Chapter Partial Draft: Mount Merapi

Edited March 19, 2023. Also, blog updates.

I don’t have this revision finished yet and have another Sunday volcano post scheduled for tomorrow (have fun in Iceland!).

However, Gunung Merapi is forcing the pace a bit:

Kok nggak takut ya? pic.twitter.com/tJARa41p9n

— JALIN Merapi (@jalinmerapi) March 11, 2023

https://platform.twitter.com/widgets.js

JALIN Merapi is an excellent source of up-to-date info, but remember: it’s meant as a civil defense network, not socializing.

These are sand miners, mentioned in my chapter draft below.

Despite the awful appearance in this video, the volcano alert (Indonesian) is still at Level III at the time of writing.

They last went to Level IV, the highest level, in 2010, and almost half a million people evacuated for more than a month.

That was a much worse situation, but this present activity seems elevated above Gunung Merapi’s typical low-level activity.

However, per the Jakarta Post, it could be a one-off event:

Official at local monitoring post, Yulianto said no residents have been evacuated.

“This has only been observed as one time event, there have been 5-6 avalanches. If the coverage continue to increase and the distance is further than 7 kilometers, it is likely that the residents will be recommended to evacuate,” he said.

Those experts really know the volcano, and with two crumbly domes up there recently, it’s not surprising to see such flows.

But it’s always good to keep an eye on Mount Merapi.

Here is a livestream (watch out for the electronic whistle).

And here is what I’ve got with the chapter revision thus far.

Everything from the hazards section on is incomplete, including the source list, and the section on the 2010 eruption remains unwritten at the moment.

But there is enough here, I hope, to give you at least some background understanding of this restless Indonesian volcano.

Please contact me at bjdeming at gmail dot com or via Twitter if you have questions about sources, etc.

Pretty, isn’t it?

For contrast, just add a thin ribbon of incandescent red lava coming down the emerald green hillside — no, wait. Let’s not do that.

There are anywhere from 900 and 1900 people per square kilometer (0.4 mi2) living up there. (Mei et al.; Thouret et al.)

That greenery is not a wilderness — most of it is under cultivation.

Good land is so scarce here that hundreds of small farming villages, and their associated fields, pastures, stock pens, and plantations, occupy the lower two-thirds of this active volcano. (Thouret et al.)

Above the villages and vegetation towers the volcano’s rugged summit, where pyroclastic flows run out almost constantly.

You’d think no one ever goes up there, and it is officially a Forbidden Zone. But some 80,000 miners nevertheless haul sand off those flow fields every day. (Nossin; Voight et al.)

Sand miners?

What? Are there also light-saber duels in the summit crater when an eruption’s on?

Picture it. The real-life story behind these images is cool, too, though written as a technical paper; here’s the abstract.

Actually, while researching this chapter, I was surprised to learn that there is a global sand shortage because of the demand for high-grade silica in electronics manufacturing.

Most beach and desert sand doesn’t have the right qualities to be turned into processors, etc. Volcanic ash does, and it’s a valuable global commodity.

High prices, plus some harsh economic realities here in Central Java, mean that sand miners will do their thing at this productive volcano despite the risk, both up at the summit and in dry river channels down below that are prone to sudden mudflows.

All told, per Thouret et al., more than a million people live and work on this 9,700-foot-tall cone-shaped fire mountain. (“Mount Fire Mountain” is its name — Gunung Merapi in the local language).

Sure, it’s dangerous — but at least you can earn a living here.

(A little foreshadowing: What arguments would you use to convince these hardscrabble folks to evacuate before an eruption? Force seems to have only worked once, for the Japanese Army in 1943, during its occupation of Java during World War II, per Voight et al.)

Down in the lowlands live several million more Javanese. Many have settled at Mount Merapi’s feet, where the tropical climate quickly turns volcanic ash and mudflow material into rich topsoil; others live in Yogyakarta, whose downtown area is less than twenty miles south of the volcano’s often fiery summit.

Tradition is very important here.

Yogyakarta is a famous cultural center and the only major Indonesian city still ruled by a monarchy. (Wikipedia)

There is tremendous respect for nearby Gunung Merapi, too, even on a secular level:

Living harmony with Merapi
Sebagai gunung berapi aktif, fenomena erupsi merupakan hal yang wajar bagi Merapi, sebagai sebuah "tugas" dari Sang Pencipta untuk menjaga keseimbangan alam.

Merapi, keseimbangan, dan keberkahan. Begitulah sekiranya dapat kita pahami. pic.twitter.com/Ywx66h1Xtd

— Merapi Uncover (@merapi_uncover) March 12, 2023

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Per Twitter translation of this and the next post in the thread: “Living harmony with Merapi
As an active volcano, the phenomenon of eruption is a natural thing for Merapi, as a “duty” from the Creator to maintain the balance of nature.

Merapi, balance and blessings. That’s if we can understand.

Because behind the eruption that people call a “disaster”, in fact there are various blessings that come after it.

We humans as “guests” on the site of Merapi, it is appropriate to be self-aware, that in fact we are the ones who have to adapt to the “hosts”.

And, according to traditional beliefs still held by many of those at risk from Gunung Merapi, the volcano is a sacred place that, in the midst of danger, offers them many gifts. (Mei et al.)

It even has a spiritual gatekeeper. Mas Lurah Suraksosihono (better known as Asih) received the royal appointment after his father, gatekeeper Mbah Maridjan, died during the opening hours of Gunung Merapi’s unusually large 2010 eruption.

The overall story of that eruption comes closest to the imaginary short film that sometimes plays in our heads when we hear the words “Decade Volcano.”

You know: scientists, while studying a restless volcano, save tens of thousands of lives by making a high-stakes evacuation call just before the cataclysmic explosion.

That really happened here during the night of November 4-5, 2010.

However, this Decade Volcano is usually much more low-key. The last time something as big as the 2010 eruption happened was in 1872.

There is still plenty to be concerned about on a daily basis, though.

The people of Java call the volcano “Mount Fire Mountain” for a reason.

What is Mount Merapi?

Gunung Merapi is a very young cone-shaped stratovolcano that sits inside a two-mile-wide somma ampitheater opening generally south and westward. (Gertisser et al., 2011; Newhall et al.; Nossin; Thouret and Lavigne)

A somma! Sound familiar?

If that doesn’t already have you thinking of some of the other Decade Volcanoes, then here’s another tie-in: Mount Merapi, just like Mexico’s Colima, is the youngest and southernmost of a whole family of volcanoes!

At Colima, north to south, it’s El Cántaro, Nevado de Colima, Paleofuego (now a somma), and active Fuego de Colima. (Cortés et al., 2010)

Here on Java, north to south, it’s active Ungaran, Telomoyo, Merbabu, and Merapi (Thouret et al.; Yudistira et al.) — but this is where a big difference between the two Decade Volcanoes shows up.

The mysterious somma

Merbabu, about six miles north of Mount Merapi’s summit, didn’t collapse the way Colima’s ancient Paleofuego Volcano did. It’s not responsible for that somma around Merapi.

Although there’s no sign of molten rock inside Merbabu right now (as there is at Merapi, even between eruptions), it is still with us; Merbabu’s last eruption was a VEI 2 in 1797. (Ramdhan et al.; Yudistira et al.)

In fact, it’s still joined to the northern somma wall. (Selles et al.) There might also be an underground intrusive connection — see Yudistira et al. for (highly technical) details.

For these reasons, some researchers call this the Merapi-Merbabu Complex. (In daily life, though, it’s Gunung Merapi that everyone talks about.)

The Smithsonian’s Global Volcanism Program, which keeps track of active volcanoes, also has pages on its website for Telomoyo and Ungaran, noting that each of these slightly older volcanoes north of Merbabu might have erupted in the last 14,000 years or so. Ungaran even has steaming fumarole fields! (Per Nadeau et al., the two summit fumaroles that Mount Merapi used to have were destroyed in its 2006 and 2010 eruptions.)

Okay. Despite these differences from the Colima Volcanic Complex, it’s still the same big picture, right?

At one level, yes.

Both Merapi & Co. and Colima & Co. are there because volcanoes form in subduction zones (at Merapi, the Indo-Australian plate is subducting under the Sunda microplate).

So, what Colima-style geological dramas led to the somma around Merapi, brought the present cone into existence, and keep perilous “Fire Mountain” burning today?

[Crickets chirping…]

Unfortunately, Merapi hides its secrets well.

Murderous Mount Fire Mountain — with more than seven thousand human lives claimed since 1548 AD (Mei et al.) — usually just sits there and rumbles at the boffins with relatively mild (VEI 1-2) lava dome-forming eruptions, starting a new one every four to six years or so and carrying on for months to a couple of years before winding down for a short nap.

It does not explain itself or the reason why it also goes on deadly rampages every few decades (VEI 3) to once or twice a century (VEI 4), last in 2010. (Surono et al.; Thouret et al.; Widiyantoro et al.)

People living on and around Gunung Merapi know their volcano well — perhaps too well, in the sense that they’re used to the low-level activity and sometimes have difficulty believing official warnings about atypical events, like the VEI 4 eruption in 2010 that sent pyroclastic flows outside the usual channels and into a few villages, killing hundreds of people who had either refused to evacuate or had put it off for too long. (Charbonnier and Gertisser; Gertisser et al., 2011; Lavigne et al.; Mei et al.; Thouret et al.)

Evacuations are based on hazard maps, which experts develop by studying a volcano’s structure as well as the geologic record of its past eruptions. (Gertisser et al., 2011; Lavigne et al.)

Studying such things requires long-term data — something that doesn’t come easy, even for experienced field workers, at Mount Merapi.

The volcano sits in a tropical monsoon climate. Here, heavy rainfall and intense vegetation growth quickly destroy or cover up evidence of geologic structure and past volcanism that the much drier tropical savanna climate around Colima Volcanic Complex has left intact for millennia.

For instance, Selles et al. report that, in less than three years, rainfall and rivers washed away more than 300 feet of the ash and other debris laid down on Mount Merapi’s south flank during its big 2010 eruption. (Later, we’ll see where that material went.)

Good luck trying to collect field data from a somma that has been exposed to the Javan elements for thousands of years!

Most of what hasn’t been lost to erosion is now buried deeply under sediment, volcanic deposits, and overgrown topsoil.

The somma structure, though, does indicate that another volcano probably stood here recently and then collapsed. (Thouret and Lavigne)

But field workers can’t find unquestionable evidence of debris from such a collapse (Newhall et al.) as they’ve done at Colima — or even at Mauna Loa and Teide, where hummocky terrain spreads out across the ocean floor.

Neverthess, scientists in a variety of disciplines keep working on it — as Gertisser et al. (2011) note, understanding Mount Merapi’s past is the key to knowing what it will do in the future.

Since research at Mount Merapi began to intensify during the International Decade (Gertisser et al., 2011), at least two major hypotheses about this somma have developed.

Differences between the two views are not minor. The debate hasn’t been settled, and discussions not only are technical but also go way beyond the scope of this book.

If you are curious, detailed reviews of the issue in Thouret et al., Thouret and Lavigne, and Gertisser et al., 2011, as well as references in each paper, are good places to start.

Both sides do describe an earlier version of Mount Merapi — variously named “Old Merapi,” “Ancient” or “Middle” Merapi, etc. — that collapsed to the west at least once during the past seven thousand years.

We laypeople can cut to the chase: How stable is Gunung Merapi today?

The bad news is that, at least from my reading, no one really knows, although I did see that, in 2000, Thouret et al. called for a reassessment of the west, southwest, and south flanks.

Some good news: There apparently is no Indonesian version of Colima’s Tamazula fault running underneath Mount Merapi to shake it down again and again.

It’s not that anyone is ignoring the stability issue; research teams are probably working on it.

I think it’s that short-term hazards from Merapi’s almost continuous activity outweigh longer-term concerns about any possible structural weakness here.

As long as written records have been kept, no one here has died in a flank or sector collapse.

Gunung Merapi uses other murder tools.

Common Hazards at Mount Merapi

It’s easiest to list times recently when this very active Decade Volcano hasn’t been erupting.

During the 20th century, per Voight et al., Mount Merapi slept only during:

1925-1929
1935-1939
1962-1966
1987-1992

The rest of the time, it kept everyone on their toes with frequent low-level (VEI 1-2) eruptions, as well as a somewhat stronger VEI 3 blast every now and then — the last one of those, before 2010’s VEI 4 cataclysm, was in 1961. (GVP; Surono et al.; Thouret et al.; Webley and Watson; Widiyantoro et al.)

The commonest volcanic hazards from all this geological hubbub are pyroclastic flows near the volcano and lahars, which are mudflows that can travel much farther — all the way to Yogyakarta in the 1960s and again during the 2010-2011 rainy season! (De Belizal et al.; Gertisser et al., 2011; Thouret et al.; Voight et al.; Yudistira et al.)

Writer’s note: What follows is the material I’m working on just now, so it still needs serious editing.

Pyroclastic flows

Pyroclastic flows are those nasty-looking ground clouds that you see in videos, racing down steep volcanoes and, sometimes, out across flat land or water just as far as gravity will take the dense mixture of rock, ash, and hot gas.

At Mount Merapi, that’s usually 8 to 9 km for low-level eruptions and up to 15 km or more for the more explosive events. (Newhall et al.)

Given the risk these flows present to those 80,000 or so sand miners working up there, and the hundreds of thousands of farmers and other residents dwelling just outside the Forbidden Zone, we need to take a quick look at what is going on here.

Subduction-zone volcanoes like Merapi and Mexico’s Fuego de Colima have very “sticky” lava because reasons (Section 11.2 here).

Both Mount Merapi and Colima also happen to have “open systems” (Chaussard et al.), meaning that a lot of magmatic gasses escape through their unplugged vents even when they aren’t erupting.

Since gas is what powers eruptions, the degassed magma is not only sticky but also sluggish.

No Hawaiian-style fountains for this stuff! It just oozes out and piles up around the vent as a lava dome.

Some of the lava might advance out of the summit crater a little way as a coulee, but it doesn’t get very far — it is very stiff.

When the lava dome or coulee reaches a certain size, depending on the summit crater’s configuration, the force of gravity makes small pieces of it crumble off. These turn into the spectacular but typically small pyroclastic flows (Surono et al.; Walter et al.) that everyone loves to watch online.

Mount Fire Mountain does this so often during its frequent low-level activity that such dome-collapse-pyroclastic flow eruptions around the world are called “Merapi-style” events. (Dermawan et al.; Gertisser et al., 2012; Lavigne et al.)

Typically, the longest flows come from occasional lava dome explosions, which are gassier and stronger than the much more common dome collapses caused by gravity. (Lavigne et al.; Mei et al.; Metaxian et al.; Thouret et al.)

Gunung Merapi has been running its dome-eruption “pyroclastic-flow delivering-system” every few years for well over two millennia. (Gertisser et al., 2012; Thouret et al., including quote)

This is so regular a pattern that, while no one yet can predict when a summit lava dome is going to fail (Darmawan et al.; Kelfoun et al.), people have a good idea where the resulting fiery death cloud is likely to go — into the upper reaches of one of the thirteen rivers that drain the volcano’s flanks.

These drainage channels, for instance, in 2018-2019.

Over and over again. But don’t let yourself get hypnotized into thinking that the repeat pattern will last.

Volcanic landscapes are very dynamic.

The changes can be horribly sudden.

If there is a lot of gas in a pyroclastic flow, or if it’s unusually large (as happened at Merapi in 1994, destroying two villages and killing more than sixty people), the cloud might surge out of its regular channel, overtop and/or erode local topography, and unexpectedly go down another drainage. (Charbonnier and Gertisser: Kelfoun et al.; Newhall et al.; Thouret and Lavigne)

No one knows when a surge will happen. However, recent studies of the geologic record do show that these “unconfined overbank, pyroclastic flows” have occurred fairly often at Mount Merapi. (Charbonnier and Gertisser, including quote)

No one can outrun a pyroclastic flow or surge. Hiding inside a building isn’t much good either, as demonstrated during the Pompeii eruption of Mount Vesuvius.

On Java, they did try building bunkers at Gunung Merapi for anyone caught out in the open, but two people perished in one during a pyroclastic flow spawned by the 2006 dome-forming eruption. (Lavigne et al.)

The only sure way to survive pyroclastic flows is to evacuate before one happens. (Lavigne et al.; Mei et al.)

Since time travel isn’t a thing yet, experts go with the next best option: establishing an evacuation or exclusion zone by studying what the volcano has done in the recent past. (Lavigne et al.)

The question is, how recent?

The most likely scenario, based on what Merapi did throughout the twentieth century, is a pyroclastic flow maximum runout of 15 km.

At the end of International Decade, though, scientists had an idea of the worst-case scenario.

Newhall et al. put it this way in 2000:

Are the relatively small eruptions of the 20th century a new style of open-vent, less hazardous activity that will persist for the foreseeable future? Or, alternatively, are they merely low-level “background” activity that could be interrupted upon relatively short notice by much larger explosive eruptions? The geologic record suggests the latter, which would place several hundred thousand people at risk. We know of no reliable method to forecast when an explosive eruption will interrupt the present interval of low-level activity. This conclusion has important implications for hazard evaluation.

For both emergency planners and volcanologists, how far to set the evacuation zone was a hard question: 15 km (most likely) or at least 20 km (worst case). (Thouret et al)

Keep in mind that if a forecast didn’t verify and experts therefore lost the trust of those hardscrabble people on and around Mount Fire Mountain, no one would ever listen to them again.

The experts mapped out all the twentieth-century pyroclastic-flow fields they could find — a significant achievement at this prolific tropical volcano! — and set their official pyroclastic flow hazard zone (also an evacuation zone, since flows are unsurvivable) to the maximum runout distance they found: 15 km. (Lavigne et al.; Mei et al.)

After all, while the collapse of a tall ash column raised by an intense eruption causes base surges and long-distance pyroclastic flows, Mount Merapi rarely does anything that big (more foreshadowing: “rarely” is not the same as “never”).

Fortunately for tens of thousands of people, emergency managers also kept the worst-case scenario in mind.

Writer’s note: The rest of the revision is more noodling than a cohesive essay.

Lahar

I’m going to use italics when describing this phenomenon at an Indonesian volcano because lahar is the local word for a volcanic mudflow, first used at Kelut Volcano in the 1920s.

Volcanologists have adopted it to name the same phenomenon at volcanoes worldwide.

For instance, this is an unusually large lahar at Colombia’s Nevado del Huila (at night, so the visibility isn’t good, but you can get some idea of its terrifying power).

At Gunung Merapi, this is an unusually large lahar that dropped most of its load of loose volcanic material farther upstream but had enough water to keep going as a banjir.

That word hasn’t been picked up on the international scene yet, but perhaps it shows that such mudflows are so common in Indonesia that people have a variety of terms for them, rather like the Arctic’s Inuit people have for “snow.”

But snow is much prettier.

Lahars form when water mixes with whatever loose volcanic debris it can pick up, becoming a flood that can be as thick as wet cement — a scalding flood, if the lahar travels over fresh pyroclastic flow deposits.

At Mount Rainier, that water could come from melted snow pack and glaciers.

At Merapi, it’s heavy rainfall and all that loose pyroclastic flow material. Enough debris collects every two to four years to cause significant lahars. (Thouret et al.)

Lahars can happen anywhere on Gunung Merapi, but they’re especially common after a recent pyroclastic flow has destroyed or buried vegetation that was holding down soil on the steep slope. (Newhall et al.)

Once they start, lahars can travel farther than pyroclastic flows, up to 30 km (19 miles) at Mount Merapi. (Thouret et al.)

More than 110 square miles of lahar deposits have collected at the foot of this volcano! (Thouret and Lavigne)

These muddy flows can be lethal. They also cause more damage than a flood of water does.

Starting in 1969, therefore, Indonesia started the Mount Merapi Project, constructing a series of lahar flow-containment structures pioneered by the Japanese (who joined the project in 1977) and known as sabo dams. (Thouret and Lavigne)

I don’t understand the narration, but this 2012 video shows what the volcano’s intense 2010 eruption at the start of the 2010-2011 rainy season did to some of those dams.

Note that this project happened long before Mount Merapi was chosen as a Decade Volcano.

By the 1990s, Indonesian volcanologists had excellent baseline 20th-century data on Gunung Merapi — (spoiler) this enabled them to realize, early enough in Merapi’s 2010 eruption to make life-saving decisions, that something bigger than usual was starting up. (Surono et al.)

Mount Merapi and the Decade Volcano program

Its selection as a Decade Volcano brought in more personnel, equipment, and funding for monitoring and studies of Merapi than Indonesia could supply on its own.

Newhall (1999) notes that more international collaboration was done at Mount Merapi than probably at any other Decade Volcano.

That collaboration continued after the 1990s because Merapi erupts so often and there is so much at risk here (Widiyantoro et al.), including millions of lives, a major city (Yogyakarta), and crucial global marine and air traffic lanes nearby.

Scientific monitoring capability at Mount Merapi had greatly improved during the International Decade (Newhall, 1996; 1999) and had continued to broaden since then.

But instruments could only take them so far.

Gunung Merapi’s open conduit is also hot, thanks to its relatively small eruptions every four to six years or so (Surono et al.) — hot enough, I think, for its rocks to stand pressures from an unexpectedly large volume of fast-rising (and therefore gassy and explosive) magma without shattering.

Breaking rocks would have sent seismic signals telling the experts that something bigger than usual was on the way.

As it was, on Monday, October 25, 2010, decisionmakers (who had been issuing warnings on the restive volcano since September) maxed out the alert level, assuming that another one of those small eruptions was coming.

At highest alert, everyone within 10 km (about 6 miles) of the summit — tens of thousands of people — should evacuate. (Budi-Santoso et al.; Surono et al.)

Few, if any, did leave. As usual, they waited for Merapi to make the first move, which was expected to be some explosive activity and pyroclastic flows in the summit area, maybe a little ashfall in a few villages, and then lava oozing out to build a small dome (Mei et al.) — in other words, all that Merapi had been doing, with very few exceptions, for more than a century. (Surono et al.)

That was Monday. Mount Fire Mountain did nothing.

Tuesday, the 26th, Merapi was quiet all day. Then, around 5 p.m., it cleared its throat.

This was recorded about an hour after the first blast. As everyone fled the mountain, these brave souls went up to rescue the mountain’s gatekeeper, who lived just a couple miles from the raging summit. He refused to leave, as did 34 others. They did not make it.

As things went from bad to worse in the next few days, volcanologists around the world took notice: this was not how they had learned this Decade Volcano usually started off. Could something like the 1872 eruption be on the way?

And so the international collaboration on this volcano rapidly broadened and intensified.

….

The following video dates from November 4th, during the height of the 2010 eruption when some 400,000 people were in shelters or on the way to one.

It’s a brief look at what happens when there is a major volcanic eruption in the midst of more than 20 million people:

The following information section is from the original eBook chapter.

Location:

7.54°S, 110.446° E, on Java in Indonesia. The GVP Volcano Number is 263250.

Nearby Population:

Per the Global Volcanism Program website:

Within 5 km (3 miles): 49,205
Within 10 km (6 miles): 185,849
Within 30 km (19 miles): 4,348,473
Within 100 km (62 miles): 24,728,414

Current Status:

At the time of writing, Aviation Code Orange, Level III on a four-point alert system.

Eruptions:

Eruption styles: When it first appeared, at least 400,000 years ago, Merapi used to have runny red lava, sort of like a Hawaiian volcano. It was probably not as smooth-flowing as what we saw at Kilauea in 2018, though, and the lava only got stickier over time as its chemistry gradually changed. About 2,000 years ago, the edifice that had been built up over many millennia collapsed and the Merapi we see today began to take shape as the result of a combination of runny (effusive) and explosive eruptions. For the last 600 years, Merapi has had very sticky lava that either laps over the crater wall a little ways or else piles up into an unstable dome that is prone to collapses/explosions that trigger pyroclastic flows. (Global Volcanism Program; MVO archive)
Another lethal problem at Merapi are lahars — the Indonesian word for mudflows. Sometimes it’s called “cold lava,” but this is really a mixture of water and ash that has the consistency of wet concrete and can knock down and carry away almost anything in its path.

While melted snow and ice can cause lahars at some other volcanoes, those at Merapi usually form when heavy rain washes over freshly deposited hot ash from a pyroclastic flow (rain can also remobilize old ash flows).

Here’s video of an especially large lahar, carrying along what appears to be an entire rock quarry!
Biggest recorded event: In addition to the 2010 eruption, Merapi had a VEI 4 eruption in 1872. (Global Volcanism Program) Per Brown et al., 230 people died in it.
Most recent eruption: At the time of writing, April 10, 2020. This is part of ongoing activity that began, after almost four years of quiet, on May 11, 2018 — much to the surprise of some nearby picnickers:

Per Reuters, everyone who was on the volcano when it went off escaped harm.
Past history: See the GVP for details.

Monitoring:

There is recent official mention of the Merapi Volcano Observatory, but all I could find is this archived site, which still has much good information but hasn’t been updated in almost two decades.

The MAGMA Indonesia page is a great way to quickly check on Merapi or any other Indonesian volcano.

Just use a browser translator on the menu (the graphic is only helpful if you already know which volcano you want and can read the Indonesian popup).

Featured image: Akhmad Dody Firmanskyah/Shutterstock

Sources:

Brown, S.K.; Jenkins, S.F.; Sparks, R.S.J.; Odbert, H.; and Auker, M. R. 2017. Volcanic fatalities database: analysis of volcanic threat with distance and victim classification. Journal of Applied Volcanology, 6: 15.

Budi-Santoso, A.; Lesage, P.; Dwiyono, S.; Sumarti, S.; and others. 2013. Analysis of the seismic activity associated with the 2010 eruption of Merapi Volcano, Java. Journal of Volcanology and Geothermal Research, 261: 153-170.

Charbonnier, S. J., and Gertisser, R. 2012. Evaluation of geophysical mass flow models using the 2006 block-and-ash flows of Merapi Volcano, Java, Indonesia: Towards a short-term hazard assessment tool. Journal of Volcanology and Geothermal Research, 231: 87-108.

Chaussard, E.; Amelung, F.; and Aoki, Y. 2013. Characterization of open and closed volcanic systems in Indonesia and Mexico using InSAR time series. Journal of Geophysical Research: Solid Earth, 118(8): 3957-3969.

Darmawan, H.; Troll, V. R.; Walter, T. R.; Deegan, F. M.; and others. 2022. Hidden mechanical weaknesses within lava domes provided by buried high-porosity hydrothermal alteration zones. Scientific Reports, 12(1): 3202.

De Bélizal, E.; Lavigne, F.; Hadmoko, D. S.; Degeai, J. P.; and others. 2013. Rain-triggered lahars following the 2010 eruption of Merapi volcano, Indonesia: A major risk. Journal of Volcanology and Geothermal Research, 261: 330-347.

European Volcanological Society (SVE). n. d. Decade volcano program 1990/2000. http://www.sveurop.org/gb/program/program.htm

Fearnley, C.; Winson, A. E. G.; Pallister, J.; and Tilling, R. 2018. Volcano crisis communication: challenges and solutions in the 21st century. Observing the Volcano World: Volcano Crisis Communication: 3-21. https://link.springer.com/chapter/10.1007/11157_2017_28

Gertisser, R.; Charbonnier, S. J.; Troll, V. R.; Keller, J.; and others. 2011. Merapi (Java, Indonesia): anatomy of a killer volcano. Geology Today, 27(2): 57-62.

Gertisser, R.; Charbonnier, S. J.; Keller, J.; and Quidelleur, X. 2012. The geological evolution of Merapi volcano, central Java, Indonesia. Bulletin of Volcanology, 74: 1213-1233.

Global Volcanism Program: Mount Merapi. https://volcano.si.edu/volcano.cfm?vn=263250 Last accessed May 28, 2018.
https://volcano.si.edu/volcano.cfm?vn=263250&vtab=GeneralInfo

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