Reflecting on risk

USGS photo of the May 18, 1980 eruption.

I don't have any stories to share with you about the 1980 Mount St. Helens eruption, since I wasn't around then - and the other geobloggers are doing a fine job of collecting reminiscences already.

Volcanologists, like everyone else, sometimes joke about their jobs, but it's anniversaries like today that have prompted me to reflect on it instead. I love the work that I'm doing, and what I'm training to do. It's exciting, and takes me to exotic places, and I get to learn all sorts of fascinating things about how volcanoes work. But whenever I'm near or on an active volcano, there is always an element of danger as well. Because volcanoes are natural systems, they always have some element of unpredictability. It is possible for scientists to forecast what a volcano may or may not do, but it's impossible to predict anything with absolute certainty, so we can't be absolutely sure that any part of a volcano is safe, no longer how long it's been dormant or how mild its activity seems. Not to mention that volcanic settings in general are not safe or nice - there are any number of dangers from unstable or rough terrain, toxic gases, and just the remoteness and inaccessibility of many volcanic areas.

Those are all things I have to consider when I'm doing fieldwork at active volcanoes. In the past year, I've visited Stromboli and Etna and Santiaguito; this summer I'll be traveling to Montserrat, where Soufriere Hills is still erupting. Each time I set foot on a volcano, I acknowledge - consciously or not - that the chance to learn about it overrides the potential hazards of the setting. I don't take unnecessary risks, or make careless or foolhardy decisions if I can avoid it; I'm not going to wander into an exclusion zone or into an active crater just for the sake of samples and photos. But the recent significant eruption at Santiaguito reminded me that even the settings that seem safe at one moment can become deadly in the next, and the lateral blast that occurred at Mount St. Helens thirty years ago today is an excellent example of the same.

USGS photo of David Johnston from April 4, 1980.

Dr. David Johnston was one of the 57 people who lost their lives in the 1980 eruption of Mount St. Helens. He knew the dangers of working on an active volcano, and no one could possibly fault him for being at the Coldwater II observation station when St. Helens erupted; if it hadn't been him there, it would have been someone else. The volcanologists working there at the time hadn't even considered that the volcano might produce a lateral blast, though they - including Dr. Johnston - were certainly uneasy about the setting.  In interviews, his friends, family and colleagues invariably say that Dr. Johnston died doing something that he loved.  As a volcanologist, I am doing something that I love whenever I go to study an active volcano; I can't imagine myself as happy in any other job. But it isn't a safe job. I know it's difficult for my family to think about, and I don't like to bring it up, but there is always a chance that I could be hurt - or worse - working at an active volcano. It's the same risk that many of my friends and professors take. True, all of us take risks every day - driving, flying, playing sports - but volcanology involves unique risks that most people don't have to deal with on a regular basis.

I hate to write such a depressing post about what would otherwise have been an exciting event, but it's what's been on my mind today. Volcanology is an exciting, unique science; volcanic eruptions are fascinating events. But it's always good to remember that this is one of the sciences where the researchers take risks for the sake of their work.

Volcano Vocab #4: Lahar

As suggested by a commenter on the last Volcano Vocab post, here's a water-and-volcano-related term for you: Lahar ("lah-haar"). 

Lahar is an Indonesian word for a mudflow of volcanic material - that is, a mass movement of volcanic debris that contains some amount of water. (A dry flow of volcanic material would usually just be called a debris flow or debris avalanche.) The key thing that distinguishes a lahar from a "regular" mudflow is the presence of volcanic material in the flow, which can include tephra, ash, hydrothermal alteration products, blocks of lava flows, and other pyroclastic materials. Some descriptions liken this mixture to a flow of cement, and it's capable of moving house-sized boulders huge distances from their source.

Lahar deposits characteristically show poor sorting (lots of different sizes of material, from boulders to sand), multiple rock types, rounded clasts, and muddy matrix supporting the clasts. (Sometimes in deposit matrices you can find rounded voids where bubbles of air were trapped as the deposit hardened around them!) Lahars are most common on stratovolcanoes, but (as we've seen in Iceland), other types of volcanoes can also create the correct conditions to form a lahar. Lahar formation depends on having lots of loose material, and the addition of lots of water over a short period of time (such as from a melting glacier, a hurricane or storm, or a breached crater lake, among other things). They do not require the volcano to be actively erupting, which is one reason why they are so dangerous.

Here's a video of a lahar from Mount Ruapehu in New Zealand (March 2007):

Lahars are an especially dangerous volcanic hazard because they appear and disappear so quickly. Lahar debris that's deposited in a riverbed can easily be eroded by normal river flow, and lahars that have spread beyond valleys and drainages can easily become reclaimed by vegetation. In fact, one of the most devastating lahars to have come from Mount Rainier in Washington State (the Osceola Mudflow)  is now covered with small towns. Because the people in the area are now aware of the danger a repeat lahar would present, they are required to hold evacuation drills. Lahars are somewhat easier to monitor and avoid; acoustic flow monitors (specially calibrated seismometers) can be placed in source zones, and a timely warning can be sent downstream when lahar signals are detected. Sometimes evacuation can be simply a matter of climbing to a higher elevation, although on a floodplain it could be necessary to travel much greater distances to safety, but it does require advance warning.

Armero, Colombia, destroyed by lahar on November 13, 1985. Photo from the USGS CVO website.

Lahar warnings aren't always heeded, however. It's impossible to mention lahars without also mentioning the town of Armero in Columbia. On November 13, 1985, a small eruption of the nearby volcano Nevado del Ruiz melted part of the snow and ice capping the volcano's summit, and produced a lahar. Volcanologists knew that river valleys on the volcano's flanks could channel lahars toward populated areas, and sent warning to towns in the lahar's path; unfortunately, local officials either received incomplete or conflicting information, and/or decided not to listen to the scientists' warnings. As a result, more than 23,000 people were killed in Armero and nearby villagees, when they could have reached safety by climbing only a short distance up the slopes on the sides of their valley. This tragedy drove a USGS scientist to develop the Acoustic Flow Monitors mentioned above, in hopes that more deaths could be avoided; the system is now used at lahar-prone volcanoes worldwide.

Looking backward: Past eruptions at Volcán Santa Maria

On our way to visit the Santiaguito Volcano Observatory, Gustavo Chigna of INSIVUMEH (the Guatemalan equivalent of the USGS) was kind enough to take an afternoon off and show us some of the older deposits near Santiaguito. Our first stops were at an exposure of the air-fall deposit from the October 24, 1902 eruption of Volcán Santa Maria. This eruption was a devastating one, stripping the land for more than 50 km around the volcano, burying villages and fincas (plantations) in more than 3 meters of ash, mud and rock, and killing more than 7,000 people (the exact number will probably never be known). The area had already experienced months of earthquakes prior to the eruption, and activity at the crater formed in Santa Maria continued for weeks afterward.

This location is about 4 km from the volcano. The 1902 air-fall deposit here is more than 2 meters thick (the photo is only showing the top bit, and Gustavo is standing a few meters behind the outcrop, so the sense of scale is a bit wonky. The big clast in the center is about fist-sized, though.). This fall deposit contains a mix of lithics (old and new lava and country rock) and pumice, and what's really impressive is that many of the lithics are the same size as the pumice (up to 15 cm). Generally, in a fall deposit the material will have had the same terminal velocity, which means the mass of the pumice and lithics should be roughly equal. Because pumice is much less dense than lithics, this usually means that the lithics are much smaller than the pumice. Possibly the lack of difference in clast sizes here has to do with the proximity to the volcano; in other places that we stopped, the pumices were definitely larger than the lithics.

The view from this location was pretty spectacular, and it highlighted the deposits from the November 2, 1929 dome collapse. Here you can just see the summit of Santa Maria, and the El Brujo and other domes in front of it. Brujo is the dark green dome farthest to the left, and the hummocky low hills in front of it are may be the result of that 1929 collapse. Hummocks are a classic sign of a debris avalanche of some sort, and can be seen in places like Mount St. Helens and Mount Shasta. ***Note: After speaking with Rudiger Escobar, a Santiaguito expert and fellow volcanologist (see the comments section), I wanted to note that the hills pictured here probably have more to do with lava flows coming off of Brujo than older collapse deposits, although some portion of them may be collapse remnants. It's also possible that I have faulty notes, as the conversation was mostly being conducted in Spanish at the time, and my Spanish skills are limited. 

After a bit of backroad driving around the fincas, we reached the Rio Tambor, which was the site of many deaths in the 1929 dome collapse. The 1929 event, in which more than 3 million cubic meters of the lava dome collapsed, was mostly described by foreign geologists who interviewed survivors. Their accounts tell of glowing rains of ash and rock; boiling mudflows in the rivers covered with rafts of glowing rock; a blast that rushed back toward the volcano after it blew down the river valleys, scouring the south side of tree trunks; and people suffocating on gases and hot air. More than 3,000 people were killed, mainly because they were on the fincas for a religious holiday rather than in their villages. Sadly enough, this was a very  minor dome collapse by volcanology standards (a large one might be in the hundreds of millions of cubic meters, such as those at Soufriere Hills on Montserrat).

The coffee plantations that were destroyed in 1929 are no longer here, but the new ones are beginning to encroach. Frankly, I'm not sure I'd want to spend my days working in an area where there are outcrops like this:

These photos are looking east across the Tambor at a mudplain created by lahars, and at the 1902 deposit (the white strip at the base of the cliff) overlain by block-and-ash flow and lahar (volcanic mudflow) deposits. Here the 1902 deposit is about 2 meters thick, and overlain by a thinner gray ashy deposit (perhaps from the 1929 collapse, although it hasn't been well studied and it wasn't clear if that guess was right). The upper blocky deposits are probably post-1929, and consist of a mix of lahar and block-and-ash (pyroclastic flow) leavings.

It was a bit difficult to get a scale into this picture, but the cliff is about 10 meters high, and the bigger boulders at the base are roughly the size of me. This is an interesting photo because it shows a very distinct division between two deposits. What we ended up discussing at this site was what kind of deposits these were, and how to tell them apart. Both block-and-ash flow deposits and lahar deposits look similar at first glance: very poorly sorted, with a clast size range from ash (< 2 mm, in the matrix) to boulders (> 25 cm, supported by the matrix). Both deposits are matrix-supported and both have a bit of a mix of angular and rounded clasts.

So how to tell them apart? One clue might be the angularity of the clasts; block-and-ash flows tend to be a bit more violent in terms of knocking rocks around, and they're dry, which means no muddy cushion for the rocks like a lahar might provide. But what happens if the block-and-ash flow goes down a river (like here)? It could become a lahar, which brings up all sorts of messy discussion about naming conventions. A better indicator of a block-and-ash flow would be the lithology of its clasts; lahars will pick up anything in their path and tend to have a big mix of rock types, while block-and-ash flows tend to be monolithological. Again, however, if a block-and-ash flow travels far enough, it may pick up enough clasts from other places to confuse this.

As it turns out, there is one sure indicator that you've got a lahar deposit, and it's not always easy to find (or present). Because a lahar is a wet flow, it will contain bubbles. When the lahar stops, sometimes those bubbles are unable to rise through the muddy liquid and are trapped; when the deposit dries out, the bubbles leave little spherical cavities in the fine-grained matrix. These are really hard to see and it's easy to debate what you're seeing if you're not sure.

So what was the verdict for these deposits? Based on a bit of arguing discussion, we decided that we were fairly sure we saw bubbles in the lower deposit, but that the upper one had more indicators of a block-and-ash flow deposit. So at this outcrop, we have about 4-5 meters of visible lahar deposits overlain by about 5-6 meters of block-and-ash flow deposits. Needless to say, this would not have been a fun place to have been standing for either event. In fact, Gustavo mentioned that very few people will come down to this area after dark, because some of the victims of the 1929 collapse are thought to haunt the riverbed. Having been down there in the evening, I can attest that it does get a little creepy when it's dark, and it would certainly be easy to turn the jungle sounds into the moaning or wailing of ghosts. Better not to stay there too long, ghosts or no ghosts; it is a channel filled with lahar deposits, after all.

Poor land-use planning and volcanoes

From http://news.nationalgeographic.com/news/bigphotos/images/090319-tonga-volcanic-eruption-ap-video_big.jpg

So it looks like someone is already moving in on the new land created by the eruption of Hunga Tonga-Hunga Ha'apai near Tonga*. That's right - with enough Pa'angas, you could own some of the newest land on the planet, if you don't mind digging yourself out from under the tephra every few days. The article I found didn't say much about who's claimed the land, but it seems to have been through a loophole in Tongan land use laws (one that their Royal Land Commission will no doubt be fixing soon). I suspect we'll soon see signs on the more stable parts of the island calling the new land "Trump" and advertising the finest in pumice exfoliating stones.

Now, I've heard of this sort of thing happening in Hawaii - people buying up and selling land on the slopes of Kilauea or Mauna Loa that is very likely to get run over by the next lava flow. The land is usually covered in lava already (not a fun building surface), and completely uninsurable. So, if you have a movable house - a yurt, for instance - and you don't mind packing up and moving for a bit when the next flows come through, I guess you're okay. (This would probably necessitate having a tank or other AWD vehicle in order to get back to your house, though.)

But speculation before the land's even done being formed is a bit much. And, despite the fantastic views and desirable location (get away from everything!), I should think that the danger of living next to an active volcano might bring down property values a bit. Then again, if you're a volcanologist, this could be a plus. Any takers out there in the geoblogosphere? I bet we could probably afford the place if we pooled our resources, although my contribution would have to be much smaller due to my grad student status.

Given the intense tourist interest in the eruption, the article is unsurprising, though. Bunker on the beach, anyone?





*Wow, really? No comments? Either the blog is getting too boring, or I was really believable on this one. Or everyone is too paranoid to believe anything written on April 1.

Happy belated April Fools...and no, I still wouldn't be surprised if Trump jumped on the Tonga Pumice Stone idea.

More news from Hawaii: Volcanoes National Park evacuated

(Image from the Hawaii Volcano Observatory)

Looks like shifting wind + gas plumes = not fun out at Kilauea. Enough that the park closed completely yesterday, and several of the surrounding communities were put under voluntary evacuation notice. Shifting winds are blowing the gas plume emanating from Halema'uma'u crater out over the inhabited parts of the park and into local communities, which usually don't have to deal with vog, or volcanic fog. Here's part of the story from the Honolulu Advertiser:

"That evacuation included the Volcano House hotel within the park, with guests at the hotel moved to the Naniloa Volcanoes Resort in Hilo, [Big Island Mayor Harry] Kim said. He said staffing at the park would be limited to required personnel only.

Civil defense officials at 9 p.m. last night announced voluntary evacuations for five communities northeast of Halema'uma'u crater as sulfur dioxide fumes in the area are expected to intensify today.

The voluntary evacuation advisory covered the Mauna Loa Estates, Ohia Estates and Volcano Golf Course subdivisions as well as the Volcano Village and Keauhou Ranch areas."

Here's another comment from Kim in the AP:

"As far as we know the number was light because the sulfur dioxide levels really did not materialize to the degree that was much anticipated," Hawaii County Mayor Harry Kim said. "What did happen during the day is that we did have some ... brief periods of high levels of sulfur dioxide in the affected areas, mainly in the national park areas."

Vog is nasty stuff. Usually it's Kona that has the most problems with it, enough so that they put out daily advisories of vog levels, much like air quality notices or pollen counts on the mainland. On my trips, it was barely noticeable, which was quite lucky - although that's not to say that I didn't have encounters with volcanic gases.

One part of my field course the second time around was to learn how to sample volcanic gases; to do this, we first had to familiarize ourselves with the hazards involved. The instructor filled up some balloons with samples of CO2, SO2, and H2S. The CO2 was, naturally, undetectable; the SO2 was a little stinky, but no more than, say, exhaust from a car engine. The H2S, though, was like a kick to the face. It's extremely acidic, smells horribly like rotton eggs and made pretty much everyone screw up their eyes and cough for the next five minutes. Going out to the sampling sites, we all wore gas masks, and after an hour or so even the hardiest of us was dealing with the coughing and stinging eyes. At one point, I couldn't see or stop coughing long enough to breathe - and that was with a heavy-duty gas mask with fresh filters. (I suspect this was mostly because of very high concentrations of SO2, since enough H2S will kill you, but high levels of pretty much any acidic sulfur gas are not fun.)

Hopefully the hazardous conditions won't last long, and the wind will shift, because it would be a shame for people to miss out on seeing the changes happening on Kilauea right now. Not to mention that living in a vog haze is pretty miserable, especially if you have respiratory problems (like me).

The Gods must be restless? Take a look at the scientists.

I just finished reading the most recent National Geographic, and I spent some time thinking about Andrew Marshall's article, "The Gods Must Be Restless". In it, he talks about some of the beliefs that have grown up around Indonesian volcanoes - and there are a lot of them, considering that Indonesia has the most active volcanoes of anywhere in the world.

I found myself conflicted about the attitudes of some of the people who live in the shadow of these volcanoes, especially the Gatekeeper of Merapi. While I can certainly understand the importance of respecting beliefs and traditions of the Indonesian poeple regarding their volcanoes, it almost seems criminally negligent of their spiritual leaders to ignore or even oppose the efforts of scientists and local civil authorities to alert them to the dangers they face. Scientists are sincerely trying to help, and it seems that they're hitting an impossible situation: if people don't heed their warnings because local spiritual leaders say not to, and nothing happens, then people are more inclined to trust them than the scientists; if they choose not to listen and something does happen, the scientists are blamed for not trying hard enough, or telling them sooner, etc. (I know this isn't always the case, and that many people take the scientists very seriously, but it's those few who don't that make things difficult for everyone.)

I'm reminded of Harry Truman at Mt. St. Helens, or the Aetas on Pinatubo. It boggles my mind that people somehow think that volcanologists are somehow trying to advance personal agendas or take their land or otherwise screw them over. Every volcanologist I've ever met has certainly not been in the job for the money or the prestige - they're working in the field because they're passionate about it, and they care about making people's lives safer. Those are my motivations, at least. I want to specialize in volcanic hazards mitigation because I love volcanoes, AND because I want to use my skills to help others. And it's why this article has touched on such a sore spot. I know I'll come across this sort of bias and willful ignorance in my work, and I hope I can prepare myself to deal with it, but I really wish it didn't exist.

And the quote that suggests the Merapi Gatekeeper thinks "the alerts are merely guesses by men at far remove from the spirit of the volcano"? That just makes my blood boil. How can you not be in touch with the spirit of a volcano when you're listening to it breathe, feeling its pulse under your feet and watching it bleed molten rock and explode with all the violence of a savage beast? How can you not feel a connection with something like that? Just because I will use electronic equipment and the latest technologies to monitor a volcano doesn't mean I won't also fight up and down its slopes, and get ash and mud under my fingernails, and make a thousand little blood sacrifices in my efforts to learn about it. To me, a volcano can't be anything other than a living thing, one with its own personality and temperment, and I take offense at anyone who says that I can't forge a connection with it because I am a scientist.

Now, I won't deny that superstition can have its place in dealing with volcanoes. I myself took the precaution of leaving tokens for Pele on my last visit to Hawaii (especially after the strep throat and ear infection I picked up after my first trip, where I did do some legal sample collecting off National Park land). I'll probably do the same thing again wherever I end up studying volcanoes for graduate school. But when people have their heads buried so thoroughly in their superstitions and rituals and traditions that they ignore the efforts of the scientists who are trying to protect them? That's when I start to get angry.