What is the primary reason that rhyolitic magma tends to be more explosive than basaltic magma?

Higher gas content and viscosity

Volcano, types of magma, silica content of magma, factors that determine eruptions, yellowstone volcano, kilauea, Mt. Vesuvius, Mt. St. Helens

Volcanic Eruptions Earthquakes are sometimes used in predicting volcanic eruptions. An earthquake alerts the authorities to observe a nearby volcano. When a volcano shows signs of eruption, evacuation of the nearby villages should be immediately implemented Active volcanoes are the ones that are usually closely monitored by volcanologists These are commonly located along plate boundaries specifically along the Pacific Ring of Fire. The Philippines is one of the countries that have a lot of volcanoes. The Pacific Ring of Fire is a region in the Pacific where most active volcanoes are located. The dots in the figure represent the active volcanoes in the world. Active volcanoes are those that have a recorded volcanic eruption in their history. There are two types of volcanic eruptions depending on the magma composition: the explosive type and the Hawaiian or nonexplosive type. The types of eruptions depend on the viscosity and amount of dissolved gases in a magma. Explosive eruptions have magma that is highly viscous and contains large amounts of dissolved gases. On the other hand, the Hawaiian type or nonexplosive eruptions have magma that has low viscosity and low amount of dissolved gases. Viscosity determines the ability of magma to flow. The lower the viscosity, the easier it is for the magma to flow. This viscosity of the magma is affected by silica content and temperature. Low-temperature magma with high silica content are highly viscous, high-temperature magma with low silica content has low viscosity. Therefore, in explosive eruptions, the magma could not easily get out of the vent. This impedes the remaining magma below, causing an increase of pressure. Once the pressure is released. an explosive eruption occurs. Volcanic Hazards Explosive volcanic eruptions release pyroclastic flows and materials that are considered to pose the greatest threat. The pyroclastic flows often render people in a shock state since they become overwhelmed with what they are seeing Too much pyroclastic material (eg., tephra), may bury people and severely damage the agricultural land and livestock. Damaged agricultural land could lead to famine. After an eruption, pyroclastic materials that have settled along the slope of the volcano get mixed with rainwater. This would start a mudflow or lahar moving at high speed, destroying everything along its path. Poisonous gases are also released by volcanoes. These gases can be lethal to people, animals, and plants. Just like earthquakes, violent volcanic eruptions may also happen underwater, which can trigger a tsunami.

3. Volcanoes are often found at meeting points of “tectonic plates”. These plates are pieces of the Earth’s surface that fit together just like a jigsaw puzzle. 4. Volcanoes can also occur over “mantle plumes”. Ever heard of mantle plumes? They’re super-hot areas of rock inside the Earth! Did you know that we have a FREE downloadable Volcanoes of Ecuador primary resource? Great for teachers, homeschoolers and parents alike! 5. Approximately 350 million people live within “danger range” of an active volcano. That means that around one in 20 people live in an area at risk of volcanic activity. Volcano facts 6. Volcanoes are classified as active, dormant or extinct. This refers to the amount of volcanic activity. “Active” means there’s regular activity, “dormant” means there’s been recent activity but the volcano is currently quiet, and “extinct” means it’s been so long since the last eruption that it’s unlikely to ever erupt again. 7. Volcanoes can be a variety of shapes. These geographical wonders come in various shapes and sizes, but there are two main types – composite volcanoes, which are cone-shaped with steep slopes, and shield volcanoes, which are wide with gentle slopes. 8. Magma and lava are two different things! Magma is the name given to hot liquid rock inside a volcano. Once it leaves the volcano, it’s known as lava. Psst! Make sure you download our awesome volcano facts infographic – show your friends, family, or stick it on your wall!

Subducting seafloor would lower the melting temperature of the mantle, generating magma that rises to the surface. What happens after magma is formed? Magma cools and crystallizes to form igneous rock. Igneous rock undergoes weathering (or breakdown) to form sediment.... As the sedimentary rock is buried under more and more sediment, the heat and pressure of burial cause metamorphism to occur. This transforms the sedimentary rock into a metamorphic rock. How Do Volcanoes Erupt? Deep within the Earth it is so hot that some rocks slowly melt and become a thick flowing substance called magma. Since it is lighter than the solid rock around it, magma rises and collects in magma chambers. Eventually, some of the magma pushes through vents and fissures to the Earth's surface. Magma that has erupted is called lava. Some volcanic eruptions are explosive and others are not. The explosivity of an eruption depends on the composition of the magma. If magma is thin and runny, gases can escape easily from it. When this type of magma erupts, it flows out of the volcano. A good example is the eruptions at Hawaii's volcanoes. Lava flows rarely kill people because they move slowly enough for people to get out of their way. If magma is thick and sticky, gases cannot escape easily. Pressure builds up until the gases escape violently

And explode. A good example is the eruption of Washington's Mount St. Helens. In this type of eruption, the magma blasts into the air and breaks apart into pieces called tephra. Tephra can range in size from tiny particles of ash to house- size boulders. Explosive volcanic eruptions can be dangerous and deadly. They can blast out clouds of hot tephra from the side or top of a volcano. These fiery clouds race down mountainsides destroying almost everything in their path. Ash erupted into the sky falls back to Earth like powdery snow. If thick enough, blankets of ash can suffocate plants, animals, and humans. When hot volcanic materials mix with water from streams or melted snow and ice, mudflows form. Mudflows have buried entire communities located near erupting volcanoes

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