Strategic Communications and Marketing News Bureau

What makes Merapi such a dangerous volcano?

Midwest volcanologist and geology professor Susan W. Kieffer holds a Charles R. Walgreen Jr. Chair at Illinois. In an interview with News Bureau Physical Sciences Editor Jim Kloeppel, Kieffer talked about the recent volcanic activity of Mount Merapi in Indonesia.

Is Mount Merapi a typical volcano?

Yes and no! Volcanoes are like kids: They’re all different! But, like kids, groups of them have some traits in common. Merapi is a typical active stratovolcano, with sisters like Mounts Fuji, Vesuvius, Rainier, and St. Helens. The so-called ‘Pacific Rim of Fire’ is the classic place for these volcanoes. The Cascades of the U.S. and the volcanoes of Japan, Indonesia, New Zealand and the west side of South America are all parts of the rim. In these settings one tectonic plate of Earth’s surface is subducted below another, forming a unique setting where gas-charged magmas are produced and rise up to create the stratovolcanoes. Merapi is typical of these – though a bit hyperactive! It holds the dubious distinction of producing more dangerous ash flows than any other volcano in the world.

What makes a Merapi-type eruption so dangerous?

Merapi-type eruptions are more dangerous than, say, Hawaiian eruptions, because the magma in stratovolcanoes is charged with gas. As a result, when such magma finds a conduit to the surface, it can build up a sticky, hot, gas-rich plug known as a volcanic dome. The dome can build up higher and higher, and then suddenly collapse under its own weight. This creates a very dangerous mixture of hot gas, ash and dome fragments that can flow downhill as much as 5-10 miles because of gravity, can wipe out anything on ridgetops because of the gas expansion, and can melt glaciers and mix with the meltwater to form very dangerous, hot and mobile mudflows. Such a mudflow killed 23,000 people when Ruiz in Colombia erupted in 1985.

Is the volcano’s increased activity related to the May 27 earthquake that struck the area and killed more than 5,500 people?

Almost certainly. We know, for example, that earthquakes in Alaska can affect the geysers in Yellowstone, so there’s good reason to suspect that an earthquake only 30 miles from Merapi would affect the eruptions. Is the activity in early June the response? Or will something bigger happen in the near future? We don’t know. The proximity of stratovolcanoes to faults that can generate the large-magnitude earthquakes is very worrisome. Fortunately, in the recent International Decade of Natural Disaster Reduction, Merapi was one of 16 volcanoes chosen for expedited instrumentation and concentrated study. Fortunately, also, was that Mount Rainier was chosen as well.

Does recent swelling of the volcano’s lava dome indicate imminent collapse?

Almost certainly. The dome collapses, reforms, collapses, reforms. This is dangerous enough, but the geologic record shows that Merapi has another trick that we haven’t seen recently. Sometimes these relatively small collapses unload a deeper magma chamber and a much larger eruption, called a Plinian eruption, occurs. This is the type of eruption that Vesuvius is famous for – the eruption in A.D. 79 that Pliny the Younger documented. This is also what happened at Mount St. Helens in 1980 – the dome there was buried in the north flank of the mountain, and when it blew out in the lateral blast, a bigger eruption was triggered – the one that covered part of the U.S. with a nasty layer of ash.

Read Next

Life sciences Portrait of the research team posing together.

Minecraft players can now explore whole cells and their contents

CHAMPAIGN, Ill. — Scientists have translated nanoscale experimental and computational data into precise 3D representations of bacteria, yeast and human epithelial, breast and breast cancer cells in Minecraft, a video game that allows players to explore, build and manipulate structures in three dimensions. The innovation will allow researchers and students of all ages to navigate […]

Arts Photo of seven dancers onstage wearing blue tops and orange or yellow flowing skirts. The backdrop is a Persian design.

February Dance includes works experimenting with live music, technology and a ‘sneaker ballet’

CHAMPAIGN, Ill. — The dance department at the University of Illinois Urbana-Champaign will present February Dance 2025: Fast Forward this week at Krannert Center for the Performing Arts. February Dance will be one of the first performances in the newly renovated Colwell Playhouse Theatre since its reopening. The performances are Jan. 30-Feb. 1. Dance professor […]

Honors portraits of four Illinois researchers

Four Illinois researchers receive Presidential Early Career Award

CHAMPAIGN, Ill. — Four researchers at the University of Illinois Urbana-Champaign were named recipients of the Presidential Early Career Award for Scientists and Engineers, the highest honor bestowed by the U.S. government on young professionals at the outset of their independent research careers. The winners this year are health and kinesiology professor Marni Boppart, physics professor Barry Bradlyn, chemical and biomolecular engineering professor Ying […]

Strategic Communications and Marketing News Bureau

507 E. Green St
MC-426
Champaign, IL 61820

Email: stratcom@illinois.edu

Phone (217) 333-5010