![]() ![]() Mount Etna, one of the most active volcanoes in Europe, has had a number of dangerous eruptions. Lava, gas, rocks, and other material ejected from a flank crater can rush down the side of a mountain in a phenomenon called a pyroclastic flow. Flank craters can form at lower altitudes than summit craters, near hillside towns. Eruptions from flank craters can be much more dangerous than eruptions from summit craters. Craters that form on the sides of volcanoes are called flank craters. Mount Fuji, Japan’s highest mountain, is one of the most popular places in the country to hike. ![]() Although Mount Fuji is an active volcano and magma and gases sit below the summit crater, the risk of an eruption is very low. Volcanic material in some summit craters is near the surface, but not visible. Volcanologists can fly over Mount Erebus’ summit crater to see how the lava lake is behaving and predict future behavior. Lava lakes are where magma has bubbled up to the surface. Mount Erebus, a volcano in Antarctica, has a lava lake in its summit crater. Some volcanoes are calm enough that scientists can get close to the lava in the summit crater. Volcanoes may have one summit crater, such as Mount Fuji in Japan. Summit craters are where volcanic material is at or near the Earth’s surface. Craters at the top of volcanoes are called summit craters. Craters are usually much smaller features than calderas, and calderas are sometimes considered giant craters. Calderas are formed by the inward collapse of a volcano’s magma chamber. Craters are formed by the outward explosion of rocks and other materials from a volcano. A crater is not the same thing as a caldera. Some volcanic craters are deep and have steep sides. Volcanic Craters Volcanic activity often creates craters. Most meteors burn up in the atmosphere as “ shooting stars” before ever colliding with the surface of the Earth. However, most of these meteors are the size of a speck of dust and do not cause any cratering. Meteors do collide with planets-including Earth-every day. Planets, moons, comets, and other celestial bodies have fairly stable orbits that do not interact with each other. Cratering is a rare occurrence in the solar system today. Meteors entering the atmosphere of a gas giant simply break up. These planets are made up almost entirely of gases, so there is no hard surface for a meteor to impact. The so-called “ gas giants” of the solar system- Jupiter, Saturn, Uranus, and Neptune-don’t have craters. Impact craters are found on most of the solar system’s rocky planets and moons. The event was more than a billion times more explosive than all the atomic bombs ever detonated on Earth. Scientists say half the species on Earth-including the dinosaurs-went extinct as a result of the impact. ![]() The impact was so powerful the crater is called the Chicxulub Extinction Event Crater. The object that created the Chicxulub Crater was probably about 10 kilometers (6 miles) wide. The crater is 180 kilometers (112 miles) wide and 900 meters (3,000 feet) deep. The Chicxulub Crater, on Mexico’s Yucatan Peninsula, was most likely created by a comet or asteroid that hit Earth about 65 million years ago. Meteor Crater is 1.2 kilometers (0.75 miles) in diameter and 175 meters (575 feet) deep. The crater was created instantly when a 50-meter (164-foot), 150,000-ton meteorite slammed into the desert about 50,000 years ago. Many impact craters are found on the Earth’s surface, although they can be harder to detect. One of the best-known craters on Earth is Meteor Crater, near Winslow, Arizona. Craters on the moon are named after everyone from American astronaut Buzz Aldrin to ancient Greek philosopher Zeno. Craters and debris, called ejecta, from millions of years ago are still crystal-clear on the moon’s surface. Because the moon has almost no atmosphere, there is hardly any wind, erosion, or weathering. Most were formed when meteors, bodies of solid matter from space, slammed into the lunar surface millions of years ago. Most of the material falls around the rim of the newly formed crater. Enormous amounts of shattered material jet upward, while a wide, circular crater forms where the rock once lay. Almost immediately after the strike, however, the pulverized rock rebounds. The high-speed impact of a large meteorite compresses, or forces downward, a wide area of rock. Impact CratersĬraters produced by the collision of a meteorite with the Earth (or another planet or moon) are called impact craters. A crater is a bowl-shaped depression, or hollowed-out area, produced by the impact of a meteorite, volcanic activity, or an explosion. ![]()
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