Vulkanisme dan Dampaknya pada Litosfer dan Pedosfer
(Sumber: Sudibyakto, H. A. 2009. Geografi.Jakarta: Departemen Pendidikan Nasional.)
A) Aktivitas Magma. Gunung api terbentuk oleh proses intrusi dan ekstrusi magma dari lapisan dalam kulit bumi. Setelah sampai di permukaan bumi, magma pijar yang keluar kemudian membeku dan membentuk timbunan. Magma keluar melalui proses letusan atau erupsi gunung api. Apabila erupsi sering terjadi, magma akan membetuk lapis timbunan yang membuat gunung api bertambah semakin tinggi.
1) Intrusi Magma. Magma dari dalam bumi dapat mengalir menyusup di antara lapisan batuan tetapi tidak mencapai permukaan bumi. Setelah membeku, penyusupan magma ini membentuk kenampakan sebagai berikut:
Ø Batolit adalah batuan beku yang terbentuk di dalam dapur magma.
Ø Lakolit adalah batuan beku yang terjadi pada dua lapisan litosfer dan bentuknya menyerupai lensa cembung.
Ø Sills adalah sisipan magma yang membeku pada dua lapisan litosfer berbentuk tipis dan lebar.
Ø Diatrema adalah batuan hasil intrusi magma yang memotong lapisan litosfer.
2) Ekstrusi Magma. Ekstrusi magma terjadi bila magma keluar ke permukaan bumi akibat tekanan dari dalam bumi. Aktivitas ini bisa menimbulkan letusan (Erupsi) pada gunung api. Dilihat dari bentuk lubang keluarnya magma, terdapat tiga macam erupsi sebagai berikut:
a) Erupsi Linier atau Erupsi Melalui Retakan. Magma dari dapur magma mengalir menyusup keluar melalui retake memanjang pada kulit bumi. Akibat ini erupsi ini terbentuk deretan gunung api.
b) Erupsi Areal. Magma yang keluar dan meleleh pada permukaan bumi dapat terjadi karena letak dapur magma yang sangat dekat dengan permukaan bumi. Akibat erupsi ini terbentuk kawah gunung api yang sangat luas.
c) Erupsi Sentral. Erupsi sentral atau biasa kita kenal sebagai letusan gunung api terjadi karena keluarnya magma melalui sebuah lubang di permukaan bumi hingga terbentuk gunung yang letaknya terpisah dengan gunung lainnya.
Proses erupsi sentral dapat membentuk tiga macam bentuk gunung api, yaitu:
(1) Gunung Api Perisai (Tameng). Gunung api ini terbentuk karena sifat magma yang keluar sangat encer dengan tekanan yang rendah, hampir tanpa letusan. Lereng gunung yang terbentuk menjadi sangat landai. Di Indonesia hampir tidak ada gunung yang berbentuk perisai sehingga magma mudah mengalir ke segala arah. Sebagian besar gunung ini ada di Hawaii.
(2) Gunung Api Maar. Bentuk gunung api maar seperti danau kering. Jenis letusan yang terjadi adalah jenis eksplosif sehingga membentuk lubang besar pada bagian puncak (kawah). Letusan gunung api seperti ini terjadi karena ukuran dapur magma kecil dan letaknya dangkal sehingga letusan hanya terjadi satu kali kemudian mati. Contoh: Danau Klakah di Lamongan (Jawa Timur, Indonesia) dan Danau Eifel di Perancis.
(3) Gunung Api Strato. Gunung api ini terbentuk akibat terjadi eksplosif dan erupsi efusil berselang seling. Sebagian besar gunung api di ala mini merupakan gunung strato. Contoh: gunung api Merapi, Merbabu, Semeru, dan Kelud di Indonesia, Gunung Fuji di Jepang, Gunung Vesuvius di Italia, serta Gunung Santo Helens dan Rainier di Amerika Serikat.
Berdasarkan kekuatan letusan dan kandungan material yang dikeluarkan, erupsi gunung api dibagi menjadi dua yaitu:
(1) Erupsi Eksplosif. Erupsi eksplosif adalah erupsi atau letusan yang menyebabkan ledakan besar akibat tekanan gas magmatis yang sangat kuat. Material yang dikeluarkan bersifat padat dan cair. Akibat erupsi eksplosif terbentuk bentukan permukaan Bumi berupa danau kawah besar (eksplosif), contoh danau batur di Bali.
(2) Erupsi Efusif. Erupsi efusif adalah erupsi atau letusan yang tidak menimbulkan ledakan karena tekanan gas kurang kuat. Pada proses ini material yang dikeluarkan adalah material cair atau sebagian besar lava dan sedikit material padat yang berukuran kecil. Contoh Gunung Mauna Loa di Hawaii.
Berdasarkan kekentalan magma, tekanan gas, ke dalaman dapur magma, dan material yang dikeluarkannya, letusan gunung api dibedakan menjadi beberapa tipe, yaitu:
a) Letusan Tipe Hawaii. Tipe Hawaii terjadi karena lava yang kelaur dari kawah sangat cair sehingga mudah mengalir ke segala arah. Sifat lava yang sangat cair ini menghasilkan bentuk seperti perisai atau tameng. Contoh: Gunung Mauna Loa, Mauna Kea dan Kilauea di Hawaii.
b) Letusan tipe Stromboli. Letusan tipe ini bersifat spesifik yaitu letusan terjadi dengan interval atau tenggang waktu yang hampir sama. Gunung api Stromboli di Kepulauan Lipari tenggang waktu letusannya sekitar 12 menit. Jadi setiap sekitar 12 menit terjadi letusan yang memuntahkan material, bom, lapili, dan abu. Contoh gunung api bertipe Stromboli adalah Gunung Vesuvius (Italia) dan Gunung Raung (Jawa).
c) Letusan Tipe Vulkano. Letusan tipe ini mengeluarkan material padat seperti bom, abu, lapili serta bahan padat dan cair atau lava. Letusan tipe ini didasarkan atas kekuatan erupsi dan kedalaman dapur magmanya. Contoh: Gunung Vesuvius dan Etna di Italia, serta Gunung Semeru (Jawa Timur, Indonesia).
d) Letusan Tipe Merapi. Letusan tipe ini mengeluarkan lava kental hingga menyumbat mulut kawah. Akibatnya, tekanan gas menjadi semakin bertambah kuat dan memecahkan sumbatan lava. Sumbatan yang pecah terdorong ke atas dan akhirnya terlempar keluar. Material ini menuruni lereng gunung sebagai ladu atau gloedlawine. Selain itu, terjadi pula awan panas (gloedwolk) atau sering disebut “Wedhus Gembel”. Letusan tipe merapi sangat berbahaya bagi penduduk sekitarnya.
e) Letusan Tipe Perret atau Plinian. Letusan tipe ini sangat berbahaya dan sangat merusak lingkungan. Material yang dilemparkan pada letusan tipe ini mencapai ketinggian sekitar 80 km. letusan tipe ini dapat melemparkan kepundan atau membobol puncak gunung sehingga dinding kawah melorot. Contohnya Gunung Krakatau yang meletus pada tahun 1883 dan St. Helens yang meletus pada tanggal 18 Mei 1980.
f) Letusan Tipe Peele. Letusan tipe ini biasanya terjadi jika terdapat penyumbatan kawah di puncak gunung api yang bentuknya seperti jarum sehingga menyebabkan tekanan gas menjadi bertambah besar. Apabila penyumbatan kawah tidak kuat, gunung tersebut meletus.
d) Letusan Tipe Sint Vincent. Letusan tipe ini menyebabkan air danay kawah akan tumpah bersama lava. Letusan ini mengakibatkan daerah di sekitar gunung tersebut akan diterjang lahar panas yang sangat berbahaya. Contoh: Gunung Kelud yang meletus pada tahun 1919 dan GUnung Sint Vincent yang meletus pada tahun 1902.
Masing-masing zat tersebut dapat dibedakan menjadi beberapa jenis material. Jenis material yang dikeluarkan gunung api adalah:
(a) Material Padat (Efflata), terdiri atas: bom (batu besar), terak (batu yang tidak beraturan dan lebih kecil dari bom), lapih (berupa kerikil), pasir, debu, batu apung. Menurut asalnya, efflata dibedakan menjadi dua yakni: Pertama, Efflata Allogen, berasal dari batu di sekitar kawah yang terlempar ketika terjadi letusan, Kedua, Efflata autogen (Pyroclastica), berasal dari magma itu sendiri.
(b) Material Cair. Bahan cair dari dapur magma akan mengalir keluar dari gunung api jika magma cair dari dalam bumi meleleh keluar dari lubang kawah tanpa terhambat oleh sumbatan dan tidak terdapat sumbatan di puncaknya, terdiri atas:
(1) Lava yaitu magma yang meleleh di luar pada lereng gunung api.
(2) Lahar panas yaitu campuran magma dan air sehingga merupakan lumpur panas yang mengalir.
(3) Lahar dingin yaitu terbentuk dari efflata porus atau bahan padat di puncak gunung menjadi lumpur ketika turun hujan lebat dan mengalir pada lereng serta lembah. Contohnya akibat letusan Gunung Merapi tahun 2006 yang lalu telah menghasilkan sekitar 6 juta meter kubik timbunan material yang akan membentuk aliran lahar dingin saat turun hujan.
(c) Material Gas atau Ekshalasi, terdiri atas: Pertama, Solfatar, berbentuk gas belerang (H2S), Kedua, Fumarol, berbentuk uap air (H2O), Ketiga, Mofet, berbentuk gas asam arang (CO2), gas ini berbahaya bagi kehidupan karena bersifat racun, selain itu, sifatnya lebih berat dari oksigen menyebabkan gas ini lebih dekat dengan permukaan tanah sehingga mudah dihirup oleh makhluk hidup, conthnya, gas CO2 yang keluar dari Gunung Dieng pada tahun 1979 telah membunuh 149 penduduk.
Ada beberapa fenomena alam lain yang terbentuk dari proses lanjutan atau pasca vulkanisme, yakni:
(a) Sumbatan Lava, kenampakan ini terjadi ketika lava yang padat dalam pipa vulkanik yang padam menjadi massa yang resistan. Beberapa waktu kemudian, bagian dari kerucut vulkanik yang terdiri atas materi yang kurang resistan menjadi lapuk dan terkikis, yang tertinggal hanya sumbatan lava. Ukuran sumbatan lava ini bisa sangat besar hingga menyerupai bukit. Salah satu contohnya yaitu Menara Setan di Wyoming, USA.
(b) Kaldera dan Danau Kaldera, kaldera adalah cekungan besar yang ada di puncak gunung. Kenampakan ini terjadi akibat letusan yang sangat dahsyat dan meninggalkan lubang yang besar. Jika lubang ini kemudian terisi air akan membentuk danau kaldera.
(c) Plato lava. Kenampakan ini terjadi karena magma yang keluar bersifat encer sehingga mampu menyebar dan membentuk hamparan lava yang luas dan lama kelamaan secara perlahan lava ini membeku hingga membentuk suatu dataran tinggi yang disebut plato.
(d) Geyser dan Mata Air Panas. Di kawasan vulkanik, air tanah bisa dipanaskan oleh magma. Air yang terpanaskan ini bisa muncul ke perukaan dengan tenaga eksplosif, inilah yang disebut geyser. Jika air ini keluar melalui air di celah batuan, terbentuklah mata air panas. Sedangkan geyser merupakan air panas yang memancar secara periodic. Contohnya: Geyser di Taman Nasional Yellowstone, Amerika Serikat.
b) Hidup Bersanding dengan Vulkanisme. Gunung api di Indonesia dapat dikelompokan menjadi lima rangkaian, yaitu:
(1) Rangkaian Sunda yaitu rangkaian gunung berapi yang memanjang dari Sumatera, Jawa, Bali, Lombok, Sumbawa, Flores hingga Alor.
(2) Rangkaian Banda, sebagian besar terletak di bawah permukaan laut.
(3) Rangkaian Minahasa dan Sangihe, rangkaian ini masih aktif seperti di Gunung Soputan dan Gunung Lokon.
(4) Rangkaian Halmahera, yang terdapat di sekitar Halmahera.
(5) Rangkaian Sulawesi Selatan merupakan rangkaian sudah tidak aktif (mati).
Tanda-tanda gunung api akan meletus (erupsi), yaitu:
(1) Temperatur di sekitar kawah naik.
(2) Banyak sumber air mongering.
(3) Sering terjadi gempa.
(4) Sering terdengar suara gemuruh di sekitar puncak gunung.
(5) Banyak binatang yang turun gunung atau berpindah.
Gejala gunung api akan padam (pasca vulkanik) adalah:
(1) Munculnya ekshalasi atau sumber gas, contohnya di Dieng, Jawa Tengah.
(2) Keluarnya mata air panas, contohnya di Cimelati, Jawa Barat.
(3) Munculnya mata air makdani yaitu mata air panasy ang mengandung mineral seperti belerang. Contoh di Maribaya (Jawa Barat), Baturaden dan Dieng (Jawa Tengah).
(4) Munculnya geyser yaitu mata air panas yang disemburkan ke udara. Ketinggian geyser dapat mencapai 70 m. contoh di Irlandia dan Yellowstone Park (Amerika Serikat).
IN ENGLISH (with google translate Indonesian-english):
Volcanism and its Impact on the lithosphere and Pedosfer
(Source: Sudibyakto, HA 2009. Geografi.Jakarta: Ministry of Education.)
A) Magma activity. Volcanoes are formed by the intrusion and extrusion of magma layer in the earth's crust. After reaching the Earth's surface, coming out of incandescent magma then solidifies to form piles. Magma out through the process of eruption or volcanic eruption. If the eruption is often the case, the magma will set up a heap layers that make volcanoes grow higher.
1) Intrusion of Magma. Magma from the earth to flow between the layers of rock creep in but did not reach the earth's surface. Once frozen, the intrusion of magma is formed appearance as follows:
batholiths are igneous rocks formed in the magma chamber.
Lakolit is igneous rock that occurs in two layers of the lithosphere and shaped like a convex lens.
Sills is inset magma solidifies in the form of two thin layers of the lithosphere and wide.
Diatrema is the result of intrusion of magma rocks that cut the layers of the lithosphere.
2) Extrusion Magma. Extrusion occurs when magma magma to the surface of the earth due to the pressure of the earth. This activity can lead to eruption (eruption) in the volcano. Judging from the shape of magma discharge holes, there are three kinds of eruptions are as follows:
a) Linear eruption or eruption Through the Cracks. Magma from the magma chamber to flow out through Retake infiltrate extends to the skin of the earth. As a result of this eruption formed a row of volcanoes.
b) eruption area. Magma comes out and melts at the earth's surface can occur due to the location of the magma chamber is very close to the earth's surface. Is formed due to eruption of the volcano crater is very broad.
c) Central eruption. Central eruption or commonly known as volcanic eruptions occur due to the release of magma through a hole in the earth's surface to form a mountain that is located separate to the other mountain.
The process of central eruptions can form three kinds of volcanoes, namely:
(1) Mountain of Fire Shield (shield). This volcano is formed due to the nature of the magma that comes out very thin with low pressure, almost without eruption. Slopes that form a very gentle slope. In Indonesia, almost no shield-shaped mountain that magma flows easily in all directions. Most of the mountain is in Hawaii.
(2) Volcanoes Maar. Forms of maar volcanoes such as lakes dry.Type the eruption is explosive types so as to form a large hole at the top (crater). Volcanic eruptions like this occur because the small size of the magma chamber and the location of shallow that the eruption occurred only once and then die. Example: Lake Klakah in Lamongan (East Java, Indonesia) and the Eifel lake in France.
(3) Strato volcano. This volcano formed by the explosive and the eruption occurred efusil alternate. Most of the volcano is a mountain-style mini strato. Example: Merapi volcano, Merbabu, Semeru, and Kelud in Indonesia, Mount Fuji in Japan, Mount Vesuvius in Italy, and Mount St. Helens and Rainier in the United States.
Based on the strength of the eruption and the content of the material issued, volcano eruption is divided into two, namely:
(1) Explosive eruption. Eruption explosive eruption or eruption is causing a massive explosion caused by magmatic gas pressure is very strong. Materials issued in solid and liquid. As a result of the formation of explosive eruptions formed the Earth's surface in the form of a large crater lake (explosive), examples of lake Batur in Bali.
(2) effusive eruption. Effusive eruption eruption or eruption is not an explosion as the gas pressure is less strong. In this process the released material is a liquid material or mostly lava and less dense material are small. Examples of Mount Mauna Loa in Hawaii.
Based on the viscosity of the magma, gas pressure, to depths of the magma chamber, and release material, volcanic eruptions can be divided into several types, namely:
a) Type eruption Hawaii. Type of Hawaii occurred because the kelaur lava from the crater is very liquid so it's easy to flow in all directions. The nature of this very fluid lava produced forms like a shield or a shield. Example: Mount Mauna Loa, Mauna Kea and Kilauea in Hawaii.
b) The eruption of Stromboli type. Eruptions of this type that is specific eruption intervals or nearly the same period. Stromboli volcano in the Lipari Islands eruptive period of about 12 minutes. So each about 12 minutes eruptions that spew material, bombs, lapilli and ash. Examples of type Stromboli volcano is Mount Vesuvius (Italy) and Raung (Java).
c) Type of volcano eruption. Eruptions of this type issued a dense material such as bombs, ash, lapilli and solid and liquid materials or lava. Eruptions of this type of eruption is based on the strength and depth magmanya kitchen. Example: Mount Vesuvius and Etna in Italy, and Mount Semeru (East Java, Indonesia).
d) Type of Merapi eruption. The eruption of viscous lava type issued to clog the mouth of the crater. As a result, the gas pressure becomes increasingly more powerful and resolve blockages lava.Blockages are broken up and finally pushed thrown out. This material down the slope as ladu or gloedlawine. In addition, there is also a hot cloud (gloedwolk) or often called "Wedhus Gembel".Merapi Eruption type is very dangerous for the surrounding population.
e) Type of Perret or Plinian eruption. This type of eruption is very dangerous and very damaging to the environment. Material that is thrown at this type of eruption reached a height of about 80 km. This type of eruption can throw or break into the crater of the mountain so that the walls of the crater dropped. Examples of Mount Krakatoa erupted in 1883 and St. Helens which erupted on May 18, 1980.
f) Type eruption Peele. Eruptions of this type usually occurs when there is blockage in the summit crater of a volcano that looks like a needle, causing the gas pressure becomes larger. If the blockage is not strong crater, the volcano erupted.
d) Type of Sint Vincent eruption. Eruptions of this type will cause the water to spill Danay crater with lava. The eruption resulted in the area around the volcano will buffeted by hot lava that is very dangerous. Example: Kelud which erupted in 1919 and Vincent Sint mountain that erupted in 1902.
Each of these substances can be divided into several types of material. Types of volcanic material released is:
(A) Solid Materials (Efflata), consisting of: bombs (large stone), slag (irregular stones and smaller than bombs), lapih (such as gravel), sand, dust, pumice. According to its origin, efflata divided into two: First, Efflata Allogen, derived from the rocks around the crater that was thrown when there is an eruption, Second, Efflata autogen (Pyroclastica), derived from the magma itself.
(B) Liquid Materials. Magma chamber of molten material flows out of the volcano when magma from within the Earth's liquid melt out of the pit crater without impeded by blockages and there is no blockage in height, consisting of:
(1) Lava is magma that melts out on the slopes of the volcano.
(2) hot lava that is a mixture of magma and water that is flowing mud.
(3) that is formed from cold lava efflata porous or solid material in the top of the mountain to mud when it rains and rains on the slopes and stream valleys. For example, due to the eruption of Mount Merapi in 2006 and has produced approximately 6 million cubic meters of embankment material which will form a cold lava flow when it rains.
(C) Material Gas or exhalation, consists of: First, solfatar, gaseous sulfur (H2S), Second, fumaroles, form water vapor (H2O), Third, Mofet, gaseous carbon dioxide (CO2), the gas is dangerous to lifebecause it is toxic, other than that, it is heavier than oxygen causes the gas is closer to the ground so easily inhaled by living, conthnya, CO2 gas coming out of Mount Dieng in 1979 killed 149 people.
There are some other natural phenomenon formed by a continuous process or post-volcanism, namely:
(A) Obstruction of Lava, appearance occurs when the solid lava in the volcanic pipe which goes into mass-resistant. Some time later, part of the volcanic cone composed of less resistant material being weathered and eroded, leaving behind only occlusion lava. The size of the blockage can be very large lava to resemble hills. One example is the Tower of Satan in Wyoming, USA.
(B) Caldera and Caldera Lake, the caldera is a large basin in the top of the mountain. The appearance is due to the eruption of a very powerful and left a big hole. If the hole is then filled with water will form a caldera lake.
(C) Plato lava. The appearance of this happened because of magma that comes out is diluted so as to spread out and form a vast expanse of lava slowly and over time this lava solidifies to form a plateau called the plateau.
(D) Geyser and Thermal. In volcanic areas, ground water can be heated by magma. This heated water that can come into perukaan with explosive power, this is called a geyser. If water comes out through the water at the crack of rocks, forming hot springs. While the geyser is a hot spring up periodically. For example: Geyser in Yellowstone National Park, USA.
b) live side by side with Volcanism. Volcanoes in Indonesia can be grouped into five series, namely:
(1) The series of Sunda is a series of volcanoes that extends from Sumatra, Java, Bali, Lombok, Sumbawa, Flores to Alor.
(2) The series of Banda, mostly lies below sea level.
(3) The series of Minahasa and Sangihe, the circuit is still active as at Mount Soputan and Mount Lokon.
(4) The series of Halmahera, which is located around Halmahera.
(5) The series is a series of South Sulawesi are inactive (dead).
Signs volcano will erupt (eruption), namely:
(1) The temperature rise in the vicinity of the crater.
(2) Many water sources dry up.
(3) Frequent earthquakes.
(4) Often the sound of thunder in the surrounding mountain peaks.
(5) Many of the animals down the mountain or move.
Symptoms volcano goes out (post-volcanic) are:
(1) The emergence of exhalation or gas source, for example, in Dieng, Central Java.
(2) The exit of the hot springs, for example in Cimelati, West Java.
(3) The advent of spring is makdani panasy ang springs contain minerals such as sulfur. Example Maribaya (West Java), Baturaden and Dieng (Central Java).
(4) The emergence of the hot springs geyser which sprayed into the air. Geyser can reach heights of 70 m. examples in Ireland and Yellowstone Park (United States).
(Source: Sudibyakto, HA 2009. Geografi.Jakarta: Ministry of Education.)
A) Magma activity. Volcanoes are formed by the intrusion and extrusion of magma layer in the earth's crust. After reaching the Earth's surface, coming out of incandescent magma then solidifies to form piles. Magma out through the process of eruption or volcanic eruption. If the eruption is often the case, the magma will set up a heap layers that make volcanoes grow higher.
1) Intrusion of Magma. Magma from the earth to flow between the layers of rock creep in but did not reach the earth's surface. Once frozen, the intrusion of magma is formed appearance as follows:
batholiths are igneous rocks formed in the magma chamber.
Lakolit is igneous rock that occurs in two layers of the lithosphere and shaped like a convex lens.
Sills is inset magma solidifies in the form of two thin layers of the lithosphere and wide.
Diatrema is the result of intrusion of magma rocks that cut the layers of the lithosphere.
2) Extrusion Magma. Extrusion occurs when magma magma to the surface of the earth due to the pressure of the earth. This activity can lead to eruption (eruption) in the volcano. Judging from the shape of magma discharge holes, there are three kinds of eruptions are as follows:
a) Linear eruption or eruption Through the Cracks. Magma from the magma chamber to flow out through Retake infiltrate extends to the skin of the earth. As a result of this eruption formed a row of volcanoes.
b) eruption area. Magma comes out and melts at the earth's surface can occur due to the location of the magma chamber is very close to the earth's surface. Is formed due to eruption of the volcano crater is very broad.
c) Central eruption. Central eruption or commonly known as volcanic eruptions occur due to the release of magma through a hole in the earth's surface to form a mountain that is located separate to the other mountain.
The process of central eruptions can form three kinds of volcanoes, namely:
(1) Mountain of Fire Shield (shield). This volcano is formed due to the nature of the magma that comes out very thin with low pressure, almost without eruption. Slopes that form a very gentle slope. In Indonesia, almost no shield-shaped mountain that magma flows easily in all directions. Most of the mountain is in Hawaii.
(2) Volcanoes Maar. Forms of maar volcanoes such as lakes dry.Type the eruption is explosive types so as to form a large hole at the top (crater). Volcanic eruptions like this occur because the small size of the magma chamber and the location of shallow that the eruption occurred only once and then die. Example: Lake Klakah in Lamongan (East Java, Indonesia) and the Eifel lake in France.
(3) Strato volcano. This volcano formed by the explosive and the eruption occurred efusil alternate. Most of the volcano is a mountain-style mini strato. Example: Merapi volcano, Merbabu, Semeru, and Kelud in Indonesia, Mount Fuji in Japan, Mount Vesuvius in Italy, and Mount St. Helens and Rainier in the United States.
Based on the strength of the eruption and the content of the material issued, volcano eruption is divided into two, namely:
(1) Explosive eruption. Eruption explosive eruption or eruption is causing a massive explosion caused by magmatic gas pressure is very strong. Materials issued in solid and liquid. As a result of the formation of explosive eruptions formed the Earth's surface in the form of a large crater lake (explosive), examples of lake Batur in Bali.
(2) effusive eruption. Effusive eruption eruption or eruption is not an explosion as the gas pressure is less strong. In this process the released material is a liquid material or mostly lava and less dense material are small. Examples of Mount Mauna Loa in Hawaii.
Based on the viscosity of the magma, gas pressure, to depths of the magma chamber, and release material, volcanic eruptions can be divided into several types, namely:
a) Type eruption Hawaii. Type of Hawaii occurred because the kelaur lava from the crater is very liquid so it's easy to flow in all directions. The nature of this very fluid lava produced forms like a shield or a shield. Example: Mount Mauna Loa, Mauna Kea and Kilauea in Hawaii.
b) The eruption of Stromboli type. Eruptions of this type that is specific eruption intervals or nearly the same period. Stromboli volcano in the Lipari Islands eruptive period of about 12 minutes. So each about 12 minutes eruptions that spew material, bombs, lapilli and ash. Examples of type Stromboli volcano is Mount Vesuvius (Italy) and Raung (Java).
c) Type of volcano eruption. Eruptions of this type issued a dense material such as bombs, ash, lapilli and solid and liquid materials or lava. Eruptions of this type of eruption is based on the strength and depth magmanya kitchen. Example: Mount Vesuvius and Etna in Italy, and Mount Semeru (East Java, Indonesia).
d) Type of Merapi eruption. The eruption of viscous lava type issued to clog the mouth of the crater. As a result, the gas pressure becomes increasingly more powerful and resolve blockages lava.Blockages are broken up and finally pushed thrown out. This material down the slope as ladu or gloedlawine. In addition, there is also a hot cloud (gloedwolk) or often called "Wedhus Gembel".Merapi Eruption type is very dangerous for the surrounding population.
e) Type of Perret or Plinian eruption. This type of eruption is very dangerous and very damaging to the environment. Material that is thrown at this type of eruption reached a height of about 80 km. This type of eruption can throw or break into the crater of the mountain so that the walls of the crater dropped. Examples of Mount Krakatoa erupted in 1883 and St. Helens which erupted on May 18, 1980.
f) Type eruption Peele. Eruptions of this type usually occurs when there is blockage in the summit crater of a volcano that looks like a needle, causing the gas pressure becomes larger. If the blockage is not strong crater, the volcano erupted.
d) Type of Sint Vincent eruption. Eruptions of this type will cause the water to spill Danay crater with lava. The eruption resulted in the area around the volcano will buffeted by hot lava that is very dangerous. Example: Kelud which erupted in 1919 and Vincent Sint mountain that erupted in 1902.
Each of these substances can be divided into several types of material. Types of volcanic material released is:
(A) Solid Materials (Efflata), consisting of: bombs (large stone), slag (irregular stones and smaller than bombs), lapih (such as gravel), sand, dust, pumice. According to its origin, efflata divided into two: First, Efflata Allogen, derived from the rocks around the crater that was thrown when there is an eruption, Second, Efflata autogen (Pyroclastica), derived from the magma itself.
(B) Liquid Materials. Magma chamber of molten material flows out of the volcano when magma from within the Earth's liquid melt out of the pit crater without impeded by blockages and there is no blockage in height, consisting of:
(1) Lava is magma that melts out on the slopes of the volcano.
(2) hot lava that is a mixture of magma and water that is flowing mud.
(3) that is formed from cold lava efflata porous or solid material in the top of the mountain to mud when it rains and rains on the slopes and stream valleys. For example, due to the eruption of Mount Merapi in 2006 and has produced approximately 6 million cubic meters of embankment material which will form a cold lava flow when it rains.
(C) Material Gas or exhalation, consists of: First, solfatar, gaseous sulfur (H2S), Second, fumaroles, form water vapor (H2O), Third, Mofet, gaseous carbon dioxide (CO2), the gas is dangerous to lifebecause it is toxic, other than that, it is heavier than oxygen causes the gas is closer to the ground so easily inhaled by living, conthnya, CO2 gas coming out of Mount Dieng in 1979 killed 149 people.
There are some other natural phenomenon formed by a continuous process or post-volcanism, namely:
(A) Obstruction of Lava, appearance occurs when the solid lava in the volcanic pipe which goes into mass-resistant. Some time later, part of the volcanic cone composed of less resistant material being weathered and eroded, leaving behind only occlusion lava. The size of the blockage can be very large lava to resemble hills. One example is the Tower of Satan in Wyoming, USA.
(B) Caldera and Caldera Lake, the caldera is a large basin in the top of the mountain. The appearance is due to the eruption of a very powerful and left a big hole. If the hole is then filled with water will form a caldera lake.
(C) Plato lava. The appearance of this happened because of magma that comes out is diluted so as to spread out and form a vast expanse of lava slowly and over time this lava solidifies to form a plateau called the plateau.
(D) Geyser and Thermal. In volcanic areas, ground water can be heated by magma. This heated water that can come into perukaan with explosive power, this is called a geyser. If water comes out through the water at the crack of rocks, forming hot springs. While the geyser is a hot spring up periodically. For example: Geyser in Yellowstone National Park, USA.
b) live side by side with Volcanism. Volcanoes in Indonesia can be grouped into five series, namely:
(1) The series of Sunda is a series of volcanoes that extends from Sumatra, Java, Bali, Lombok, Sumbawa, Flores to Alor.
(2) The series of Banda, mostly lies below sea level.
(3) The series of Minahasa and Sangihe, the circuit is still active as at Mount Soputan and Mount Lokon.
(4) The series of Halmahera, which is located around Halmahera.
(5) The series is a series of South Sulawesi are inactive (dead).
Signs volcano will erupt (eruption), namely:
(1) The temperature rise in the vicinity of the crater.
(2) Many water sources dry up.
(3) Frequent earthquakes.
(4) Often the sound of thunder in the surrounding mountain peaks.
(5) Many of the animals down the mountain or move.
Symptoms volcano goes out (post-volcanic) are:
(1) The emergence of exhalation or gas source, for example, in Dieng, Central Java.
(2) The exit of the hot springs, for example in Cimelati, West Java.
(3) The advent of spring is makdani panasy ang springs contain minerals such as sulfur. Example Maribaya (West Java), Baturaden and Dieng (Central Java).
(4) The emergence of the hot springs geyser which sprayed into the air. Geyser can reach heights of 70 m. examples in Ireland and Yellowstone Park (United States).
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