HISTORY OF GEOLOGY
The results show the history of the formation of Merapi stratigraphy is very complex. Wirakusumah (1989) Geology Merapi divides into 2 major groups namely Merapi Merapi Young and Old. Subsequent research (Berthomier, 1990; Newhall & Bronto, 1995; Newhall et.al, 2000) found the stratigraphic units at Merapi are more detailed. According Berthommier, 1990 based on stratigraphic studies, the history of Merapi can be divided into 4 parts:
PRE MERAPI (400,000 years ago)
Referred to as Mount Aunt with andesitic-basaltic magma ± 700,000 years old located on the eastern slope of Merapi including Boyolali district. Volcanic rocks are andesitic-basaltic aunt but does not contain orthopyroxen. Aunt peak has an altitude of about 2050 m above sea level with flat distance between the peak and the peak of Merapi Bibi is now about 2.5 km. Because of the very old age Mount Aunt experiencing strong alteration so hard to find fresh rock specimens.
MERAPI OLD (60000-8000 years ago)
At this time begin to birth, known as the Mount Merapi, which is the initial phase of its formation with immature cone. Initially in the form of basaltic lava extrusion that forms Mount Turgo and Plawangan about 40,000 years old. Product activity consists of rocks with basaltic andesite composition of awanpanas, brecciation of lava and lava.
MERAPI MID (8000 - 2000 years ago)
Occurred some molten lava that make up the hill Batulawang andesitic and Gajahmungkur, which is currently visible on the northern slopes of Merapi. Rock composed of lava flows, lava and hot clouds brecciation. Merapi activity is characterized by effusive eruptions (melt) and explosive. Also estimated that an explosive eruption with "de ¬ bris-avalanche" to the west that left morphology with a long horse shoe-7 km, 1-2 km wide with a few hills on the western slope. In this period Pasarbubar formed crater.
NEW MERAPI (2000 years ago - present)
In the crater of Merapi summit cone formed Pasarbubar currently known as Mount Anyar which is currently a central activity of Merapi. The basement of Old Merapi Merapi may be old. While Merapi is now about 2000 years old. Major eruption of Merapi occurred in the past that the distribution of the material being covered Sambisari located ± 23 km south of Merapi. Stratigraphic studies conducted by Andreastuti (1999) have shown that several major eruption, the eruption index (VEI) of 4, Plinian type, have occurred in the past. The last major eruption with a fairly broad distribution of tephra produced Selokopo which occurred around about 500 years ago. Smaller explosive eruptions observed estimated 250 years ago which resulted Pasarbubar tephra. Schematic cross-section according to the geological history of Merapi Berthommier, 1990 (picture right).
Map showing the distribution of sediment awanpanas Merapi 1911-2006. Only the eastern slope that is free from the direction of flow awapanas in this period.
HISTORY eruption
Mount Merapi eruption type can be categorized as a type Vulkanian weak. Other types such as Plinian (eg eruption of Vesuvius in 79) is a type of power vulkanian with a very strong explosion. Merapi eruption yet not so explosive pyroclastic flow is almost always occur in each eruption. The visual activity of Merapi eruption seen through a long process since it began with the formation of lava domes, lava and incandescent awanpanas (pyroclastic flow).
Including Merapi volcano erupts frequently. Until June 2006, has recorded eruption was 83 times the incident. On average interval Merapi eruption occurred between 2-5 years (short period), while the medium over that time period every 5-7 years. Merapi has experienced the longest period of rest for> 30 years, especially early in its existence as a volcano. Entering the 16th century recorded the activities of Merapi began well enough. At this time it appears that the longest break ever achieved for 71 years when the gap between in 1587 until the year 1658.
Historical eruptions of Merapi volcano began to be recorded (written) since the year 1768. However, history is more detailed chronology of the eruption of new there in the late 19th century. There is a tendency that in the 20th century eruption is more frequent than in the 19th century. This can happen karenapencatatan an event in the 20th century relatively more detailed. Monitoring active volcanoes also recently started to do since the early 20th century. During the 19th century occurred about 20 eruptions, the eruption of Merapi, which means that the interval on average every five years. The eruption in 1872 is regarded as the last and largest eruption in the 19th and 20th centuries have produced Mesjidanlama crater with a diameter of between 480-600m. The eruption lasted for five days and is classified in class D.
Cracking noise sounded until Kerawang, Madura and Bawean. Awanpanas runs through nearly all of the upstream river that is on top of Merapi is Apu, Trising, Senowo, Blongkeng, Batang, Woro, and Gendol. Awanpanas and product material eruption destroyed all the villages which are above 1000m elevation. At that time the lip of the crater that happens has an elevation of 2814m (; compare with the current peak of Merapi is located at an elevation of 2968m). From the events in the distant past eruptions, changes in body morphology is formed by the tongue Mountain lava and eruptions are relatively larger. Mount Merapi is a young volcano. Some previous posts have mentioned that before Merapi, there are already more dahuiu Mount Aunt (2025m), northeast slope of Mount Merapi. However, it is unknown whether current volcanic activity took place in the mountains Aunt. From the testing conducted, G. Bibi has a mean age of about 400,000 years old Merapi younger than 400,000 years. After the formation of Mount Merapi, G. Aunt partially buried so that now only partly visible peak. The next period of formation and Plawangan Turgo hill as the beginning of the birth of Mount Merapi. Tests showed that both the hill has a maximum around 60,000 years old (Berthomrnier, 1990). The two hills dominating the morphology of the southern slopes of Mount Merapi.
At higher elevations there are more units of lava that is the hill Gajahmungkur, Pusunglondon and Batulawang contained on the upper slopes of Merapi's body. The composition of the hills are formed at the latest on, 6700 years ago (Berthommier, 1990). These data indicate that the structure of Mount Merapi upper body recently formed in the order of thousands of years ago. Pasarbubar crater is active crater at the center of activity before the formation of the peak of Merapi.
It is estimated that the peak of Merapi was on the newly formed Pasarbubar began about 2000 years ago. It is obvious that the body mount Merapi higher and higher and higher with the fast growing process seems only a few thousand years ago. Body Mount Merapi summit as the current location of the active crater is the youngest part of the Mount Merapi. Crater happened ever take different directions with the direction of eruption varies. However, most of the eruption led to the south, west to the north. On top of this active lava dome was formed and sometimes destroyed by the eruption.
Active crater of Merapi change from time to time in accordance with the eruption that occurred. Lava dome growth was always filling weak zones that can be a gap between the old lava flows and lava in the crater before active growth of this dome ciapat begins with the eruption or also after the eruption. If this case happens, then the demolition of the old lava dome may occur by forming a new crater and a new lava dome growing inside the crater of the eruption. Besides charging or dome growth can occur in the body before the lava dome or on the border between the old crater wall with lava before.
So it is not surprising that at the peak of Merapi eruption kawahkawah varying size and location. Spread the eruption was also influential in changing the morphology, especially on the lip of the crater and upper slopes. Central landslide that occurred at the peak of Merapi, the lava dome on the body usually at the bottom of which is the result of terdistribusikannya pressure at the bottom because the top is still strong enough for the load of material.
As with the bottom of the result of pressure caused weak zones which then was a glowing centers. When filling the gap either by the growth of the dome is still limited in number, then the direction of lava can still be controlled in the gaps that exist in the vicinity. But if the cracks have started full there will be deviations dome growth. So the nature of the lava dome growth sideways (ie, the period from 1994 to 1998) will lead to changes in direction of eruption. This change also can occur in a relatively short period of time and of the same lava dome. Growth of the lava dome has grown from symmetrical to asymmetrical tongue-shaped lava. If the continuous growth and the speed is not the same, then the tongue of lava will begin to form a corrugated morphology which eventually become parallel to each other but still in one body. Chronology of growth at some point will reach a critical point and lead to avalanches or avalanche deviate dome. Chronology of this kind is observed in the years 1943 (April to May 1943).
Accumulation of new material in the peak area result of dome growth, especially seen from the change in the maximum height of the peak of Merapi. Several eruptions in history has changed the morphology of the peak, among others, the eruption period 18221823 which produces crater 600m in diameter, the period from 1846 to 1848 (200m), the period of 1849 (250 - 400m), the period from 1865 to 1871 (250m), from 1872 to 1873 (480 - 600 m), 1930, 1961.
Source From "http://merapi.bgl.esdm.go.id/informasi_merapi.php?page=informasi-merapi&subpage=sejarah"
Map showing the distribution of sediment awanpanas Merapi 1911-2006. Only the eastern slope that is free from the direction of flow awapanas in this period.
HISTORY eruption
Mount Merapi eruption type can be categorized as a type Vulkanian weak. Other types such as Plinian (eg eruption of Vesuvius in 79) is a type of power vulkanian with a very strong explosion. Merapi eruption yet not so explosive pyroclastic flow is almost always occur in each eruption. The visual activity of Merapi eruption seen through a long process since it began with the formation of lava domes, lava and incandescent awanpanas (pyroclastic flow).
Including Merapi volcano erupts frequently. Until June 2006, has recorded eruption was 83 times the incident. On average interval Merapi eruption occurred between 2-5 years (short period), while the medium over that time period every 5-7 years. Merapi has experienced the longest period of rest for> 30 years, especially early in its existence as a volcano. Entering the 16th century recorded the activities of Merapi began well enough. At this time it appears that the longest break ever achieved for 71 years when the gap between in 1587 until the year 1658.
Historical eruptions of Merapi volcano began to be recorded (written) since the year 1768. However, history is more detailed chronology of the eruption of new there in the late 19th century. There is a tendency that in the 20th century eruption is more frequent than in the 19th century. This can happen karenapencatatan an event in the 20th century relatively more detailed. Monitoring active volcanoes also recently started to do since the early 20th century. During the 19th century occurred about 20 eruptions, the eruption of Merapi, which means that the interval on average every five years. The eruption in 1872 is regarded as the last and largest eruption in the 19th and 20th centuries have produced Mesjidanlama crater with a diameter of between 480-600m. The eruption lasted for five days and is classified in class D.
Cracking noise sounded until Kerawang, Madura and Bawean. Awanpanas runs through nearly all of the upstream river that is on top of Merapi is Apu, Trising, Senowo, Blongkeng, Batang, Woro, and Gendol. Awanpanas and product material eruption destroyed all the villages which are above 1000m elevation. At that time the lip of the crater that happens has an elevation of 2814m (; compare with the current peak of Merapi is located at an elevation of 2968m). From the events in the distant past eruptions, changes in body morphology is formed by the tongue Mountain lava and eruptions are relatively larger. Mount Merapi is a young volcano. Some previous posts have mentioned that before Merapi, there are already more dahuiu Mount Aunt (2025m), northeast slope of Mount Merapi. However, it is unknown whether current volcanic activity took place in the mountains Aunt. From the testing conducted, G. Bibi has a mean age of about 400,000 years old Merapi younger than 400,000 years. After the formation of Mount Merapi, G. Aunt partially buried so that now only partly visible peak. The next period of formation and Plawangan Turgo hill as the beginning of the birth of Mount Merapi. Tests showed that both the hill has a maximum around 60,000 years old (Berthomrnier, 1990). The two hills dominating the morphology of the southern slopes of Mount Merapi.
At higher elevations there are more units of lava that is the hill Gajahmungkur, Pusunglondon and Batulawang contained on the upper slopes of Merapi's body. The composition of the hills are formed at the latest on, 6700 years ago (Berthommier, 1990). These data indicate that the structure of Mount Merapi upper body recently formed in the order of thousands of years ago. Pasarbubar crater is active crater at the center of activity before the formation of the peak of Merapi.
It is estimated that the peak of Merapi was on the newly formed Pasarbubar began about 2000 years ago. It is obvious that the body mount Merapi higher and higher and higher with the fast growing process seems only a few thousand years ago. Body Mount Merapi summit as the current location of the active crater is the youngest part of the Mount Merapi. Crater happened ever take different directions with the direction of eruption varies. However, most of the eruption led to the south, west to the north. On top of this active lava dome was formed and sometimes destroyed by the eruption.
Active crater of Merapi change from time to time in accordance with the eruption that occurred. Lava dome growth was always filling weak zones that can be a gap between the old lava flows and lava in the crater before active growth of this dome ciapat begins with the eruption or also after the eruption. If this case happens, then the demolition of the old lava dome may occur by forming a new crater and a new lava dome growing inside the crater of the eruption. Besides charging or dome growth can occur in the body before the lava dome or on the border between the old crater wall with lava before.
So it is not surprising that at the peak of Merapi eruption kawahkawah varying size and location. Spread the eruption was also influential in changing the morphology, especially on the lip of the crater and upper slopes. Central landslide that occurred at the peak of Merapi, the lava dome on the body usually at the bottom of which is the result of terdistribusikannya pressure at the bottom because the top is still strong enough for the load of material.
As with the bottom of the result of pressure caused weak zones which then was a glowing centers. When filling the gap either by the growth of the dome is still limited in number, then the direction of lava can still be controlled in the gaps that exist in the vicinity. But if the cracks have started full there will be deviations dome growth. So the nature of the lava dome growth sideways (ie, the period from 1994 to 1998) will lead to changes in direction of eruption. This change also can occur in a relatively short period of time and of the same lava dome. Growth of the lava dome has grown from symmetrical to asymmetrical tongue-shaped lava. If the continuous growth and the speed is not the same, then the tongue of lava will begin to form a corrugated morphology which eventually become parallel to each other but still in one body. Chronology of growth at some point will reach a critical point and lead to avalanches or avalanche deviate dome. Chronology of this kind is observed in the years 1943 (April to May 1943).
Accumulation of new material in the peak area result of dome growth, especially seen from the change in the maximum height of the peak of Merapi. Several eruptions in history has changed the morphology of the peak, among others, the eruption period 18221823 which produces crater 600m in diameter, the period from 1846 to 1848 (200m), the period of 1849 (250 - 400m), the period from 1865 to 1871 (250m), from 1872 to 1873 (480 - 600 m), 1930, 1961.
Source From "http://merapi.bgl.esdm.go.id/informasi_merapi.php?page=informasi-merapi&subpage=sejarah"
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