Archive | October, 2011

Surfacing volcanoes made the air we breath

20 Oct

The earth didn’t always have oxygen in it’s atmosphere. Oxygen appeared in earth’s atmosphere at about the same time that blue-green algae appeared in the earth’s oceans, which makes sense since the algae takes in carbon dioxide and spits out oxygen. We’ve known that bit for a while–but as we learned more about the exact times that these events occurred, we started to scratch our heads a bit. The ocean algae actually appeared quite a bit earlier than the oxygen in the earth’s atmosphere.

So why the time lapse? It turns out that the atmosphere became oxygenated at the same time that much of the continental crust formed and the ocean receded. Volcanoes that were once under water became exposed to air. When volcanoes are exposed to air, the gas they spew is a bit different from what comes out of an underwater volcano. It turns out that underwater volcanoes spew a lot more H2S than land volcanoes, and that H2S traps oxygen and removes it from the atmosphere. So when the volcanoes were all underwater and spitting out this oxygen-trapping substance, the atmosphere of the earth could not become fully oxygenated. When the volcanoes emerged from the oceans, they no longer impeded the building up of oxygen in our atmosphere and we got our ozone layer. At least that’s the theory. It corresponds pretty well with other evidence from that time period. Read more here.

We really understand so little about our earth and how it was formed.


Extremophiles love volcanoes

19 Oct

You may have learned as a youngin in school that all life gets its energy from the sun, and that it is only the sun that makes life on earth possible. You know… plants use the sun to make energy in the form of sugar, animals eat plants for energy, bigger animals eat those animals for energy, but all life began with the sun. While this is true in many respects, it is not strictly true. There are animals that live where there is no sunlight at all. We call them “extremophiles” because they are animals that survive and thrive in extreme environments.

At the bottom of the ocean where there is no sunlight whatsoever, volcanoes provide the energy that is needed for an extraordinary ecosystem to exist. I’m talking about the mid-oceanic ridge in the middle of the Atlantic Ocean. It is a diverging plate boundary, meaning that it is the boundary of two continental plates that are moving away from each other. It is a volcanically active region. There are fissures in the ground, called hydrothermal vents, that release water that was heated within the earth’s crust near the volcanoes. The conditions here are extreme. The temperature of the water issuing from these vents can be anything from 140 to 860 degrees Farenheit. The high temperature of the vents and high pressure at the bottom of the ocean can cause the water coming out of the vents to be supercritical, meaning that it isn’t a liquid or a gas, but something in between with strange properties.

A special type of bacteria has evolved a way to make energy from the hydrogen sulfide dissolved in the water coming out of the vents. It’s called “chemosynthesis.” There is no light, but life found another way to exist. This bacteria provides the basis for the ecosystem surrounding hydrothermal vents. Tube worms, eye-less crustaceans, snails, shrimp, crabs, octopuses and fish all thrive in this ecosystem, specially adapted to the extreme heat and pressure involved. Tube worms attach to the vents and collect the hydrogen sulfide for the bacteria to eat within them. This ecosystem based on chemosynthesis is extremely foreign to us, and was only fairly recently discovered. It is amazing how life finds a way to exist in the most extreme environments. It does make one wonder what else is out there.

Mount Rainier

18 Oct

I live about 75 miles away from the most topographically prominent volcano in the continental US: Mount Rainier. It is even more topographically prominent than K2, which is the second highest mountain in the world. If something is topographically prominent, that means that it is tall compared to the flat surrounding area. K2 is the second tallest mountain in the world, but it is surrounded by very high mountains and is therefore not as topographically prominent.

And prominent is definitely the right word for it. I remember having lived in Seattle for a few months before the clouds cleared enough to see Mount Rainier. I was so amazed at what a huge portion of the horizon it takes up. It really is monstrous, and it can even be seen from Vancouver, BC (almost 200 miles away) on particularly clear days. Topographical prominence makes Mount Rainier particularly dangerous, in that the lava and pyroclastic flows can travel further and the impact of the volcano will be felt from further away. A pyroclastic flow is a fast-moving current of superheated gas and rock. Mount Rainier is part of the “decade volcanoes” list, which is a list of the volcanoes that are considered the most dangerous because of their history of large-scale, violent eruptions and their proximity to human populations. This list also includes Mount Vesuvius and Mount Etna. Another dangerous bit about Mount Rainier is that it has the largest glacial load of any other mountain in the continental US, meaning that there’s a lot of rock and ice to melt and cause dangerous debris flows if it goes off. We don’t have very much data as to Rainier’s activity. All we know is that there have only been one or two small eruptions in the last 200 years, so it is classified dormant, but with the caveat that we don’t have very much data on it.

I’m sure us Seattleites have Mount Rainier on our minds after the 1980 eruption of Mount St Helens. Mount Rainier has a potential to be even more devastating. I hope I’m not around when that sucker blows.

USGS summary of Mt Rainier hazards as of 1998 here.

Volcano week

17 Oct

If you share my love of extremes in nature, then you will enjoy this week’s bloggings at Physics Fascination. First of all, check our this awesome picture of a volcano erupting taken from space (thank you, NASA for making all of your photos public domain):

Now let’s talk some volcano basics. A volcano is an opening in the earth’s crust that hot magma and gasses escape through. It’s called magma when it’s below the earth, and lava only once it reaches the surface. Volcanoes are generally found where there are converging or diverging tectonic plates, which makes sense as there is a lot of cracking and movement of the crusts at the boundaries. Volcanoes can also form in “hotspots,” which are places where magma rises up through the crust in a column and the heat and pressure are released, like Hawaii.

Below are some before and after pictures of Mount St Helens. When the blast went off in 1980 (triggered by two earthquakes), 3,000,000 cubic meters of material was transported 17 miles to the Colombia River. That’s a lot of power. Stay tuned this week to learn more about volcanoes.

Grape in the microwave

14 Oct

Take a grape. Cut it in half long-wise, but don’t cut through the second skin so the two halves are still connected. Then put it in the microwave, and watch. It is awesome!

The length of the grape opened up is half the length of a microwave wavelength, so a standing wave is created and electricity flows until the two halves are severed. Pretty cool. Something in the grape (probably the sugar), vaporizes and creates a plasma, which is a gas that is ionized (a reduced number of electrons) above the grape.

Future: robotic limbs with a sense of touch

13 Oct

Imagine a prosthetic limb that you can control with your brain, and that sends signals back to your brain so you can feel with it. We are one step closer to that reality.

Scientists have already created robotic limbs that are controlled directly by the brain, and have seen much success in monkeys. Now, scientists have also created a device that stimulates the correct parts of the brain to indicate touch, including textures. It took some doing to create a device that does not interfere with the brain’s outgoing signals, but they did it. They’re calling it the brain-machine-brain interface, or BMBI.

the next step is to create a robotic limb with tactile sensors so that we have a signal to send to the brain. This is some pretty exciting stuff that will definitely change lives some day.

Read more here.

Venus has an ozone layer

11 Oct

We used to think that only Earth and Mars had ozone layers. The European Space Agency’s Venus Express space probe has discovered differently. In college, I was fortunate to have taken part in the design and manufacture of some custom optics for the Venus Express. It is pleasing to see it have so much success.

The ozone layer is a crucial part of life on earth. It shields us from the sun’s harmful UV-rays (which would do worse than give you a little sunburn if we were exposed to its full force), and the ozone layer takes a large part in moderating temperature on earth. Ozone is made up of 3 oxygen molecules, O3. Sunlight breaks down carbon dioxide to make O3. On earth, it is aided by the oxygen spit out by plant life. Naturally, we are interested in the existence of ozone layers on other planets. Though it certainly isn’t an indicator of life on other planets, it may be a condition that is necessary for it. These are the kind of processes we need to understand if we are going to be able to comprehend the history and/or future of our own planet. Venus’ ozone layer is three times the height of earth’s, and much thinner. It’s exciting to see so many similarities between the rocky planets.

Read publication here.