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Types of Volcanoes

 

One of the reasons that volcanoes are so fascinating is that you could find many different types of volcanoes. The volcanoes can be classified according to their shape, size, dome and even their location. There are other aspects that can also affect the classification of the types of volcanoes found on Earth like the structure of the volcano and if there are any vents or fissure that allow air. Some of those volcanoes are not known for their features but for the type of eruption they will have. Here are some of the volcano types that you will find and how to recognize them.

Fissure Vent

A fissure vent or volcanic fissure is a linear vent on the ground of a volcanic area where lava can erupt from. Usually the lava eruption from a fissure vent will not be an explosive one. The size of the vent is not something that is standard as some can be as small as a few meters wide, but the length can be several kilometers. These types of volcanoes can be very difficult to recognize unless you know that you are standing over it as it is mostly flat. There is no central caldera to these volcanoes and the fissures can be covered up when lava cools down.

Shield Volcano

Shield volcanoes are types of volcanoes which are formed due to several lava flows which eventually give them the shape of a warrior’s shield. These volcanoes are not the tall mountains that you expect to see when you think of a volcano, but rather low profile structures that look more like a small hill than a full mountain. The summit of these volcanoes is usually flat whole the width can be very big. Usually the height of a shield volcano will be just 1/20th of the total volcano’s width.

Lava Dome

A lava dome is a circular volcanic formation which happens due to the viscous lava slow movement. Its shape happens because of the viscosity of the material coming out of the volcano. The domes are very common in volcanic areas and while they are not the awesome show that a volcanic explosion would be it is still something to be admired. Another reason that they form is that there usually is not enough pressure for an massive explosion which means that there could be some sort of vent allowing the gases to escape the structure.

Stratovolcano

A stratovolcano is recognized mostly because of its shape and size. These types of volcanoes tend to be very tall and conical. Their composition will also help you recognize them as they are made of a hardened lava layer, volcanic ash and tephra. Their profile is steep and the lava that shoots out of these types of volcanoes tends to be very viscous and because of that the cooling of the lava will be done quicker than in other volcanoes meaning that the flow will not get too far away. It is not rare for the stratovolcano to be very tall with a lot of them exceeding 2500 meters.

Because of their shape and height a lot of these types of volcanoes have become very famous. One of the most recognized volcanoes that fall under this category is Mount Fuji in Japan. Mount Vesuvius is another highly recognized and extremely famous stratovolcano. Stromboli is another very famous active volcano that falls under the same category. These volcanoes are famous not only because of their shape but also because of the damage they have caused in the past and the possibility that they will cause severe damage in the future as well.

Supervolcano

The supervolcano is out of all types of volcanoes the one that could cause the most damage. Some scientists predict that an eruption of a supervolcano today could in fact end life in the planet due to the massiveness of the eruption. The problem with that prediction is that there have been such eruptions in the past and there will be another one in the future. The last eruption of the Yellowstone supervolcano is believed to have caused the last ice age and that killed several species. If that were to happen today it could mean a world-wide food shortage that would lead to the starvation of those that survived the eruption and the ash.

The supervolcanoes are ranked by the Volcano Eruption Index and they usually fall under the VEI 7 and the VEI 8 Rankings. There have been a total of VEI 8 eruptions in the history of the planet, five of which have taken place in the United States area. There are currently six famous supervolcanoes in the world, and they are the Yellowstone Caldera in the US, The Long Valley Caldera in the US, the Valles Caldera also in the US, Lake Toba in Indonesia, the Taupo Caldera in New Zealand and the Aira Caldera in Japan.

Submarine Volcano

A submarine volcano is a fissure which can be found under water from which there can be an eruption of magma. It has been calculated that up to 75% of the magma output each year comes from these types of volcanoes. Most of these volcanoes are found close to areas where tectonic movement takes place. Those areas are called ocean ridges. Most of these volcanoes are very deep in the ocean, but there are a few of them which can also be found very close to the surface of the water. Because of the depth of some submarine volcanoes they can be very hard to detect.

Subglacial Volcano

A subglacial volcano or glaciovolcano is one that takes place under the surface of the glacier and in some cases under the ice sheet. These types of volcanoes will quickly create a lake due to the fact that the hot lava will melt the ice very fast. The places with the most subglacial volcanoes are Antarctica and Iceland, but they can also be found in Yukon and British Columbia in Canada.

The subglacial volcano is very similar to the submarine volcano because they will both cool the magma quickly creating very similar reactions on the surface. The areas close to a subglacial volcano can be affected by flooding because of the displacement of the water during the eruption and the additional volcanic material which is released. Theoretically an eruption that was massive enough could cause a tsunami to take place.

Mud Volcano

A mud volcano is a very different thing from a regular volcano, but the concept can be similar. These types of volcanoes are also called mud domes and they form by pressure from gases and liquids. The hot water and the mud mix with surface deposits and that is what pushes the surface up. Currently there are 1100 such structures identified, but more are always a possibility especially in subduction zones. Generally these volcanoes will indicate that there may be a petroleum deposit or that there is a volcano nearby.

If a volcano is close to a mud volcano then most of the gas leaving the structure will be Helium, while those that do not have a volcano nearby will emit mostly methane. Current estimates that would take into account the mud volcanoes not found yet, would have the total amount at over 10,000.

 

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Effects Of Volcanoes – The Consequences

 

A volcano eruption is one of the most impressive events in the planet and the effects of volcanoes and their eruptions could be felt as far away as a different continent. The type of effects of volcanoes depends on the size of the eruption. Some volcanoes could be erupting and not cause much damage even to people nearby while others are so massive that should they erupt they could trigger a world sized catastrophe. So what type of disturbances would you see if there were a massive eruption today? To answer that question we need to be clear about the type of volcano that we are talking about. Volcano eruptions are measured in what is called VEI or Volcano Eruption Index which goes to a most powerful eruption of a VEI8.

An Explosive Eruption

If there were an explosive eruption in your area the effects of volcanoes could be devastating. During an explosive eruption the volcano will spew lava, magma and volcanic material which could travel several miles away from the mountain. The explosiveness of the eruption could also cause pyroclastic flows which would destroy anything within their path. The ash could also cause severe damage to structures depending on the amount of it and those who breathe it in would be at risk of choking on it.

Problems To Aircraft

Aircraft are some of the things that will feel the effects of volcanoes more than others. That is because the ash spewed by a volcano can negatively affect the engines in an aircraft. To make matters worse the problem has not gotten better. Pilots who have flown through a volcanic eruption complain about the fact that they lose power and when they apply the throttle the engine will become even hotter. When that happens more ash is melted and that creates abrasive material which ends up in the engine.

Effects On Cities And Towns

The effects of volcanoes on cities and towns after an eruption could vary from no effects at all to a catastrophe of immeasurable magnitude. A lot of the effects that a city will feel depend on the size of the explosion or eruption and the atmospheric conditions. It has happened before that the conditions will take away the ash from the city. On the other hand, the same conditions could direct all the harmful effects of the lava, the ashes and volcanic material straight into the city which could cause thousands of deaths or injuries.

To look at the effects of volcanoes in towns and cities it is a good idea to look at recent eruptions. When Mauna Loa erupted in 1950 the lava headed towards the city of Hilo.  Another eruption that took place in 1973 took place on Heimaey, Iceland and the entire town was buried under cinder and lava. In 1960 Kilauea erupted and it buried the town of Kapoho and in 1980 when Mount St. Helens erupted the ash fell on several towns in the states of Oregon and Washington. There are several examples of this type of volcano impacts on cities and towns.

Effects On The Environment

There are several ways in which effects of volcanoes can be felt on the environment. Even smaller eruptions can have a measureable effect. That is because while an eruption is taking place gases are released by the volcano. Some of the gases which are released into the air include carbon monoxide, carbon dioxide, sulfur dioxide, fluorine, chlorine, hydrogen sulfide and others. The effects of volcanoes on the environment depend on climate patterns, the overall scale of the eruption and how much the gases spread. Another problem the environment is the ash that is released when a volcano erupts. Depending on the size of the eruption you could be looking at a volcanic winter.

Effects Of Supervolcanoes

Out of all the effects of volcanoes on the daily life of people, the one that is the scariest is what is known as the supervolcano. These volcanoes are the ones that will reach the VEI8 and VEI7 rankings in the scale. These are also volcanoes which are very massive and could destroy most of the life on earth if they were to erupt today.

In the case of the supervolcano in Yellowstone Park several states and their citizens would stand no chance against the lava flow and the ash. However, those are not the only people that would be affected. During the explosion a lot of ash would be released into the atmosphere, dropping temperatures by an average of well over 20 degrees Fahrenheit worldwide. That would cause crops and vegetation to die which would mean no food for animals or people.

 

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Classification Of Volcanoes

 

When studying the volcanoes in the world it is important to understand what the classification of volcanoes is and how it works. There are several factors that go into account when attempting to classify a volcano into a group and that includes things like recent activity, periodicity of eruptions, size, potential impact and others. Though it is not common to hear it volcano eruptions are actually not that rare. More often than not the classification of volcanoes refers to the life cycle and that could define them as active, extinct or dormant. However, a volcano can also be classified by the composition of the structure and that would mean that it can be a shield, conical or stratovolcano. Finally they can also be classified because of its eruption which could be quiet or explosive.

Active Volcanoes

A volcano will be classified as an active volcano if at the present time it is expected to erupt or is erupting already. One of the best examples of this classification of volcanoes would be Kilauea which has been erupting since 1983. There are a total of close to 1,500 of such volcanoes on the planet. Every year somewhere between 50 and 70 volcanoes will erupt.

Dormant Volcanoes

The classification of volcanoes which is called dormant would be a volcano that is not erupting or predicted to erupt in the near future. However, it has done so in recordable history. A dormant volcano is also expected to have an eruption sometime in the future. Sometimes the difference between a dormant volcano and an active volcano can be pretty small. That is because even though a volcano can be dormant for hundreds of years it is still expected to have an eruption in the future.

Mauna Kea is a volcano which is located on Big Island and its last eruption took place 3,500-4,000 years ago. However scientists believe that it will erupt again. What makes that volcano dormant is that currently there is no prediction as to when that eruption could take place. A dormant volcano could be very dangerous because people in the surrounding areas are usually not prepared and complacent leaving close to the mountain. Before its eruption in 1980, Mount St. Helens was dormant.

Extinct Volcanoes

An extinct volcano is a volcano that no one expects will ever have another eruption. One such volcano is also located on Hawaii’s Big Island and its name is Kohala. The last time that Kohala erupted was close to 60,000 years ago. As of now scientists do not believe that volcano will ever be active again. Keep in mind that this classification of volcanoes that are extinct is not necessarily definitive as some have gone through what is called rejuvenation.

Type Classifications

Classification of volcanoes can also be done because of the type of composition and structure of the volcano. A shield volcano is dome shaped and low. These volcanoes are mountains that have been shaped by the flows and can cover larger areas. The simplest form of volcanoes would be the cinder cone type. These volcanoes have erupted from one single vent and a bowl shaped crater will be found in the summit. The most common type of volcano is the strato or composite. These are tall mountains that have steep sides and which have alternated magma and layers of rock.

Eruption Classification

There are two types of classification of volcanoes based on eruption and these are central or explosive and fissure or quiet. An explosive eruption happens because of a buildup of gas under very viscous slow flowing and thick magma. These types of eruption are very violent and rapid; more often they will spew volcanic material, lava and ash onto a large area. A fissure or a quiet eruption will emit a lot of lava from a fracture or fissure. Because lava would usually have a low viscosity, the gas can easily escape.

Samples Of Volcanoes

There are several places in the world which can demonstrate the classification of volcanoes but most active volcanoes will be found in the Pacific Ring of Fire. There are, however, volcanoes not located in the Pacific which are active; some of them include Etna and Vesuvius, Mount Pinatubo and Stromboli.

Classification of volcanoes that are dormant will include a lot of the volcanoes still found in the Ring of Fire and other places nearby. One example would be Mount St. Helens previous to its 1980 eruption. Before a dormant volcano is about to erupt it is usually proceeded by small tremors and earthquakes.

Finally when you are looking at extinct volcanoes you can look at the ones in the Eiffel district in West Germany as well as several volcanoes in USA. There are two volcanoes in Northern Ireland which are also extinct volcanoes and those are Skye and Mull.

 

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Famous Volcanoes

 

Volcanoes are one of the most awesome natural events that the world can ever see, and they are also among the most dangerous. Currently there are approximately 1500 active volcanoes in the world but an active volcano can be described as one that has had an eruption at least within the last ten thousand years. There are many volcanoes that have been dormant for a lot longer than that and yet they could be some of the most dangerous if they were ever to explode. There are volcanoes in most of the world and some you would not be able to see even if you were standing on them even though they are some of the most famous volcanoes. Some areas are more active than others, but the most famous one is the Pacific Ring of Fire.

The Ring Of Fire

The Pacific Ring of Fire is the area in the Pacific Ocean, which has the most active volcanoes in the world. By the latest calculations over 75% of the active volcanoes in the world are located here. Because of that, you will find some of the world’s most famous volcanoes in that area. The area extends from the Chilean coast in South America to Alaska, to the East Coast of the Asian continent, down to Australia, New Zealand, and the Pacific Islands. There are a total of 452 known volcanoes in the Pacific Ring of Fire which is also known for the severity of its earthquakes.

Most Famous Volcanoes In The Ring Of Fire

Because of the amount of volcano activity in the Ring of Fire, some of the world’s most famous volcanoes can be found here. Some of the names you may recognize right away are Mount Saint Helens in Washington State, Kilauea in Hawaii, Mount Yasur in Vanuatu, Santa Maria in Guatemala, and Sangay in Ecuador all of which are still very much active. Another couple of recognizable names in the Ring of Fire are Mount Fuji in Japan, and Mauna Loa in Hawaii.

World’s Most Active Volcanoes

One thing that is important to note is that most of the famous volcanoes are also the most active in the world. Kilauea in Japan is one of the world’s most active volcano at the moment with its last spew of lava happened in 2011. The Nyamuragira volcano in the Democratic Republic of Congo is the most active volcano in Africa and it has erupted at the very least 34 times since 1882. Mount Etna, which was believed by ancient Romans to be the home of the god of fire Vulcan has a continuous history of eruptions that dates back over 3500 years. Piton de la Fournaise or Le Volcan as it is known to locals at Reunion Island has seen over 150 eruptions since the records show it in the 17th century.

What Happens When A Volcano Erupts

To understand famous volcanoes and even volcanoes in general it is important to understand eruptions. Before an eruption takes place there is a lot of commotion beneath the surface which involves melted rock. The substance that is created during that commotion is what is later spilled while the eruption takes place. The name of the molten lava that will flow down the side of a volcano is what is known as magma, but before the magma is expelled out it needs to rise and that is created by disturbances of low and high pressures.

The eruption does not have to be the big explosion that people associate with famous volcanoes. There are mild eruptions, which only cause steam blasts. Others are still considered mild but will have lava run down de side of the volcano and ejected ash or rock fragments. There are however more dangerous and stronger eruptions which can cause a lot of damage to the surrounding area. A Vulcanian explosion will contain solidified rock, which will produce a pyroclastic flow.

Volcanoes With The Potential Of Being The Deadliest

Some of the world’s most famous volcanoes have destroyed entire cities and killed everyone in the nearby area. Mount Vesuvius for example destroyed the entire city of Pompey and archeological records show the devastation it caused. There are some volcanoes that could cause the same type of damage to cities today with the difference that the population around those volcanoes is even larger than that of ancient Pompeii.

The city of Kagoshima in Japan has 680,000 people and the Sakurajima volcano located nearby has been experiencing small explosions since 1955. Catania near Mount Etna has 300,000 people in the area, which has seen the dangers of Mount Etna when an eruption destroyed some of its structures in the 1600’s. The 450,000 people in Pasto Colombia have been on guard due to the Galeras Volcano nearby. In 2005 then were forced to wear goggles and facemasks because of an explosion. Seattle’s population of 608,000 live in that shadows of Mount Rainier and though the volcano is quiet for now, its past history is anything but. Finally, close to a million people live in Naples, Italy. Their biggest and scariest neighbor is Mount Vesuvius, which has destroyed an entire city and the surrounding areas in the past. These are just some of the famous volcanoes near people, but there are a lot more.

Super Volcanoes

If the most famous volcanoes listed before were to erupt, they could cause a lot of destruction, but that destruction would be nowhere near to what would happen if a super volcano were to erupt. There are several of these volcanoes and they have caused severe destruction in the past. Their eruptions are measured using the Volcano Eruption index or VEI. The most severe eruptions are those that reach the VEI8 classification and there have been 10 of those eruptions in recorded history, 5 of which were in the US.

What Would Happen If A Super Volcano Erupted Today?

If a super volcano like the one found at Yellowstone Park in the US were to erupt today it would instantly be a famous volcano, but there would not be as many people to tell the story. The last time that the Yellowstone volcano erupted was 640,000 years ago and it is believed that it was the main cause of the latest ice age. If an eruption of that magnitude were to happen today the people nearby would stand no chance as they would be hit by 500 degree lava. Even if the lava does not reach you the ash would and that would cause you to choke to death as you inhale it.

People in other parts of the world would not get away unharmed because the global temperatures would drop by a minimum of 21 degrees. That would cause plant life and animal life to die off, leaving the people in the rest of the world without food and very cold. In other words, the great majority of people would starve.

The problem is that some scientists believe that the volcano at Yellowstone Park erupts once every 600,000 years, and if that is the case then we are overdue. No one knows when one of these famous volcanoes will erupt, but when they do it will be a spectacle that could end life as we know it.

 

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Cinder Cone Volcano

 

Although they can refer to a part of a volcano cinder cones, or scoria cones, are actually volcanoes themselves. Cinder cone volcanoes are the volcanoes that most people think of when they picture a volcano erupting. That is because these are the ones that have a cone-shaped peak most people have come to associate with volcanoes in general. The main feature of cinder cone volcanoes is their conical shape together with steeply angled sides.

You are most likely to find this type of volcano near other larger volcanoes and these are relatively small in comparison. They are frequently near calderas, stratovolcanoes and shield volcanoes. They can range from tens of meters to hundreds and will usually be created over much shorter periods of time than other volcanoes. In addition, they will generally be topped by a crater at their summit.

Eruptions

When compared to the eruptions you will find with other volcanoes, cinder cone volcanoes have relatively small ones. In their eruptions the lava will generally erupt from one of the small vents found in the crust and fragments will be sprayed into the air. Because these fragments, called scoria or cinders, are melted rock with gas-filled pieces they cool very quickly and will generally accumulate near the opening of the vent, continuing the development of the cone shape of the volcano. Because these fragments can seem to sparkle and glow, they can make very beautiful and dramatic displays during eruptions.

In some cases when strong winds are blowing at the time of the eruption, cinder cone volcanoes may have slightly different shapes at their base, such as more of a horseshoe instead of the normal circular base.

Cerro Negro

Cerro Negro is located in Nicaragua and is currently the youngest volcano in Central America. It was first created in April of 1850 and since then has been one of the most active in the country. This volcano is in a group of four cinder cone volcanoes located in the Maribios Range. This cone is the result of Strombolian eruptions that occurred several years apart and is 500 meters high.

Paricutin

Paricutin is a cinder cone located in Mexico and first started developing on a farm in 1943. It was caused by gas escaping from the molten lava within, which then formed cinders which landed around the vent and eventually built the cone to an altitude of 1,200 feet. It also has a crater at the top that is the result of its last explosive eruption. Paricutin was active for nine years, during which time it destroyed the nearby town San Juan and covered a large area of around a hundred square miles with ash.

Lava Butte

Lava Butte is one of the over 400 cinder cone volcanoes that surround the Newberry volcano. Normal cones in this area are generally 200 feet high while some of the larger ones reach 400 feet. Lava Butte, however, is 4,970 feet high and has created a flow that goes five miles north and three to the west.

Raton Clayton Volcanic Field

Another area with a great deal of cinder cone volcanoes is the Raton Clayton volcanic field located in the northeastern portion of New Mexico. This area has around 120 cinder cones that range from 2,300 years old to over a million. The youngest cone in this field, Capulin, is also one of the most impressive as its rim has a circumference of around 1.7 kilometers, the volcano itself is 305 meters tall and its crater is 125 meters deep.

Sunset Crater

Sunset Crater is in the group of the youngest cinder cone volcanoes found within the United States (with the exception of Hawaii and Alaska). This volcano was created when a 15 kilometer fissure opened and produced small lava flow in addition to a curtain of fire. Over time the volcano built from the results of this fissure.

 

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Fissure Vent Volcano

 

Fissure vents are a type of volcano in which the lava eruptions through a linear volcanic vent. Usually these eruptions do not involve an explosion. Because fissure vent volcanoes are usually only several meters wide but can range in length up to many kilometers, they are hard to spot when on the ground or from a bird’s eye view because they are mostly flat on the surface with no caldera indicating their location. Instead, they will usually appear to simply be a crack found in the surface of either the ground or ocean floor.

Although fissure vent eruptions are not usually explosive, they can be very large in size and have created large lava fields that have covered many thousands of square miles all over the world including in Ethiopia and Iceland. In Hawaii, several volcanoes have radial fissure vents which will actually create “curtains of fire” when lava fountains erupt on various parts of the fissures.

Location

This type of volcano is usually found on the rift zones or along rifts on the surrounding area. They can frequently be found extending radially away from the volcano’s summit and may even be long enough to reach its base. Although fissure vent volcanoes can be long, the activity within them will sometimes occur at a few specific locations, in some cases causing craters or cones to form.

Shin-dake

Shin-dake is the summit crater found on the Kuchinoerabujima Island in Japan. In September of 1980 a brief eruption occurred along the fissure vent on Shin-dake which ejected ash and blocks above the crater up to an altitude of 2 kilometers.

Pagan

The Pagan volcano is part of the Mariana Islands and during an eruption in 1981, a fissure formed. This fissure goes directly across the volcano’s summit and initially had three principal active vents. The activity of this fissure led to the construction of a cinder cone on its north flank. Vents located on the both the south and north rims of the summit fed lava flows which traveled down the volcano’s flanks.

Banda Api

The Banda Api volcano found in Indonesia is one of the world’s fissure vent volcanoes. In 1988, a fissure on the island that led from north to south-southwest erupted on 9 May, causing both a release of lava and explosive activity along the path of the fissure. The north-side fissure’s vents released large eruption plumes that were full of ash. In addition, the lava flow from the volcano reached the coast, but only after destroying two villages in its path.

Pinatubo

Pinatubo is a stratovolcano on Luzon, an island in the Philippines, that erupted in 1991.  The fissure was 1.5 kilometers in length and throughout the course of the eruptions new craters were created. In addition, onlookers could see steam and small amounts of ash rise from the fissure vent. The fissure vent was active from April 2nd until June 15th when the main volcano erupted.

Krafla

The Krafla volcano is located in Iceland and on September 1984, two eruptive fissures both became active and connected achieving a combined length of 8.5 kilometers. Although at the beginning of the eruption there was volcanic activity along the entire length of the fissure, it later concentrated on the northern part.

Iceland’s volcanic vents usually occur in locations where the lithospheric plates are diverging and later eruptions will generally happen at new fractures that are parallel and thousands of meters from the original ones. The Laki system of fissures actually produced the largest eruption in historical times on the planet when a flood basalt occurred in 934 during the eruption of Eldgja.

 

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Lava Dome Volcano

 

A lava dome is a mound that will form when lava piles up over a volcano’s vent instead of moving away. Since the eruption of lava is slow there is no chance for a lava flow to occur and therefore the lava dome will form. Most of the time the sides of a dome will be steep and they are usually composed of what’s called silica-rich lava which in some cases will contain pressurized gas so that explosions can occur. The domes can be described as a small bulbous mass of lava. As the lava cools down it becomes hard and the dome forms.

Size And Shape

The size and shape of a lava dome can change from one volcano to the next. However, you can expect them to be thick and steep sided. The thickness of the lava dome can vary from up to a kilometer in height to just a few meters. The length or diameter can also vary a lot from several kilometers to just a few meters. The shape of the dome can also be very different from one to the next with some of the more common shapes being circular, flat topped, spiny, piston shaped and even a combination. The form of the dome depends on different factors including the viscosity of lava, strength and the slope of the surrounding area it is being erupted onto.

Where Do They Form?

A lava dome can form anywhere there is any volcanic activity. Usually they can be found in the crater of larger volcanoes like Mount St. Helens. However they will not only appear at the craters. In some cases the domes will form on the sides or flanks of the volcano. In rare cases they can even form away from volcanic features. It all depends on the magmatic attributes of the area around them. There are domes on Mount St. Helens which are located on its flanks. These types of domes will eventually help rebuild the mountain.

What They Are Made Of

There are different types of composition that a lava dome can have and those include anything from rhyolite to basalt. It is important to know however that most of the time the lava that will form a dome will have a higher content of silica (Si02). That composition is what makes the lava more viscous. While a dome can take one of many different types of textures, usually they tend to be blocky in nature.

Types

A lava dome can take many different shapes the first one of which is the Tortas kind. The reason for the name is the similarity that the shape has to a cake or otherwise known as a torta. This is a very common type of formation but it does happen more often in South America near the Andes Mountains.

The Peleean type of lava dome is probably the steepest of all domes. Typically they are similar to Tortas with the difference that they have smoother upper surfaces. They also have vertical spines and can collapse.

The Coulees are somewhere between a lava dome and a lava flow. This type of dome usually takes place on the side of a slope and that is why it can run down. It is rare for this type of dome to be very large but there are a few examples which are over 10 kilometers.

Finally you will be able to find what is called an Upheaved Plug which is a very interesting and very rare type of dome. The lava when it erupts tends to be stronger than that of other domes and because of that the lava is pushed up, almost like a piston. These extrusions can travel very high when compared to the surface.

 

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Magma

 

Magma is a molten and liquid rock that is only found below the earth’s surface. That is because once it reaches the surface it becomes lava. This substance is made up of a combination of dissolved gases, rock fragments and crystals and the liquid part of it is referred to as the melt. Because of its creation due to high pressure and temperatures, this is an extremely hot substance, ranging from 1,292 to 2,372 degrees Fahrenheit. Frequently you will find this substance pooling in magma chambers which can feed volcanoes. It can also intrude into nearby rocks, rise to the surface in the form of lava or become an explosive ejection of tephra.

How It Forms

Magma forms in either the lower portion of Earth’s crust or the upper part of its mantle. It is produced when high amounts of pressure combine with high temperatures, causing some of the rocks in the area to melt, creating this substance. Without this combination of pressure and heat, this substance would not be able to form.

Magma Chambers

This substance is most frequently found in magma chambers under the surface of the earth. These are basically underground pools of this liquid rock. In order to maintain its form, the liquid in these chambers must be exposed to constant high temperatures in addition to a great deal of pressure. Because of this, the high pressure can eventually create a fracture in the surrounding rock, allowing the liquid to escape to the surface at which point it becomes lava.

Basalt

Magma comes in three major types, all of which have different properties and are more common with different types of volcanoes and eruptions. The first type of this liquid is basalt and it is very low in silica and has a very low gas content as well. In addition, this liquid has a low viscosity, meaning that it appears thicker. This type of liquid rock is formed at a much higher temperature than the other two varieties, at around 1,200 degrees Celsius. It is more common in volcanic fields than other types of volcanoes and is usually present in flowing eruptions that produce thin lava flows that form shields.

Andesite

Andesite magma occurs at a slightly lower temperature than basalt, ranging from 800 to 1,000 degrees Celsius. It also has a slightly higher content of silica and gas and is moderately viscous compared to the low viscosity of basalt liquid rock. Andesite is most common in stratovolcanoes and will usually produce moderately explosive eruptions that include a liquid flow as well. These eruptions will generally create thick lava flows that are full of rubble.

Rhyolite

The third type of magma is rhyolite and it occurs at the lowest temperature possible for this substance, ranging from 750 to 850 degrees Celsius. It is the complete opposite of the basalt version as it is rich in silica and has high gas content. In addition, it has a high viscosity. This type of liquid is most commonly related to caldera volcanoes that are distinguished by very explosive eruptions. These eruptions will usually produce pumice, ash fall and pyroclastic flows. In cases in which this substance has lower gas content than normal, the lava will begin to flow.

Magma Eruptions

Volcanic eruptions frequently occur because of the accumulation of magma within which then erupts. Usually these eruptions occur because of high pressure stemming from the dissolved gases within the liquid rock. The gases usually remain dissolved because the pressure of the rocks confining the substance is larger than that of the gas’s vapor pressure. If this balance shifts, however, the result is many tiny gas bubbles filling the substance and trying to escape. Once the pressure becomes too great, the eruption occurs.

 

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Mauna Loa Volcano

 

The Mauna Loa Volcano is the largest volcano on the planet as it rises over 4 kilometers above the sea level but the 4 kilometers that you see on top is not even half the size of the volcano. From the seafloor it is an additional 5 kilometers and from the seafloor it is depressed an additional 8 kilometers which makes the sum a total of 17 kilometers or 56,000 feet from the base. Half of the island of Hawaii is made up by the volcano and its sheer size makes it about 85% of every other Hawaiian island combined.

Activity

The Mauna Loa Volcano is not only a big size; it is also one of the most active volcanoes in the world. Since the first documented eruption in 1843 there have been an additional 32 eruptions. The last eruption took place in 1984 but scientists believe that the current signs point to the fact that it will erupt again. The volcano is currently being monitored at all times for any unrest that it may show. Scientists also believe that the Mauna Loa Volcano has been erupting for 700,000 years at least with its emerging above the sea level taking place close to 400,000 years ago. The magma seen at the Mauna Loa Volcano comes directly from the Hawaii hotspot.

Comparing It To Kilauea

When you are in Hawaii you will be seeing several volcanoes and it is impossible to go without comparing them. The Mauna Loa Volcano is pretty close to the Kilauea Volcano and even though it is not as active as its neighbor, it is still considered one of the most active in the world. There are a total of 333,000 acres that form Hawaii’s Volcanoes National Park and Kilauea and Mauna Loa are the most famous of them. What you may not know is that it appears that both volcanoes are connected which would explain the behavior of both volcanoes. In fact, they used to think that Kilauea was a part of Mauna Loa until they discovered its own set of lava tunnels. The increased inflation of both volcanoes is due to the fact that there is increased pressure in the source of magma for the two of them.

Is The Mauna Loa Volcano Awakening?

For a while the Mauna Loa Volcano was undergoing deflating but recently that changed. From 2002 to 2005 the summit of the volcano started to reverse the deflating period which had taken ten years. In 2004 earthquake activity also increased but by 2005 it went down again. Scientists believe that Mauna Loa will more than likely erupt again within the next few years so it may be that the citizens of Hawaii will need to be on the alert regarding this awakening giant.

Hazards

Because of its history the Mauna Loa Volcano has been designated as a decade volcano. There are only 16 such volcanoes in the world and it means that more attention needs to be paid to it. It is important to know that volcanoes in Hawaii do not usually produce multiple casualties. In fact the last one occurred in 1924 when an explosive eruption sent rocks to onlookers, killing one. One of the most common hazards that volcanoes in Hawaii like Mauna Loa can cause is inundation by lava. The lava flows are usually slow moving and do not usually exceed a walking pace but that is not necessarily the case. In 1950 the volcano erupted as much lava as Kilauea produces currently every three years. The lava reached the sea level in only four hours which destroyed large parts of the village known as Ho’okena Mauka as well as parts of the highway in the area. Other communities have also been affected by eruptions from the volcano.

Monitoring

The Hawaii Volcano Observatory or HVO is the organization that is currently monitoring Mauna Loa. A close eye is kept on the activity of the volcano due to its past history. Usually an eruption of the Mauna Loa Volcano will be followed by several tremors for a few days. Warning mechanisms and an observatory are used to cover the area. The more modern mechanisms for monitoring the volcano were installed in the early 1970s so an eruption in 1975 was forewarned by seismic unrest which lasted close to a year. The same happened for the last eruption in 1984 except that the tremors lasted three times as long.

Today the seismic network monitors Mauna Loa as well as several GPS stations, strainmeters and tiltmeters which are currently monitoring deformation in the ground which can be caused due to the swelling of the volcano’s magma chamber. With all the equipment used there are a lot more possible warnings when an eruption is close to happening. As if that were not enough there are also two gas detectors at the summit caldera and a webcam that keeps an eye on the volcano.

Location

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Lava

 

A lava flow is a stream of molten rock which will pour out of an erupting volcano’s vent. This substance can be erupted either during the explosive activity or a non-explosive event. Most lava flows will move slowly but it will destroy anything in its path. But the good news is that due to the low speed of the flow most people should have a chance of getting away from it. The speed of the flow will depend on different factors and those include the viscosity of the substance, the steepness of the hill, channeling in the area and the amount that had been produced at the volcano’s vent.

Speed

As stated earlier flows can be rather slow but some can reach speeds of over 30 kilometers per hour. Most of the edges of the flow will travel at around 10 kilometers per hour provided that the slope is steep. However, on a flatter surface the speed can be less than one kilometer per hour. The viscosity of the lava will affect the speed as the higher viscosity the lower the speed. It is rare for a viscous lava flow to go over 8 kilometers per hour from their vent.

Destruction

Anything in the path of a lava flow will be destroyed and eventually buried by the flow. Some materials which will not fall will catch on fire due to the extremely high temperatures found in the flow. If the lava were to enter a body of water such as the ocean, lake or a river, the water will boil on contact. Vegetation stands no chance as it will simply be buried and burnt by the flow, creating methane gas. The good news, however, is that it is rare for deaths to happen due to flows and that is because of the low speed at which they move.

Injuries To People

Even though deaths are uncommon, injuries do happen when people stay close to a vent. People have been killed and injured when they approach a lava flow to get a better look. Most of the deaths related to flows usually have to do with the explosions that take place when the substance interacts with a body of water. Other things that could kill or injure a person include asphyxiation on toxic gases, collapse of a delta, pyroclastic flows and lahars which happen from melted water. Though it may be tempting to get a closer look, it is never recommended to do so as there is simply too much danger in the area of a flow.

No Rebuilding

When an area is affected by a volcano it is much different than what you would find with most other types of natural disasters. It is possible to rebuild a home after a tornado, hurricane or earthquake hits an area. However, when lava hits an area it is nearly impossible to rebuild there. The homes that were in the area are buried by the substance and the landscape changes immediately as it cools down. There is an entire new area which becomes really hard to build over and the owners may not want to anyway.

Evacuation

There are problems associated with evacuation of an area when a volcano is erupting. The flow of lava could cover evacuation routes so the cities that are in areas that could be affected need to design more than just a couple evacuation plans. When a volcano is believed to be close to erupting scientists can look at the conditions and make a prediction of where the flow will go but currently it is not an exact science so there is always a chance that the prediction will be wrong.

 

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