A volcano is a mountain or hill built up around a vent that connects to a reservoir of molten rock from beneath the surface of the Earth. The molten rock is lighter than the surrounding hard rock and will eventually break through a weak point in the Earth’s crust. When this happens the volcano may have a violent eruption of gas, rocks, molten lava, and ash. Volcanoes are generally grouped into four categories: cinder cone, composite volcanoes, shield volcanoes, and lava domes.
Cinder cone volcanoes are formed when gas-charged lava explodes into the air. The pieces of lava that fall from the air solidify and create a cone-shaped hill with a cup-shaped depression. Composite volcanoes are large, steep, symmetrical cones with a crater at the summit that contains a vent or cluster of vents. Composite volcanoes are responsible for some of the biggest eruptions to have ever happened. Shield volcanoes form from fluid lava flows spreading out from a central location. As each new layer of lava dries, it creates a broad, round mound that resembles the shape of a shield. A lava dome is a circular-shaped mound formed from an overflow of very viscous lava.
Kilauea is a shield volcano located on the southern shore of the largest Hawaiian island and is between 300,000 and 600,000 years old. The shield is built up of pahoehoe lava with a smooth surface that looks like coiled ropes when it cools. It is part of the Hawaiian Ridge-Emperor Seamount chain, a mostly underwater chain with more than 80 volcanoes. This chain is caused by the movement of the Pacific tectonic plate over the Hawaiian hot spot and extends more than 6000 km from the big island of Hawaii. Kilauea erupts from its summit caldera, from its East Rift Zone and the Sou...
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... all the Hawaiian volcanoes. Yellowstone is by far the largest of the 3 areas while Kilauea is the smallest. Kilauea is currently the most active of these areas with continuous lava flow from Pu’u’O’o, but historically Yellowstone’s eruption history involves much larger explosions 640,000 years to 2.1 million years ago. Both Yellowstone and Craters of the Moon are part of the Snake River Plains and geographically are only around 200 miles from each other, while Kilauea is part of the large island of Hawaii and is quite far away from the other two sites. All three sites are capable of further volcanism. While Kilauea is currently experiencing an ongoing eruption, Craters of the Moon is dormant but retains the potential of further activity. Based on previous eruptions, Yellowstone erupting again could potentially be one of the biggest eruptions of modern times.
Mauna Loa is located on a hot spot in the Pacific Ocean. It is not near a plate boundary, in fact it is 3,200 km from the nearest plate boundary, and is situated in the middle of the Pacific tectonic plate. This is actually a rarity, as 90% of volcanoes are along a tectonic plate boundary. A hot spot occurs where long, stationary vertical pools of magma rise up and towards the plate. Movement of the tectonic plates above the hot spot created Mauna Loa, along with the other Hawaiian volcanoes. The older Hawaiian Islands were once above this stationary hot spot, but have been carried northwest by the slowly moving Pacific plate. As the plate moves, it carries the previously formed, older, volcanoes with it, creating a trail of younger, new volcanoes behind. The islands are lined up along the Hawaiian Ridge-Emperor Seamounts chain, which is 3,750 miles and includes Kauai, Maui, Oahu and Hawai’i, from north to south, respectively. There are around 80 volcanoes in this chain; most of them underwater, consequently the term seamount refer to submarine volcanoes. Three volcanoes of Hawai’i, Mauna Loa, Kilauea and Loihi seamount, are all currently sharing the Hawaiian hot spot. Although, recent evidence has shown that all three volcanoes use have separate plumbing systems to expel the lava from the pool of magma deep below them. It has also been suggested that Loihi is slowly moving Mauna Loa from the center of the island, thus shifting directly over the hot spot. The closer to the hot spot a volcano is, the more active it will be. The Hawaiian hot spot has laid down layers of lava, building up enormous islands from the ocean floor.
As Kohala Volcano emerged from the sea and joined with Mahukona, a much larger Big Island began forming. With continued movement of the Pacific Plate, the center of volcanism migrated on to Mauna Kea and Hualalai, the middle-aged volcanoes, and finally on to Mauna Loa and Kilauea, which are the youngest volcanoes on the island. Over the geologically short time of several hundred thousand years, these volcanoes erupted thousands of thin flows which spread over, and built upon, older flows; each volcano growing until it finally emerged from the sea. As time went on, lava flows from one volcano began to overlap flows from other, nearby volcanoes and eventually the peaks coalesced into a single island, the Big Island. In geologically recent times, a new volcano, Loihi, began forming about 18 miles off the southeast coast of the Big Island.
Lassen Peak and Mount St. Helens are the only two volcanoes in the contiguous United States to erupt during the 20th century.
Basalt forms due to the partial melting of the layer of the mantle called the asthenosphere. The asthenosphere is the plastic zone of the mantle beneath the rigid lithosphere. Mantle plumes coming from the mesosphere can cause the asthenosphere to melt with heat or even if pressure decreases, which is called decompression melting (Richard 2011). The magma that forms from this melting is mafic magma that solidifies once it reaches the earth’s surface and cools quickly. The above process mainly occurs mainly during intraplate igneous activity which is the main explanation for volcanic activity that occurs a long distance away from a plate boundary. If the tectonic plate above the mantle plume is moving it can create a string of volcanic activity such as in Hawaii. See Fig 2.
Like most of the other volcanoes in the Cascade Range, St. Helens is a great cone of rubble, consisting of lava rock interlayered with ash, pumice and other deposits. Volcanic cones of this internal structure are called composite cones or stratovolcanoes. Mount St. Helens includes layers of basalt and andesite through which several domes of dacite lava have erupted. The largest of the dacite domes formed the previous summit; another formed Goat Rocks dome on the northern flank. These were destroyed in St. Helens' 1980 eruption.
To start, these names are the names of two big volcanos, both in Washington State, both deadly, but on different scales. Mt. Rainier’s last eruption was 150 years ago. Yellowstone’s last eruption was 640,000 years ago. Yellowstone’s reputation of being the ultimate super volcano versus Mt. Rainier, the most dangerous volcano in the country. The difference between these volcanos is looks, damage, stability and tourism.
In the central area of the Pacific Ocean lies the Hawaiian Islands spanning 2,400 kilometers long beginning at Kure Island, located in the northwest to big island of Hawaii (Edge of Fire). This island is 3,000 kilometers away from the nearest continent, which is North America. The creation of the islands today came from “Hotspots”, which are characterized as plumes of magma rising from the mantle of the Earth through the continental crust, creating huge shield volcanos which contribute to the land mass that subsequently gets created. With the help of divergent (creation) and convergent (destruction) zones, the Earth’s crust eventually moves the newly created landmass off the Hot Spot plume, effectively rendering the volcano extinct, and allowing for new land to be created over the still stationary (and active) plume in the mantle.
Stories about volcanoes are captivating. Myths come in different versions, but all of them are capable of capturing yours, and everybody’s imagination.
Kilauea is the youngest volcano on the Big Island of Hawaii. Still active, there have been 34 eruptions since 1983. Kilauea is a shield volcano, meaning it covers a wide range of area, and has sloping sides. Kilauea is usually confused as being a smaller part to the neighboring Mauna Loa volcano, but it has it’s own lava flow system which makes it special to the Hawaiian islands. The history of eruptions from Kilauea is lengthy and the volcano’s name actually means, “spewing.” The oldest documented samples of lava date back almost 3,000 years and the oldest human documented eruption happened in 1823.
Maunaloa last erupted in 1938 and Kilauea has been erupting since January 3,1938. The Hawaii Volcanoes National Park was named a World Biosphere site by UNESCO in 1987. Kilauea is also called the world's only drive-in volcano.
A volcano is a mountain that opens downward to a pool of molten rock below the surface of the earth. When pressure builds up, eruptions occur. In another definition it is a mountain
The Mauna Loa volcano is located in Hawaii and means "Long Mountain" in Hawaiian. It is a giant, basaltic shield volcano. It is one of the largest volcanoes and mountains in the world and has been called the "monarch of mountains". It has an estimated volume of 9,600 cubic miles and takes up half the land of Hawaii. It extends about 120 km starting from the southern tip of the island to the northern region. It is 97 km (60 miles) long, 48 km (30 miles) wide, and is 8,742 km (28,680 miles) high from the base on the sea floor to the top. The slopes are steeper than 12 degrees and about 4 degrees at the top of the volcano. Mauna Loa formed about half a million years ago and in the middle stages of forming into a shield volcano where lava flows to form a sloped and broad flat domed volcanic cone. Along with Mauna Kea, the Mauna Loa volcano is responsible for the creation of the Hawaiian Islands. Mauna Loa has erupted thirty-three times since 1843 and is known as one of the most active volcanoes in the world today. The last eruption was 1984 and lava flowed within 4 miles of the city of Hilo. This shows that it is dangerous to live anywhere near Mauna Loa and that it poses as a threat to anyone living near it because it has a very high possibility of erupting within a very short span of time. Below is a picture of Mauna Loa taken from a bird's eye view.
Magma is a hot liquid made of melted minerals. Minerals can form crystals when they are cool. Igneous rock can form underground, where the magma cools. slowly. Or, igneous rock can form above ground, where the magma cools.
Volcanoes can be one of the most destructive forces on Earth. It is estimated that some