Presentation on theme: "By: Zaisha Brothers & Jen Cleveland. Volcanoes, are a mountain or hill formed by the accumulation of materials erupted through one or more openings in."— Presentation transcript:
By: Zaisha Brothers & Jen Cleveland
Volcanoes, are a mountain or hill formed by the accumulation of materials erupted through one or more openings in the earth’s or other planets surfaces. Most volcanoes have steep sides, but some can be gently sloping mountains or even flat tablelands, plateaus, or plains. The volcanoes above sea level are the best known, but the vast majority of the world's volcanoes lie beneath the sea, formed along the global oceanic ridge systems that crisscross the deep ocean floor.
Formation All volcanoes are formed by the accumulation of magma; molten rock that forms below the earth's surface. Magma can erupt through one or more volcanic vents, which can be a single opening, a cluster of openings, or a long crack, It forms deep within the earth, generally within the upper part of the mantle; one of the layers of the earth’s crust. High temperatures and pressures are needed to form magma. The solid mantle or crustal rock must be melted under conditions, commonly to reach depths of 80 to 100 km below the earth’s surface. Once tiny droplets of magma are formed, they begin to rise because the magma is less dense than the solid rock surrounding it. For magma to rise is, it generally moves upward toward lower pressure regions, squeezing into spaces between minerals within the solid rock. When individual magma droplets rise, they join to form larger blobs and move toward the earths surface. The larger the rising blob of magma, the easier it is for it to move. Rising magma does not reach the surface in a steady manner but tends to accumulate in one or more underground storage regions, called magma reservoirs, before it erupts onto the earths surface. With each eruption, whether it is explosive or non-explosive, the material erupted adds another layer to a growing volcano. After many eruptions, the volcanic materials pile up around the vent or vents. These piles form a hill, mountain, plateau,or a crater, that we today recognize as a volcano. Most of the earth's volcanoes are formed beneath the oceans surfaces.
Volcano Formations Around The World DaytimeNight Time
Volcanic Materials There are 3 different types of materials that can erupt from an active volcano. These materials are lava, tephra and gases. The type and amount of the material that erupts from an active volcano depends on the composition of the magma inside the volcano.
May 18, Mount St Helens Eruption BeforeDuringAfter On May 18th, 1980 the eruption of Mt. St. Helens in southwest Washington state disrupted the lives of thousands and changed more than 200 square miles of rich forest into a grey, lifeless landscape. Now, twenty-two years later, the land around the mountain is slowly healing itself. Nature is covering the scars of the eruption but many people will never forget what happened that day.
Cinder Cone Volcanoes Cinder Cones are the easiest type of a volcano. They are built from particles and blobs of congealed lava ejected from a single vent. As the gas- charged lava is blown into the air, it breaks into small fragments that solidify and fall as cinders around the vent to form a circular or oval cone.
Composite Volcanoes Composite volcanoes are steep-sided. These volcanoes can blast fragments up to 8,000 feet above the base of the volcano.
Lava Dome Volcanoes Lava Domes are formed by small, bulbous masses of lava, which piles over and around the vent of the volcano. The dome grows larger within itself.
Shield Volcanoes Shield volcanoes are built almost entirely of lava flows. The lava flows out in all direction from the central vent.
This is an eruption of Stromboli Volcano in August 2002.
Volcano damage is caused by clouds of ash that rise above a volcano, and in addition some explosive eruptions produce avalanches of hot ash, rock and gas that move at high speeds down the slopes of a volcano. Ash flows are the most destructive type of volcanic activity. They are extremely hot and move across the ground as fast as, several 100 kilometers per hour. Ash flows knock down and burn everything in their way. Very few living things can survive an ash flow. The damage a volcano causes is life-altering and can even causes death in a lot of situations This is a picture of a forest that has been cleared from a volcano eruption
There are several processes that occur on the slopes of the volcano that are hazards to humans and the environment around them. Most of the hazards are directly caused by volcanic eruptions. BLASTS OR PROJECTILES Large projectiles can damage buildings; if these are hot they can start fires. MUD FLOWS Frequently accompany volcanic eruptions and can be lethal. Lakes can mix with volcanic rock and debris to form a near- solid flow which engulfs all in its path. PYROCLASTIC FLOWS Mixtures of hot gases, ash, fine pumice and rocks; danger lies in the density and temperature of the ash and rock fragments. Pyroclastic flows can move at very high speeds, possibly over 100 km/h. Hazards include body surface burns, inhalation injuries and asphyxia. GASES These may be asphyxiants which are concentrated near the volcanic crater or fissure or respiratory irritants which are more dispersed and can be harmful at lower concentrations. LAVA FLOWS These are flows of extremely hot molten rocks extruded by the volcano. The viscosity and high temperature make these flows very dangerous and they are capable of destroying all in their path. LOCAL EARTHQUAKES Possible loss of human life and property. TSUNAMIS Tsunami is Japanese for "tidal wave", the seismic wave that can hurtle across oceans at up to 600 miles per hour (800 km/hour). Occurrence is unpredictable and can destroy coastlines. Expected Hazards After A Volcano Eruption
Volcanic eruptions are predicted by signs, some of which are not detected by any instruments, or observed by volcanologists. The following are some points that should be taken into consideration to respond effectively to a volcanic eruption: BEFORE THE ERUPTION Community Preparation Demarkation and evacuation of areas of risk. Formulation of and familiarization with search and rescue plans. Preparation of hospital emergency plans to cope with large influx of patients with burns, lung damage and trauma. Identification of facilities to collect and analyse ash for toxic elements and drinking water quality. Facilities and equipment for monitoring air. Plans for procurement of emergency supplies. Report any and all unusual physical changes around volcanoes to the Seismic Research Unit, e.g. the drying up of vegetation, rumbling sounds, earthquakes, landslides and other possible abnormalities. DURING THE ERUPTION Pay attention to Warnings, which would include evacuation notices and escape from area as quickly as possible. Listen to the radio for information and advice. Find shelter, but NOT in a building with low-pitched or flat roof, if heavy ash is falling. Avoid basements and closed spaces where gases may accumulate. Wear protective clothing over head and body if you have to move in an ash shower. Breathe through a handkerchief. Always carry a flashlight, even during the daytime.
NORMAL - All the monitored parameters are within the levels exhibited during non-eruptive (normal) periods, no eruption may be expected in the near future. ABNORMAL - Some of the monitored parameters had recently deviated from the normal patterns. The abnormality may persist for some time and may deteriorate and eventually lead to an eruption within the next few months. ALARMING - Monitored parameters indicate conditions that resemble recorded precursors, the abnormality may lead to an eruption in the near future, probably within weeks or a few months. CRITICAL - Monitored parameters indicate pre-eruptive conditions; the volcano's condition may lead to an eruption in the immediate future, probably within several weeks. ERUPTION IMMINENT - The volcanoes condition indicate a high probability for an eruption to occur in the immediate future, probably within a few weeks or days. ERUPTIVE - The volcano had entered an eruptive condition.