CHAPTER 6 GEOL

at very shallow levels, such as within the volcano

At what depth do gas bubbles have the most effect on magma?

volcanic eruptions.

Changes in topography, water chemistry, and gas output all are used to help predict

large volumes of flood basalts are erupted during a short time. eruptions can release large amounts of gas that cool the atmosphere. eruptions can release large amounts of gas that warm the atmosphere. All of these choices are correct.

Flood basalts influence life on Earth because

topography

Geologists use tiltmeters, GPS, and satellite radar maps to analyze the changes in __________ of a volcano.

seismic shaking.

Magma rising through the crust fractures rocks, producing rhythmic, repeating

blocking of sunlight by volcanic ash and aerosols.

Reduced temperatures and growing seasons in Europe following the 1783 Laki eruption were primarily caused by

Minoan

The downfall of which ancient civilization in the Mediterranean closely followed the caldera-forming eruption at Santorini?

collapse of the roof of a magma chamber as magma erupts.

The main cause of caldera collapse is

composite volcano.

The most dangerous type of volcano is a

steep parts of the dome collapse and cause small pyroclastic flows.

Volcanic domes commonly are partially destroyed when

large amounts of rain and snowmelt mix with loose ash on steep slopes.

Volcanic mudflows (lahars) are common on composite volcanoes because

lava dome

What type of eruption is shown in this photograph?

felsic and intermediate lava flows pyroclastic rocks from an eruption column pyroclastic rocks from pyroclastic flows rocks with fragments formed by landslides and mudflows All of these choices are correct.

What types of rocks would be common in a composite volcano?

A pyroclastic flow forms when the gas flux cannot support the column.

Which of the following are differences between an eruption column and pyroclastic flow?

High gas pressures commonly lead to highly explosive eruptions. All these are true of felsic magmas. Correct They tend to have high viscosities. They do not allow gas bubbles to escape easily.

Which of the following are true of felsic magmas?

increased gas flow from a volcano steam eruptions from the volcanic crater increased heat flow from the volcano All of these choices are correct.

Which of the following commonly precede a volcanic eruption?

They are fed from large interconnected composite volcanoes.

Which of the following is NOT true about flood basalts?

a scoria cone that erupts hot molten fragments on an unpopulated Pacific island

Which of the following is a hazard but not a risk, according to the textbook?

a large circular depression with steep walls thick sequences of volcanic ash rounded mountains that are volcanic domes All of these choices are correct.

Which of the following is common in most calderas?

Continent-continent convergent boundary with a high mountain range (Himalayas)

Which of the following plate boundaries is least likely to produce composite volcanoes?

3

Which of the numbered features is a pyroclastic column? https://gyazo.com/883bd054e13529263a4aa61039ee0c2f

shield volcano

https://gyazo.com/2ac0f04977b82e4f1ee815f193d87aa5

composite volcano

https://gyazo.com/46a11ad37659c51c4bb286263daf1f1a

the low viscosity of basaltic magma allows it to flow downhill for long distances.

https://gyazo.com/ef40a57fc43a7a3df08fff0c5bf992d8