Mount Merapi History

Mount Merapi - Geological History

Mount Merapi is the youngest volcano in the series that leads to the south of Mount Ungaran. The mountain is formed due to subduction zones of activity in the Indo-Australian Plate under the Eurasian plate moves cause the appearance of volcanic activity along the central part of the island of Java. This current peak is not overgrown vegetation due to high volcanic activity. This peak grows in the southwest side of the summit of Mount Batulawang more tua.Hasil stratigraphic studies indicate the formation history of Merapi is very complex. Wirakusumah (1989) Geology Merapi divides into two major groups, namely Merapi Merapi Young and Old. Subsequent research (Berthomier, 1990; Newhall & Bronto, 1995; Newhall et.al, 2000) found the stratigraphic units in 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 Aunt with andesitic-basaltic magma ± 700,000 years old located on the eastern slope of Merapi including Boyolali. Aunt mountain rock is andesite-basaltic but does not contain orthopyroxen. Aunt peak has an altitude of about 2050 m above sea level with a flat distance between the peak and the peak of Merapi Bibi is now about 2.5 miles. Due to the very old age Mount Aunt experiencing strong alteration so fresh rock samples are hard to find.

Merapi OLD (60000-8000 years ago)
At this time nascent known as Mount Merapi, which is the initial phase of its formation with cone rudimentary. Extrusion initially took the form of basaltic lava that formed Mount Turgo and Plawangan approximately 40,000 years old. Product activity consists of basaltic andesite rocks with composition of awanpanas, brecciation of lava and lava.

Merapi MID (8000 - 2000 years ago)
Occurred some andesitic lava that make up the hill Batulawang and Gajahmungkur, which is currently visible on the northern slopes of Merapi. The rock is composed of lava flows, lava and pyroclastic brecciation. Merapi activity is characterized by effusive eruptions (melt) and explosive. It is estimated that explosive eruptions also occur with "de¬bris-avalanche" to the west of the left-horse poultice morphology with a length of 7 km, 1-2 km wide with a few hills on the western slopes. In this period Pasarbubar formed crater.

NEW Merapi (2000 years ago - present)
In Pasarbubar crater formed conical peak of Merapi, which is now known as Mount Newer which is currently at the center of the activity of Merapi. Bedrock of Old Merapi Merapi estimated age. While Merapi currently about 2000 years old. Great eruption of Merapi occurred in the past that the distribution of the material has been covered Sambisari located ± 23 km south of Merapi. Stratigraphic studies conducted by Andreastuti (1999) have shown that some major eruption, the eruption index (VEI) of about 4, Plinian type, has occurred in the past. The last major eruption with a fairly broad distribution of produce Selokopo tephra that occurred about 500 years ago. Smaller explosive eruptions observed an estimated 250 years ago which resulted in Pasarbubar tephra. Schematic cross-section of the geological history of Merapi according Berthommier, 1990

Map shows the distribution of sediment awanpanas Merapi 1911-2006. Only the eastern slopes of the free area of ​​flow direction awapanas in this period.

HISTORY OF ERUPTION

Volcanic eruption types can be categorized as weak Vulkanian type. Other types such as Plinian (eg eruption of Vesuvius in 79) is a type of power vulkanian with a very strong eruption. Merapi eruption is not so explosive however pyroclastic flow is almost always the case in every eruption. Visually activity of Merapi eruption seen through a long process since it began with the formation of lava domes, lava and incandescent awanpanas (pyroclastic flow).

Merapi including volcanoes erupt frequently. Until June 2006, the eruption of which is recorded at 83 times the incident. On average interval Merapi eruption occurred between 2-5 years (short period), while the interval of intermediate 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 activity of Merapi started quite well. At this time it appears that time the longest break ever achieved for 71 years when the interval between 1587 until 1658.

Historical eruptions of Mount Merapi began to be recorded (written) since 1768. However, the history of a more detailed chronology of recent eruptions there 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 on Century 20 is relatively more detail. Monitoring volcanoes also was active since the early 20th century During the 19th century eruption occurred around 20, which means the interval Merapi eruption on average every five years. The eruption in 1872 is regarded as the last and largest eruption in the 19th century and 20 have resulted in Mesjidanlama crater with a diameter of between 480-600m. The eruption lasted for five days and is classified in class D. eruption voice sounded through Openwork, Madura and Bawean. Awanpanas flowing through almost all existing upstream at the peak of Merapi is Apu, Trising, Senowo, Blongkeng, Trunk, Woro, and Gendol.

Awanpanas and product material eruption destroyed entire villages which are above 1000m elevation. At that time the crater rim that happens to have elevation 2814m (; compare with the current peak of Merapi is located at an elevation of 2968m). Of events that have past eruptions, changes in body morphology Mount formed by the tongue of lava and eruptions are relatively larger. Mount Merapi is a young volcano. Some previous article mentioned that before there Merapi, has more dahuiu there is Mount Bibi (2025m), northeastern slopes of Mount Merapi. However, it is unknown whether the current volcanic activity took place in the mountain Aunt. From the tests, G. Aunt has a lifespan of about 400,000 years younger mean age Merapi 400,000 years. After the formation of Mount Merapi, G. Aunt buried partially so that the current peak is only partially visible. The next period is the establishment of a hill Turgo and Plawangan as the inception of Mount Merapi. Tests showed that both the hills around maximum 60,000 years old (Berthomrnier, 1990). The two hills dominating the south slope of Mount Merapi morphology.

At higher elevations there are units of lava that Gajahmungkur hill, Pusunglondon and Batulawang contained in the upper part of the body slopes of Merapi. The composition of these hills form the longest, 6700 years ago (Berthommier, 1990). These data indicate that the structure of the upper body of the Merapi volcano newly formed in the order of thousands of years ago. Pasarbubar crater is active crater at the center of the activity of Merapi before crests.

It is estimated that the top of Merapi, which is above the newly formed Pasarbubar started about 2000 years ago. Thus it is clear that the body of Mount Merapi higher and higher and higher with a fast growing process seems only a few thousand years ago. Body peak of Mount Merapi as the location of the active crater is currently the youngest part of Mount Merapi. Aperture crater happens once took different direction with the direction of eruption varies. However, most of the eruption leads to the south, west to north. At the peak of this active lava dome formed and sometimes smashed by the eruption. Active crater of Merapi change from time to time in accordance with the eruption. The growth of the lava dome always fill weak zones that can be a gap between the old and the lava lava earlier in the active crater dome growth is ciapat begins with the eruption or also after the eruption. If this case happens, the demolition of the old lava dome can occur by forming a new crater and the new lava dome growing in the crater eruption. Besides charging or dome growth can occur in the body of the previous lava dome or on the border between the old crater wall with previous lava. So it is not surprising kawahkawah peak of Merapi eruption in varying size and location. The distribution of the eruption also affects the morphology changes, especially on the lip of the crater and upper slopes. Center avalanches 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 quite strong due to the load of material.

As with the bottom of the result of the insistence causing weak zones which then are centers where avalanches. When filling a gap either by growing dome is still limited in number, then the direction of lava can still be controlled in the gaps that exist in the vicinity. However, if the cracks have started full there will be deviations dome growth. So that the nature of the lava dome growth sideways (ie, the period from 1994 to 1998) will lead to changes in the direction of 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 asymmetric shaped lava tongue. If the continuous growth and the speed is not the same, then the lava tongue will begin to form a wavy morphology eventually become parallel to each other but still in one body. Chronology of growth at some point will reach a critical point and distorted causing avalanches or avalanche dome. The chronology of this kind was observed in the years 1943 (April to May 1943).
Stacking of new materials in the area of ​​the peak due dome growth mainly comes from changes in the maximum height of the peak of Merapi. Several eruptions in history has changed the morphology of the summit include the period 18221823 eruption that produced the crater diameter of 600m, the period from 1846 to 1848 (200m), the period of 1849 (250 - 400m), the period from 1865 to 1871 (250m), 1872-1873 (480 - 600 m), 1930, 1961.

merapi 1935