How does cinder volcano erupt

Helens is an example of a composite cone volcano. Also called a scoria cone. The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited. Tyson Brown, National Geographic Society. National Geographic Society. For information on user permissions, please read our Terms of Service.

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According to the United States Geologic Survey, there are approximately 1, potentially active volcanoes worldwide. Most are located around the Pacific Ocean in what is commonly called the Ring of Fire. A volcano is defined as an opening in the Earth's crust through which lava, ash, and gases erupt. The term also includes the cone-shaped landform built by repeated eruptions over time. Helens , in Washington state, is a stratovolcano that erupted on May 18, Approximately square miles square kilometers of forest was completely obliterated and 57 people were killed.

Over the course of the day, winds blew million tons of ash eastward across the United States and caused complete darkness in Spokane, Washington, miles kilometers from the volcano, according to the U. Shield volcanoes are huge, gently sloping volcanoes built of very thin lava spreading out in all directions from a central vent. They have wide bases several miles in diameter with steeper middle slopes and a flatter summit.

Eruptions of these volcanoes are not generally explosive, but are more like liquid overflowing around the edges of a container. The world's largest volcano, Mauna Loa in Hawaii , is a shield volcano, according to the U. Mauna Loa is about 55, feet 17, meters from its base beneath the ocean to the summit, which is 13, feet 4, meters above sea level. It is also one of the Earth's most active volcanoes and is carefully monitored. The most recent eruption was in Lava domes are built up when the lava is too viscous to flow , according to the U.

A bubble or plug of cooling rock forms over a fissure. This cooler, thick lava usually rises near the end of an explosive eruption and lava domes often form within the craters of stratovolcanoes. Helens has several well-defined lava domes inside the crater , according to NASA. Besides well-known symmetrical volcanoes such as Mount Fuji in Japan and Kilimanjaro in Tanzania, volcanic activity is responsible for several other distinctive landforms.

Calderas : A caldera is a bowl-shaped depression formed when a volcano collapses into the void left when its magma chamber is emptied. There are three types , according to San Diego State University. The first type is a crater lake caldera. This is the result of a stratovolcano collapsing into its magma chamber during a violent eruption. Basaltic calderas have a concentric ring pattern resulting from a series of gradual collapses rather than a single event.

They are often found at the summit of shield volcanoes such as the craters at the tops of Mauna Loa and Kilauea. Resurgent calderas are the largest volcanic structures on Earth. They are the result of catastrophic eruptions that dwarf any eruptions ever recorded by human beings. Yellowstone caldera, sometimes called a "super volcano," is one example. Volcanic plugs : When magma solidifies in the fissure of a volcano the hard dense rock may form a " neck " that remains when softer surrounding rock has been eroded away, according to the U.

Tuff cones : also known as maars, tuff cones are shallow, flat-floored craters that scientists think formed as a result of a violent expansion of magmatic gas or steam, according to the U.

Maars range in size from to 6, feet 60 to 1, meters across and from 30 to feet 9 to meters deep, and most are commonly filled with water to form natural lakes. The result is the classic cone shape of composite volcanoes. A cross section of a composite volcano reveals alternating layers of rock and ash: 1 magma chamber, 2 bedrock, 3 pipe, 4 ash layers, 5 lava layers, 6 lava flow, 7 vent, 8 lava, 9 ash cloud.

Frequently there is a large crater at the top from the last eruption. Shield volcanoes get their name from their shape. Although shield volcanoes are not steep, they may be very large. Shield volcanoes are common at spreading centers or intraplate hot spots Figure below. Mauna Loa Volcano in Hawaii in the background is the largest shield volcano on Earth with a diameter of more than kilometers 70 miles. The volcano forms a significant part of the island of Hawaii.

The lava that creates shield volcanoes is fluid and flows easily. The spreading lava creates the shield shape.

Shield volcanoes are built by many layers over time and the layers are usually of very similar composition. The low viscosity also means that shield eruptions are non-explosive. Cinder cones are the most common type of volcano. A cinder cone has a cone shape, but is much smaller than a composite volcano. Cinder cones rarely reach meters in height but they have steep sides.

Cinder cones grow rapidly, usually from a single eruption cycle Figure below. Cinder cones are composed of small fragments of rock, such as pumice, piled on top of one another. The exact composition of a cinder cone depends on the composition of the lava ejected from the volcano. Cinder cones usually have a crater at the summit. In , a Mexican farmer first witnessed a cinder cone erupting in his field.