VOLCANOESAND

VOLCANIC ERRUPTIONS

Prepared by:Tricia Suazo

Types of volcanoes

Shield Volcano

Shield volcanoes are the largest volcanoes on earth. They are built by basalt lava flows and have gentle slopes that move from the top of the volcano to the bottom.

Lava Dome

Lava domes are built by a kind of viscous lava. Viscous lava is a thick mixture that can not flow quickly, so the lava cools too quickly to really move any distance from the eruption.

Strato volcanoCinder Cone VolcanoCinder cones are steep sided hills made up of fragments from a volcanic eruption. The fragments that form these cinder cones are blown down wind from an eruption from a stratovolcano. You can see the stratovolcano that formed this cinder cone in the background.

Strato volcanoes are shaped like a cone, but have very steep sides. They are formed during violent eruptions by lava flows , tephra, and pyroclastic flows. They are formed by several vents that lead from deep underground and may form cinder cones nearby.

Mud Volcanoes

Mud volcano is A conical accumulation of variable admixtures of sand and rock fragments, the whole resulting from eruption of wet mud and impelled upward by fluid or gas pressure. Also known as hervidero; macaluba.

A caldera is a cauldron-like volcanic feature usually formed by the collapse of land following a volcanic eruption, such as the one at Yellowstone National Park in the US. They are sometimes confused with volcanic craters

Caldera

Pyroclastic rocks

Pyroclastic rocks or pyroclastics are clastic rocks composed solely or primarily of volcanic materials. Where the volcanic material has been transported and reworked through mechanical action, such as by wind or water, these rocks are termed volcaniclastic. Commonly associated with explosive volcanic activity–such as Plinian or krakatoan eruption styles, or phreatomagmatic eruptions–pyroclastic deposits are commonly formed from airborne ash, lapilli and bombs or blocks ejected from the volcano itself, mixed in with shattered country rock.Pyroclastic rocks may be composed of a large range of clast sizes; from the largest agglomerates, to very fine ashes and tuffs. Pyroclasts of different sizes are classified as volcanic bombs, lapilli and volcanic ash. Ash is considered to be pyroclastic because it is a fine dust made up of volcanic rock. One of the most spectacular forms of pyroclastic deposit are the ignimbrites, deposits formed by the high-temperature gas and ash mix of a pyroclastic flow event.

Olympus mons

Olympus Mons (Latin for Mount Olympus) is a large volcanic mountain on the planet Mars. At a height of almost 22 km (14 mi),[2] it is one of the tallest mountains in the Solar System, three times as tall as Mount Everest and more than twice the height of Mauna Kea the tallest mountain on Earth. Olympus Mons is the youngest of the large volcanoes on Mars, having formed during Mars' Amazonian Period. Olympus Mons had been known to astronomers since the late 19th century as the albedo feature Nix Olympica (Latin for "Snows of Olympus"). Its mountainous nature was suspected well before space probes confirmed its identity as a mountain

Coal fires and extinction

About 250 million years ago, about 95 percent of life was wiped out in the sea and 70 percent on land. Researchers at the University of Calgary believe they have discovered evidence to support massivevolcanic eruptions burnt significant volumes of coal, producing ash clouds that had broad impact on global oceans.

"This could literally be the smoking gun that explains the latestPermian extinction," says Dr. Steve Grasby, adjunct professor in the U of C's geoscience department and research scientist at Natural Resources Canada.

Grasby and colleagues discovered layers of coal ash in rocks from the extinction boundary in Canada's High Arctic that give the first direct proof to support this and have published their findings in Nature Geoscience. Unlike the end of the dinosaurs, 65 million years ago-where there is widespread belief that the impact of a meteorite was at least the partial cause-it is unclear what caused the late Permian extinction. Previous researchers have suggested massive volcanic eruptions through coal beds in Siberia would generate significant greenhouse gases causing run away global warming.

Volcano lightning

How can a volcano create lightning? Why is volcanic lightning often contained within or in close proximity to the ash plume? What types of eruptions are most conducive for the creation of volcanic lightning? These are all good questions, and in order to answer them we must first look at the physics that makes it all possible.In order for lightning to form there is one key component; a large charge separation between two masses. If the charge separation becomes big enough it is then able to overpower the air resistance, create a path of ionized air, and conduct electricity in the form of lightning. The ash that is to be erupted begins as electro statically neutral rock or rock fragments. Heat and movement within the volcano is thought to be the first source of particle charging, although the main process by which ash particles acquire a charge is friction. When an object (in this case ash) with a neutral charge comes in contact with another object with differrent electro static qualities, electrons can potentially flow and one of the objects can become charged relative to the other. Think of skidding your socked feet rapidly across the carpet or rubbing a balloon quickly against your head. The same type of charge is accumulating within the ash cloud, only on a much larger scale.

Volcanic Hazards

volcanoes can be exciting and fascinating, but also very dangerous. Any kind of volcano is capable of creating harmful or deadly phenomena, whether during an eruption or a period of quiescence. Understanding what a volcano can do is the first step in mitigating volcanic hazards, but it is important to remember that even if scientists have studied a volcano for decades, they do not necessarily know everything it is capable of. Volcanoes are natural systems, and always have some element of unpredictability. 

Volcanologists are always working to understand how volcanic hazards behave, and what can be done to avoid them. Here are a few of the more common hazards, and some of the ways that they are formed and behave. (Please note that this is intended as a source of basic information only, and should not be treated as a survival guide by those who live near a volcano. Always listen to the warnings and information issued by your local volcanologists and civil authorities.)

 

WHAT IS AN ACTIVE VOLCANO?

THE TERM "ACTIVE VOLCANO" IS USED MAINLY IN REFERENCE TO EARTH'S VOLCANOES. ACTIVE VOLCANOES ARE ONES THAT ARE CURRENTLY ERUPTING OR THAT HAVE ERUPTED AT SOME TIME IN HUMAN HISTORY. 

THIS DEFINITION WORKS WELL FOR VOLCANOES ON EARTH BECAUSE WE CAN OBSERVE THEM EASILY. HOWEVER, BEYOND EARTH OUR ABILITIES TO DETECT VOLCANIC ERUPTIONS DID NOT BEGIN UNTIL THE INVENTION OF POWERFUL TELESCOPES. TODAY A NUMBER OF TELESCOPES ARE AVAILABLE TO DETECT THESE ERUPTIONS - IF THEY ARE LARGE ENOUGH. HOWEVER SMALL ERUPTIONS WOULD NOT BE NOTICED AND THERE ARE NOT ENOUGH TELESCOPES TO WATCH ALL AREAS OF THE SOLAR SYSTEM WHERE A VOLCANIC ACTIVITY MIGHT OCCUR. 

ALTHOUGH ONLY A FEW EXTRATERRESTRIAL ERUPTIONS HAVE BEEN DETECTED, MUCH HAS BEEN LEARNED ABOUT THEM. PERHAPS THE MOST IMPORTANT DISCOVERY IS THE ONES THAT HAVE BEEN OBSERVED SO FAR ARE VERY DIFFERENT FROM VOLCANOES THAT OCCUR ON EARTH. THEY ARE CRYOVOLCANOES. 

Volcanic eruptions

An eruption begins when pressure on a magma chamber forces magmaup through the conduit and out the volcano's vents.  When the magma chamber has been completely filled, the type of eruption partly depends on the amount of gases and silica in themagma.  The amount of silicadetermines how sticky (level ofviscosity) the magma is and waterprovides the explosive potential ofsteam. Obstacles also influence the type of eruption.  When the pipe is blocked by a stopple or an accumulation of pumice, the pressure in thepipe will build up very high resulting in an explosion.     When magma reaches earth's surface it is called lava.  It may pour out in gentle streams called lava flows or erupt violently into the air.  Rocks ripped loose from the inside of the volcano or torn apart by the gas may be shot into the air with the lava.  These rocks blown out of a volcano are called pyroclastic rocks.  The rock fragments fall back to earth in many different shapes and sizes: Volcanic activity is classified by how often a volcano erupts.  A volcano may be active, intermittent, dormant, or extinct.  Activevolcanoes erupt constantly.  Intermittent volcanoes erupt fairly regularly.  Dormant volcanoes are inactive, but not long enough to determine whether they will erupt again or not.  Extinct volcanoes have been inactive since the beginning of recorded history.

Lava Flows

Lava is molten rock that flows out of a volcano or volcanic vent. Depending on its composition and temperature, lava can be very fluid or very sticky (viscous). Fluid flows are hotter and move the fastest; they can form streams or rivers, or spread out across the landscape in lobes. Viscous flows are cooler and travel shorter distances, and can sometimes build up into lava domes or plugs; collapses of flow fronts or domes can form pyroclastic density currents (discussed later). 

Most lava flows can be easily avoided by a person on foot, since they don't move much faster than walking speed, but a lava flow usually cannot be stopped or diverted. Because lava flows are extremely hot - between 1,000-2,000°C (1,800 - 3,600° F) - they can cause severe burns and often burn down vegetation and structures. Lava flowing from a vent also creates enormous amounts of pressure, which can crush or bury whatever survives being burned. 

 

 volcano is a geological landform usually generated by the eruption through a vent in a planet's surface of magma, molten rock welling up from the planet's interior. Volcanoes of various types are found on other planets and their moons as well as on earth. Roughly defined, a volcano consists of a magma chamber, pipes and vents. The magma chamber is where magma from deep within the planet pools, while pipes are channels that lead to surface vents, openings in the volcano's surface through which lava is ejected during an eruption. Though the common perception of a volcano as a mountain spewing lava and poisonous gases from a crater in its top is not wrong per se, the features of volcanoes are much more complicated and vary from volcano to volcano depending on a number of factors. Some volcanoes even have rugged peaks formed by lava domes rather than a summit crater, whereas yet others present landscape features such as massive plateaus. Vents that issue volcanic material (lava, which is what magma is called once it has broken the surface, and ash) and gases (mainly steam and magmatic gases) can be located anywhere on the landform. Many of these vents give rise to smaller cones such as Pu‘u ‘Ō‘ō on a flank of Hawai‘i's Kilauea.

Volcano

What is Volcanic Ash?

Volcanic ash consists of powder-size to sand-size particles of igneous rock material that have been blown into the air by an erupting volcano . The term is used for the material while it is in the air, after it falls to the ground and sometimes after it has been transformed into rock. The terms "volcanic dust" and "volcanic ash" are both used for the same material, however "volcanic dust" is more appropriately used for powder-size material. Ash deposited on the ground after an eruption is known as ashfall deposit. Significant accumulations of ashfall can lead to the immediate destruction of most of the local ecosystem, as well the collapse of roofs on man-made structures. Over time, ashfall can lead to the creation of fertile soils.

Asphalt volcano

About 10 miles off the Santa Barbara coast, at the bottom of the Santa Barbara Channel, a series of impressive landmarks rise from the sea floor. 

They've been there for 40,000 years, but have remained hidden in the murky depths of the Pacific Ocean--until now. 

They're called asphalt volcanoes. 

Scientists funded by the National Science Foundation (NSF) and affiliated with the University of California at Santa Barbara (UCSB), the Woods Hole Oceanographic Institution (WHOI), University of California at Davis, University of Sydney and University of Rhode Island, have identified the series of unusual volcanoes. 

How They Avoided Discovery  The largest of these undersea Ice Age domes lies at a depth

of 700 feet (220 meters), too deep for scuba diving, which explains why the volcanoes have never before been spotted by humans, says Don Rice, director of NSF's Chemical Oceanography Program, which funded the research. 

"They're larger than a football-field-long and as tall as a six-story building," says David Valentine, a geoscientist at UCSB and the lead author of a paper published on-line this week in the journal Nature Geoscience. "They're massive features, and are made completely out of asphalt." 

Valentine and colleagues first viewed the volcanoes during a 2007 dive on the research submersible Alvin. Valentine credits Ed Keller, an earth scientist at UCSB, with guiding him and colleagues to the site. 

Arenal volcano

Arenal Volcano, the youngest stratovolcano in Costa Rica, is one of the most active volcanoes in that country and in the world. It has been producing lava and pyroclastic flows almost continuously since 1968; this activity has been both a danger to people living near the volcano and a draw for thousands of tourists over the years. Located on the eastern shore of Lake Arenal in northwestern Costa Rica, Volcan Arenal was thought to be extinct prior to the eruptions of 1968, although it is now known that eruptions have occurred on and off for the last 7,000 years. 

The volcanic arc of Costa Rica, where Arenal is located, is a chain of mountains resulting from the subduction of the Cocos tectonic plate under the Caribbean Plate. Costa Rica is part of the Central American isthmus, which connects the North and South American continents Volcanoes are mostly confined to a NW-SE trending strip in the northern part of Costa Rica because the Cocos plate subducts at a very steep angle there, and because the Cocos Ridge disrupts normal subduction to the southeast. Arenal is located northwest of the Chato volcanic complex, which last erupted about 4,000 years ago. 

Arenal Volcano: Plate Tectonic Setting

Rock cycle and volcanoes

Geologists identify the three major rock types as igneous, sedimentary, and metamorphic. Each specific rock begins due to the Earth's mantle melting and forcing magma to the ground surface. The process of nature transforms the molten rock into igneous, sedimentary, and then metamorphic. (2004, Rock Cycle).The Rock Cycle Igneous rocks may be formed due to the cooling of molten rock released by volcanic magma above or below the Earth's surface. Volcanic igneous rocks begin to form when the temperature of molten rock is cooled quickly after an eruption above the surface. Plutonic igneous rocks are formed beneath the surface after the molten rock slowly cools and solidifies. (2004, Rock Cycle). 

Metamorphic rocks may be formed due to chemical and physical changes of igneous or sedimentary rocks. Igneous and sedimentary rocks endure high levels of pressure, heat, and force which produce the metamorphic rock. Igneous, sedimentary, or metamorphic rocks can be heated to such a degree in which they are melted and repeat the rock cycle. (2000, Fichter).

Sedimentary rocks are a result of igneous rocks enduring weathering, erosion, and lithification. Igneous rocks are exposed to nature's process of transporting small particles of the rocks and depositing them as sediments. Sediments endure the process of lithification which compacts and cements the small particles of igneous rocks. The hardened particles are then formed into sedimentary rocks. (2005, Rocks). 

Hawaii 

Hawaii is a very popular vacation spot and tourist attraction. The island is apart of the United States and is surrounded by five volcanoes. Kohala, Mauna Kea, Hualalai, Mauna Loa, and Kilauea are the volcanoes that make up the big island of Hawaii. One volcano is considered dormant, one extinct, and the remaining three are said to be active. (2007, Fisher). Visiting Hawaii can be very exciting, especially if you wish to see volcanoes. However, it's nearly impossible to see the entire rock cycle process. The Earth's mantle pushes melting magma towards the surface and erupts through a volcano.

The magma is spread across land which is viewable to people on the island of Hawaii. The molten rock would be cooled and hardened into igneous rock. This process may also take place underground which would not be viewable to tourists and residents of Hawaii. Viewing volcanic activity is an everyday event for residents but can be rather scary for tourists if they don't know what to expect! Sedimentary and metamorphic rocks would not be able to be seen immediately after an eruption. Often the process of their transitions into rocks is below the Earth's surface. (2004, Rock Cycle).

The Philippine Institute of Volcanology and Seismology (Filipino: Suriang Pilipino ng Bulkanolohiya at Sesmolohiya, abbreviated as PHIVOLCS) is a Philippine national institution dedicated to provide information on the activities of volcanoes, earthquakes and tsunamis, as well as other specialized information and services primarily for the protection of life and property and in support of economic, productivity and sustainable development. It is one of the service agencies of the Department of Science and Technology.Phivolcs monitors volcano, earthquake, and tsunami activity, and issues warnings as necessary. It is mandated to mitigate disasters that may arise from such volcanic eruptions, earthquakes, tsunami and other related geotectonic phenomena.

PHIVOLCS

HistoryThe predecessor to PHILVOCS, the Commission on Volcanology (COMVOL) was created on June 20, 1952 by Republic Act no. 766 after the disastrous eruption of Hibok-Hibok Volcano in 1952.Under Executive Order no. 784 of March 17, 1982, the umbrella department of COMVOL, the National Science Development Board (NSDB) was reorganized into the National Science and Technology Authority (NSTA), and COMVOL was restructured to become the Philippine Institute of Volcanology or PHILVOLC.The seismological division of the PAGASA, the successor to the Philippine Weather Bureau created in 1907, was transferred to PHILVOLC on September 17, 1984, renaming the institute as the Philippines Institute of Volcanology and Seismology or PHILVOCS. NSTA, the umbrella department for PHILVOCS and PAG-ASA became the Department of Science and Technology (DOST) in 1987.PHILVOCS was headed by Raymundo Punongbayan  from 1982 to 2003, and it is currently headed by Renato U. Solidum Jr. from 2003 to the present.