The magnitude 8.9 earthquake that devastated coastal areas in Japan shows up very clearly on the United States Geologic Survey’s recent earthquake page.
The big red square marks an aftershock of the magnitude 8.9 earthquake off Japan. (Image via USGS). Note that most of the earthquakes occur around the edge of the Pacific Ocean (and the Pacific Plate).
Based on our studies of plate tectonics, we can see why Japan is so prone to earthquakes, and we can also see why the earthquake occurred exactly where it did.
The obvious trench to the east and the mountains and volcanoes of the Japanese islands indicate that this is a convergent margin. The Pacific plate is moving westward and being subducted beneath the northern part of Japan, which is on the Okhotsk Plate.
The tectonic plates and their boundaries surrounding Japan. The epicenter of the earthquake is along the convergent margin where the Pacific Plate is being subducted beneath the Okhotsk Plate. Image adapted from Wikimedia Commonsuser Sting.
The epicenter of the earthquake is on the offshore shelf, and not in the trench. Earthquakes are caused by breaking and movement of rocks along the faultline where the two plates collide.
In cross-section the convergent margin would look something like this:
Diagram showing the tectonic plate movement beneath Japan. Note the location of the earthquake is beneath the offshore shelf and not in the trench.
The shaking of the sea-floor from the earthquake creates the tsunamis.
So where are there similar tectonic environments (convergent margins)? You can use the Google Map above to identify trenches and mountain ranges around the world that indicate converging plates, or Wikimedia Commonsuser Sting’s very detailed map, which I’ve taken the liberty of highlighting the convergent margins (the blue lines with teeth are standard geologists’ markings for faults and, in this case, show the direction of subduction):
Convergent plate boundaries (highlighted blue lines) shown on a world map of tectonic boundaries. The blue lines with teeth are standard geologic symbols for faults, with the teeth showing the direction of the fault underground. Image adapted from Wikimedia Commonsuser Sting.
The Daily Dish has a good collection of media relating to the effects of the quake, including footage of the tsunami inundating coastal areas.
Cars being washed away along city streets:
Our thoughts remain with the people of Japan.
UPDATES:
1. Alan Taylor has collected some poignant pictures of the flooding and fires caused by the tsunami and earthquake. TotallyCoolPix has two pages dedicated to the tsunami so far (here and here).
2. Emily Rauhala summarizes Japan’s history of preparing for this type of disaster. They’ve done a lot.
3. Mar 12, 2011. 2:10 GMT: I’ve updated the post to add the map of the tectonic plates surrounding Japan.
4. A CNN interview that includes video of the explosion at the Fukushima nuclear power plant (my full post here).
5. NOAA has an amazing image showing the tsunami wave heights.
Tsunami wave heights modeled by NOAA. Note the colors only go up to 2 meters. The maximum wave heights (shown in black in this image), near the earthquake epicenter, were over 6 meters.
They also have an excellent animation showing the tsunami moving across the Pacific Ocean. (My post with more details here).
6. The United States Geological Survey (USGS) put out a podcast on the day of the earthquake that has interviews with two specialists knowledgeable about the earthquake and the subsequent tsunami, respectively. Over 250 kilometers of coastline moved in the earthquake which is why the tsunami was so big. They also have a shakemap, that shows the area affected by the earthquake.
USGS ShakeMap for the earthquake. Image via the USGS.
9. A detailed article on earthquake warning systems, among which, “Japan’s system is among the most advanced”, was recently posted in Scientific American.
10. Mar 15, 2011. 9:15 GMT: I’ve added a map of tectonic boundaries highlighting convergent margins.
Shinmoedake Volcano.
11. The Shinmoedake Volcano erupted two days after the earthquake, but they may be unrelated.
Fukushima reactor status as of March 16th, 5:00 pm GMT from the Guardian live blog.
12. The Guardian’s live blog has good, up-to-date information on the status of the nuclear reactors at Fukushima.
This short hike that follows a limestone bedded creek, will likely take a while because there’s quite a bit of geology to see.
The start of the hike is on the eastern side of the bridge between the villas and the hotel. Head north (left in the image) toward the lake.
This year, it was on a chilly, rainy morning in February, that we started on our hike. We took a left off the concrete stairway onto the trail that runs parallel to the river flowing in the ravine just below our cabins.
We’d stayed at the villas at Montgomery Bell State Park, which is about an hour east of Nashville. The villas are quite nice. Built into the side of the valley, sitting just across a small river from the park’s hotel/conference center, and designed to be energy efficient, they’re quite comfortable with their geothermal heating and vaulted ceilings.
They’re so nice that some wanted to stay in the warm. Others, however, were eager to get outside, despite, or perhaps even because of, the rain. I gave them the choice, but everyone came.
With the rain, we soon ran into trouble. Runoff from the road and building uphill converted part of the trail into a small stream. The first few brave souls committed to wet feet, and waded through.
The dam and lake at Montgomery Bell.
But the stream along the trail did not last long. Pretty soon we left it behind, and coming out of the valley the lake and dam opened up to the right and left. Though it had been raining for much of the previous night, the lake was still very low after the dry autumn and winter. The line of grass that marks its usual shoreline was over a meter above the level of the water.
Short concrete wall that acts as the outlet level for the dam.
So we crept along the southern edge of the dam to follow the path of the overflow channel. It was quite interesting to see the sediment and debris that choked the reservoir side of the concrete wall that regulates the level of the lake. The other side of the wall, where the water must accelerate as it overtops the barrier, was clean, bare and smooth, looking a lot like concrete until you get close enough to see that it’s hard, dark, limestone bedrock.
Drill-hole with radial shatter pattern.
But not hard enough. Small, round holes pockmark the rock. Clearly artificial, with radial cracks diverging from the center, they remind me of Sarajevo roses.
They’re probably contemporaneous with the building of the dam. In order to have their outflow channel, the dam builders needed to blast away some of the rock, so they drilled holes and filled them with explosives. The blasts crushed the upper layers of rock, but the bedding plane, upon which we are walking, dissipated the force and remained, mostly, intact.
Following the reservoir outflow channel.
The bedding plane is a bit slippery with the rain and light coating of moss, so we take a bit more care with our footing. The sides of the outflow channel are steep, with nice exposures of horizontal layers of limestone rocks.
Though I don’t go into it in detail, the different layers, with their different colors, hardness, and fossils, show the changing environment in which the sediments that created these rocks were deposited. The more friable, tan-colored layers were likely formed at a time when sea-level was lower, when this area was closer to the coastline so more sand and clays could settle out of the muddy waters emerging from fecund deltas. On the other hand, the dark, dense, grey limestone rocks are much more typical of deeper seas, offshore environments.
Tree roots prying apart the bedrock: biological weathering.
I did take the time to elaborate on the topic of weathering when my students pointed out the tree growing on the side of the cliff, with its roots entwining and pulling apart the limestone rock. It’s a part of the rock cycle that we had not spent a whole lot of time talking about in the classroom so I was glad for the opportunity.
Joints in limestone. Notice how the layers on either side of the joint line up.
Weathering also plays a part in the widening of joints, and the joints we saw were obvious and important in shaping the course of the channel. Joints are simply breaks in the rocks. When this region was uplifted, the rocks were squeezed and fractured by tectonic forces. There was not enough tectonism to seriously deform the region, the rocks are after all still close to horizontal, but they did break, creating joints that cut right through the bed of our channel and straight through the wall.
You’ll notice that the layers on either side of the joint line up, so this is just a fracture in the rock. Often, the rock will break and one side will be pushed up relative to the other; that would be considered a fault.
Runnoff from the rain, flowing along and widening joint in limestone.
One of the nice things about being out in the rain, was that you could see the water in action. Gliding along the joints, picking up and eroding small pieces of debris, while slowly, imperceptibly, dissolving away the rock and enlarging the joints. It’s the same process that created the caves we saw last year at Merimec; the reprecipitation of dissolved calcium carbonate from the limestone rocks is what creates the stalactites, stalagmites and other cave formations.
Looking up the channel at exposed bedding planes and joints.
It took a bit of care to follow the channel down. It also took teamwork. We’ve been practicing all year and it’s under these conditions that all the teambuilding, from the challenge course onward, really pays off.
Committing to wet feet.
At the bottom of the bedrock traverse was a big puddle. The water from the regular outflow of the dam creates pushes up sediment that blocks the free flow of the runoff from the current rainfall. Undoubtedly, this gets washed away when the reservoir overflows through the outlet channel, but today there was just a big puddle.
Here we faced a choice. We could have taken a hard right and walked back up to the dam along the edge of the small cliff that overlooked the outlet channel we’d just come down. It’s a nice walk, through last year’s leaf litter, and the overhang is just high enough to provide a small taste of vertigo. But the students wanted to push on, past the confluence, and follow the stream downhill. A second set of students had made the full commitment to wet feet, and any initial reluctance to be outside on a rainy day had disappeared. We followed the stream.
Convergence of the overflow channel and the drainage stream for the reservoir.
Just a few meters downstream from our decision puddle, we ran into the confluence of the regular outflow from the dam and the ephemeral, rainfall driven stream we’d been following. It’s a good place to talk about tributaries, deltas, and sediment transport, deposition and erosion, because the channel deepens into a little pool with lots of small scale features.
Following the stream.
Past the confluence the stream straightens out. It’s remarkably straight. If it weren’t for the fact that we’re in limestone rocks, it would be easy to assume, given the dam and all, that the lack of sinuosity is artificial. But it seemed like the stream was flowing parallel to the joints we’d seen earlier, so it’s not unlikely that the water is following a fracture in the rock. When convergent, tectonic forces fracture rocks, the rocks tend to break at an angle to the direction of the forces (somewhere around 60 degrees to the direction of the forces, if I remember correctly).
Climbing up to the trail that follows the ridge.
Following the stream brought us close to the picnic shelter near the entrance to the park. Just across the water is a pathway up the rocks on the side of the valley that takes you up to the trail that follows the ridge that parallels the valley.
Looking down at the stream and its floodplain from the top of the ridge.
It’s quite peaceful, standing on the ridge while water droplets drip through the sparse winter canopy, with last fall’s leaf litter beneath your feet.
Looking back down into the valley you could see (and talk about) the stream and its flat flood plain. It’s a chance to anthropomorphize. The stream “wants” to meander. It has to be constrained to one side for a reason.
Crossing the dam on the way back to the cabins (upper left).
The ridge trail takes us back to the reservoir and dam, which are quite noticeable if you’re paying attention. We traipsed down the hill and walked a narrow path between the tall, reddish-tan grass that tops the dam, and the bouldery rip-rap that protects the earthen structure from the force of the waves.
Shackelton’s Antarctic expedition remains one of the most ridiculously epic adventures I have ever encoutered. Through excellent leadership, and remarkable feats of navigation, every member of the expedition survived the destruction of their ship, The Endurance, and made their way across the harshest landscapes and oceans to find safety.
Sir Ernest Shackleton scouting the way across the Antarctic ice.
How to be a Retronaut has posted the color pictures taken by Frank Hurley, the expedition’s photographer.
According to the State Library of New South Wales, after their ship had become irretrievably stuck in the ice:
Hurley managed to salvage the photographic plates by diving into mushy ice-water inside the sinking ship in October 1915.
This is kind of emblematic of the dedication of the explorers on this expedition. There’s so much for middle-schoolers to learn about dealing with hardship and immense adversity. I strongly recommend the book, but little anecdotes like this one continue to impress.
I used my notes and the Keynes versus Hayek music video as part of our reading this week. As usual, half the class tried skipping directly to the video, but it became pretty clear, as I suspected it would, that they didn’t understand what was going on if they had not read the notes.
We’ll be discussing the video tomorrow when we try to wrap up the week’s work, but, as one student mentioned, it can be a little hard to figure out the words in the rap. Fortunately, the Econ Stories website has been updated to include the lyrics.
Even without the lyrics, however, I really like that you can get a good idea about the competing economic theories solely from the video itself, since it’s just a very detailed extended metaphor. It’s so chock full of symbols that it could probably be used to supplement the Calvin and Hobbes comic strip in our language lessons on finding symbols in texts.
Excel program for running the Middle School Bank in the personal finance simulation. As you can see, I'm creating an account for my student, Inigo Montoya.
To get students a little more familiar with personal finance, we’re doing a little bank account simulation, and I created a little Excel program to make things a little easier.
It’s really created for the class where students can come up to the bank individually, and the banker/teacher can enter their name and print out their checks as they open their account.
Excel program for running the Middle School Bank in the personal finance simulation.
The front sheet of the spreadsheet (called the “Bank Account” sheet) has three buttons. The first, the “Add New Account” button, asks you to enter the student’s name and it assigns the student an account number, which is used on all the checks and deposit slips. The other two buttons let you delete the last account you entered, and reset the entire spreadsheet, respectively.
One of Inigo's checks (number 4).
Once you’ve created an account the spreadsheet updates the “Checks and Deposit Slips” sheet with the student’s name and account number. If you flip to that sheet you can print out eight checks and five deposit slips, which should be enough to get you through the simulation. The checks are numbered and have the student’s account number on them.
There are two other sheets. One is the “Checkbook Register”, which is generic and each student should get one, and the other is called “Customer Balances”. The latter is set up so you (the teacher) can enter all the deposits and withdrawals the students make, and keep track of it all on the same page.
Yes, it’s a bit of overkill, but I though that, since I was going through the effort, I should probably do a reasonable job. Besides, it gave me a chance to do a little Visual Basic programming to keep my hand in. While I teach programming using VPython (see this for example, but I’ll have to do a post about that sometime) you can do some very interesting things in Excel.
My students are playing SPENT (previous post), and some of them have figured out how to easily make it to the end of the month even while living in poverty. Unfortunately, lots of moms are going without crucial medication.
At least this will contribute to a nice discussion of ethics and morality.
Velasquez and other, (2010) have a nice explanation of “What is Ethics?“.
Ethics is two things. First, ethics refers to well-founded standards of right and wrong that prescribe what humans ought to do, usually in terms of rights, obligations, benefits to society, fairness, or specific virtues. … Secondly, ethics refers to the study and development of one’s ethical standards. … feelings, laws, and social norms can deviate from what is ethical. So it is necessary to constantly examine one’s standards to ensure that they are reasonable and well-founded.
While the Stanford Encyclopedia of Philosophy has a great definition of morality:
The term “morality” can be used either
1. descriptively to refer to a code of conduct put forward by a society or,
— 1. some other group, such as a religion, or
— 2. accepted by an individual for her own behavior or
2. normatively to refer to a code of conduct that, given specified conditions, would be put forward by all rational persons.
—Gert (2008): The Definition of Morality (The Stanford Encyclopedia of Philosophy)
In fact, given how difficult it is to win the game without making some hard moral choices, a couple very interesting questions for a Socratic dialogue would be,
“Can someone survive in poverty while living ethically?”
and, to follow up,
“Does this push poorer people into being unethical and immoral, and towards crime?”
I’m curious to see where a dialogue might lead, especially if it leads back to our discussions of wealth distribution.
Adam Smith (1776) described how each individual, working solely for their own self-interest can interact, in a fair marketplace, to maximize the benefits for everyone. The unintentional, “invisible hand” of the market converts selfish actions toward a greater good if the conditions are right. The key condition is the rule of law.
Without clear, enforced laws, to prevent theft and to ensure property rights, the free-market economic system breaks down. Of necessity, the laws must be fair. If they are not then they will be violated, and in general it helps to minimize the number of laws people have to keep track of. People are free to do whatever they want, as long as they follow the law.
Similarly the classroom. Students need clear rules. Rules that establish the proper way to interact with their peers, and rules that protect individual rights to property and autonomy. While we hope they subscribe to their natural altruism, and indeed encourage its development, there need to be clear laws that they all can agree on. This is why we spend a lot of time at the start of each year be developing our set of rules and classroom constitution. To gain the maximum legitimacy, students develop the rules themselves, with some guidance, and establish ways of enforcing them. In my classroom, for example, we also dedicate time twice a week for a sort of legislative/judicial session, designed to deal with issues and problems that crop up.
But the reason for setting these limits is to allow freedom: freedom to learn.
Poster by Brian Moore (2009) (click image for his Flickr page).
Next year we’ll be looking at (and creating) propaganda posters when we study 20th century conflicts. Brian Moore has a wonderful set of adaptations of WWII posters for WWIII.
Inspired by the 2009 Iran election protest and activism and censorship therein, the WWIII Propaganda Posters were conceived as a mostly playful statement on wartime, citizen journalism, censorship, and how they all play with the advent of the Internet.
