The more fluid a magma, the more likely it is to erupt. On the other hand, when more viscous (higher viscosity) lavas do erupt, they usually do so explosively. Viscosity also affects the shapes of lava flows and the mountains they erupt from. The more viscous the magma, the fatter the lava flow. Also, the more viscous the magmas a volcano erupts, the steeper the volcano. Thus, shield volcanoes like we have in Hawai'i have gentle slopes (less than 10 degrees), while stratovolcanoes like the Cascades in the northwestern mainland are much steeper (roughly 25 degrees).
http://www.spacegrant.hawaii.edu/class_acts/ViscosityTe.html
To determine how fluid a liquid really is by measuring its viscosity. Viscosity is an internal property of a fluid that offers resistance to flow. For example, pushing a spoon with a small force moves it easily through a bowl of water, but the same force moves mashed potatoes very slowly.
http://www.spacegrant.hawaii.edu/class_acts/ViscosityTe.html
• caused by high gas content. Composite Volcano or Stratovolcano Mount Mageik, Katmai National Park Layered with lava Flows and ashfall Deposits – massive explosions FEATURES OF STRATOVOLCANOES (composite volcanoes) • Alternating andesitic lava flows and layers of explosively ejected pyroclastics.
http://www.soest.hawaii.edu/coasts/lecture/gg101/powerpoints/Volcanoes.pdf
^A volcano is any landform from which lava, gas, or ashes, escape from underground or have done so in the past. What is causing this eruption? What factors influence its character? We learned from Chapter 5 that magma (and lava) can be felsic, intermediate, or mafic.
http://www.soest.hawaii.edu/coasts/lecture/gg101/powerpoints/Volcanoes.pdf
The low viscosity is due to low silica content. Aa-rough, fragmented lava blocks called clinker_ Pahoehoe-smooth, shiny, and ropy surface BASALTIC ANDESITIC Andesitic magma erupts explosively because RHYOLITIC Mount St. Helens, 1980 it tends to have high gas content.
http://www.soest.hawaii.edu/coasts/lecture/gg101/powerpoints/Volcanoes.pdf
Lava flow during a rift eruption at Krafla, Iceland in 1984. Lava is the molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. The source of the heat that melts the rock within the earth is geothermal energy.
https://en.wikipedia.org/wiki/Lava
It is viscous and therefore traps gas, builds pressure and explosively erupts. High viscosity is related to high silica content There are three common types of magma: BASALTIC ANDESITIC RHYOLITIC Rhyolitic magma erupts catastrophically because Rhyolitic lava flow it has high gas content. It is viscous and therefore traps gas, builds pressure and explosively erupts.
http://www.soest.hawaii.edu/coasts/lecture/gg101/powerpoints/Volcanoes.pdf
When it has stopped moving, lava solidifies to form igneous rock. The term lava flow is commonly shortened to lava. Explosive eruptions produce a mixture of volcanic ash and other fragments called tephra, rather than lava flows.
https://en.wikipedia.org/wiki/Lava
The faster the sphere falls, the lower the viscosity. This makes sense: if the fluid has a high viscosity it strongly resists flow, so the sphere falls slowly. If the fluid has a low viscosity, it offers less resistance to flow, so the ball falls faster.
http://www.spacegrant.hawaii.edu/class_acts/ViscosityTe.html
Basaltic columnar-jointed lava (Iceland). Brief explanation: Basalt is the usually hard and black volcanic rock formed from (liquid) balsalitc lava. Balsaltic lava contains less than about 52 percent silica (SiO2) by weight. Because of its low silica content, it has a low viscosity (resistance to flow). Therefore, basaltic lava can quickly and easily flow more than 20 km from a vent. The low viscosity typically allows volcanic gases to escape without generating enormous eruption columns, although basaltic lava fountains and fissure eruptions, however, still can be hundreds of meters tall.
http://www.decadevolcano.net/photos/keywords/basalt.htm
what volcano has low viscosity lava flows
Basaltic volcano has low viscosity lava flows.