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Which 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 lessWhich of the following is not included in the three classes of volcanoes that are classified based on the frequency of their eruptions?
Geologists classify volcanoes in two main ways: by their activity and by their physical form. Based on the "frequency of eruption," we only use Active, Dormant and Extinct. Composite volcanoes, along with Shield volcanoes and Cinder cones, describe the morphology—how the volcano looks and what it isRead more
Geologists classify volcanoes in two main ways: by their activity and by their physical form. Based on the “frequency of eruption,” we only use Active, Dormant and Extinct. Composite volcanoes, along with Shield volcanoes and Cinder cones, describe the morphology—how the volcano looks and what it is made of. Composite volcanoes are known for their tall, symmetrical peaks and explosive eruptions, but they can be active, dormant or extinct. Therefore, “Composite” does not belong in a list that defines how often a volcano erupts.
See lessWhich type of volcano erupts frequently? (A) Extinct volcano (B) Dormant volcano (C) Active volcano (D) Sleeping volcano
Active volcanoes are those that have erupted in recent historical times and are expected to erupt again soon. There are approximately 1,500 active volcanoes on land globally. These volcanoes are often located at plate boundaries, such as the Ring of Fire. Their "frequent" eruptions can range from coRead more
Active volcanoes are those that have erupted in recent historical times and are expected to erupt again soon. There are approximately 1,500 active volcanoes on land globally. These volcanoes are often located at plate boundaries, such as the Ring of Fire. Their “frequent” eruptions can range from continuous activity (like Kilauea in Hawaii) to eruptions every few years. Monitoring active volcanoes is critical for global safety, as they pose the most immediate threat to human life and aviation through ash clouds and lava flows.
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