Mount Merapi“Mountain of Fire”Java, Indonesia

Matt Treveloni & Ryder ArsenaultDepartment of Geology @ Colby College

LocationPacific Ring of Fire

30 km North of Yogyakarta, Indonesia

Destructive plate margin (Indo-Australian Plate & Eurasian Plate)

Form & Dimensions

Stratovolcano

Elevation: 2,930 m,1,356 m above ground

Summit is higher on the North, lahars and pyroclastic flows run down the South side

Years of eruptions created distinct trench

EruptionsFault line: Sunda-Banda Arc

Subduction of Indo-Australian Plate under the Eurasian Plate (twice as thick)Erupts: Hot gas, ashes, volcanic bombs (pyroclastic flows, lahars)

Mt. Merapi erupts every 4-5 years with bigger eruptions every decade (2010), but smoke is seen emerging 300 days a year!

Most of the lavas from Merapi are high potassium basaltic andesites.

The lava from Mt. Merapi is mainly porphyritic. Plagioclase and clinopyroxene are the most common phenocrysts.

Silica content ranges from 52 to 57%.

Rocks & Deposits

Phenocrysts can occupy up to 60% of the total rock volume in Mt. Merapi’s lava.

2010 Eruption

Effects of the 2010 Eruption

Dome Collapse

Crop Destruction

The safe zone for the 2010 eruption was 20 km from the volcano. Over 4 million people live within 30 km.

Fun Facts

Over 300,000 people were forced to evacuate their homes.

Why is Mt. Merapi So Dangerous?

● Mt. Merapi has produced more pyroclastic flows than any other volcano in the world

● Only 30 km away from Yogyakarta (population ~400K) which lies directly in flow path

● Indonesia’s intense rainfall causes massive lahars

Culture & Other Info● Considered sacred by local people, they believe

that a supernatural kingdom exists at the summit and a priest makes an offering once a year

● Ash leads to fertile soil● Conservation area (unsafe to live) and illegal to

climb to summit● Tourism lies in museums● No geothermal energy or hydrothermal activity

Monitoring● Seismology

○ There are 8 seismograph stations in the network.● Volcanomagnetism

○ Since 1977 they monitor the magnetism beneath the Earth’s surface.

● Deformation○ Three GPS signals measure to make sure the distance and

angles between all three remain the same.○ In 1990 they introduced tilt monitors to measure deformation.

● Geochemistry○ There are two solfatara fields used for measuring the volcanic

gases.● Lahar Detection

○ Lahars are usually triggered by heavy rainfall.○ An acoustic sensor measures the noise given off by a lahar in

order to detect when one begins moving.

ReferencesMarliyani, G.I., 2010: An Overview of Merapi Volcano, Central Java, Indonesia, at

http://mountmerapi.net/mount-merapi/ (accessed 22 January, 2015)Leontiou, A., 2010: FAQ: A Look Inside Mount Merapi, at

http://www.livescience.com/11081-faq-mount-merapi.html (accessed 24 January, 2015)Lavigne, F. & Thouret, J.C., 2003: Sediment transportation and deposition by rain-triggered

lahars at Merapi Volcano, Central Java, Indonesia, at http://www.sciencedirect.com/science/article/pii/S0169555X02001605 (accessed 23 January, 2015)

Seach, J., 2012: Merapi Volcano, at http://www.volcanolive.com/merapi.html (accessed 25 January, 2015)

Simkin, T. & Siebert, L., 1994: Volcanoes of the World, at http://volcano.oregonstate.edu/oldroot/volcanoes/merapi/merapi.html (accessed 25 January, 2015

References

Boston.com 2010: Mount Merapi’s eruptions at http://www.boston.com/bigpicture/2010/11/mount_merapis_eruptions.html (Accessed 25 January, 2015) Geotalk, 2012. Mt. Merapi Eruption at

http://www.geotalk.info/#!mt-merapi/c21bv (Accessed 25 January, 2015) Gertisser, R. 2003: Temporal Variations in magma composition at Merapi

Volcano at http://www.sciencedirect.com/science/article/pii/S0377027303000258 (Accessed 25 January, 2015) Smithsonian Institution, 2013: Global Volcanism Program at http://volcano.si.edu/volcano.cfm?vn=263250 (Accessed 25 January, 2015)

Youtube 2010: Merapi Eruption: Travel chaos as volcano spews massive clouds of ash at https://www.youtube.com/watch?v=nEBTfQ79Z7A (Accessed 25 January, 2015)