Simulation of Volcano Eruption

PRACTICAL REPORT

SCIENCE EDUCATION

‘SIMULATION OF VOLCANO ERUPTION’

 

 

 

Arranged By:

OKTAVIANI PRATAMA PUTRI

10315244034

INTERNATIONAL OF NATURAL SCIENCE EDUCATION

FACULTY OF MATEMATHICS & NATURAL SCIENCE EDUCATION

YOGYAKARTA STATE UNIVERSITY

2011

 A.    Litle

Simulation of Volcano Eruption

B.     Goal

1. Students are able to observe how a model of volcano can erupt proceed wich caused by pressure

2. Students are able to observe the characteristic of chemical reaction in a model of volcano

3. Students are able to explain the effect of volcanic eruption for the surrounding area

4. Students are able to explain process of volcano that actually

C.    Background

Disaster is an event or series of events that threaten and disrupt the lives and livelihoods caused by both natural factors and non-natural factors and human factors that lead to the emergence of human casualties, environmental damage, property loss and psychological impact. Examples of natural disasters, among others, which include earthquakes, tsunamis, volcanic eruption, floods, droughts, hurricanes and land langsor. While non-natural disasters are examples of social conflict, epidemics and outbreaks of disease.

Judging from the location of geological, weather and social conditions, Indonesia is prone to various disasters such as earthquakes, tsunamis, floods, landslides, storms and hurricanes, plagues, droughts and volcanoes. Disasters occur when natural hazards (such as volcanoes) met with vulnerable communities (villages on the slopes of a volcano) that have a low ability or lack the ability to respond to this threat (no training or understanding of volcanoes, or not ready). The impact that arises is the disruption of community life such as the destruction of homes, property damage and casualties.

 D.    Basic Theory

Volcano or volcanoes in general is a term that can be defined as a system of hot fluid channel (in the form of molten rock or lava) that extends from a depth of about 10 km below the surface of the earth to the earth’s surface, including the accumulation of sediment material issued on when erupted. Furthermore, the term volcano is also used to name the phenomenon of ice formation Volcanoes or ice and mud volcanoes Volcanoes or volcanic mud. Ice volcanoes commonly occur in areas that have a snowy winter, while the mud volcanoes can be seen in the area Kuwu, Grobogan, Central Java are popular as Bleduk * Kuwu. Volcanoes are found in several forms throughout their lifetime. Active volcano might become active half, rest, before becoming inactive or dead. However the volcano could break in time 610 years before it became active again. Accordingly, it is difficult to determine the actual state of a volcano, the volcano is in a resting state or died. If the volcano erupts, magma is contained in the room magmar under the volcano erupted out as lava or lava. Other than lava flows, volcanic devastation caused by a variety of ways as follows:

  1. The flow of lava.
  2. The eruption of the volcano.
  3. The flow of mud.
  4. Abu.
  5. Forest fires.
  6. toxic gas.
  7. Tsunami waves.
  8. Earthquakes.

Volcanic eruptions are part of the volcanic activity is known by the term “eruption”. Almost all volcanic activity associated with an active seismic zone associated with plate boundaries cause. On this plate boundary change in pressure and temperature is very high so as to melt the surrounding material which is an incandescent fluid (magma). Magma will mengintrusi surrounding rock or soil through cracks, fractures near the surface of the earth. Each volcano has its own characteristics when viewed from vomit or type of product. However, any product type volcanoes activity remains to be disastrous for life. Dangers of volcanic eruptions have the risk of damaging and deadly. Volcano Eruption hazard is divided into two by the time it happened, that is

Main Danger (Primary)

  1. Heat clouds, is a mixture of materials eruption of gas and rocks (all sizes) pushed down due to the high density and a saturated roll dough in turbulence like clouds along the mountain slopes. In addition to very high temperatures, between 300-700 degrees Celsius, the speed lumpurnyapun very high,> 70 km / h (depending on slope).
  2. Burst of Materials (incandescent), occurs when the eruption (magmatic) takes place. Lontarannya very much depends on the size of the eruption of energy, can reach hundreds of meters away. In addition to high temperature (> 200 º C), the size of the material was large with a diameter> 10 cm so it can burn at once injure, even kill living things. Also commonly referred to as “volcanic bombs”.
  3. Abu heavy rain, occurs when a volcanic eruption is underway. Fine-sized material (ash and fine sand) that the wind and falls as rain of ash and its direction depends on the wind direction. Because the size is fine, this material would be very harmful to the respiratory, eye, ground water pollution, destruction of vegetation and contains chemical elements that are acidic so they can lead to corrosion of zinc and aircraft engines.
  4. Lava is magma that reaches the surface, its liquid (viscous liquids and high temperature, between 700-1200 º C. Because of the liquid, then the lava generally flows follow the slopes and burn everything in its path. When the lava has cooled, then his form into rock (igneous ) and the area in its path will be a field stone.
  5. Poison gas, appears not always preceded by volcanic eruptions because gases can escape through cavities or fractures-fractures are found in volcanic regions. The main gas that usually appears is CO2, H2S, HCl, SO2, and CO. Which often causes death is CO2. Some of the mountain that has the characteristics of poisonous gas eruption was Mount Tangkuban Fire Boat, Dieng Volcano, Mount Ciremai, and the Mountain of Fire Papandayan.
  6. Tsunami, can generally occur in volcanic islands, where the eruption occurs when the materials will provide great energy to push water toward the sea coast, causing a tsunami. The larger the volume of material greater eruption waves lifted ashore. For example, the case is the eruption of Mount Krakatoa in 1883.

Joined Danger (Secondary)

Danger follow-up is the danger of volcanic eruptions that occurred after the explosion took place. When a volcano erupts it will happen accumulation of material in various sizes at the summit and upper slopes. During the rainy season arrives, some material will be carried by rain water and mud to create the dough down into the valley as rocks flood, floods are called lahars. Volcanoes are formed from magma, molten rock that is deepest in the earth. Magma is formed due to the heat inside the Earth’s interior. At a certain depth, the temperature is very high heat so as to melt the rocks inside the earth. When this molten rock, gas dihasilkanlah which then mixes with the magma. Most of the magma formed at depths of 60 to 160 km below the earth’s surface. Others are formed at depths of 24 to 48 km. Magma containing gas, gradually rising to the surface because of its mass is lighter than the solid rock around it. When the magma rises, the magma melts the nearby rocks, forming a large cabin at a depth of about 3 km from the surface. Cab magma (magma chamber) is what is the warehouse (reservoir) where volcanic eruptions originating materials.
Magma containing gas in the cabin in a state of magma under the pressure of heavy rocks that surround it. This pressure causes the magma erupts or melt conduit (channel) on the rocks brittle or cracked. Magma moves out through these channels leading to the surface. When magma approaches the surface, the gas content in it regardless. Gas and magma exploded together and form a hole called the main hole (central vent). Most of the magma and other volcanic material and then gush out through this hole. After bursts of stops, the crater (crater) that resemble bowls usually formed at the peak of the volcano. While there are major holes in the bottom of the crater.
Once the volcano is formed, not all magma that appears on the next eruption rises to the surface through the main hole. When the magma rises, some may break through walls or branched cracks through the smaller channels. Magma is through these channels may be out through another hole formed on the side of the mountain, or may also remain below the surface.

The characteristics of a volcano will erupt.

Volcano will erupt can be known through several signs, including:

  1. The temperature in the surrounding mountains rise.
  2. Springs become dry
  3. Often issued a thundering voice, sometimes accompanied by vibration (earthquake)
  4. Wilted plants in the surrounding mountains
  5. Animals in the surrounding mountains migrate

The occurrence of the process of eruption

This is the content of the Earth, where the age of the Earth who has reached 4.5 billion years old. Earth is actually composed of a hot core of the Earth and its rocks and soil. Because covered by rocks and soil, then the surface is not hot. Then, heat from the core will be channeled to the soil and rocks, so that the inside of the Earth will be turbulent because of the heat.

Heat generated by the core of the Earth will continue to burn part of stones and soil that protects the Earth’s surface. However, the coat that protects it would not be able to withstand the magma core of the Earth is too long. This resulted in deposition of magma from the Earth’s core is increased. This is what is called a stratovolcano. If this magma is not strong enough to hold, it will be ejected out along the rocks and smoke from the volcano eruption. Magma erupted lava that will generate some where if on an object, will make a fire on the object that is passed.
Lava ejected by the volcano can reach a considerable distance, which is about 40km. In the distance, moving lava was still in a fairly hot temperature. And if past the 40km distance, lava began to cool down gradually. Lava Lava is called with. Not to forget also the smoke produced. This smoke contains sulfur dioxide that can reach areas far enough. These substances can stimulate the occurrence of an acid rain in the area around the smoke. In addition, smoke can lead to the eruption of shortness of breath for living things. The crust is a thin layer of solid rock (10 to 70 km) that floats over a thick layer of molten rock, the mantle, where the stone is at a temperature of 1100-1200 ° C in the most superficial layers and hotter and hotter with increasing depth. This molten rock magma is fluid that comes out of volcanoes on the surface of the earth’s crust and the lava rock when it freezes. The crust gives a great pressure on the mantle magma that tend to benefit at any weak point that is above the earth’s crust, formed by several faults, to go up and come out on top surface. The volcano with a distinctive conical shape is formed into many layers of compacted lava eruptions for hundreds of thousands of years. This is a normal life of the volcano.

How magma from the mantle could be so easy to get out through the crust of the earth?

The answer lies in the same coat, this is indicated by large convective movements that cause a decline in magma the top of the cooler, replaced by magma in a hotter part of a continuous cycle, similar to water boiling in a kettle. Convection flow is widely present in the mantle and move like conveyor belts, are able to move an area of the earth’s crust. For this reason, divided into many crustal plates that move between one another a few centimeters each year. Only the edges of crustal plates is weak and unstable regions of the earth’s crust where magma from the mantle can easily appear to form a volcano. The crust is the shortest (only 50-10 km) proximity to the sea bottom and thick at the bottom of the main volcanic mountains, but most are formed or are still being formed today only along the boundary between two crustal plates where the collision occurred between one another. So, one of the two plates (A) to subside / ebb and move down another plate (B), submerged in the mantle and the melt becomes less dense; new magma is pushing the edge contributes to the upper crustal plates B and form a mountain range ( mountains), parallel to the edge of the crust. This is what happened to the Indian plate with the hit and returned to normal under the Asian plate and the results of a large pressure is of the Himalayas and the Tibetan plateau. Magma eruption subsided by the gases dissolved in it, mainly because of magma through the crust layer and decomposing parts of the rocks along the way. So saturated magma under great pressure with gases such as CO2, SO2, HCl, HF, H2O, H2 and others. When magma rises along the main hole of the volcano, the pressure is reduced and the gas separated from the magma to form bubbles. This tends to rise to the top and increase upward pressure exerted by the lava. It is important to note that the magma erupted from the volcano did not come directly from the mantle, but from a large magmatic chamber or “caldera” and is located in the crust of the earth. Caldera is located in several kilometers beneath the volcano, directly related to the crater.
Viscosity of magma is very important to explain the eruption of the volcano because it is very varied. The most viscous magma volcanoes form where molten rock tends to condense soon after the eruption, or even before it came out of the crater. As a result, it tends to clog the volcanic magma plug the hole with a cap of dense magma at the end of each eruption. Conclusions for each explosive eruption is only the first step towards the next eruption, although after several centuries, even the pressure of basic magma and gas, sooner or later tend to make it explode so that the lid of a volcano eruption is usually sudden and explosive, after a long period of time calm. The severity of the eruption in the surrounding area is triggered by an explosion caused by gases released by hard by a very viscous magma, moving along with some ash, embers and debris originating from the parts of the mountain which was destroyed by the explosion. This form of hot gas clouds are high and big and solid particles that can be collapsed on the sides of the volcano and formed clouds of ash and gas that burn everything along their path.

The threat of Mount Merapi

The volcano erupted as a result of magma in the bowels of the earth is pushed out by high-pressure gas or due to movement of the Earth’s plates, pile the pressure and heat the liquid magma. The explosion brought ash and rock that burst with a loud, while the lava could flood the surrounding area. As a result of the eruption could cause casualties and huge property in the area of a radius of thousands of kilometers and can even affect the climate on earth is round, as happened at Mount Pinatubo in the Philippines, and Mount Krakatoa in Banten Province, Indonesia.

1. Impact of eruption

Volcanic gases are gases released during volcanic eruptions such as Carbon Monoxide (CO), Carbon Dioxide (CO2), Hydrogen Sulfide (H2S), Sulfur Dioxide (SO2) and nitrogen (N2) are harmful to humans. Lava is a very high-temperature fluid magma that flows to the surface through a volcanic crater. Lava flows can dilute away from its source to follow the river or valley there, while the thick lava flows not far from the source. Lava is also one threat to the community around Mount Merapi. Lahar threat has occurred in the eruption of Mount Merapi in 1994 and 2006. Lahar is a flash flood on the slopes of the mountain that consists of a mixture of volcanic material sized lump of clay till. Lahars can be either hot or cold lava lava. Hot lava from the eruption of a volcano that has a crater lake, the lake where the water gets hot and then mixed with material from the mouth of the eruption and the mountain. Cold or raining lava lava eruption occurs because the material mixing with rain water around the mountain and then make a thick mud flows from the mountain slopes. This sludge can be hot or cold.

Hot cloud (wedhus trash) is the result of volcanic eruptions of the most dangerous because there is no way to save themselves from the hot clouds except to evacuate before the mountain erupted. Blowing hot cloud is a cloud of small eruptions of hot material, blown by the wind speeds reach 90 miles per hour. Dropping the hot cloud is a cloud of hot material large and small eruption that was brought up by the power of a large eruption. Large-sized material will fall around the peak, while the fine would fall in the tens, hundreds or even thousands of kilometers from the summit because of the influence of wind gusts. Hot clouds can cause burns on exposed body parts such as head, arms, neck or legs, and also cause shortness of breath could not even breathe. Even the eruption in 2006, heat clouds had claimed two lives in Kaliadem.
Ash eruption volcano eruption is a very delicate material. Because the effects of wind can be felt hundreds of miles away. At such large eruptions have occurred at Mount Krakatoa, even covered the ash produced matahasi rays for weeks.

2. Preparedness actions Preparation in Facing Mount Merapi Eruption

Concrete step in the eruption of Mount Merapi preparedness include:

  1. Recognizing the signs of disaster, the character of the mountain and threats
  2. Make a map of threats, recognizing the threat area, safe area
  3. Create an early warning system
  4. Developing community radio for information dissemination status of volcano
  5. Observing and understanding the volcano Prone Area Map issued by the competent authorities
  6. Preparing for disaster planning and refugee pathways that have been prepared with basic ingredients (water, latrines, food, first aid) if required
  7. Preparing for basic needs and essential documents
  8. Monitor the information provided by the volcano Observation Post (coordinated by the Directorate of Volcanology and Geological Hazard Mitigation). Volcano observation post usually communicate development status of the volcano over the radio communications
  9. Actions Do When Should Happen eruption of Mount Merapi

Action taken when the eruption has occurred are:

  1. Avoid areas prone to disasters such as mountain slopes, valleys, streams and rivers dried lava flow area Avoid open space, protect themselves from ash eruptions
  2. Sign in protected space in case of emergency hot cloud
  3. Prepare yourself for the possibility of subsequent disasters Wear clothing that can protect the body, such as long sleeves, long pants, hats and other
  4. Protect the eyes from dust, if any such use eye protection goggles or anything that could prevent the entry of dust into the eyes Do not wear contact lenses
  5. Wear a mask or cloth to cover the mouth and nose
  6. When volcanic ash falling try to cover her face with both hands
  7. Actions that should occur after eruption

After the eruption the thing to do is:

  1. Stay away from areas affected by ash fall
  2. Clean the roof of the heap of ashes because of the weight can damage or tear down the roof of the building
  3. Avoid driving in areas affected by ash fall could cause damage to the engine, brakes, gearbox and ignition

Acetic acid

Acetic acid, ethanoic acid or vinegar is a chemical compound of organic acids known as the taste and aroma acids in the diet. Acetic acid has the empirical formula C2H4O2. This formula is often written in the form CH3-COOH, CH3COOH, or CH3CO2H. Pure acetic acid (glacial acetic acid is called) is a colorless hygroscopic liquid, and has a freezing point of 16.7 ° C. Acetic acid is one of the simplest carboxylic acid, the formic acid. Acetic acid solution in water is a weak acid, meaning that only partially dissociates into ions H + and CH3COO-. Acetic acid is a chemical reagent and industrial raw materials are important. Acetic acid is used in the production of polymers such as polyethylene terephthalate, cellulose acetate, and polyvinyl acetate, as well as a variety of fibers and fabrics. In the food industry, acetic acid is used as an acidity regulator. In households, diluted acetic acid is also frequently used as a water softener. Within a year, the global thirst for acetic acid reached 6.5 million tons per year. 1.5 million tonnes per year is obtained from recycled, the rest is obtained from the petrochemical industry as well as from biological sources.
Acetic Acid (Acetic Acid, Ethanoic Acid, Methyl carboxylic acid) is a chemical compound with molecular formula CH3COOH, a clear liquid colorless, pungent, and sour taste. These  C at a pressure of 1°chemicals have a boiling point of about 117.9  atm, and at high concentrations will corrode various metals.

In a real volcano, molten rock from deep within the Earth erupts through a volcano (the molten rock is called magma when it is within the Earth and is called lava when it comesout of a volcano). In this project, a mock volcano will erupt with a bubbly, fizzy liquid that is created by a simple chemical reaction.

This project shows what happens when an acid (vinegar) and a base (baking soda) interact. Chemically, the acid and base neutralize each other, producing carbon dioxide gas as a byproduct. The exact reaction is:  HC2H3O2 (vinegar = acetic acid) + NaHCO3 (baking soda = sodium bicarbonate) = CO2 (carbon dioxide gas) + NaC2H3O2(sodium acetate) + H2O (water)

Volcanic Gases and Their Effects

Magma contains dissolved gases that are released into the atmosphere during eruptions. Gases are also released from magma that either remains below ground (for example, as an intrusion) or is rising toward the surface. In such cases, gases may escape continuously into the atmosphere from the soil, volcanic vents, fumaroles, and hydrothermal systems.

At high pressures deep beneath the earth’s surface, volcanic gases are dissolved in molten rock. But as magma rises toward the surface where the pressure is lower, gases held in the melt begin to form tiny bubbles. The increasing volume taken up by gas bubbles makes the magma less dense than the surrounding rock, which may allow the magma to continue its upward journey. Closer to the surface, the bubbles increase in number and size so that the gas volume may exceed the melt volume in the magma, creating a magma foam. The rapidly expanding gas bubbles of the foam can lead to explosive eruptions in which the melt is fragmented into pieces of volcanic rock, known as tephra. If the molten rock is not fragmented by explosive activity, a lava flow will be generated.

Together with the tephra and entrained air, volcanic gases can rise tens of kilometers into Earth’s atmosphere during large explosive eruptions. Once airborne, the prevailing winds may blow the eruption cloud hundreds to thousands of kilometers from a volcano. The gases spread from an erupting vent primarily as acid aerosols (tiny acid droplets), compounds attached to tephra particles, and microscopic salt particles.

Volcanic gases undergo a tremendous increase in volume when magma rises to the Earth’s surface and erupts. For example, consider what happens if one cubic meter of 900°C rhyolite magma containing five percent by weight of dissolved water were suddenly brought from depth to the surface. The one cubic meter of magma now would occupy a volume of 670 m3 as a mixture of water vapor and magma at atmospheric pressure (Sparks et. al., 1997)! The one meter cube at depth would increase to 8.75 m on each side at the surface. Such enormous expansion of volcanic gases, primarily water, is the main driving force of explosive eruptions.

The most abundant gas typically released into the atmosphere from volcanic systems is water vapor (H2O), followed by carbon dioxide (CO2) and sulfur dioxide (SO2). Volcanoes also release smaller amounts of others gases, including hydrogen sulfide (H2S), hydrogen (H2), carbon monoxide (CO), hydrogen chloride (HCL), hydrogen fluoride (HF), and helium (He).

  • Chemical reaction

Means of chemical reactions chemical changes that occur in the material or substance. In chemical reactions, always there is a change that produces new substances, the properties are different from the previous substance. As an example of a paper that is burned will generate black ash. dust is a new substance because of its properties are different from paper, so that the burning of paper belonging to the chemical reaction.

Characteristic of chemical reaction

1. Color changes occur

In a chemical reaction, reactants are converted into products. Changes that can occur due to the termination of the bonds between atoms of the reactants and the formation of bonds that make up new  product. Energy required to decide ties. To form a new bond, release some energy. Thus, the chemical reaction energy changes. Chemical reactions that produce energy in the form of heat is called exothermic reaction. Reactions that absorb heat energy is called endothermic reactions.
Example: Fire can warm the body when breathing cold and the heat released in the body due to exercise so the body becomes cold.

2. Temperature changes occur

In a chemical reaction, reactants are converted into products. Changes that can occur due to the termination of the bonds between atoms reagents and formation of new bonds that form the product. Energy required to decide ties. Chemical reactions that produce energy in the form of heat is called exothermic reactions, whereas reactions that absorb heat energy is called endothermic reactions. Chemical reactions occur in a space that we call the system, a place outside the system is called with the environment.

In exothermic reactions, heat transfer occurs from system into the environment. In endothermic reactions occur transfer heat energy from the environment to the system.

3. The precipitate formation occurs

When the reaction of two solutions in a test tube, sometimes forming an insoluble compound, solid, and separated from the solution. The solid is called the precipitate (precipitate)

4. Gas formation occur

Simply put, the chemical reaction of gas that is formed is shown by the presence of bubbles in the solution are reacted. The presence of gas can be known from the typical smell, such as acid sulfide (H2S) and ammonia (NH3), which stinks.

  • Chemical reaction between acetic acid and baking soda

The reaction between acetic acid (CH3COOH) with baking soda (NaHCO3) produces carbon dioxide gas (CO2) by the following equation

CH3COOH + NaHCO3 + H2O + CO2 CH3COONa (gas)

So one of the characteristics of chemical reactions is the formation of gas as a result of the reaction

To distinguish the type of gas that occur in chemical reactions can be seen from the properties of the gas. For example:

–          Gas-hydrogen would produce a burst of small explosion when the gas is charged with burning coals

–          Gas oxygen will cause the burning embers

–          Carbon dioxide gas will be shut down embers

–          Gas will remove the smell of urine ammonia

–          Gas sulfur dioxide and hydrogen sulfide gas will produce a foul odor

E.     Tools and Materials

1. Hose

2. Injection

3. Tray

4. Acetic acid (CH3COOH)

5. Sodium bicarbonate (NaHCO3)

6. Red dye

F.     Procedures

1. Make a model of volcano in the tray and make a hole in center of imitation mountain as a crater

2. Put a hose under a clay

3. Pour a acetic acid in to beaker glass and give red dye

4. Poue a sodium bicarbonate in to creater of model a volcano

5. Suck a acetic acid with the injection

6. Push the injection with slowly and to be careful

7. Observe it

G.    RESULT

Make a miniature volcano from clay, then perforated in advance to make way hose. Next connect the volcanic clay with a hose. After the peak of the volcano put baking soda, then fill with fluid injection of acetic acid. After injection of acetic acid is filled with fluid that has been colored with red dye, then connected with the end of the hose. Then the injection pressure. Finally, there small sebuaherupsi of volcanic eruption similar to the current. This occurs because the chemical reaction between baking soda and acetic acid (CH3COOH). This reaction produces bubbles.

H.    Data of observation

    

 I.       Discussions

Praktikum yang dilakukan pada hari kamis 13 Oktober 2011, berjudul “Simulation of Volcanic eruption” memiliki tujuan mampu mengamati bagaimana model dari gunung berapi dapat meletus yang disebabkan oleh tekanan, mampu mengamati karakteristik reaksi kimia dalam suatu model dari gunung berapi, mampu menjelaskan pengaruh letusan gunung berapi untuk daerah sekitarnya, mampu menjelaskan proses dari gunung berapi pada kenyataan. Alat dan bahan yang kami gunakan dalam percobaan ini antara lain clay/sand/soil, hose, injection, tray, acetic acid (CH3COOH), sodium bicarbonate (NaHCO3) dan red eye.

Pada praktikum kali ini membahas mengenai letusan gunung berapi meliputi tekanan yang menyebabkan erupsi, reaksi kimia yang terjadi antara natrium bikarbonat dengan asam asetat, pengaruh dari letusan gunung berapi bagi ekosistem sekitar dan proses letusan gunung berapi pada kenyataan. Kami membuat sebuah simulasi gunung berapi yang berbahan dari plastisin. Plastisin tersebut dibentuk sedemikian rupa sehingga terbentuklah sebuah tiruan gunung berapi yang dilengkapi dengan alat-alat yang diperlukan untuk melakukan simulasi.

Gunung api secara umum adalah istilah yang dapat didefinisikan sebagai suatu sistem saluran fluida panas (batuan dalam wujud cair atau lava) yang memanjang dari kedalaman sekitar 10 km di bawah permukaan bumi sampai ke permukaan bumi, termasuk endapan hasil akumulasi material yang dikeluarkan pada saat meletus.

Letusan gunung api adalah merupakan bagian dari aktivitas vulkanik yang dikenal dengan istilah “erupsi”.

Pada dasarnya, gunung berapi terbentuk dari magma, yaitu batuan cair yang terdalam di dalam bumi. Magma terbentuk akibat panasnya suhu di dalam interior bumi. Pada kedalaman tertentu, suhu panas ini sangat tinggi sehingga mampu melelehkan batu-batuan di dalam bumi. Saat batuan ini meleleh, dihasilkanlah gas yang kemudian bercampur dengan magma. Sebagian besar magma terbentuk pada kedalaman 60 hingga 160 km di bawah permukaan bumi. Sebagian lainnya terbentuk pada kedalaman 24 hingga 48 km.

Magma yang mengandung gas, sedikit demi sedikit naik ke permukaan karena massanya yang lebih ringan dibanding batu-batuan padat di sekelilingnya. Saat magma naik, magma tersebut melelehkan batu-batuan di dekatnya sehingga terbentuklah kabin yang besar pada kedalaman sekitar 3 km dari permukaan. Kabin magma (magma chamber) inilah yang merupakan gudang (reservoir) darimana letusan material-material vulkanik berasal.

Magma yang mengandung gas dalam kabin magma berada dalam kondisi di bawah tekanan batu-batuan berat yang mengelilinginya. Tekanan ini menyebabkan magma meletus atau melelehkan conduit (saluran) pada bagian batuan yang rapuh atau retak. Magma bergerak keluar melalui saluran ini menuju ke permukaan. Saat magma mendekati permukaan, kandungan gas di dalamnya terlepas. Gas dan magma ini bersama-sama meledak dan membentuk lubang yang disebut lubang utama (central vent). Sebagian besar magma dan material vulkanik lainnya kemudian menyembur keluar melalui lubang ini. Setelah semburan berhenti, kawah (crater) yang menyerupai mangkuk biasanya terbentuk pada bagian puncak gunung berapi. Sementara lubang utama terdapat di dasar kawah tersebut.

Kerak yang menindih mantel hampir seluruhnya terdiri dari oksida yang tidak melebur. Proses vulkanik membawa fragmen batuan ke permukaan dari kedalaman lk. 200 km melalui mantel, hal tersebut ditunjukkan dengan adanya mineral-mineral olivine, piroksen dan garnet dalam peridotit pada bagian atas mantel.

Panas bagian dalam bumi merupakan panas yang dibentuk selama pembentukan bumi sekitar 4,5 miliar tahun lalu, bersamaan dengan panas yang timbul dari unsure radioaktif alami, seperti elemen-elemen isotop K, U dan Th terhadap waktu. Bumi pada saat terbentuk lebih panas, tetapi kemudian mendingin secara berangsur sesuai dengan perkembangan sejarahnya. Pendinginan tersebut terjadi akibat pelepasan panas dan intensitas vulkanisma di permukaan.

Berdasarkan percobaan yang telah dilakukan, terdapat beberapa hubungan antara percobaan yang kami lakukan yaitu simulasi gunung merapi dengan gejala fisika, kimia dan biologi yang terjadi pada erupsi tersebut.

Ditinjau dari segi biologi, letusan gunung berapi dapat memiliki dampak buruk terhadap masyarakat dan lingkungan. Namun, tidak seperti gempa bumi, gunung berapi juga dapat memiliki dampak positif pada suatu daerah. Dampak positif dapat membantu untuk menjelaskan mengapa orang memilih untuk tinggal di dekat gunung berapi. Pemandangan dramatis yang diciptakan oleh letusan gunung berapi menarik wisatawan. Hal ini membawa penghasilan ke suatu daerah. Banyak nyawa bisa hilang sebagai hasil dari letusan gunung berapi. Lava dan abu diendapkan selama letusan yang menyusup ke bawah untuk memberikan nutrisi yang berharga untuk tanah. Hal ini menciptakan tanah yang sangat subur yang baik untuk pertanian. Jika abu dan lumpur dari campuran letusan gunung berapi dengan air hujan atau salju mencair, lumpur bergerak cepat diciptakan. Arus ini disebut lahar. Tingginya tingkat panas dan aktivitas di dalam bumi, dekat dengan gunung berapi, dapat memberikan peluang untuk menghasilkan energi panas bumi. Arus Lava dan lahar dapat menghancurkan permukiman dan area yang jelas hutan atau pertanian. Manusia dan lanskap alami dapat dimusnahkan dan berubah selamanya.

Selain berdampak positiv bagi kehidupan manusia, letusan gunung berapi juga berdampak negative bagi kehidupan manusia, antara lain berdampak pada kesehatan pada manusia. Abu yang dikeluarkan Gunung Merapi bisa berdampak serius bagi kesehatan yang menghirupnya. Abu adalah partikel halus batuan vulkanik yang kelaur dari erupsi gunung. Diameternya kurang dari 2 mikrometer. Abu vulkanik yang baru saja jatuh memiliki kandungan lapisan asam yang dapat menyebabkan iritasi pada paru-paru dan mata. Lapisan asam akan mudah tercuci oleh air hujan, sehingga dapat mencemari persediaan air setempat. Abu asam juga dapat merusak tanaman, hal ini mengakibatkan kegagalan panen. Menurut The International Volcanic Health Hazard Network, secara umum, abu vulkanik menyebabkan masalah kesehatan. Namun selain kesehatan, ada juga dampak yang yang ditimbulkan oleh abu dari gunung itu. Berikut dampak dampak tersebut. Dampak abu vulkanik terhadap kesehatan dapat dibagi menjadi beberapa kategori, antara lain dampak terhadap pernapasan, penyakit mata, iritasi kulit dan dampak tidak langsung akibat abu vulkanik. Partikel abu sangat halus sehingga dapat masuk ke paru-paru ketika kita bernapas. Apabila paparan terhadap abu cukup tinggi, maka orang yang sehat juga susah bernapas. Berikut tanda gangguan pernafasan; (1) Iritasi hidung dan pilek; (2) Iritasi dan sakit tenggorokan, kadang disertai dengan batuk kering. Untuk penderita penyakit pernapasan, abu vulkanik dapat menyebabkan penyakit menjadi serius seperti tanda-tanda bronkitis akut selama beberapa hari (seperti: batuk kering, produksi dahak berlebih, mengi dan sesak napas); (3) Iritasi saluran pernapasan bagi penderita asma atau bronchitis; (4) Ketidaknyamanan saat bernapas Dalam beberapa kasus, paparan jangka panjang terhadap abu vulkanik halus dapat menyebabkan penyakit paru-paru serius. Dalam hal ini, abu vulkanik harus berukuran sangat halus serta mengandung silika kristal (untuk penyakit silikosis) dan orang-orang tersebut terkena abu dalam konsentrasi tinggi selama bertahun-tahun. Para penderita asma atau masalah paru-paru lainnya seperti bronkitis dan emfisema, dan gangguan jantung parah adalah mereka yang paling berisiko. Abu halus juga menyebabkan lapisan saluran pernapasan menghasilkan lebih banyak sekresi yang dapat membuat orang batuk dan bernapas lebih berat. Penderita asma, khususnya anak-anak, dapat menderita serangan batuk dan sesak dada. Beberapa orang yang tidak pernah menderita asma dapat mengalami gejala seperti asma setelah hujan abu, khususnya jika mereka yang terlalu lama melakukan kegiatan di luar ruangan. Iritasi mata merupakan dampak kesehatan umum yang sering dijumpai. Hal ini terjadi karena butiran-butiran abu yang tajam dapat merusak kornea mata dan membuat mata menjadi merah. Selain bagi kesehatan, dampak negative yang ditimbulkan oleh letusan gunung berapi adalah dapat menghancurkan area yang luas, diantaranya area persawahan. Dampak yang berkepanjangan pasca erupsi gunung berapi pun dapat merusak jalan, aliran sungai bahkan pedesaan yang letaknya relative jauh dari gunung berapi, akibat dari lahar dingin yang membawa material gunung berapi. Lahar (lumpur abu dan air) meliputi wilayah yang luas di sekitar gunung berapi. Arus lahar dingin pun menyebabkan banjir. Hal ini pada gilirannya menghancurkan tanaman dan ternak. Banjir menghancurkan komunikasi seperti jalan dan jembatan.

Selain itu, dampak dari gunung meletus bagi ekosistem adalah Semua tumbuh-tumbuhan hancur. Banyak Pohon yang tumbang, bercampur dengan abu. Menyebabkan penyimpangan iklim global. Sebagai contoh adalah terjadinya Letusan gunung Tambora tahun 1815 mengeluarkan sulfur ke stratosfer, menyebabkan penyimpangan iklim global.

Makhluk hidup selalu berinteraksi dengan lingkungan. Interaksi antara makhluk hidup dan tak hidup dalam suatu tempat tertentu disebut ekosistem. Jika suatu lingkungan mengalami perubahan maka ekosistem yang terdapat di situ akan mengalami perubahan juga. Perubahan lingkungan dapat terjadi secara alamiah dan perubahan yang diakibatkan oleh kegiatan manusia. Perubahan Ekosistem secara Alamiah akhir-akhir ini sering terjadi bencana alam berupa gunung meletus atau gempa bumi. Peristiwa-peristiwa tersebut dapat menyebabkan terjadinya perubahan ekosistem. Misalnya, di hutan sekitar Gunung Merapi di Jawa Tengah banyak hewan, tumbuhan, dan makhluk hidup lainnya yang hidup di sana. Jika terjadi gunung meletus di Gunung Merapi maka makhluk hidup di sana akan banyak yang mati. Begitu pula dengan bencana alam gempa yang terjadi di Indonesia. Dengan peristiwa alam yang terjadi, ekosistem akan berubah secara drastis. Dalam sebuah ekosistem, jika salah satu makhluk hidup berkurang makan akan mempengaruhi keadaan makhluk hidup yang lainnya.

Ditinjau dari segi kimia, percobaan yang kami lakukan menggunakan percampuran antara baking soda dan cuka. Dalam sebuah gunung berapi yang nyata, batuan cair dari dalam bumi melalui sebuah letusan gunung berapi (batu cair disebut magma ketika dalam bumi disebut lava dan ketika datang keluar dari gunung berapi). Dalam percobaan ini, sebuah gunung berapi akan meletus mengejek dengan cairan, gelembung soda yang dibuat oleh reaksi kimia sederhana. Pada simulasi yang kami buat, setelah pada lubang diisi dengan baking soda dan suntikan yang berisi asam asetat sudah ditekan, maka terjadi sebuah erupsi kecil gunung berapi. Percobaan ini menunjukkan apa yang terjadi ketika asam (cuka) dan basa (soda kue) berinteraksi. Kimia, asam dan basa menetralisir setiap gas, karbon dioksida lainnya diproduksi sebagai produk sampingan. Reaksi yang tepat adalah:

HC2H3O2 (cuka asam asetat =) + NaHCO3 (soda kue = natrium bikarbonat) = CO2 (gas karbon dioksida) + NaC2H3O2 (natrium asetat) + H2O (air).

Berdasarkan persamaan reaksi diatas sudah terlihat bahwa reaksi antara asam asetat (CH3COOH) dengan baking soda/soda kue (NaHCO3) menghasilkan gas karbondioksida (CO2).  Sesuai dengan kajian pustaka yang ada, reaksi diatas termasuk kedalam reaksi yang menghasilkan gas. Yaitu ditandai dengan munculnya gas karbondioksida. Sedangkan pada simulasi gunung berapi yang kami buat diunjukkan dengan munculnya buih-buih gelembung udara.

Magma mengandung gas-gas terlarut yang dilepaskan ke atmosfir selama letusan. Gas juga dirilis dari magma yang baik tetap di bawah tanah (misalnya, sebagai penyusupan) atau naik ke permukaan. Dalam kasus tersebut, gas bisa melarikan diri terus menerus ke atmosfer dari tanah, ventilasi vulkanik, fumarol, dan sistem hidrotermal. Pada tekanan tinggi jauh di bawah permukaan bumi, gas-gas vulkanik dilarutkan dalam batuan cair. Tapi seperti magma naik ke permukaan di mana tekanan lebih rendah, gas diadakan di cairkan mulai membentuk gelembung-gelembung kecil. Meningkatnya volume diambil oleh gelembung gas membuat magma kurang padat dari batuan sekitarnya, yang dapat memungkinkan magma untuk melanjutkan perjalanan ke atas nya. Lebih dekat ke permukaan, gelembung peningkatan jumlah dan ukuran sehingga volume gas yang dapat melebihi volume magma meleleh, menciptakan busa magma. Gelembung gas yang berkembang pesat dapat menyebabkan letusan eksplosif yang meleleh terfragmentasi menjadi potongan-potongan batu vulkanik, yang dikenal sebagai tephra.

Ditinjau dari segi fisika, pada percobaan yang kami lakukan menggunakan alat suntikan sebagai pendorong bagi magma (dalam percobaan percampuran antara baking soda dengan cuka) untuk keluar dari dapur magma. Penggunaan alat suntik yang kami pakai hanya dengan mendorong batang suntikan hingga cairan cuka yang ditambahkan dengan red dye bercampur dengan baking soda yang sudah berada dalam dapur magma (dalam percobaan kami, didalam gunung-gunungan yang kami buat dengan plastisin). Selain karena tekanan dari dorongan suntikan, keluarnya magma dari dapur magma dalam percobaan kami disebabkan karena adanya gas karbondioksida yang dihasilkan antara reaksi cuka dan baking soda. Gas karbondioksida ini meningkatkan tekanan keatas yang diberikan oleh larva. Reaksi tersebut menghasilkan gelembung-gelembung berupa busa. Munculnya buih-buih gelembung gas yang berasal dari gas karbondioksida tersebut maka akan meningkatkan tekanan ke atas yang diberikan oleh lava, yang pada awalnya saat magma bergerak sepanjang lubang utama gunung berapi tekananya berkurang, akan tetapi akibat adanya gelembung-gelembung udara tersebut maka justru meningkatkan tekanan magma yang berasal dari ruang magmatik atau kaldera. Sehingga membantu pergerakan magma untuk bergerak keatas mencapai puncak gunung berapi sehingga terjadilah erupsi dan magma dapat meluber atau terliah seperti terjadi lelehan larva.

J.      Conclusions

1. Generated from the magma pressure caused by the encouragement of injections that we use in our experiments, to be able to get out of the magma chamber. In addition because of the pressure impulse injection, discharge of magma from the magma chamber in our experiments due to carbon dioxide gas produced by the reaction between vinegar and baking soda. Carbon dioxide gas is increasing upward pressure given by the larvae. The reaction produces bubbles of foam. The emergence of bubbles of gas bubbles from the carbon dioxide gas will increase upward pressure given by the lava, which at first when magma moves along the main hole tekananya volcano decreased but because of the air bubbles are then actually increase the pressure magma derived from the magmatic chamber or caldera. Thereby helping the movement of magma to move up to the top of the volcano eruption and the magma, so there may overflow or terliah like molten larvae occur.

2. Chemical reactions that exist in a simulation model of the volcano are:

HC2H3O2 (vinegar = acetic acid) + NaHCO3 (baking soda = sodium bicarbonate) = CO2 (carbon dioxide) + NaC2H3O2 (sodium acetate) + H2O (water).

This reaction is a mixture of baking soda with vinegar acetic acid which produces carbon dioxide resulting in a simulation of this volcano bubbles remove air bubbles.

3. The effects of volcanic eruptions for the surrounding area is in real life, volcanic eruptions can provide a variety of impacts on the lives of the surrounding ecosystem. These impacts include the effects of negative and positive impacts. Negative impacts include all the plants were destroyed and the dead, many fallen trees and mixed with ash, other than that for example in the forests around Mount Merapi in Central Java, many animals, plants and other living creatures that live there. In the event of volcanic eruption at Mount Merapi, the creatures living there will be many dead. Negative impacts resulting from volcanic eruptions can affect health. Volcanic ash that is produced is very dangerous when inhaled by human beings and animals particularly. According to the theory that there is volcanic dust contains high levels of silica (Si) is high. The second impact, the flow of lava and steam pans can turn off all forms of life / ecosystems in its path, while the cold lava flow can be washed and stockpiled soil surface layer. In addition the sulfur vapor out of the pores can contaminate soil and water, because it can increase levels of acid water and soil acidity. Negative impact to human life is the dramatic scenery created by volcanic eruptions attract tourists. This brings revenue to an area. Many lives could be lost as a result of volcanic eruptions. Lava and ash deposited during the eruption that infiltrate downward to provide valuable nutrients to the soil. This creates a very fertile soil good for agriculture.

4. Basically, a volcano formed from magma, molten rock that is deepest in the earth. Magma is formed due to the heat inside the Earth’s interior. At a certain depth, the temperature is very high heat so as to melt the rocks inside the earth. When this molten rock, gas dihasilkanlah which then mixes with the magma. Magma containing gas, gradually rising to the surface because of its mass is lighter than the solid rock around it. When the magma rises, the magma melts the nearby rocks, forming a large cabin at a depth of about 3 km from the surface. Cab magma (magma chamber) is what is the warehouse (reservoir) where volcanic eruptions originating materials. Magma containing gas in the cabin in a state of magma under the pressure of heavy rocks that surround it. This pressure causes the magma erupts or melt conduit (channel) on the rocks brittle or cracked. Magma moves out through these channels leading to the surface. When magma approaches the surface, the gas content in it regardless. Gas and magma exploded together and form a hole called the main hole (central vent). Most of the magma and other volcanic material and then gush out through this hole. After bursts of stops, the crater (crater) that resemble bowls usually formed at the peak of the volcano. While there are major holes in the bottom of the crater.

 K.    References

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Diunduh dari http://vco-milanisti.blogspot.com/2010/11/proses-terjadinya-gunung-meletus.html pada hari Senin, 17 Oktober 2011, jam 16.39 PM.

Diunduh dari http://id.shvoong.com/exact-sciences/physics/2069989-apa-penyebab-gunung-berapi-meletus/#ixzz1az9y3F6F pada hari Senin, 17 Oktober 2011, jam 16.47 PM.

Diunduh dari http://id.shvoong.com/exact-sciences/physics/2069989-apa-penyebab-gunung-berapi-meletus/ pada hari Senin, 17 Oktober 2011, jam 16.56 PM.

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Diunduh dari http://dvallen.blogspot.com/2010/03/baking-sodanatrium-bikarbonat.html pada hari Senin, 17 Oktober 2011, jam 17.20 PM.

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Diunduh dari http://mersi.wapka.mobi/site_73.xhtml pada hari Senin, 17 Oktober 2011, jam 17.58 PM.

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