Chapter 14 - GEO 200

The Alaskan earthquake of 1964 was extraordinarily violent and has been assigned a moment magnitude of ________. 2.3 47.5 21.6 5.7 9.2

9.2

Crater Lake, Oregon, is an example of a volcanic ________. caldera neck batholith peak lava flow

Caldera

What are the four basic types of volcanoes and their characteristics?

Composite cone - consist of a mix of lava flows and pyroclastic materials Shield volcano - composed of lavas and relatively little ash or cinders and gentle slopes Plug domes - extrude extremely stiff acidic lava that fills the initial pyroclasitc cone and steep sided Cinder cones - smallest type, produces litle lava and consists largely of pyroclastics

A fault is any break in the Earth's surface or crust. True False

False

Prior to Mt. St. Helens in 1980 there had never been an active volcano in the United States. True False

False

What is the difference between "folding" and "faulting?"

Folding is the wrinkling of the earth's surface from slow lateral compression - faulting is the rupture or breaking of the earth's surface from faster process.

A crustal block which is downthrown with a steep fault scarp on either side is a ________. horst fault block mountain graben rift valley syncline

Graben

Similar in nature to a batholith but much smaller in size is a ________. vein sill stock dike all of the above

Stock

________ is an area of extensive flood basalts.

The Deccan Plateau The Columbia Plateau

A foreshock sometimes comes before a major earthquake. True False

True

A simple symmetrical upfold in topography is an anticline. True False

True

Deep fault zones apparently serve as conduits allowing water and heat to approach the surface. True False

True

In the Cascade Range, there are many peaks larger or taller than Mount Saint Helens which exploded. True False

True

The Earth's crust is rigid as compared to the mantle directly underneath. True False

True

The largest recorded earthquake had a moment magnitude of 9.5 and occurred in Chile. True False

True

The southern portion of the "super continent" envisioned by Wegener is called Gondwanaland. True False

True

On the Modified Mercalli scale, the largest earthquakes would be assigned a value of ________. 10 3 1 8.5 XII

XII

In earthquakes, P waves________. arrive more slowly than surface waves are absent are also known as surface waves are faster than S waves travel towards the focus

are faster than S waves

Presently, the North American and Eurasian plates are moving ________. toward each other toward the Equator nowhere away from each other toward the North Pole

away from each other

The ________ is an igneous intrusion which has a surface area of at least 100 square kilometers. vein butte stock laccolith batholith

batholith

The most massive form of igneous intrusion is a ________. batholith sill none of the above stock laccolith

batholith

Radial walls extending outward from a volcano are ________. veins dikes plugs clay pans sills

dikes

A(n) ________ is an abrupt movement of the Earth's crust usually associated with a fault zone.

earthquake

ava flows often create ________. volcanoes batholiths volcanic necks flattish plains dikes

flattish plains

Grabens are commonly found in association with ________. batholiths concretions horsts sag ponds anticlines

horsts

A volcanic mudflow is known as a(n) ________.

lahar

Currently, the rate of sea-floor spreading in the Atlantic is thought to be: 0 centimeters per year (stopped). 100 meters per year. 10 meters per year. less than 1 centimeter per year. 1 kilometer per year.

less than 1 centimeter per year.

Mt. St. Helen's is ________. the largest volcano in the world dead the world's best example of intrusive vulcanism scheduled to erupt in the year 2050 likely to vigorously erupt again

likely to vigorously erupt again

A ________ is a one-sided fold connecting horizontal or gently inclined strate. overthrust symmetrical fold monocline anticline syncline

monocline

Volcanic activity that takes place deep under the crust is termed ________. pyroclastic plutonic intrusive subduction metamorphic

plutonic

The totality of materials ejected from a volcano, including liquid material, ashes and dust is termed ________. granite magma pyroclastic material lava silica

pyroclastic material

A lengthy complex of grabens forms a ________ valley.

rift

Water collected in small bodies along a recently active fault line forms ________. sills sag ponds dikes reservoirs playas

sag ponds

Instead of the vertical displacement of other faults, a ________ fault has horizontal displacement between the two sides

strike-slip

Relatively cooler magma in an erupting volcano is apparently the result of ________. depth of magma formation the amount of water present the relatively high amount of silica present position of astronomical bodies surface salinity

the relatively high amount of silica present

A ________ plate boundary is associated with lateral slippage, conservation of existing crust, and the San Andreas fault system? fault scarp transform divergent subducting convergent

transform

The Andesite Line refers to the numerous volcanoes which dot the rim of the Pacific Ocean. True False

true