GEOL QUIZ 6
Which type of volcano results from high viscosity, low volatiles, and small volume? (sorry - on an earlier version of this question there was a typo) Shield volcano Caldera Lava dome Scoria (cinder) cone
Lava dome
A genuine success story of advance warning before a large eruption occurred in the Philippines in 1991 before the climactic eruption of ________. Mont Pelée Popocatepetyl Mt. Pinatubo Mt. Mayon Nevado Del Ruiz
Mt. Pinatubo
Which type of volcanic rock below has the highest silica (SiO2) content? Basalt Andesite Rhyolite
Rhyolite
The fossils seen at Ashfall, Nebraska, perished as result of an eruption of Yellowstone some 1500km (931mi) away. True False
True
When magma crystallizes slowly, _____ are formed. volatiles extrusive (volcanic) igneous rocks intrusive (plutonic) igneous rocks pyroclastic debris
intrusive (plutonic) igneous rocks
What is a stratovolcano? All of these answers are correct The name of volcanoes in Italy Volcanoes with mild eruptions A steep-sided volcano composed of alternating layers of lava and pyroclastics
A steep-sided volcano composed of alternating layers of lava and pyroclastics
Which of the following plate boundaries hosts lots of volcanoes that erupt mainly basalt? Divergent boundary Subduction zone Collision zone Strike-slip boundary
Divergent boundary
Magma at oceanic spreading centers is low-temperature, high-viscosity, and granitic, with easy escape of gases, providing all the factors that promote the peaceful eruption of magma. True False
False
The primary reason magma forms at subduction zones is that the subducting plate carries a cover of sediments, water, and hydrated minerals down with it, which lowers the temperature required for the adjacent overlying mantle lithospheric rock to melt. True False
True
Mt. St. Helens killed a geologist studying the volcano because ____________. the eruption produced a greater volume of ash than anyone predicted the geologist disregarded orders to keep a safe distance from the vent a landslide produced a lateral blast of volcaniclastic debris that no one anticipated lahars swept down all sides of the volcano and buried all towns within 100 km
a landslide produced a lateral blast of volcaniclastic debris that no one anticipated
Slow flowing, more viscous basaltic lava commonly has a rough, blocky texture called ________. aa cc pahoehoe bb poi
aa
Several geologic phenomena are being studied as signs of an impending volcanic eruption. These include seismic waves, ________, and the release of gases. flash floods crystallization rates landslides unusual animal behavior ground deformation
ground deformation
Active volcanoes today in Oregon and Washington, including Mt. St. Helens, result from ________. spreading of the Juan de Fuca Ridge continent-continent collision heat generated by friction on the San Andreas Fault the subduction of the Juan de Fuca Plate beneath North America
the subduction of the Juan de Fuca Plate
A shield volcano has a greater ________. width compared to its height proportion of pyroclastic material, compared with lava flows height compared to its width amount of pumice
width compared to its height
