Share & grow the world's knowledge!
We want to connect the people who have knowledge to the people who need it, to bring together people with different perspectives so they can understand each other better, and to empower everyone to share their knowledge.
Which of the following is called the ‘safety valve of nature’?
The Earth’s interior is a high-temperature environment where radioactive decay and residual heat create intense pressure. Volcanoes act as natural pressure-release mechanisms. When the internal pressure of gases and magma exceeds the strength of the overlying crust, an eruption occurs, releasing thiRead more
The Earth’s interior is a high-temperature environment where radioactive decay and residual heat create intense pressure. Volcanoes act as natural pressure-release mechanisms. When the internal pressure of gases and magma exceeds the strength of the overlying crust, an eruption occurs, releasing this energy. This process maintains the Earth’s thermal equilibrium. By providing a controlled (albeit often violent) exit for subterranean energy, volcanoes prevent the buildup of pressure that could otherwise lead to even more massive and unpredictable global tectonic shifts. Therefore, they are essential for the geological stability of the planet over millions of years.
See lessWhich of the following statements about volcanoes is true? (A) Volcanoes are classified into three main types: active, dormant and extinct. (B) It is a conduit in the Earth’s crust through which molten rock (magma) and other materials erupt. (C) Often, a circular, funnel-shaped hill or mountainous area develops around its vent. (D) All of the above.
A volcano is more than just a mountain; it is a complex geological system. It begins as a rupture in the crust (conduit) through which magma, ash and gases escape. As this material cools and solidifies around the vent, it builds up the classic cone-shaped structure or a volcanic hill. The classificaRead more
A volcano is more than just a mountain; it is a complex geological system. It begins as a rupture in the crust (conduit) through which magma, ash and gases escape. As this material cools and solidifies around the vent, it builds up the classic cone-shaped structure or a volcanic hill. The classification into active (currently erupting or frequently), dormant (hasn’t erupted recently but could) and extinct (unlikely to erupt again) provides a framework for scientists to assess hazard levels. Together, these features define the mechanical, physical and temporal nature of volcanic activity on Earth.
See lessWhich type of volcano has not erupted since historical times?
Extinct volcanoes are essentially "dead." This happens when the tectonic plate moves away from a volcanic "hotspot" or when a subduction zone ceases to function, cutting off the source of magma. For example, Mount Kilimanjaro in Africa has three volcanic cones; while two are extinct, one is dormant.Read more
Extinct volcanoes are essentially “dead.” This happens when the tectonic plate moves away from a volcanic “hotspot” or when a subduction zone ceases to function, cutting off the source of magma. For example, Mount Kilimanjaro in Africa has three volcanic cones; while two are extinct, one is dormant. To be classified as extinct, a volcano usually must show no activity for at least 10,000 years. However, the distinction can be tricky, as some volcanoes thought to be extinct have “woken up” after millennia, technically reclassifying them as dormant.
See lessWhen does ‘Pele’s Tear’ originate? (A) Plate tectonics (B) During mountain formation (C) During earthquakes (D) During volcanic eruptions
These glass droplets form during fountaining eruptions of fluid (low-viscosity) basaltic lava. As the lava is sprayed into the air, surface tension pulls the molten liquid into tiny spheres or teardrops. If the wind is strong, these droplets can be stretched into long, thin threads known as Pele's HRead more
These glass droplets form during fountaining eruptions of fluid (low-viscosity) basaltic lava. As the lava is sprayed into the air, surface tension pulls the molten liquid into tiny spheres or teardrops. If the wind is strong, these droplets can be stretched into long, thin threads known as Pele’s Hair. Pele’s Tears provide geologists with “frozen” snapshots of the lava’s chemistry at the moment of eruption. They are often found caught in cracks in the rock or in downwind areas near vents like Hawaii’s Kilauea.
See lessCrater and caldera landforms are related to which of the following?
These landforms represent the destructive phase of volcanism. A crater is typically small (less than 1 km wide) and is the primary exit point for magma and gases. In contrast, a caldera is a massive feature (often exceeding 10 km) formed by structural failure. When a huge volume of magma is eruptedRead more
These landforms represent the destructive phase of volcanism. A crater is typically small (less than 1 km wide) and is the primary exit point for magma and gases. In contrast, a caldera is a massive feature (often exceeding 10 km) formed by structural failure. When a huge volume of magma is erupted rapidly, the “roof” of the magma chamber loses its support and sinks. Famous examples include Crater Lake in Oregon and the Yellowstone Caldera. These depressions often fill with water over time, forming picturesque but geologically significant volcanic lakes.
See less