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Lab on Volcanoes1

Lab on Volcanoes1 - Lab on Volcanoes A volcano is a conical...

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Lab on Volcanoes A volcano is a conical landform or mountain built from lava and ash. The lava and ash erupt from the volcano through a vent that connects with reservoirs of hot molten rock or magma deep within the Earth. More than 50 volcanoes in the United States have erupted one or more times in the past 200 years. The most volcanically active regions of the Nation are in Alaska, Hawaii, California, Oregon, and Washington. There are more than 1500 volcanoes on the Earth which have the potential to become active because they have erupted within the past 10,000 years. Approximately 10% of the Earth's population live close enough to a volcano to be at risk of volcanic hazards. Volcanoes produce a wide variety of natural hazards that can kill people and destroy property. This simplified sketch shows a volcano typical of those found in the Western United States and Alaska, but many of these hazards also pose risks at other volcanoes, such as those in Hawai`i. Some hazards, such as lahars and landslides, can occur even when a volcano is not erupting. Types of volcanoes
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1. Shield basaltic composition runny, low viscosity lava sides slope at 15 degrees or less (resembles a Roman shield lying on the ground, hence its name) characterized by relatively quiet eruptions with lava flows relatively little explosive activity Mauna Loa Volcano, Hawaii, a shield volcano, as viewed from the summit of Kilauea, about 33 miles to the southeast. Mauna Loa, on the Big Island of Hawaii, is the largest active volcano in the world. It last erupted in 1984. Mauna Loa erupted 14 times in the 20th Century, and 37 times since 1832. Mauna Loa is the most massive mountain on Earth, rising to an elevation of 13,677 feet above sea level, or 31,677 feet above the sea floor. Its volume is 10,000 miles 3 . The tallest mountain on Earth is located nearby, also on the Big Island of Hawaii. It is Mauna Kea, rising to an elevation of 13,796 feet above sea level, or 31,796 feet above the sea floor. Both Mauna Loa and Mauna Kea are shield volcanoes. In comparison, Mt. Everest (in the Himalayas), the highest point on Earth above sea level, rises to an elevation of 8848 m (or 29,028 ft). Mt. Everest is NOT a volcano, however. The largest volcano in the Solar System is also a shield volcano. It is located on the planet Mars. Its name is Olympus Mons (or Mount Olympus), and it is three times as high as the largest volcanoes on Earth (nearly 27 km high). It is about 100 times as massive as one of the Hawaiian volcanoes. 2. Cinder Cone relatively small (less than 300 m or 1000 ft high) relatively steep slopes (30 - 40 degrees) made of pyroclastic material
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Cinder cone, Puu Puai, created by eruption in 1959, Devastation Trail, Kilauea, Hawaii Volcanoes National Park. The volcano Paracutin, in Mexico, is a well-known example of a cinder cone. 3. Composite Volcano or Strato-volcano Eruption of Mt. St. Helens large (1 - 10 km across) layered structure, consisting of alternating layers of lava and pyroclastic material high silica content (sialic or intermediate) with composition of andesite, dacite, and occasionally rhyolite
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