So I'm really quite busy this fall trying to get a bunch of work done. Expect a more or less silent time until I have a life again in January... In the mean I will try to post a least some little snippets for entertainment.
Number one: The Science news cycle! Almost in line with my last post about the Alaskan underground fire...
Friday, 11 October 2013
Tuesday, 3 September 2013
There was an article on CBC last week which really upset me. What they were talking about was - to put it midly - outrageous! The author(s) talk about an underground fire which has been burning for close to a year in the little town of Eagle, Alaska, close to the border to the Yukon. The headline says:
"Mysterious underground fire perplexes Alaska town
Possible volcano or shale gas fire has been burning for more than a year"
The whole thing is accompanied by this photograph:
For those of you who don't want to read the "whole" article, here's the one line synopsis: An underground fire has been burning approximately 40 km outside of Eagle since September last year. Now they go on speculating about the cause of the fire, and here's where I stumbled (after stumbling over the headline and subheader, of course...):
"Aerial photos suggest a volcano forming but geologists say it's likely an underground shale gas fire."
Excuse me?? So geologists say it's a shale fire, but "aerial photos suggest a volcano"? Where did they get that statement? Sure, let's not believe the geologists who clearly have no idea what they're doing, let's get a random statement that has no scientific basis whatsoever. Or maybe it does and the authors just haven't provided enough background info? Sloppy journalism, either way. So I decided to investigate a bit more, see whether maybe that statement came from information that didn't make it into the article instead. After all I was really curious to see who decided that this a "possible volcano" (title...) forming here. I didn't even have to look far to discover that this sentence was even more ridiculous than I originally thought. There is a link to an interview with a local park ranger embedded next to the article. So I went and clicked on it, and sat through the entire 8 minute and 20 second interview by the CBC host with the park ranger. Sure enough, at 5:51 the host asks whether it is the oil shale that's burning, and the park ranger replies:
"It is. It is the oil shale that is burning"
So, uhm, there's somebody who has dealt with this thing for 11 months, probably done a lot of investigation, met with various groups of experts, surely we can just completely ignore her crystal clear statement and suggest that there is a VOLCANO FORMING??? And then in the end, when it turns out it isn't, maybe we can go ahead and sue the scientists for providing false information??? Granted, that's a bit of a stretch and I definitely don't want to get into this debate, but really CBC, I would have hoped you're just a tad less sensation-seeking and a tiny bit more on the credible journalism side. Apparently I was wrong... This is exactly the reason why many scientists really dislike talking to the media. Statements get turned and twisted and taken out of context just to potentially attract one more reader/viewer/listener. The public is mislead with information that is clearly wrong. It's so sad! Wouldn't it have been much nicer of the author to do his/her/their homework, go on the internet, and for example do a really quick search on where the volcanoes of this world are located:
|modified, original source: USGS|
All the red dots are volcanoes, and the black lines are plate boundaries. The white star shows where Eagle, Alaska, is. Yep, definitely doesn't look like there should be any volcanoes nearby. But who knows? But nope, there's also no signs of lava coming out of that fire. And yep, Eagle, Alaska, used to be home to miners in the area, it's a region rich in geological resources, so uhm, without even being an expert or something I would say a shale fire sounds pretty likely? But even if it really really is a volcano, how about giving a bit more background on where that info is coming from? Spending 5 more minutes (and I don't even get paid to do this, unlike some other people...) on this magic thing called "internet" I found this article on Alaska Dispatch. Much better researched, with lots of background info, it does what an article like this is supposed to do: It's catching, interesting, it educates the public about an interesting phenomenon and provides information relevant for locals about whether or not they ought to worry about the gases emitted by the fire. Seems almost like the CBC writer found the Alaska Dispatch article, decided to make life really simple, took the info out of context and wrote a short but potentially catching (ridiculous) blurp and called it a day... Just saying. Again, I'm exaggerating, but I'm SO UPSET about this! Journalists out there, please take a second, talk to a scientist or somebody else who knows about the topic you're writing about, and then do not, I repeat, DO NOT ignore what they say but write a proper, well researched, educating and still entertaining piece of news. Sounds like a challenge? Well, maybe it's time to look for a different job then... Since there is one person who actually did that, let me take the time and end on a positive note: Great job, Ben Anderson at Alaska Dispatch!
Tuesday, 20 August 2013
I'm gonna take this "opportunity" to shift my focus for this post. Well in line with my blog title we're still talking about shaking, but this time it's not volcano-related. Instead, we're going back to one of my awesome previous homes: Wellington! You Wellingtonians out there will, of course, immediately know what I'm talking about. And those of you outside the coolest little capital in the world should have heard about it by now: Wellington is shaking A LOT!
It all started on Jul 21, when a magnitude 6.5 hit the city late in the afternoon. Centred in the Cook Strait at 13 km depth it thankfully did not result in any casualties or major damage. From GeoNet's shake map below we know that it must have felt most intense in the region around Blenheim, which is a bit closer to the epicentre (the point at the surface of the Earth that is closest to the source of the quake) than Wellington.
The earthquake was followed by a bunch of aftershocks, which is normal after an event like this. According to the Gutenberg-Richter law for every earthquake of magnitude X in one region we expect roughly 10 earthquakes of magnitude X-1, 100 of magnitude X-2 and so on. In other words, and to make things a bit easier to understand, say the Cook Strait earthquake was a magnitude 6, we expect 10 magnitude 5, 100 magnitude 4, 1000 magnitude 3 earthquakes following the main shock. This is what we call a mainshock-aftershock sequence. The timing of these aftershocks depends, but in general there is a lot of aftershocks in the first few hours and days, and they will become fewer and fewer over time. Here's an animation showing the first few hours of earthquake activity before and after the main shock.
Now if everything was perfectly simple we could stop right here. But things are slightly more complicated: There are also sequences of earthquakes where a bunch of smaller events lead up to a bigger one. The smaller ones are sometimes referred to as foreshocks, because they happen before a larger event. This is exactly what happened in the Italian town of L'Aquila in 2009, when a magnitude 6.3 struck after a few weeks of smaller earthquakes. There was a lot of media coverage on this tragic event and the trial that some of involved scientists had to go through, but to talk about this would be a new post. Instead I will sum up the essence: We can (and should!) advise people to act more cautious under certain circumstances. However, we cannot predict whether a larger earthquake will follow a sequence of smaller ones. There are probabilities for earthquake sequences to develop in one way or another. These probabilities are e.g. based on records of previous earthquake sequences for any given region. But again, how these probabilities should be communicated with the local people is not really that clear. There is a definite need for improvement! (see also my previous post about communication)
To get back on topic: Wellington. So why are there earthquakes in the first place? Well, the situation is again rather complicated. In New Zealand we're really lucky (or unlucky, from a non-geoscience perspective...): North and east of the North Island, the Pacific Plate in the East dives (or subducts) under the Australian Plate in the West. Southwest of the South Island, on the other hand, it's the other way round: The Australian Plate dives under the Pacific Plate. In between those two subduction zones, there is a large transform fault, which is called the "Alpine Fault". In this area, the two plates slide past each other sideways. Here is an image showing a transform fault:
How exactly does the transition from one to the other work? Nobody really knows... that's why people like me love New Zealand, it's like a natural laboratory with lots of things that are yet to be discovered! :) So in Wellington we're just north of the region where we go from subduction to sliding sideways. The Pacific Plate is sinking into the mantle, and we sit on the Australian Plate riding on top of that process. The Cook Strait earthquake, however, was in the sideways sliding zone, an area with lots of little transform faults that eventually all merge into the Alpine Fault in the South. Such an earthquake with side-by-side motion is called strike-slip earthquake. These earthquakes are (usually) not as strong as the subduction zone earthquakes. Examples for large subduction zone earthquakes would be the Japanese "Tohoku" earthquake in 2011, or the Sumatra-Andaman "Boxing Day" earthquake in 2004. Yet, strike-slip earthquakes can be quite damaging! A recent example for an earthquake that was partly strike-slip would be the 2011 Christchurch earthquake ("only" magnitude 6.3, but a lot of damage and many casualties!). Wellington was a bit luckier than Christchurch, partly because it was further away from the epicentre, partly because the event in Wellington was deeper (13 km vs. 5 km for Christchurch), and for a number of other potential reasons.
But... this doesn't mean that Wellingtonians get to lean back and rest assured that nothing will ever happen to them! First of all, based on the aftershock law that I mentioned above, Wellington - just as Christchurch and any other place that has experienced large earthquakes - will continue to get aftershocks for the next year or more. Second, there is always the possibility of similarly large or even larger earthquakes following, on the same fault, or on other faults nearby. Third, there is still the subduction zone that wasn't too much involved with this particular event, so it's going to be quite interesting to see some studies on the probability of subduction earthquakes based on this most recent event. So, as harsh as it sounds, if you're a bit faint hearted or are simply looking for a quiet place to live then you might want to consider a place different from Wellington! Bear in mind though, a lot of places including my lovely current home Vancouver may also have a high chance of getting potentially large and destructive earthquakes. I strongly suggest that everyone living in places like this have an emergency kit packed and ready to go. The NZ campaign "Get ready - Get thru" has some good advice on what to put in such a kit, how to prepare for an earthquake, and how to act during and after. In Canada, the BC government for example provides similar information. Both websites also have a lot of info on other natural disaster that might happen in the area. To end - in all seriousness - a little line from Pineapple Express:
Well be careful, man. Be careful. Wear shoes in the house. Safety. Safety first, then teamwork.
Monday, 5 August 2013
So turns out I was waaaay to busy to publish the last part of my triple feature before leaving for Japan. Also turns out the travel plan had to be changed a little bit (of course...). Instead of climbing Fuji, which probably would have been quite a rushed trip on a rainy day, I decided to go south to visit the beautiful island of Yakushima. More details on my non-volcano blog :)
But now the important thing: Sakurajima! This volcano gets an award for making the most volcanologists happy in 2013. Sitting on an island within Aira caldera in the South of Kyushu, Sakurajima erupts several times per year, and has been doing so since 1955! The perfect venue for the IAVCEI 2013 conference. Over 1,000 volcanologists gathered in the city of Kagoshima, roughly 4 km across the bay from the volcano. Whereas in June the volcano was sitting there rather quietly, she put on quite the show with sometimes multiple eruptions per day in July for the conference. I'm gonna let the pictures speak for themselves! Enjoy :)
Monday, 24 June 2013
It's time for another volcano profile! This time our focus is the famous Mount Fuji, which even made the news a few days ago (see end of this post). It's really well known (type "Mount Fuji" into Google and it comes up with over 8 Mio. hits in 0.27 seconds...), mostly for its iconic shape - the shape that most people have in mind when they hear the word "volcano". This shape is characteristic for a type of volcano called "stratovolcano". These volcanoes are almost perfectly cone shaped, with relatively steep slopes.Stratovolcanoes are made up of alternating layers of different types of volcanic materials, for example ash, lapilli (loose pieces of volcanic rock that are bigger than ash), bombs (even bigger pieces of volcanic rock), lava flows, pyroclastic flows (really hot, really fast, really deadly flows of loose volcanic material; see Harry Dalton in the very hilarious and awesome movie Dante's Peak for some insights on the topic... Here's the crucial scene:)
In most cases, stratovolcanoes are made out of very "sticky" rock types like rhyolite or andesite. With rocks it's essentially the same as with honey: There's the real runny stuff, that drips of your slice of toast no matter what, and then there's the type that's more viscous, so that even eating-habit-challenged people like me can finish their breakfast without letting hands and table and chair and pants and shirt enjoy their part of the honey. So the runny rock type (basalt) would form shield volcanoes, because all of the lava just runs down the mountain easily, whereas the sticky rock types actually produce volcanic output that can stick together and form a steeper mountain. Makes sense?
So Fuji-san sits on the island of Honshu, the biggest of all the parts of Japan. It's over 3,700 metres high, and I'm definitely planning on climbing at least part of it when I'm on my way back from Kagoshima to Tokyo in a bit over a month from now! I won't have to be too worried about activity there: The last "big" eruption was in 1707, with a VEI of 5 (see previous post for some info about VEI). Fuji's history in general is quite uncertain, there may have been some smaller eruptions in later in the 1700s and 1800s, but definitely nothing has happened in recent history. They're monitoring it tightly since it's so close to sooooo many people, but at this point there's not too much going on.
However, it did get quite interesting just a few days ago: On Saturday, the United Nations Educational, Scientific and Cultural Organization (UNESCO) announced that Mount Fuji is now officially a World Heritage site (read the full article). Only around 30 volcano-related sites have made it this far! Granted, it was probably given the status not based on it's volcano-y awesomeness but because it's a "sacred place and source of artistic inspiration", but hey, we can give it some credit anyways, don't you think?!
Monday, 10 June 2013
This post will be part of an exciting triple feature on Japanese volcanoes. Why Japanese volcanoes? Because I'm going to Japan! :) There is a conference coming up in July, and I am planning to spend some time afterwards to explore a bit of Japan's volcanoes. I hope I get a chance to visit Sakurajima, Aso and Fuji, all of three of which I'm going to feature here over the next few weeks!
Let's start with an old friend: Aso-san (The Japanese have the awesome tradition of politely addressing their volcanoes just like people). This is the volcano I studied for quite a while during my Master's. Aso Volcano is a large caldera on the island of Kyushu in southwestern Japan. Japan is really close to some major plate boundaries. For those who care: The Philippine Sea Plate is subducting under the Eurasian Plate at an angle, the Pacific Plate is also subducting, and the North American Plate is potentially stuck somewhere in between...... whew, it's really quite complicated! Because of all those plates pushing in different directions, Japan gets tons of earthquakes (as if we didn't know that by now...) and, of course, a bunch of active volcanism. So Aso Volcano sits somewhere behind one of the plate boundaries, and has been sitting there quite happily for more than 300,000 years. Quite happily? Well, it does get upset sometimes, and 4 of those volcanic "rants" have been pretty devastating to the island of Kyushu. Thankfully for the people there, the last big eruption was roughly 90,000 years ago. However, that doesn't mean that it is just quietly sitting there. Within the past 20 years alone there have been 11 "small" eruptions! (What does "small" mean? Click here for some info on what we call "Volcanic Explosivity Index", or VEI.)
Those smaller eruptions, of course, don't make the whole caldera (something like 18 times 25 km) blow up. Instead, in the centre of the caldera there is a bunch of little peaks, called cones. One of those, Nakadake, is the one that's causing most of the trouble nowadays. It's around 1,600 m above sea level, and has a crater lake that apparently looks really cool! Now if there are only small eruptions, why would anybody care? Why did I spent months and months studying it?
Well, one reason why we should care is, of course, the fact that it looks really cool. At a relatively low elevation it's easily accessible (especially in comparison to some other volcanoes). There is a road leading up to the crater lake, and a cable car goes all the way up too! It's a big tourist attraction on the island of Kyushu. Of course one wouldn't want a volcano blow up in the face of some peaceful tourists, so the least we can do is monitor it. Then there is the oh-so-insignificant fact that the island of Kyushu alone is home to over 13 Mio. people!! You can imagine that none of those people would be very excited if the entire caldera decided to blow up at some point out of the blue (except for volcano-crazy people like me, they might get a little bit excited...). So there you have 13 Mio. and some more good reasons to monitor and study what the mighty Aso-san is up to.
There is an additional excitement factor at this volcano: Volcanoes with crater lakes often have what we call "phreatomagmatic" eruptions! These eruptions can be pretty dangerous if you're close by, even when only small amounts of magma come up to the surface. This is because of the water, of course! Have you ever made some pasta and forgot to turn the stove down once the water was boiling? When it flows over the top of your pot and onto the hot plate it usually starts sizzling and evaporates, i.e. gets so hot that it turns into steam and goes up in the air. If hot magma comes up through a volcano neck and finds a lake at the top of that neck, something very similar happens: The water in the lake gets heated up really really fast, and can suddenly turn into steam. But the steam needs much more space than the lake water that it used to be, so if the whole process happens fast enough then the water/steam/magma mixture will push away the surrounding rocks or whatever is in the way. It creates a really big explosion! If we're really unlucky, that mixture can then flow out of the crater and down the slopes of the volcano, taking with it anything that's in the way. These strong flows of water, rocks, and "stuff" are often called lahars. They can even wipe out bridges! (Read the story about the Tangiwai disaster in New Zealand, where a passenger train was wrecked when it crossed a bridge previously damaged by a lahar and collapsed with it on Christmas Eve, 1953)
This is really crazy stuff! And of course I'm very excited to check out the crime scene! Can't wait to see the crater lake after my conference in July!
PS: When I was in New Zealand I went to check out the way the lahar came down the slopes of Ruapehu and took out that train. It must have been so exciting and scary for anybody to witness!
Sunday, 26 May 2013
In line with my previous post about communication, I think it's time to talk a bit about outreach. After all, I can't preach about something that I don't believe in, and it just happens that I have an "active interest" (what a great phrase...) in science education. There's a bunch of really good ways in Vancouver to get involved in science outreach activities. If you enjoy hanging out with kids, if you like explaining science-y things to non-experts, if you want to think about science outside of your little box, or if you've always loved the potato clock, there's a way to make yourself useful and do what you enjoy at the same time.
There was a great episode on the Big Bang Theory recently (click here, for those of you in Canada): Sheldon and Leonard invite their childhood idol, Professor Proton (the host of a kids science TV show, who never pursued a science career and had to retire to doing shows at kids' birthday parties etc.) to their house. He appears and starts his show, only to stop half way through. He announces his disappointment in his life, emphasizes that he actually has a PhD, but was never again taken seriously after doing the TV show. Both Sheldon and Leonard try to cheer him up, and in the end it's Sheldon who turns the story around by telling Professor Proton how influential he was on Sheldon's (and probably hundreds of other kids') career choice(s). According to Sheldon, in a way Professor Proton is contributing to a big portion of science that is done by just those kids who back in the day loved his show.
Ok, it's just a TV show, and sometimes the way science is portrayed in this particular one isn't exactly epic, but really, they have a point here! We need good science educators and outreach activities as much as we need the science itself. Who's going to inspire kids and young people to pursue careers in science? It's their environment, whether it's through books, role models, TV shows, computer games, parents, or school trips and classroom activities. This is where everybody can come in! I can talk the most about things I've done myself (d'uh), so I'll give you guys a quick overview:
1) Let's Talk Science: A great outreach program that operates nationwide. The part that I particularly like is called a "Teacher Partnership". Grad students and other volunteers get paired up with a teacher, and go to that teacher's class for at least 3 times over the course of a school year. In the classroom, we deliver hands-on activities for the kids. Depending on their curriculum they can really be any kind of science, but I mostly do Earthscience stuff (surprise!). The age range varies, over the past couple of years I've taught grades 2-3 and it's tons of fun!
2) At the Pacific Museum of Earth, the little Earthscience museum in our department, I lead tours and workshops for incoming groups of any age. From school classes to home schooled kids or ESL adults, anybody can learn about fossils, plate tectonics, rocks and more. And we recently bought an interactive 3D projection of the Earth, which is the most amazing toy I've seen in a long time!
3) Last but not least, I recently started being a mentor for a kid who's interested in volcanoes and earthquakes. This mentorship is one of many organized through the Vancouver School Board, and anybody with a special interest or area of expertise can volunteer to be a mentor. It's quite different from the mostly group-focused activities above, since it's obviously much more individualized, but definitely no less important!
I'm sure there are a lot more opportunities for outreach and education out there, and they're really all super fun and a good use of your time. So get off your couch and put yourself out there! You might even like it :)
PS: If anybody wants to discuss or has ideas for activities let me know!
Monday, 13 May 2013
Shame on me, I haven't blogged in *forever*! But this radio silence actually leads me to an important topic: Communication.
Hold on, why are we talking about communication, I thought this was a science blog?, is what you're gonna say. True. But it is also true that communication is (or should be, but I'll get to that) a big part of science. There's two parts to this story: There's science communication related to outreach, education, the "getting young (and old) people excited about science" communication, and then there's science communication in the sense of informing the public about past, current, and future events and processes, potentially for their safety and well-being. For now I just wanna talk about this second part.
Let me give you an example. I'm sure you remember what in science journals is called the 2011 Tohoku earthquake, a 9.0 magnitude earthquake offshore Japan that caused a major tsunami (just in case you don't remember every little detail, here's some info). Of course everyone was talking about it, newspapers were writing about how big the earthquake was, why it was so big, how earthquakes can cause tsunamis, etc etc. At this point, most of us are beyond "the gods are punishing us for xy" as the ultimate explanation for any natural disaster. Instead, we get our very scientific explanation from the newspaper, websites, tweets, blogs, ... But where does the newspaper get that kind of information? That's right, from the scientists, of course.
The problem is now that us scientists don't really know how to talk to people who know nothing about the subject. It's just the same way as it used to be in highschool: Most teachers are quite good at the material they're supposed to teach. But only very selected few are similarly good at actually making us understand and learn. So some scientists are naturally good at explaining scientific facts to the reporters, their students, or their mum. And other scientists are, well, let's say not so good at doing the same thing, even though they might be as knowledgeable as their colleagues. In the example of the Japanese earthquake and tsunami above, the outcome might be that in the end my grandma doesn't quite understand how an earthquake can cause a tsunami. Since she lives somewhere in southern Germany there's probably worse things that can happen to her. However, if she decides to move to, say, some island in Indonesia it might become more important to her to understand what's going on.
To give a more drastic example, I'm sure everybody also remembers the 2009 L'Aquila earthquake, or to be more precise, the aftermath of that earthquake (check out these interesting articles in Nature and Science). Seven officials, among them four scientists, were found guilty of manslaughter by failing to give an accurate analysis of the seismic risk and provide the public with adequate information. The uproar among scientists and others was huge, the perception of the verdict was that the scientists failed to "predict" the earthquake - we simply cannot predict earthquakes. Whether the trial and the verdict make sense or not, something else was widely overlooked or ignored:
The actual root of the problem is the fact that most of us trained or training to be scientists never receive any training on how to effectively and adequately communicate our work to lay people.
Yes, we write tons for our advisors/colleagues/... and have extensive rules and traditions for peer review in scientific journals. But most of us don't often have to discuss our work with non-scientists. So now there are seismic network managers, volcano observatory directors, climate change panelists, government science advisors, all of whom do great science, but potentially fail to provide crucial information to the public. This is not because they're stupid, in fact they're probably very bright people, but because once we learn all about our subject matter and about the scientific method we forget that not everybody has the same level of understanding.
Here's an example of where problems arise: Science is as accurate as possible, but always deals with uncertainty. This uncertainty could come e.g. from the measurements that we make (a measurement usually has to be made with an instrument, but any instrument has limited accuracy). It could also come from the fact that we often use statistics to draw conclusions.
When we study earthquakes, for example, there is no way of *knowing* when the next one is gonna strike, or where. Instead, we can look at earthquakes that have happened in the past in a specific region (we can get that info from e.g. tree rings, tsunami deposits, eyewitness accounts). Based on this history, we can calculate an *average* time between earthquakes of a certain magnitude. Let's look at Vancouver, for example: There was a magnitude 7.4 earthquake in 1872, a 7.0 in 1918, and a 7.3 in 1946 close to Vancouver. Based on that information, we could say that the average time between earthquakes with roughly magnitude 7 around Vancouver is 37 years. If we were in the year 1983, we might expect another magnitude 7 earthquake around Vancouver soon, since it would have been 37 years since the last one. However, that earthquake in 1983 didn't happen. So there is a certain probability for it, but that doesn't mean that it actually has to happen.
In a different example we might say that there is a 20% chance of a volcano eruption at a hypothetical volcano. Now different people perceive facts differently, sometimes based on their understanding of the subject. 20% might sound pretty low to some people, and they might say, let's just stay and not evacuate. On the other hand, 20% is the same as saying, in one out of five cases this volcano is going to erupt. How do you perceive this statement? Does it "feel" more likely, less likely, or equally likely compared to the previous statement? Do you think a town nearby should be evacuated (of course there are more factors going into this decision, but that's a different story...)?
There is, of course, no right answer here. It's all about the way information is given, and the way it is perceived. Science is just like a human relationship, it lives and dies with the quality of communication. My whole point is that us scientists should be given more opportunities, but also make it a higher priority for ourselves to learn about these different forms of communication. After all it definitely is our responsibility to provide information (What use are a bunch of scientists that find out about some awesome and cool science just to keep it to themselves?) and it most definitely should be our responsibility to make sure that the information is perceived correctly! Enough said. What do you think?
Tuesday, 12 February 2013
So the North Koreans apparently conducted a nuclear test. How do we know this? Because of seismology! The CTBTO (Comprehensive nuclear Test-Ban Treaty Organization, http://www.ctbto.org/) has seismometers all around the world to detect potential nuclear explosions. But seismometers, aren't those the thingies that record earthquakes? That's right. But an earthquake and an explosion are very similar: Both make the ground shake, quite a lot if you're close by or it's a really big earthquake/explosion, and only a little if it's a smaller event. A seismometer has a mass with a needle with ink attached to it (ok, this is how seismometers USED to work back in the day, now it's all fancy electronics, but the principle remains the same). When the ground shakes even just a little bit the mass wants to stay where it is (inertia! Ever experienced that? It's that feeling when you're watching a movie and you feel like eating some chips, but you don't want to get off the couch to get them out of the kitchen cupboard, because you need energy to get up. Isaac Newton was pretty big on inertia, I bet he always wanted to sit on his couch and watch movies - or whatever the equivalent was back in the day. You might also know what I'm talking about from driving your car: If you slam on the brakes because you're trying to not run a red light you feel your body moving forwards - it wants to maintain its current state, which is moving forward. Anyways, back to seismometers.). So the mass wants to stay put, but the ground moves under it, so the needle attached to the mass draws wiggles on the piece of paper that's attached to the ground - boom, you have a seismogram! That's also how the volcano generated wiggles are recorded that I was talking about last time.
Because in an explosion the ground shakes too, we can see it on our seismograms. People have worked very hard to figure out what type of ground movement causes different types of wiggles, so now we can use that knowledge to figure out the type of ground movement by looking at the wiggles. That's also how scientists know whether an earthquake happened e.g. on a subduction zone (Indonesia, Japan) or on a so called strike-slip fault (San Andreas Fault!).
Ok, now we have some wiggles on paper and think they look like they might come from an explosion. But where did this happen? This is why we need several seismometers in different places! If you drop a pebble in a pond it generates waves, and they grow bigger and bigger around the place where you initially dropped your pebble. The same happens with seismic (ground shaking) waves. If we look at a few different stations and the exact time at which this explosion wave arrived we can backtrack where it came from. Once we know that, just be sure, we can look at whether there have been earthquakes recorded in the same area before. Here's a map of earthquakes around North Korea since 2004 (data courtesy of Google Earth and the GEOFON program, http://geofon.gfz-potsdam.de/).
|Circles are past earthquakes since 2004 around North Korea. The two red dots are the nuclear tests in 2009 and 2013.|
As you can see North Korea doesn't usually get many earthquakes, and the location of the event yesterday is suspiciously close to the location of the 2009 nuclear test. And this is what the seismograms look like:
|Nuclear tests conducted by North Korea in 2006, 2009 and 2013. Image courtesy of NORSAR.|
So this is how we know that there was indeed a nuclear test conducted by North Korea. Without science, seismometers might have never been invented and we might not be able to know whether anything happened at all. Granted, without science we might also not have the technology to have nuclear explosions in the first place, but that again is a whole different story... Still, isn't it cool how we can sit somewhere peaceful and awesome and yet find out within minutes of an event (North Korea is some 70º from Vancouver, which means the waves took just over 10 minutes to get here) that it has happened thousands of kilometers away?
Wednesday, 30 January 2013
Where to start? Why not with something obvious: the blog title. Shaken, not stirred! Where does this even come from? For one, my (now obvious, *sigh*) affection for James Bond movies. But of course there is also a relation to science, or more specifically: my project. So what is this project all about?
My "victim" right now is something called "volcanic tremor". In essence, this tremor is like an earthquake on a volcano, but unlike an earthquake, it doesn't last for a few seconds but for minutes or hours or sometimes weeks! Crazy shit, eh? But what's even more interesting, a lot of the times this tremor happens the volcano is doing something, like, uhm, ... erupting! Kind of like, say, when your TV gets these little hick-ups where you see black and white stripes gliding across the screen (I know, how old-school does it get?? To be fair, for this analogy to work we have to think back to the times before plasma TVs. Anybody remember those days? But I'm diverting...). So when your TV does that once in a while, you hit it on the top and usually that solves the problem. But when it doesn't wanna stop the whole stripe-thing you know for sure it's up to no good! And you better watch out that it doesn't blow up in your face... just like the volcano! So that of course explains why some of us (granted, definitely the more nerdy part of the population) are really interested in this tremor thing: Where does it happen, what does it look like when it happens, and WHY IS IT HAPPENING AT ALL??? OK, this last question we could ask ourselves about many things, but let's save this discussion for another day.
So first things first: Where? There's many answers to that question, but for now I went with a pretty horrible location... Hawai`i! Roughing it for science, as always. But hey, we all have to make sacrifices! So I went there a few months ago, and with the help of my awesome friends at the Hawai`an Volcano Observatory got some examples for tremor that they recorded. Now what?
This gets us to the second question: What? OK, for one we can just look at the tremor records. They look like this:
Mostly a bunch of wiggles, sometimes with a few spikes. If you're a really really optimistic person you could say it looks somewhat pretty, maybe artistic (the discussion about the definition of art will also be left for another time...), but that's definitely a stretch. The only thing that we can say for sure is that it's more wiggly in the end, compared to the beginning. So now what?
This is where all the fancy stuff comes in (and where I wish I had first of all actually gone to any maths classes in my undergrad, and second of all, if I had gone, paid attention to what my professor was trying to explain. Oh well.). The fancy stuff in this case is called "Fourier Transform". "Fou.... what????", I can hear you asking. "She must be crazy", I can imagine you thinking (Darn, I think you're right. As you know, sanity isn't exactly my strong suit... but hey, it wouldn't be half the fun if I was actually sane, don't you think? Yikes, I'm diverting again, back to those crazy transforms.). It's not that hard, really. Imagine somebody has painted a picture, and now you're looking at it. You know all the different colors, because they're still lying around on the floor (Yes, the painter isn't exactly the tidiest person in the universe, and no, of course this is not based on my personal experience at all, and also, again, what about the fun??). So anyways, the colors are still there, but the painter mixed them to get different shades and tones. But since we know the components we can roughly figure out how much of each color was used to create a particular shade on the canvas. Makes sense? So I basically try to figure out which components are needed to make tremor. And once we know that we can try to work out where the components are made. It's like, yeah, we had this much yellow and this much blue to make some green, but where does yellow come from? And then we go to the paint factory and ask the guys who work there, hey, where does the yellow come from? I really like it, it's so bright and shiny and happy... Unfortunately there is no factory for volcano parts, so I can't just go and ask. This then gets me back to the point where I remember all those math classes in undergrad that I spent sleeping, eating ice cream in the sun, drinking beers, ... and the circle is closed.
So anyways, to get back to the point, in super short, there's this wiggly thing, some sort of shaking that happens when volcanoes blow up, and all I have to do is try to figure out where the bright shiny happy parts that make the wiggles come from. Pretty simple, eh?
Tuesday, 29 January 2013
to my new blog! From now on, this will be my place to talk about anything science-related. Don't worry though, I'll keep things at a minimum of nerdiness, and hopefully each and everyone of you, from outdoor freak to science lover, from volcano enthusiast to I-haven't-take-any-science-credits-since-grade-11, even if you consider yourself a mixture of all of the above, will find something on here to enjoy. I will transfer a few things from my old online self, and start posting very soon. Stay tuned! :)