Admin What type of volcano consists of layers of lava flows and pyroclastic material?
Stratovolcanoes
Composite or Stratovolcanoes (Fig. 5.14) erupt both lava and pyroclastic deposits. The slopes of stratovolcanoes are therefore composed of lava flows alternating with layers of pyroclastic deposits. Stratovolcanoes have steeper slopes than shield volcanoes and are common along convergent plate boundaries (Fig.
Which of the following below shows the correct order from left to right of increasing magma viscosity?
geo quiz 6
| Question | Answer |
|---|---|
| What volcanic events formed Crater Lake, Oregon? When did they take place? | Caldera collapse followed major ash and pyroclastic-flow eruptions 6000 years ago. |
| Which one of the following shows the correct order (left to right) of decreasing magma viscosity? | rhyolite, andesite, basalt |
Which of the following volcanoes is formed from cinders and ash?
Cinder cones
Cinder cones are the simplest volcanic formation. They form from explosions of red, hot magma cinders and ash. These cinders and ash settle around the main vent and build a steep sided cone. Very little lava is erupted from a cinder cone.
Which volcanic hazard is a hot mixture of ash pumice and gas traveling down the flanks of a volcano?
If you witness a pyroclastic flow, run in the opposite direction as quickly as possible. Pyroclastic flows contain a high-density mix of hot lava blocks, pumice, ash and volcanic gas. They move at very high speed down volcanic slopes, typically following valleys.
What is the relationship between silica and the viscosity of the magma?
Viscosity is the resistance to flow (opposite of fluidity). Viscosity depends on primarily on the composition of the magma, and temperature. Higher SiO2 (silica) content magmas have higher viscosity than lower SiO2 content magmas (viscosity increases with increasing SiO2 concentration in the magma).