History of Mount Merapi since 700 000 years ago.

History of Mount Merapi since 700 000 years ago.

Hot clouds, the nature of the eruption of Mount Merapi, Yogyakarta.
Of course, to avoid the dangers and take advantage of boondoggle is not only necessary when in need of it. The story of the history of Mount Merapi is also interesting to note as a common knowledge for us volcanologist. Below is the article from the Geological Agency of the history of Mount Merapi in October 2010 it was turbulent.
GEOLOGICAL HISTORY
The results show the history of the formation of Merapi stratigraphy is very complex. Wirakusumah (1989) Geology Merapi split into two major groups, namely Merapi Merapi Young and Old. Subsequent research (Berthomier, 1990; Newhall & Bronto, 1995; Newhall et.al, 2000) found stratigraphic units at an increasingly detailed Merapi. According Berthommier, 1990 based on stratigraphic studies, the history of Merapi can be divided into 4 parts:
PRA MERAPI (+ 400,000 years ago)
Referred to as Mount Bibi with andesitic-basaltic magma ± 700,000 years old located on the eastern slopes of Merapi including Boyolali. Volcanic rocks are andesitic-basaltic aunt but do not contain orthopyroxen. Bibi has a peak elevation of about 2050 m above sea level with the flat distance between the peak and the peak of Merapi Bibi is now about 2.5 km. Due to the very old age Gunung Bibi experiencing strong alteration so hard to find fresh rock samples.
MERAPI OLD (60000-8000 years ago)
During this nascent known as Mount Merapi, which is the initial phase of the formation with the cone is not perfect. Extrusion originally a basaltic lava that forms Mount Turgo and Plawangan approximately 40,000 years old. Product activity consists of basaltic andesite rocks with a composition of awanpanas, brecciation of lava and lava.
MERAPI MIDDLE (8000 - 2000 years ago)
There were some andesitic lava that make up hills and Gajahmungkur Batulawang, which currently visible on the northern slopes of Merapi. The rock consists of lava flows, brecciation of lava and hot clouds. Merapi activity is characterized by effusive eruptions (melt) and explosive. Explosive eruption is also expected to "de ¬ bris-avalanche" westbound leaving the horses hooves morphology with a length of 7 km, width of 1-2 miles with some hills on the western slope. In this period Pasarbubar crater formed.
NEW MERAPI (2000 years ago - present)
In the crater of Merapi summit cone formed Pasarbubar currently referred to as Mount Anyar is currently a central activity of Merapi. Bedrock of Old Merapi Merapi was estimated. While Merapi currently about 2000 years old. Great eruption of Merapi in the past that the distribution of the material has been covered Sambisari located ± 23 km south of Merapi. Stratigraphic study conducted by Andreastuti (1999) have shown that several major eruption, the eruption index (VEI) of about 4, Plinian type, have occurred in the past. The last major eruption with a wide distribution of tephra produced Selokopo going around about 500 years ago. Smaller explosive eruptions observed predicted 250 years ago that produced a tephra Pasarbubar. Schematic cross-section of the geological history of Merapi according Berthommier, 1990 (right image).
Map showing the distribution of sediment awanpanas Merapi 1911-2006. Only the eastern slopes of the free flow directions awapanas in that time.
HISTORY eruption
Type of eruption can be categorized as a type of weak Vulkanian. Another type as Plinian (eg eruption of Vesuvius in 79) is a type of eruption vulkanian with a very strong power. Merapi Eruption however not so explosive pyroclastic flows almost always occur in every eruption. Visually activity of Merapi eruption seen through a long process since it began with the formation of a lava dome, and awanpanas incandescent lava (pyroclastic flow).
Including Merapi volcano erupts frequently. As of June 2006, recorded eruptions has reached 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 had experienced the longest period of rest for> 30 years, especially in the early days of its existence as a volcano. Entering the 16th century recorded the activities of Merapi began well enough. At times it appears that the longest break ever achieved for 71 years when the gap between the year 1587 until the year 1658.
Evolution of Mount Merapi
Historical eruptions of Mount Merapi began to be recorded (written) since the year 1768. However, history is more detailed chronology of the recent eruption was in the late 19th century. There is a tendency that the more frequent eruptions of the 20th century than in the 19th century. This can happen karenapencatatan an event in the 20th century are relatively more detail. Monitoring also was active volcanoes done since the early 20th century. During the 19th century eruption occurred around 20, which means the interval Merapi eruptions on average every five years. The eruption in 1872 is regarded as the last and the biggest eruption of the 19th century and 20 have produced Mesjidanlama crater with a diameter of between 480-600m. The eruption lasted for five days and is classified in class D. Loud pop sound to filigree, Madura and Bawean. Awanpanas runs through almost all of the upstream rivers in the peak of Merapi is Apu, Trising, Senowo, Blongkeng, Trunk, Woro, and Gendol.
Awanpanas and product material eruption destroyed all the villages that are above elevation 1000m. At that time the crater rim has happened elevation 2814m (; compared to the current peak of Merapi is located at an elevation of 2968m). Of events in the distant past eruptions, changes in body morphology in mountain formed by lava tongue and a relatively larger eruption. Mount Merapi is a young volcano. Several previous article mentioned that before Merapi, there are already more dahuiu Mount Bibi (2025m), north-eastern slopes of Mount Merapi. However, it is unknown whether the current volcanic activity that took place on the mountain Bibi. From the tests conducted, G. Bibi has a life of about 400,000 years mean age Merapi younger than 400,000 years. After the formation of Mount Merapi, G. Aunt partially buried so that now only partially visible peak. The next period is the formation of hills and Plawangan Turgo the inception of Mount Merapi. Tests showed that both the hill was about a maximum of 60,000 years (Berthomrnier, 1990). The two hills dominating the morphological southern slopes of Mount Merapi.
At higher elevations there is lava units Gajahmungkur hill, Pusunglondon and Batulawang located on the upper slopes of Merapi body. The composition of the hills are formed later than on, 6700 years ago (Berthommier, 1990). These data indicate that the structure of the upper body of Merapi 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 is in the newly formed Pasarbubar started about 2000 years ago. It is obvious that the body mount Merapi higher and higher and higher with the rapid increase seen only a few thousand years ago. Body peak of Mount Merapi as the location of the active crater is now a part of the youth of Mount Merapi. Aperture crater happens once took different directions with varying direction of eruption. However, most of the eruption leads to the south, west to the north. At the height of the active lava dome formed and sometimes shattered by the explosion. Active crater of Merapi change from time to time in accordance with the eruption. The growth of the lava dome always fill weak zones can be a gap between the old and the lava in the crater of an active lava earlier this dome growth ciapat also preceded by eruptions or after eruption. If this case happens, then dismantling the old lava dome could occur by forming a new crater and a new lava dome growing in the crater of the eruption. Besides charging or dome growth can occur in the body of the lava dome before or at the boundary 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. The distribution of the eruption also affects the changes in morphology, especially in the lip of the crater and upper slopes. Center landslide that occurred at the peak of Merapi, on the body of the lava dome is usually at the bottom of which is a result of terdistribusikannya pressure at the bottom because the top is still strong enough for the weight of the material.
As with the bottom of the result of the pressure causing weak zones which gave glowing centers. When filling a gap either by the growth of the dome is still limited in number, the direction of lava can still be controlled in a gap in the vicinity. However, if the cracks are beginning to fill up, there will be deviations dome growth. So that the nature of the lava dome growing sideways (ie, the period from 1994 to 1998) will result in a change of direction eruption. These changes can also occur in a relatively short period of time and from the same lava dome. The growth of the lava dome has grown from symmetric to asymmetric shaped lava tongue. If the continuous growth and speed are not the same, then the lava tongue will begin to form a wavy morphology that eventually become parallel to each other but still in one body. Chronology of growth at some point will reach a tipping point and cause avalanches or avalanche deviant dome. The chronology of this kind observed in th 1943 (April to May 1943).
Stacking of new materials in the area of ​​the peak effect of dome growth mainly comes from changes in the maximum height of the peak of Merapi. Several eruptions in history have transformed morphology among others eruption peak generating periods 18221823 600m diameter crater, 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.