic ridge
is an underwater mountain range, formed by plate tectonics. This uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary.
shield volcano
is a type of volcano usually built almost entirely of fluid lava flows. They are named for their low profile, resembling a warrior’s shield lying on the ground. This is caused by the highly fluid (low viscosity) lava they erupt which travels farther than lava erupted from stratovolcanoes.
cinder cone volcano
are the simplest type of volcano. They are built from particles and blobs of congealed lava ejected from a single vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as cinders around the vent to form a circular or oval cone.
composite volcano
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava, tephra, pumice, and volcanic ash.
