CSS - PMS - CCE - PCS - Geography
Volcanoes
A phreatomagmatic eruption involves interaction between:
A. Magma and external water
B. Two rivers
C. Wind and sand
D. Ice and limestone only
Correct Answer: A
Direct magma-water interaction can cause highly explosive fragmentation.
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Volcanoes
A phreatic eruption is driven mainly by:
A. Steam expansion from heated water
B. Fresh magma necessarily reaching surface
C. Glacial erosion
D. River flooding
Correct Answer: A
Groundwater flashed to steam can explosively fragment rock without new magma eruption.
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Volcanoes
Lahars often follow:
A. River valleys and low-lying channels
B. Mountain ridges only
C. Air currents only
D. Plate boundaries only
Correct Answer: A
Mudflows are gravity-driven and channelized by drainage networks.
CSS - PMS - CCE - PCS - Geography
Volcanoes
Pyroclastic flows are particularly dangerous because they are:
A. Hot, fast and dense
B. Always slow and cold
C. Only underwater
D. Harmless ash clouds
Correct Answer: A
Their speed, temperature and concentrated debris make escape difficult.
CSS - PMS - CCE - PCS - Geography
Volcanoes
A volcanic hazard map is used to:
A. Identify areas potentially affected by hazards
B. Predict exact eruption time
C. Stop lava chemically
D. Measure mineral hardness
Correct Answer: A
Hazard zonation supports land-use planning and emergency preparedness.
CSS - PMS - CCE - PCS - Geography
Volcanoes
Ground deformation near a volcano can be measured by:
A. GPS and InSAR
B. Only thermometers
C. Only barometers
D. Only rain gauges
Correct Answer: A
Satellite radar and geodetic GPS can detect inflation/deflation.
CSS - PMS - CCE - PCS - Geography
Volcanoes
Volcanic monitoring commonly includes:
A. Seismicity, ground deformation and gas emissions
B. Only rainfall
C. Only population census
D. Only magnetic compass readings
Correct Answer: A
Changes in earthquakes, swelling and gas chemistry can signal magma movement.
CSS - PMS - CCE - PCS - Geography
Volcanoes
Geothermal energy is especially associated with:
A. Regions of high crustal heat flow and volcanism
B. Only stable deserts
C. Only polar ice sheets
D. No tectonic activity
Correct Answer: A
Hot rocks and fluids in volcanic/tectonic regions provide geothermal resources.
CSS - PMS - CCE - PCS - Geography
Volcanoes
Volcanic soils can be fertile because volcanic material:
A. Weathers to release mineral nutrients
B. Contains no minerals
C. Prevents all plant growth permanently
D. Is always pure quartz
Correct Answer: A
Fresh volcanic deposits can weather into nutrient-rich soils.
CSS - PMS - CCE - PCS - Geography
Volcanoes
Large explosive eruptions can cool climate temporarily by injecting:
A. Sulfur aerosols into the stratosphere
B. Oxygen into rivers
C. Sand into the core
D. Salt into groundwater only
Correct Answer: A
Sulfate aerosols reflect sunlight and can cause short-lived global cooling.
CSS - PMS - CCE - PCS - Geography
Volcanoes
A volcanic plug or neck is:
A. Solidified magma in a volcanic conduit exposed by erosion
B. A river meander
C. A mineral cleavage
D. A seismic station
Correct Answer: A
Erosion can remove the cone and leave resistant conduit fill.
CSS - PMS - CCE - PCS - Geography
Volcanoes
A lava dome commonly forms from:
A. Viscous lava piling near a vent
B. Very fluid basalt spreading hundreds of km only
C. River sediment
D. Glacial till
Correct Answer: A
Silica-rich viscous lava may extrude slowly and accumulate as a dome.
CSS - PMS - CCE - PCS - Geography
Volcanoes
Hawaiian eruptions are typically:
A. Effusive basaltic eruptions
B. Highly explosive rhyolitic eruptions only
C. Non-volcanic
D. Glacial
Correct Answer: A
Low-viscosity basalt favors lava fountains and flows.
CSS - PMS - CCE - PCS - Geography
Volcanoes
Strombolian eruptions typically involve:
A. Intermittent bursts of lava and scoria
B. Only giant caldera collapse
C. No explosions
D. Only mudflows
Correct Answer: A
Gas slugs produce discrete moderate explosions.
CSS - PMS - CCE - PCS - Geography
Volcanoes
Plinian eruptions are known for:
A. Sustained high eruption columns and explosive ash release
B. Only quiet lava lakes
C. No gas
D. Only underwater pillows
Correct Answer: A
Plinian activity can inject ash and gas high into the atmosphere.
CSS - PMS - CCE - PCS - Geography
Volcanoes
The VEI scale primarily describes:
A. Explosiveness of eruptions
B. Mineral hardness
C. Earthquake intensity
D. River discharge
Correct Answer: A
VEI compares explosive eruption magnitude/intensity.
CSS - PMS - CCE - PCS - Geography
Volcanoes
VEI stands for:
A. Volcanic Explosivity Index
B. Vertical Erosion Indicator
C. Volcanic Energy Instrument
D. Variable Elevation Index
Correct Answer: A
VEI is a logarithmic-style scale based largely on erupted volume, plume height and qualitative observations.
CSS - PMS - CCE - PCS - Geography
Volcanoes
An extinct volcano is generally considered:
A. Unlikely to erupt again
B. Certain to erupt tomorrow
C. Currently erupting
D. A mid-ocean ridge
Correct Answer: A
Extinct classification implies its magma supply/system is no longer expected to reactivate.
CSS - PMS - CCE - PCS - Geography
Volcanoes
A dormant volcano is one that:
A. Is not currently erupting but may erupt again
B. Can never erupt again by definition
C. Is erupting continuously
D. Has no magma system ever
Correct Answer: A
Dormant denotes present inactivity with potential future activity.
CSS - PMS - CCE - PCS - Geography
Volcanoes
Fractional crystallization can:
A. Change magma composition as minerals crystallize and separate
B. Stop all cooling
C. Turn sediment directly into magma at surface
D. Eliminate crystals
Correct Answer: A
Removal of early crystals drives residual melt toward different compositions.