4 Interesting Facts about Mount Merapi that are not widely known, Number 3 Changes in the Direction of the Eruption

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Mount Merapi rises 2,986 meters above sea level and is located on the border of Central Java and Yogyakarta Provinces. Photo/SINDOnews/Antara/BPPTKG

JAKARTA – Mount Merapi, towering as high as 2,986 meters above sea level, is on the border of Central Java Province and the Special Region of Yogyakarta (DIY). Mount Merapi, which was once known as Mandrageni, is an active volcano on the islands of Java and Indonesia.

Quoted from the website of the Ministry of Energy and Mineral Resources, Saturday (18/3/2023), in general, the geological history of Mount Merapi is divided into four periods, namely Pre-Merapi, Old Merapi, Young Merapi, and New Merapi. The first period is Pre-Merapi, which started around 700,000 years ago, which currently leaves traces of Mount Bibi (2025 m asl) on the northeastern slope of Mount Merapi.

However, the history of the eruption of Mount Merapi in writing began to be recorded since the beginning of the Dutch colonial period around the 17th century. Previous eruptions were not clearly recorded. Here are 4 interesting facts about Mount Merapi, summarized from the ESDM page.

1. 80 Eruption

Since 1768, more than 80 eruptions have been recorded, some of which are major eruptions. The 19th century eruptions had relatively greater intensity, while the 20th century eruptions were more frequent.

Large eruptions can be explosive and the range of hot clouds reaches 15 Km. The 19th century eruptions were much bigger than the 20th century eruptions, as hot clouds reached 20 km from the summit.

2. Big Eruption

In the new Merapi period (about 2000 years ago) there have been several major eruptions. Based on the eruption index of the Volcano Explosivity Index (VEI) between 1-3, major eruptions (VEI ≥ 3) namely the period of the 19th century, (years 1768, 1822, 1849, 1872) and the period of the 20th century namely 1930-1931.

Mount Merapi’s eruption activity in the 20th century occurred at least 28 times, with the largest eruption occurring in 1931. It has been three-quarters of a century or 75 years since there has been no major eruption. The possibility of a major eruption occurs once in 100 years (Newhall, 2000).

3. Eruption Direction

The eruption of Mount Merapi since 1872-1931 leads to the west-northwest. However, since the big eruption in 1930-1931, the direction of the dominant eruption was to the southwest until the 2001 eruption.

Except for the 1994 eruption, there was a deviation to the south, namely upstream of Boyong River, located between the hills of Turgo and Plawangan. The last eruption was in 2006, there was a change in direction from southwest to southeast, forming a crater opening that leads to Kali Gendol.

4. Located on the Border of 4 Regencies

Mount Merapi is located on the border of four districts, namely Sleman Regency, DIY Province and Magelang Regency, Boyolali Regency and Klaten Regency in Central Java Province. Geographical position is located at 7° 32’30” South Latitude and 110° 26’30” East Longitude.

Mount Merapi appears in the southern part of the lineament of the volcanic range in Central Java starting from north to south, namely Ungaran-Telomoyo-Merbabu-Merapi with the N165 E direction. This alignment is a fault related to cracks caused by tectonic activity that preceded volcanism in Central Java .

(wib)