Volcano monitoring from a distance

In the past few weeks, there has been an eruption that keeps littering my inbox with emails: Bogoslof Volcano, on a tiny island of roughly 1 by 2 km out in the Bering Sea, west of the Alaska Peninsula.

View from a helicopter onto Bogoslof Island. Photo: Dan Leary, Maritime Helicopters

Despite the fact that it's effectively in the middle of nowhere (the nearest town is roughly 100 km away), Bogoslof is an interesting one. Being up in the Aleutian Chain, it sits along a very important corridor for international air traffic. If you remember the chaos all over Europe after the 2010 eruption of Eyjafjallajökull in Iceland, it's hardly surprising that monitoring volcanoes even in parts of the world as remote as Alaska is an important task. But how do you monitor a volcano that sits on an uninhabited, far away island?

An obvious answer would be to put a bunch of instruments onto the island. However, the island is so small, so far away from any population, in such a harsh environment, that the Alaska Volcano Observatory has to focus its limited resources elsewhere. In addition, the last eruption previous to this one had occurred in 1992, and it's been at least 40 years since the last eruption before that, so unsurprisingly the volcano was relatively low on the monitoring priority list.

This changed on 20th December 2016, when several pilots in the area reported an ash cloud that had risen up to over 10 km above sea level. Because there is so much air traffic going through the region, reports like that are an important part of monitoring volcanic activity in remote areas. Whereas the eruption had stopped within an hour or two, activity at the Alaska Volcano Observatory certainly wouldn't have.

Data had to be analysed, statements had to be published and scientists were looking for signs of any unrest that may have preceded the eruption. Indeed, looking back through the data, the volcanologists realised that Bogoslof had been showing signs of activity throughout the month of December, and the first explosion may have occurred as early as 16th December. So what kind of data can volcanologists use to monitor Bogoslof?

Even though there are no seismometers on the island itself, nearby Okmok and Makushin volcanoes have extensive monitoring networks. Because seismometers are very sensitive instruments, and volcanic eruptions make the ground shake with waves that can travel a long way, it is actually possible to look at seismic signals from Bogoslof on other islands.

Similarly, microphones recording "infrasound" (i.e. sound at frequencies much lower than the range we can detect with our ears) can detect pressure signals coming from far away, and volcanic eruptions often produce distinct infrasound.

Satellite image show the ash cloud at Bogoslof Volcano on 18th January 2017. Image: NASA Earth Observatory/Jeff Schmaltz

Satellites are also quite useful. A volcanic ash cloud can often be detected from space. Some satellites capture light of many different wavelengths, others can detect different types of gases in the atmosphere, some of which can be traced back to volcanoes. Visual observations by pilots, local residents or fishermen help to complement the picture we get from satellites.

Last but not least, volcanic lightning (i.e., lightning strikes in or around the ash cloud coming up in an eruption) has been an increasingly valuable tool to detect volcanic eruptions over the last few years. Volcanic lightning is still not fully understood and subject to active study by volcanologists around the world, but even without a complete understanding of the exact mechanism it is a spectacular sight and can be used for eruption detection. You can watch lightning happen all around the world through the World Wide Lightning Location Network if you're interested, almost in real time.

Spectacular eruption with volcanic lightning at Mt. Etna, Italy. Photo: Karl-Ludwig Poggemann

At the time of writing this post, Bogoslof continues to have explosions every few hours to days, and scientists are analysing these eruptions through all the different types of data mentioned above, even though there are no instrument directly on the volcano. Pretty amazing, isn't it?

Learning from Darwin - the naturalist approach

An 1871 caricature following publication of Darwin's The Descent of Man. Charles Darwin (1809-1882) was one of the most famous naturalists, whose scientific studies included geology, botany, palaeontology, human evolution and more. Image: Public Domain.

I've recently been branching out in terms of topics to write about. I contributed to the Science Borealis blog with two posts: one on rivers and their interaction with the environment, and one reviewing a podcast by CBC on earthquakes in the Pacific Northwest. Whereas earthquake science has always been close to my heart, rivers were not something I used to spend lots of time thinking about. Yet, it has been a very rewarding experience that allowed me to think scientifically about a new topic. It also made me wonder whether as scientists we should be more aware of the old school way of doing science. There was a time when scientists weren't seismologists, or volcanologists, or evolutionary biologists, but really "naturalists", who studied many different things a once, often leading to a less detailed but more complete picture of the world.

On the one hand, we need specialists. It takes time and effort to research the tiniest detail that could push humanity forward. As small as some advances in science seem, it takes years to build the detailed background knowledge to get to that point of understanding.

On the other hand, science couldn't survive without generalists. Inevitably, if time is spent digging deeper and deeper into a particular subject, it becomes more difficult to keep an eye on other branches of our field of study, discipline, or science in general. Without somebody to tie together the big picture, it is easy to get lost in the details of a small subfield of science. Without looking into other disciplines, we may be wasting time by reinventing something that has already been successfully applied in a different context.

In a way, specialists are the pieces and generalists the glue, that holds everything together. As an individual, striking a balance between the two can be tricky. Is the specialist vs. generalist a career decision that needs to be made early on and cannot be reversed? Is this a black or white decision, or can there be a grey area where we place ourselves somewhere along a continuous spectrum between two extremes? How do we interact with each other along this spectrum, and do we need to consider this when assembling scientific projects and teams? Are certain personalities more drawn towards or suited for one or the other?  And last but not least, at times of "publish or perish", can we sustain being generalists without sacrificing our careers, when it may be much easier to publish continuously by becoming an expert in a small discipline and continue building research in the same direction? I would love to hear your thoughts, as comments, or messages, or in whichever way.

Disaster preparedness - Plan, pack, proof

Natural disasters can strike pretty much anywhere and anytime. I'm not just talking about volcanic eruptions, but anything from flooding through wind to earthquakes, landslides, and more. I have never lived in a place that was 100% free from natural disasters, and probably never will. Neither do you. 

When I was in southern Germany, we got thunderstorms, hail, and crazy rain that can lead to flooding, especially in the plains at the foot of the European Alps. In the mountains themselves, landslides and rockfalls are not unheard of. In New Zealand, we had earthquakes, volcanic eruptions, storms, and even the odd tsunami alert from earthquakes happening far away. In BC, volcanoes are only a smaller problem, but (potentially large) earthquakes can happen. Whereas the West coast of Vancouver Island may get hit by Tsunamis, Vancouver is relatively sheltered. Winter storms can still hit pretty badly. I recently did a temporary move to Houston, Texas. If you've been following some US news I'm sure you heard/read about the Memorial Day flooding we've had down there. Tropical storm Bill, which followed a couple weeks later, was relatively harmless, thankfully, but Hurricane season has just started and we don't yet know what it will bring. The storm, however, got me thinking once again about being prepared for natural disasters.

Even though we may have little or no warning of what's coming our way (depending on whether we're talking weather, volcanic eruptions, or earthquakes, for example), there are definitely ways in which we can at least try to soften the impact natural disasters have on our lives. Of course, my German-ness makes me biased - after I all I love planning things, but in this particular case we could all benefit from some small preventative measures. The type of preparation might change depending on what kind of natural disasters your region is prone to, but some things are the same no matter whether you live in a volcanic area or somewhere with blizzards dumping snow on you. There are two important things to keep in mind:

1. Come up with a plan well in advance. Whereas with a hurricane we might get a few days warning ahead of time, earthquakes unfortunately don't do us favours like that. We want to be ready when disaster strikes, and it will only take maybe an afternoon to come up with the basics.
2. Most of your planning will not go into the logistics for the actual event, but mostly the aftermath - when power and water might be gone, infrastructure might be damaged, shops closed, and when we might have to be self-sustained for a number of days.

So that being said, here are some simple things that you can do to reduce the damage a natural disaster might do to your home, belongings, and loved ones.

Phase 1: Plan

Educate yourself about natural disasters that might happen in your area. Geologic surveys, met offices, and other (potentially government run) organizations and their websites are great resources. Work your way down from large to small: What natural disasters occur in my part of the world? How would my town be affected? My neighbourhood? My house? My commute? My workplace? My kids' school? For example, you might live in an area where flash flooding can occur after heavy rain, but your house is on top of a hill, in which case you would not necessarily have to be super worried about large amounts of water accumulating in or around your house. Or you may live in an earthquake prone region, and your house might be on top of sand or gravel type sediments, in which case the shaking from an earthquake might be worse than if the building was on a thick, stable granite. Knowing what could happen can win you half the battle. Below an example of an earthquake hazard map for Victoria, BC, from the Ministry of Energy and Mines. Similar resources might also be available in public libraries.

Relative earthquake hazard map for Victoria, BC. Monahan et al, 2000, from Ministry of Energy and Mines (http://www.empr.gov.bc.ca/Mining/Geoscience/NaturalHazards/VictoriaEarthquakeMaps/composite/Pages/default.aspx)

Furthermore, come up with a plan for your family. How are family members going to get in touch in case of a disaster? Is there somebody outside the area who could serve as a check-in point? What if the event occurs when you are at work/school? What if it's at night? Do you have a pet that needs extra consideration? Make sure everyone is aware of the hazards and knows what to do. Again, there are some amazing online resources that make coming up with a plan really easy.

Phase 2: Pack

Once you know the potential natural disasters and their impacts, pack an emergency kit. Imagine being without water/power/outside help for several days. You will need enough water for everyone in the house, dry/canned food, medications, first aid, flashlights, spare batteries, cell phones and chargers (ideally with portable power sources), some tools and/or an army knife, your most important documents such as passports, some blankets, warm/waterproof clothes, and so on. Having documents in a waterproof case/envelope might be useful. Some extra items like sleeping bags, or your children's favourites toys could be a good idea too. Make sure everything is in one, easily accessible place, and everyone knows where that is. If you don't want to assemble a kit yourself, you can even buy them online! Be sure to change water/food/medication every few months so that nothing is out of date. And again, having everything ready well before a natural disaster occurs is crucial - when I went to the supermarket the night before Bill was supposed to make landfall they were almost out of bottled water, and canned food was running quite low too.

Phase 3: Proof

Last but not least, try to proof your house for the potential event. For example, in earthquake regions you could move heavy items to the bottom of shelves instead of the top, to avoid heavy objects such as books tumbling down and injuring people. Or, in regions along hurricane paths it might be useful to always secure or limit the number of loose items in the backyard/on your balcony, outdoor shutters, and more. It all depends on the type of natural disaster happening in your area.

That doesn't sound so difficult, does it? By doing all this you won't be able to reduce the hazard (i.e. the potential for natural disasters) to your particular area, but at least you have done everything in your power to lower the risk (i.e. your vulnerability to the existing hazards). In the grand scheme of things, it doesn't take long, it doesn't cost much, but it might make your life a lot easier in case something really does happen! Stay safe!

Calbuco Volcano - a beginner's guide to its hazards

I'm sure you all have read tons about Calbuco Volcano now, so I'm not going to bore you with the details. Hopefully you've seen some of the stunning photos that have emerged, e.g., the ones on the Flickr stream by the Chilean Geological Service.

I quickly want to talk about hazards though. This volcano has quite the selection of hazards for you to choose from. The explosive eruptions have sent ash more than 15 km high into the air (click on the orange links to learn more about each hazard). This ash is covering a lot of infrastructure, property, and destroying crops. Most of it is being blown to the North-East at this point. With eruptions this explosive there will also be big blocks of rock being thrown out of the volcano, sometimes landing several kilometers away!

If an ash cloud collapses it can produce a pyroclastic flow. The deposits from old eruptions at Calbuco show that pyroclastic flows in the past have reached as far as Puerto Montt, a city with around 200,000 inhabitants around 30 km away from the mountain. For now I would guess that these pyroclastic flows are more likely to go towards the North-East, following the direction of the wind, but there is no way to know for sure, especially if the weather conditions change.

In addition, if ash settles on the mountain and is mixed with water (for example from snow on the top, of if there is a bit more rain over the next few days or weeks), big lahars (mudflows, mixtures of ash, dirt, water, snow, and debris such as trees etc.) can happen and travel down the valleys of some of the many rivers flowing down the slopes of the mountains. These flows can be incredibly powerful and destructive. Lahars can also reach tens of kilometers, so the 20 km exclusion zone they've put up makes a lot of sense.

In addition, some lava fountaining has been seen at Calbuco after the initial, more explosive phase that sent the ash into the skies. This means that some small lava flows can occur on the mountain. And of course, the gases that accompany volcanic eruptions can be quite dangerous too, if you get too close. Better stay at a safe distance. That way it's also much easier to take photos of the entire ash cloud!

It currently looks like the activity is getting a bit weaker: Whereas the Chilean Geological Survey observed more than 1,500 earthquakes between April 22-23, this number went down to just over 1,000 between April 23-24, just over 500 one day later, and to around 300 today. Unfortunately it's very difficult to know whether this number is going to increase again, which could mean another pulse of eruptive activity. For now all we can do is to closely monitor and to keep away from the mountain as much as possible.

View image | gettyimages.com

View image | gettyimages.com

Volcanic whistles and more

We've been talking about science and being a scientist and girl power for a while, so I reckon it's time to get back to volcanoes. In August 2012 I went to Hawai`i for the AGU Chapman conference on Hawaiian volcanism. The lovely people at the Hawaiian Volcano Observatory (HVO) were nice enough to let me stay for a bit to get familiar with the volcano and to get some of their data to play with. It was also a good opportunity to catch up and collaborate with my friend and colleague Jess Johnson again. My supervisor Mark and I had decided that Kilauea would be a good volcano to study earthquake recordings.

What were we trying to achieve by studying Kilauea Volcano? The main question we had was 

"Do the continuous earthquake recordings look different for different types of eruptions?"

Intuitively one might say, of course there are differences (or at least that's what I would have said). But we wanted some real evidence. Kilauea tends to erupt most of the time, and the style of activity varies, so this was an ideal place for us to go and test our hypothesis. 

I got data from the continuous recordings of earthquake activity around Kilauea volcano for an eruption in the eastern section of the volcano (called the East Rift Zone, close to a crater called Pu'u `O`o) in 2007, and a similar eruption in 2011. These eruptions were related to magma breaking and pushing open a big crack a few kilometres underground. This is called a dike intrusion.

I also got data from a series of more explosive eruptions in the western part of the volcano, close to a crater called Halema`uma`u, in 2008. During the year 2008 these explosive eruptions slowly formed a connection between the magma supply at Kilauea and the surface. Now there is a lava lake that's something like 200 m across, and visitors can no longer access the crater like they used to. The explosions probably only moved magma around that was a few 100 metres below the surface, not kilometres like in 2007 and 2011.

So we had data for two types of eruptions:

fissure eruptions in the east (i.e., lava fountains)

vs. explosive eruptions in the west

We used a technique called Fourier Transforms to find out what frequencies the earthquake waves were composed of at the different points in time (if you want an analogue explanation for what Fourier Transforms do check out this old post). That way we can make what's called a "spectrogram". You can learn a lot of things about the earthquake waves by doing that. For example, you can get an idea if the movement of the ground is from an earthquake that happened close by, or from an earthquake that was hundreds of kilometres away. The graphic below shows the seismic ground movement (the black wiggly thing) and the spectrogram (the rainbow coloured rectangle) for a few days in 2011. I've added some labels to explain in a bit more detail what we can see on it.

Seismic ground movement and "spectrogram" from Kilauea Volcano during an intrusion and fissure eruption. The coloured spectrogram shows how much of each frequency we have in the seismic wave at each point in time. Red means a lot of that frequency, blue means not a so much of that frequency. The red diagonal streaks across the graphic are the volcanic whistles, described below, where the frequency goes up (or down) over time. You can just hear the first one when you listen to the audio from the link in the text below.

So by doing that we learned three main things about eruptions at Kilauea:

1) Fissure eruptions and dike intrusions at Kilauea really do generate ground movement that is different from explosive eruptions.

2) These fissure eruptions and dike intrusions show two phases of ground movement:

Phase I (purple in the graphic above): The first phase is made up of lots of short earthquakes, close to the dike intrusion and the eruption. These earthquakes are probably related to breaking the rocks when the magma pushes open the crack. 

Phase II (blue in the graphic above): The second phase starts a few hours after the first phase. It doesn't have as many short earthquakes, but instead shows continuous (small) movement of the ground for a few days. This continuous movement is what we call "volcanic tremor". Phase II happens quite far away from the eruption and the dike. 

3) The second phase has something called "frequency gliding" (the diagonal streaks in the graphic above). It means that the frequencies of the waves slowly change over time, a bit like a kettle on the stove that starts whistling at a higher and higher tone when the water is boiling.

To give you an idea what I'm talking about I've taken some of the ground movement and sped it up by a lot. You can play the movement that happened over roughly 1 day in just over 1 minute. That way we can actually HEAR the ground move. Click here to listen to the earthquake activity during the 2011 eruption at Kilauea. At first you just hear some noise like the wind. That's before anything is happening. All of a sudden (around 7 seconds in) you start hearing a lot of clicking sounds, maybe like gun shots or like rain drops on a metal roof. Those are the little earthquakes during Phase I. Then it gets a bit quieter again, and then you start hearing something continuous, like a boiling kettle (around 45 seconds). That's the volcanic tremor from Phase II. If you listen really carefully you can even imagine that you're hearing the frequency gliding, i.e., the whistling getting higher and higher.

You may remember a study in 2013 from Redoubt Volcano up in Alaska. Redoubt was also whistling, for around 1-3 minutes before some of the explosions that happened there in 2009. They called it "screams". It turned out that the screams where actually little earthquakes getting closer and closer together in time, until you can't distinguish them anymore and they're just one continuous scream. 

The screaming or whistling at Kilauea is quite different: It's really slow and lasts for many hours. Nobody has seen gliding that lasts this long anywhere before. Also, the little earthquakes that you can hear in the beginning actually SLOW DOWN before the whistling starts, so the explanation from Redoubt doesn't work here. Many other models that explain this type of behaviour can't produce whistling that would last for several hours, so we spent some time exploring what could generate a signal like that. In the end we decided that the Kilauea tremor and whistling may be related to bubbles in the magma: We think that it's possible that gas bubbles in the magma reservoir beneath the western crater Halema`uma`u can form "bubble clouds", or areas where lots of bubbles collect in one place. These bubble clouds can start swinging, or oscillating, if there is magma flow or something else that can start the oscillation. This swinging is transferred into the ground. When the magma flow changes (for example when a crack breaks open somewhere else in the system, like the dikes in 2007 and 2011) the frequency of the bubble cloud tone can change, and produce the whistling that we observe. 

To know whether that is actually what was happening at Kilauea we would need some more info, for example a detailed study of where exactly the whistling was coming from on the volcano. However, it was still really interesting to see how by comparing the earthquake recordings from several different eruptions we were able to identify similarities and differences, and how that - in combination with other observations during those eruptions - made it quite tricky to come up with possible explanations for what we observed. Many studies focus on just one eruption, but we showed that we can learn a lot by looking at the bigger picture.

If you're still reading this you really must have a lot of spare time, so feel free to check out the journal article that we wrote about all this.

A road to studying volcanoes

Whether I'm at a party or talking to strangers on a plane - the question "What do you do for a living?" is almost always followed at one point or another by "How did you get into that?".

Sometimes I even ask myself this question. Ten years ago, when I finished high school (yes, I'm that old...), I certainly didn't have the faintest idea that life was going to take me right to this point. Yet, here I am. So whether you're curious about my path, or trying to determine whether it's the right one for you, let's explore how I ended up in the here and now.

1. Geophysics.

In Germany, geophysics isn't really much on people's radar. Having grown up there, it wasn't on mine either. When I was little, maybe 7 or so, I thought whales and dolphins were really cool, so I wanted to be a marine biologist (yep, 7-year old me was that specific). A couple years later, inspired by who-knows-what, I thought archeologist would be a better idea. This phase was soon followed by my Egyptologist period, when I loved everything from scarabs to hieroglyphics, and was extremely excited about finally getting history classes in school in grade 6. What I didn't realize at the time was that all these lines of employment (or lack thereof?) have something in common: I've always loved to study things, alive (dolphins) or dead (neanderthal men, pharaohs), and I've always loved mysteries. In a way, this is what science is all about: solving puzzles. 

The closer I got to the end of high school the more urgent became the question of what I thought I was going to do with my life. I had lots of favourite subjects in school - languages, maths, physics, and geography - which didn't make the choice any easier. I took tests in newspapers which were supposed to give me the answer. Needless to say, even though the results brought some interesting ideas they didn't solve the problem. In the end, my Mom - inadvertently - gave me the deciding clue. She asked me whether maybe I would enjoy studying meteorology. Her suggestion didn't throw me into complete ecstasy, but was worth taking into consideration, so I flipped open the "career bible", a book published by the German Employment Agency every year summarizing almost any study or career choice you can imagine. The page about meteorology read somewhat interesting, but it really hit me when I flipped to the next page and saw the headline "geophysics". You mean you can combine all the cool topics from geography with physics and that is actually a thing? Even better, they offered a program in Munich, really close to where I grew up. My first decision was made: I was going to give this at least a try.

I looked up a professor in the geophysics department in Munich, Heiner Igel, and sent him an email. For some magical reason he agreed to meet me if I was going to come to Munich to pay the department a visit. In retrospect I realize that this was probably a very special and amazing act of friendliness of him - which professor takes time to meet with a high school student who may or may not be interested in his subject? He invited me into his office, told me about his research and then took me to one of his classes. It was a 3rd year class or so, everything was in English, and little high school me only understood about 25% of what was going, but those 25% really captured my attention. After the class, he introduced me to two of his Master's students who added the final bit: You could go hiking in the mountains, or travel to remote destinations for work? I was in! I signed up for a geosciences Bachelors degree.

2. "Fernweh" - or The nomad story.

During my high school years I had already wanted to go overseas - it just never worked out. Ok, I had done 3 student exchange/language school visits to England and 1 to France, but it just wasn't enough. I needed more. A mapping field trip to the Italian island of Elba and a volcanology field trip to the Canaries just made my travel bug more impatient. I needed to go somewhere - far away! And indeed, for my Master's degree I ended up about as far away from Germany as you can get: New Zealand! I had worked hard for about a year and a half, contacting geosciences departments, applying for scholarships, university housing, etc, before I finally stepped onto that plane into the big unknown. The fact that I didn't know a single person in this country on the other side of the world that I had never been to that was going to be my home for the next 2 years certainly added to the adventure. I loved Wellington as soon as I got there, but a disappointment was waiting for me at the university: The funding for the project I was supposed to work on hadn't been approved (just another day in academia, as I now know). My supervisor, Martha Savage, encouraged me to chat with people in the department and read some papers before deciding what to do instead. My life was about to take another unexpected turn: I was about to find out that I had a passion for volcanoes. Sure, there was the volcanology field trip to the Canaries, but it wasn't until now that I realized that, yes, I can study volcanoes if I want to. ME! For real.

The next two years flew by, and I was so busy exploring this awesome little country and its surroundings (Samoa! Australia!) that I hadn't noticed that - somewhere along the way - I had lost my plan to go back to Germany after my degree was done. I had milked my New Zealand visa as much as I could, and left the country on the last day I was legally allowed to be there. I said goodbye with one crying and one laughing eye: I was about to leave my dear friends and my dear Wellington and my dear kiwi land behind, but only to embark on a new adventure. I had signed up for a PhD in Vancouver, Canada. When I had visited Vancouver that spring, I think the new vibe combined with the odd familiarity had influenced my decision: This was a new city, a new country, and yet there were the familiar elements of nature so similar to New Zealand (water. trees. mountains. whales. birds.) and the ever friendly people who softly tickled my about-to-be-missed kiwiness with their always present "eh". This is my 4th year in Canada.

Of course the traveling didn't stop there: Pretty much all of geosciences are so small that conferences happen all over the world, that at any given moment you're likely to work with people from as many different countries as you can count. I've had the luxury and pleasure to travel to Austria, Italy, Spain, Australia, Japan, Mexico, Ecuador, and to 9 different states in the US (Alaska, Hawai`i, Washington state, Oregon, California, Arizona, New Mexico, Colorado, Washington DC) all for work related reasons, and I've had the chance to live and work on research vessels twice. Do I need to say more?

3. Geoscience - an allrounder

In geoscience, a field that goes back centuries, you can be a lab rat, an outdoors man (or woman), a computer geek, an explorer, a big picture thinker, a writer, a talker, a listener - it doesn't matter. There is a place for everyone. Geoscience turned out to be the perfect combination for my needs: I get to travel, speak different languages, work with people from all over the world, and help to unravel mysteries that affect our every day lives. These mysteries are visible (eruptions!), we can feel some of them (earthquakes!), and yet they are strangely fleeting, almost intangible, and continue to astound!

At Cotopaxi Volcano in Ecuador last November. Can you tell my excitement? Photo credit: James Hickey

Iceland vs. Japan - the art of eruption forecasting

Finally I'm getting around to writing a new post, after I've taken my summer break since the end of the last term.

Work is in full swing again, undergrads are back, and campus is as busy as ever. After some intense work over the summer I managed to finally submit my manuscript about Hawai`i tremor. Fingers crossed that it gets accepted!

In the meantime, lots of volcano-y things have been happening, so an update is well overdue. Everybody has heard about the eruption of Bárdabunga, of course. We know that a dike (a vertical crack in the rocks, filled with magma) pushed its way through the Earth's crust for quite some time, before it reached the surface and started a stunning fissure eruption. How do we know that? Because lots of earthquakes happened underground where the dike was breaking its way up! But all this is, of course, yesterday's news - and I'm sure many of you have read tons about this eruption and seen some of the spectacular videos and photos.

Another big event was the eruption of Ontake-san last weekend. Pretty much out of the blue this volcano started to erupt explosively - and in the process sadly took many lives. Volcano disaster wise in Japan, this is about as bad as the 1991 eruption of Unzen, which killed over 40 people. After the Ontake eruption some people claimed that the disaster could have been avoided. But the truth is, from what I've seen in terms of data it was very difficult, or maybe even impossible, to see this coming. Why is that?

1. The eruption appears to have been a so-called "phreatic" eruption. That means that instead of magma pushing upwards through the crust, water was seeping into the volcano. This (cold) water probably reached a hotter region underground, where it immediately turned into steam. This steam wanted to rise and expand - it increased the pressure underground which then lead to the explosive eruption. A very similar thing happens in your kitchen: Have you ever heated up a pan or pot without anything in it, and then poured water onto the hot surface? You immediately get a big sizzle and lots of steam.

When scientists analyze the ash from this eruption, they will probably find mostly fragments from old rock that was broken into ash, and probably not many fresh magma pieces. Because no (or very little) fresh magma pushes upwards during these kinds of eruptions usually there aren't many precursors. No large numbers of earthquakes like we had in Iceland just a few weeks earlier, no big changes of the shape of the volcano like there was before the eruption of Mount St. Helens in 1980.

2. That "nothing" was happening on the volcano before the eruption is not 100% true. Since mid September there had been some more earthquakes than usual. However, the highest numbers were recorded on Sep 10 and 11, and they went down again afterwards. Furthermore, these "seismic crises" aren't unusual on volcanoes. Ontake had very similar periods with increased earthquake activity for example in the mid 90s, without eruptions following. Other volcanoes such as Long Valley caldera in California frequently have earthquake swarms - the latest one just a week ago, yet it hasn't erupted in the last 10,000 years or longer. Based on what we know about volcanoes, earthquake swarms CAN mean an eruption is coming, but they don't mean that an eruption HAS to happen. Often other warning signs accompany or follow earthquake swarms, in which cases eruptions become easier to forecast. These other warning signs could be a change on the volcano shape because of magma pushing rock out of the way, or more gases coming out of the volcano. Whereas in Iceland we had some idea what was gonna happen, in Japan we just couldn't see it coming. Despite all our research and efforts, unfortunately we aren't at a point where we can completely understand and forecast the processes happening below our feet in volcanically active areas.

In the case of Ontake, around 10 minutes before the eruption started another earthquake-like signal showed up on the instruments: Volcanic tremor. I've talked about tremor in one of my very early posts, but it might be time for a little update.

Volcanic tremor is a little bit like an earthquake, but with two main differences:

• Tremor ground oscillations are usually a little bit "slower" than earthquake ground oscillations: Whereas earthquake oscillations go back and forth anywhere between say 1 and 25 or more times per second, tremor oscillations only make it up to 5 or 10 times per second for one full cycle of back and forth.
• Tremor can go on for a really long time: Whereas earthquakes are usually over after a seconds, tremor can last for minutes, or hours, or days.

Luckily tremor usually only happens very close to the volcano, and the shaking is very small, so people don't usually feel it - otherwise shaking going on for several days or longer might be quite annoying. Yet, we can record these oscillations on our seismometers and usually when we see them we keep a good eye on the volcano to make sure we don't miss any eruption warning signs. Something like 2/3 of all tremor cases happen just before or during eruptions - but that also means that 1/3 of tremor cases don't appear to have anything to do with eruptions. That's why tremor isn't a very reliable warning sign - certainly worth to keep an eye out for but not a unique sign that something is about to happen. Lots of people have had ideas about what causes this tremor signal, but unfortunately many of these studies don't agree with each other, or only work for one specific volcano. In my research I study tremor from volcanoes in lots of different places: Hawai`i, Alaska, Latin America, ... I am trying to find out whether there are different tremor "types", that can tell us more about what causes tremor in different places. That way, maybe one day it will be easier for us to know whether the tremor that we record on our instruments is just harmless, or whether it tells us to get the hell out - and maybe disasters like the Ontake one can be avoided in the future!

What happened at Ontake is certainly worrying - after all there are lots of other volcanoes in the world and other "blue sky eruptions" (i.e. without clear warning signs) might happen elsewhere. Some people here in the Pacific Northwest started to worry a bit, and a radio station got in touch with Mark and me to check whether they could ask some questions in a radio interview. Of course I said yes, after all I love talking about volcanoes and I thought it could be fun. I expected that they would ask me some questions and then cut it and broadcast it at some later point in time. Instead, the whole thing was a 30 minute live interview - which I only realized as we started the interview! Whoops... That made it of course slightly terrifying, after all I hadn't ever given a radio interview. I also felt a little bit weird, sitting alone on the phone in one of our meeting rooms at work and yet talking to anybody who was listening to the radio station at the time. In my surprised state I probably sounded like a complete fool, and most likely made something like 80 out of "100 mistakes scientists make when talking to the media". But what the heck, everybody has to start somewhere, after all! If you're interested you can listen to or download the podcast here - don't judge me too harshly though! Thanks to Cfax 1070 and Terry Moore for hosting me - it was definitely a fun experience :)

A little digression: Large earthquakes, Alaska in 1964, and why people in Vancouver should be prepared

Time for a little digression. Let's talk about earthquakes! I've recently come back from a conference in Anchorage, Alaska, the Annual Meeting of the Seismological Society of America. I've only ever been to general geophysics/geosciences, or volcano conferences, so this one was quite the change. Since I study a specific type of earthquakes related to volcanoes I'm a bit in between volcanology and seismology, so it made sense to go.

Around 600 or so seismologists met up to talk about earthquakes and related stuff for three days. Overall it was a great conference. The "small" number of attendees was great - it was really easy to meet lots of people with very similar interests. I also liked the fact that they provided breakfast, lunch, and dinners (mostly). One reason for that is - of course, me being a student - the free food aspect, but there is something else: When you find a table to eat you may opt to find people you know, or you can go to a random table, introduce yourself, and start some interesting science talk. Bigger meetings like AGU are great to catch up with friends in different fields, but generally tend to be more anonymous.

A highlight of the conference was the post-conference field trip. Maybe around 1/3 to 1/2 of the conference attendees got on a bunch of busses to head down south towards the Kenai Peninsula. After leaving Anchorage, we stopped in Whittier, this interesting, tiny Alaskan town. We talked about the effects of the 1964 Alaska earthquakes, one of the biggest earthquakes ever recorded.

Around 5:30 in the afternoon on Good Friday, Mar 27, 1964, an earthquake with a magnitude somewhere around 9.2-9.3 struck just East of Whittier at approximately 25 km depth. The shaking was quite intense for a few minutes, but the real damage came from landslides and a tsunami generated by the earthquake. 

Ruins of a house that was abandoned after the earthquake in 1964, close to Girdwood, Alaska.

There was a heartbreaking account of one family's experience of the earthquake in the Anchorage Daily News a few weeks ago. From a seismology perspective, the earthquake is interesting for one specific subfield: paleoseismology. Paleoseismologists can study the change in ground elevation during the 1964 earthquake. A large area reaching from Kodiak island in the West through Anchorage out to Valdez and further East dropped in elevation during the earthquake because of the new plate configuration. Trees in the region that were slightly above sea level before now found their roots in the salt water, and died within a short time. They can be seen as eerie ghost forests until today. 

Ghost forest close to Girdwood, Alaska.

With the trees, a bunch of grass and shrubs ended up in saltwater. They were quickly covered by sand and silt washed up by the tides, and were preserved. During the field trip, we accessed one of the marsh areas. Our field trip guide Peter Haeussler showed us that when you remove the top layer of silt at the edge of the marsh during low tide, you can see a brown peat horizon. That's the grass from the 1964 earthquake!

Peat horizon from the 1964 earthquake. The brown is grass and shrubs that died after they ended up in saltwater after the earthquake, the grey on top is the silt that quickly covered everything.

A piece of grass that died when it was covered in saltwater after the ground dropped in elevation after the 1964 earthquake.

If you dig down deeper you can find more horizons like that, telling tales from previous large earthquakes in the area. Fossils in those peat horizons can be dated, and we thus know approximately at what intervals large earthquakes occur. Offshore BC and the Pacific Northwest, for example, people were speculating whether large earthquakes can occur at all (there aren't many small ones like e.g. in Alaska or New Zealand). Once paleoseismology became established, people found evidence of large earthquakes offshore the West coast of North America. That's how we know! And because we know now, everybody should consider having an emergency kit in the house. Because what we DON'T know is when the next big one is gonna strike.

Back with a BANG: Volcanoes 2014 and eruption forecasting?

Finally the silence is over. Happy New Year to everybody - we're just gonna ignore the fact that it's already Feb 6th.

I'm gonna start the year with an issue that has come up quite a bit lately when talking with friends and family... Eruption forecasting. Yep, I said it, the dreaded term. Sad events like 15 deaths due to the latest activity at Mt. Sinabung in Indonesia bring the forecasting topic into the focus of the public from time to time. 

Most recent eruption at Mt. Sinabung, Indonesia, Feb 1, 2014. Image from Twitter, @BBCBreaking.

So let's look into this a bit more. We're gonna learn about what signs of volcanic activity there are are at the surface, what we can do to monitor them, and what the difficulties with forecasting are.

To explore this topic in the detail it deserves, however, we need to start with something very basic: The difference between "forecast" and "prediction". If you look up the two words in a dictionary you will most likely find little difference between their meanings, often they're even listed as synonyms of each other. In science, however, things are a little different. In particular, in seismology (the study of earthquakes) the two terms have very distinct meanings: A "forecast" assesses the likelihood of an earthquake of a certain magnitude in a given area and time span, e.g. "there is a 1 in 10 probability that a magnitude 7 earthquake will occur in the Pacific Northwest in the next 100 years" (and of course I made this one up). A prediction, in contrast, is much more specific than that, e.g. "a magnitude 7 earthquake will occur within 100 km of Vancouver on Mar 15 at 10:45 AM" (again, obviously I'm making these things up. Yes, my imagination is just wild today.). In seismology, earthquake forecasting is done quite commonly, whereas the general scientific consensus is that earthquake prediction is currently (and might always be) impossible (despite some individuals or groups claiming otherwise...). 

So back to volcanoes. In volcano monitoring, people generally don't make "predictions" for when an eruption will occur. Instead, there are short-term forecasts (compared to the long-term forecasts that are usually given in seismology). These forecasts depend on how volcanic activity evolves over time. So what do we use to determine what our volcano is doing? Just like a patient in a hospital might be hooked up to a bunch of instruments measuring vital signs like heart rate, oxygen levels, and body temperature, our volcano is usually hooked up to a bunch of scientific instruments. The vital signs of a volcano are called "precursors", they are for example:

• Earthquakes - we usually look at how many there are say per day or hour, how big they are, at what depth they occur and whether that depth (and horizontal location) changes, and what "type" of earthquake they are. Types of earthquakes might be "regular" earthquakes with (relatively) high frequency waves, earthquakes with (relatively) low frequency waves, a mixture between the two (so-called "hybrids"), or volcanic tremor. These different types of earthquakes sometimes show how magma is moving from one place to another.
• Deformation - how the surface of the volcano changes its shape. We use instruments on the ground and satellites images to determine whether the surface is moving upwards and inflating like when you're blowing up a balloon, or deflating like when you let the balloon go. The deformation usually happens because of a change of pressure below the ground.
• Gases - volcanoes spit out gases in different places most of the time. The gases come - in one way or another - from the magma below the ground. The amount of gases, their temperature, and their type (e.g. sulfur dioxide or carbon dioxide) can help us to determine whether magma might be getting closer to the surface.
• Temperature - sometimes we see higher temperatures around volcanoes on satellite images.

Usually, when we see more earthquakes per hour, a lot of deformation, a lot of gases, and high temperatures, we become worried that magma might be getting close to the surface and ready to cause an eruption. This is what we call "unrest". Volcano observatories use alert or hazard levels to put a number on the state of volcano unrest. Below are examples of two different alert/hazard level systems from two different volcano observatories (GeoNet, New Zealand; and Montserrat Volcano Observatory, Lesser Antilles):

Alert levels for frequently active volcanoes in New Zealand (courtesy of GeoNet)

Hazard levels for Soufrière Hills Volcano, Montserrat (courtesy of Montserrat Volcano Observatory)

You can see that Montserrat has zones in addition to the hazard levels, and access to the zones is controlled based on what the hazard level is. The way the alert/hazard level is determined depends on the observatory and the specific volcano. The assessment is based on what is known from previous eruptions, scientific studies, and sometimes from other volcanoes.

So far so good. So we now know that a volcano has vital signs like a person, and that we might be able to use them to tell us whether an eruption might be happening soon or now. But of course, things aren't that simple. Unfortunately, volcanoes are like people in another sense (not just in terms of the vital signs analogy): Sometimes they have their own mind, behave in ways that can't be anticipated, and surprise us all. Also, many volcano may look similar but have quite different behaviours from one to another. For example, on some volcanoes precursors build up over weeks or months, whereas on other volcanoes we get only short or no warning at all. Whereas many volcanoes have MORE earthquakes just before an eruption, Telica Volcano in Nicaragua, for example, sometimes goes quiet and has no more earthquakes within an hour or so before explosions (listen to Mel Rodger's recent podcast on this). Similarly, whereas many volcanoes inflate before eruptions, Uturuncu Volcano in Bolivia has been inflating quite a lot for over 10 years without an eruption (read James Hickey's blogpost on this).

And just like we have good days and bad days, even one volcano can change its behaviour from one eruption to the next. Obviously in that case we're gonna have a hard time making a good forecast. 

Furthermore, the situation is complicated by people. One would think that it's always better to be safe than sorry, so ideally we would move everybody who lives close to a volcano to a safe place? Obviously that's quite unrealistic. Some countries have so many volcanoes that there simply would be no space at all to put people: On the website of the Global Volcanism Program, a search for volcanoes in Indonesia returns 1182 matches. Granted, some of them might be individual cones on one bigger volcano, or synonyms for different craters and cones, but the number is still really really large if we were to take those duplicates out. Where would we move all the people living close to those volcanoes? We also can't just take them away from their homes, the places where they grew up, away from their property, their fields, their places of income. Even evacuating an area can have significant economic losses the longer it lasts (ignoring the obvious potential loss of life and damage to the economy through the eruption itself). To make things even more complicated, there's the famous "cry wolf" phenomenon. People tend to become less responsive to evacuation orders or instruction for precaution if they have experienced several scenarios in which no eruption occurred in the end. In other words, if you cry wolf too often nobody will believe you anymore.

We can see now that it's quite difficult to give good eruption forecasts. The volcanoes can give us hints, but ultimately we might never know for sure what's going to happen. As scientists, in many cases, we are advising decision makers from a purely scientific perspective with what we know about a volcano and its state. Ideally, there is a dialogue between scientists and decision makers, who will then have to take into account economic, psychological, and other considerations to make a call for evacuation or against it. In Indonesia at Sinabung, on Friday authorities decided to let people back into the area (but with a certain distance to the volcano) after 10s of thousands had been evacuated following eruptions in the previous weeks. Clearly they did not anticipate the eruption that happened just one day later. A fairly large eruption at Tungurahua Volcano, Ecuador, which also happened on Saturday, thankfully appears to have had a less fatal outcome than the one in Indonesia. In the end, the outcomes of an eruption depend on many factors. As scientists, we are doing our best to study the processes happening on volcanoes. We might not make huge leaps, but every project is a little step towards understanding our volcanic neighbours a little bit better, and maybe make forecasting a tiny bit more reliable.