Merapi Volcano | John Seach


Central Java, Indonesia

7.54 S, 110.44 E
summit elevation 2911 m

Note: a volcano with a similar name "Marapi" is located in Sumatra, Indonesia.

Merapi volcano is one of the world's most active and dangerous volcanoes. It contains an active lava dome which regularly produces pyroclastic flows. Eruptions occur at intervals of 1-5 years and are of low gas pressure. Since magma is poor in gas, eruptions are usually less than VEI 3 in size. A larger VEI 4 eruption occurred in 2010.

Merapi volcano produces more pyroclastic flows than any other volcano in the world. It has been active for 10,000 years.

Merapi volcano photos by John Seach

John Seach at summit of Merapi Volcano 2000

merapi volcano
Merapi volcano 2012

Yogyakarta, central Java

merapi 2010
Inside the exclusion zone, Merapi volcano eruption 2010

Merapi volcano
Pyroclastic flow damage 2010 - John Seach

merapi volcano
Pyroclastic flow destruction 2010 - John Seach

merapi volcano
Pyroclastic flow damage 2010 - John Seach

Merapi eruption 2010 - John Seach

merapi volcano
House destroyed by pyroclastic flow, 2010

Most eruptions of Merapi involve a collapse of the lava dome creating pyroclastic flows which travel 6 to 7 km from the summit. Velocity of pyroclastic flows can reach up to 110 km/hour. A slow up flow of andesitic magma leads to an extrusion of viscous magma, which accumulate and construct a dome in the crater.

Violent Eruptions at Merapi volcano
There is evidence that the current low level of activity may be interrupted by larger explosive eruptions. Eruptions of Merapi volcano during the 7–19th centuries A.D. were more violent than the past hundred years, and produced explosion pyroclastic flows. Widespread pyroclastic flows and surges traveled up to 25 km down the flanks of Merapi.

Scientists predict that the quiet of the 20th century will be broken by a larger
explosive eruption within coming decades. (Scientific report published in 2000).
This was proved true with the large 2010-211 eruptions.

2021 Eruptions
A pyroclastic flow was reported in NW direction on 9 Jan 2021. The event lasted 2 minutes as recorded on seismogram. Visible ash emissions reached 10,000 ft altitude. On 27 January a large eruption sent ash to an altitude of 40,000 ft, accompanied by pyroclastic flows.

2020 Eruption
Eruption of Merapi volcano occurred on 3 March 2020. Ash emissions reached an altitude of 35,000 ft.

2018-19 Eruptions
An explosive eruption occurred at Merapi volcano on 11 May 2018. An eruption plume reached 18,000 ft above the summit. A lava dome grew in the summit crater during the second half of 2018 and throughout 2019.

2013 Eruption
An eruption occurred at Merapi volcano, Indonesia on 18th November 2013. Ash reached an altitude of 6500 ft and drifted 40 km east to the city of Solo.

2012 Activity
A small emission of ash occurred at Merapi volcano, Indonesia on 15th July 2012. The small eruption was not followed by other signs of unrest and the alert status remained unchanged. The eruption was caused by a small collapse of the lava dome which remains unstable after the 2010-11 eruptions. Ash emission reached a height of 1 km above the crater, and ashfall occurred at Jurang Jero and Srumbung.

2010-11 Eruption
The eruption of Merapi volcano in 2010was a one in 100 year event. Merapi volcano began erupting on 26th October 2010. The eruption was the was the largest at the volcano in 100 years. Ash emissions reached an altitude of 40,000 ft, and 370,000 people were evacuated from a 20 km radius danger zone. Over 190 people were killed by pyroclastic flows and ashfall.

2006 Eruptions
Seismic activity began increasing at Merapi volcano in March 2006, and 10,000 residents were prepared for evacuation. On 10th April people were banned from climbing the volcano. On 12th April the Alert Level was raided from 2 to 3. An 8 km exclusion zone was placed around the volcano. On 27th April nearly 2,000 villagers were evacuated from Sidorejo and Tegalmulyo villages around Merapi volcano. On 13th May, the Alert Level was raised to the highest level 4, and about 4,500 people living near the volcano were evacuated. On 15th May pyroclastic flows traveled up to 4 km west. By 16th May, more than 22,000 people had been evacuated. On 8th June, the lava-dome growth rate at Merapi was an estimated 100,000 cubic meters per day, with an estimated volume of 4 million cubic meters. Pyroclastic flows and rockfalls decreased in frequency and intensity after 28th June 2006.

2006 Earthquakes
On 27th May 2006 a magnitude 6.3 earthquake killed about 5,400 people produced in a three-fold increase in activity at Merapi volcano. On 17th July 2006 a magnitude 7.7 earthquake hit 50 km south of Merapi volcano. The earthquake was the result of thrust-faulting on the boundary between the Australian and Sunda tectonic plates. The earthquake produced an 8 m high tsunami which hit the southern coast of Java. This event was classified as a tsunami earthquake, because of the low earthquake magnitude compared to the tsunami size. The earthquake caused 5,750 deaths, 38,560 injuries, and up to 600,000 people displaced in the Bantul-Yogyakarta area.

2001 Eruption
A major eruption began at Merapi volcano on 10th February 2001. A 30-minute-long pyroclastic flow occurred at 0200 hr. At 0330 hr there was a collapse of the 1998 lava dome which ejected ash 5 km above the summit and produced a pyroclastic flows that extended 7 km in the direction of the Sat River.

1998 Eruptions
Activity at Merapi volcano began increasing in July 1998. On 11th July 37 nuées ardentes occurred between midnight and 0500 hr. Between 11-19 July, 128 nuées ardentes occurred, including a strong pyroclastic ash and block flow at 1500 on 19th July.

1994 Eruptions
On 22nd November 1994, a large number of dome-collapse nuees ardentes were generated over a period of several hours at Merapi volcano. The nuees ardentes descended mainly the Boyong valley and the Bedog valley, a tributary of the Krasak-Kecil valley. This was in contrast to the 1984 and 1992 flows which traveled exclusively towards the southwest and west.

1986-87 Eruptions
Lava dome formation at Merapi volcano in 1986-87 was the largest since 1973.

1984 Eruption
On 15th June 1984 explosions at the lava dome produced pyroclastic flows which extended 7 km from the volcano, and ashfall 80 km NW.

1969 Eruption
A pyroclastic flow travelled 13 km during the 1969 eruption.

1968 Eruptions
At the end of May 1968 a lava tongue had extended 875 m and was the result of new lava done extrusion after the 1967 collapse. The number of avalanches from the lava tongue were 1432 in June, 1370 July, 329 August, and 12 in September. Renewed activity began at Merapi volcano in October 1968 with an increasing number of lava avalanches.

1967 Eruptions
A lava dome extruded in April 1967 at the upper Batang River on the SW slope of Merapi volcano. The dome collapsed in October 1967.

1822 Lahar
A hot lahar at Merapi volcano on 28th December 1822 destroyed 4 villages with 100 casualties.

Further reading
Jousset, P., Pallister, J., Boichu, M., Buongiorno, M.F., Budisantoso, A., Costa, F., Andreastuti, S., Prata, F., Schneider, D., Clarisse, L. and Humaida, H., 2012. The 2010 explosive eruption of Java's Merapi volcano—a ‘100-year’event. Journal of volcanology and geothermal research241, pp.121-135.

Newhall, C.G., Bronto, S., Alloway, B., Banks, N.G., Bahar, I., Del Marmol, M.A., Hadisantono, R.D., Holcomb, R.T., McGeehin, J., Miksic, J.N. and Rubin, M., 2000. 10,000 Years of explosive eruptions of Merapi Volcano, Central Java: archaeological and modern implications. Journal of Volcanology and Geothermal Research100(1-4), pp.9-50.

Bardintzeff, J.M., 1984. Merapi volcano (Java, Indonesia) and Merapi-type nuée ardente. Bulletin volcanologique47(3), pp.433-446.

Merapi Volcano Eruptions

2018-23, 2014, 2013, 2012, 2010-11, 2007, 2006, 2001-02, 1992-98, 1972-90, 1971, 1967-69, 1961, 1953-58, 1948-49, 1944-45, 1942-43, 1939-40, 1933-35, 1930-31, 1924, 1923, 1922, 1920-21, 1918, 1915, 1909-13, 1908, 1906-07, 1905, 1902-04, 1902, 1897, 1894, 1893, 1891, 1889, 1888, ?1885, 1883-84, 1878-79, 1872-73, 1872, 1869, 1865-67, 1862-64, ?1854, 1849, ?1848, 1846-47, 1846, 1840, 1837-38, 1832-35, 1828, 1822-23, 1820-22, 1812-13, 1810, 1807, 1797, 1786, 1755, 1752, 1745, 1678, 1677, 1672, 1663, 1658, 1587, 1584, 1560, 1554, 1548, 7630 BC.