26 January 2012

Deformation and GPS

We get a LOT of questions about volcanoes, including how to Know if they'll Blow. There are a number of ways we can track magma movement at depth, including deformation and "LP's" - long-period seismic tremor that is indicative of fluid movement. At late stages of unrest, we will start seeing "VT's" - short-period volcanic tremor that is indicative of shallow rock-breaking - and increases in CO2 and H2S gases. There is at least the possibility that we can detect early movement of magma at 30 - 40 km depths using magnetotelluric systems, but so far there hasn't been funding to try this. As I write this, deformation reaches out the longest time ahead of all these detection systems to give us warning of an impending eruption.

The term "deformation" is used by specialists in ground movement in the geosciences; these guys themselves are called "geodesists". Geodesists measure movement as a component of strain along an active fault, to try to get a sense of the energy accumulating that could lead to an earthquake. Deformation is used in volcanology to look for - and then track - inflation in a volcanic edifice. Deformation is done in several ways:

  1. By surveying the ground with high precision. This has been done at Yellowstone since the mid-1920's, and those early data have helped us get a much better sense of how the huge caldera moves and breathes. 
  2. By deploying tiltmeters. Originally these were long tubes of water laid out over the ground. If the ground under the flank of a volcano started tilting, it would show up in amplified movement of water in vertical tubes at the end of the long tube. Modern tiltmeters are ultra-sensitive cylinders placed in a vertical hole in the volcanic rock, then packed in with sand. The signal from these devices and all the following systems is generally telemetered back to a recording and monitoring system. 
  3. By using radar satellites - this is called InSAR for Interferometric Synthetic Aperture Radar. If two images can be captured over the same volcano, they can be used to make interferograms. These are colored, Moire patterns - generated with enormous mathematical calculations to geometrically correct and ratio each pixel to another, called "rubber sheeting" - that will show inflation over the surface of a volcano and its environs. Each rainbow-colored ring-set represents one radar wavelength (typically 5 - 15 centimeters) of uplift. These often form a bulls-eye centered over an inflating volcano or deflating caldera, and I've seen several gorgeous examples at Ngiragongo volcano, in Central Africa; at Pavlof, Akutan, Okmok, Shishaldin, and many other volcanoes in the Aleutians, and at Mauna Loa and Kilauea volcanoes in Hawai'i. 
  4. Gravity level-lines. This is like survey leveling, but is done by making repeat measurements with a gravity meter over a line of stations every six months or so. All other things (including the water table) being equal, an inflating volcano will show up as a decrease in the gravity field - the gravimeter is being moved farther away from the Earth's center, and the pull of gravity falls off as (1/radius distance squared). I did this to monitor magma moving into the Harrat Rahat volcanic field east of Madinah al-Munawarrah ("Medina") in Saudi Arabia. Seismic telemetry also showed small earthquakes associated with this magma movement at the same time. The events died out by 1995, causing a lot of people to breathe a collective sigh of relief, but this kind of one-again-off-again restive behavior is not at all unusual for a volcano.
  5. Telemetered GPS. These use the same GPS satellites you and I utilize in our cars or when hiking, but the precision measurements made by geodesists (the formal name for the deformation guys) are made using different signals from the same satellites.
  6. We also instrument volcanoes with sensitive analog, and ultra-sensitive broadband seismic sensors. Some of these data are telemetered, some are recorded and just stored in the instrument box on a small hard-drive until retrieval the following summer. That is, unless bears decide to play ball with one. One over-winter seismic network campaign at Katmai in Alaska found 5 of 11 very expensive stations had been trashed by bears before they could get back and retrieve them. 
GPS is a fascinating field, and applies far beyond the earth sciences. A brief run-down might be useful here.

The Global Positioning System was first envisioned by DARPA - the Defense Advanced Research Projects Agency of the Department of Defense - during the 1980's. Navigation at that time was complex and difficult, and getting any sort of location precision over vast distances including oceans was very important to some people. Like, the people targeting ballistic missiles, for instance.

In the late 1980's I worked in the Venezuelan jungle, where our main form of navigation was using 1:250,000-scale airborne radar (SLAR) maps. These were assembled by flight strips - and it was not unusual to find splice errors as large as 3 kilometers. Basically that means I could be standing on a rock - and half of the rock was 2 miles along the strip edge from the other half of the rock. I have been on a helicopter traveling for an hour over trackless forest using a half-meter-sized roadmap of the country (except there are no roads in the jungle) and crudely-penciled lines with the azimuth and distance for the site we wanted to visit. If that helicopter's fuel line had a single bug in it, we would have dropped down into the trees. Even assuming we had survived such a crash (the incident statistics gave me a 50% chance of this), how would you call in a rescue helicopter? How in the world would you tell them where you were?!?

I first began using a GPS device in the early 1990's in Saudi Arabia. In the northern reaches of the country there is a vast plain that is dead flat for hundreds of kilometers in all directions. Some of our guys had accidentally strayed across the Iraqi border because there is no way to know where the line arbitrarily drawn by the British a century earlier actually was. The first GPS units were incredibly slow, the size of a Betty Crocker cookbook, and didn't always work - but the idea fascinated me. With a radio, I could then precisely tell people where I was. 

Since then, hand-held GPS devices have shriveled to matchbox sizes, strap to your wrist, and have maps built in. You can program them, collect precise tracks... the list of bells and whistles goes on and on.

But how do they work? What actually is out (or up) there?

The American GPS constellation has at any given time about 24 active satellites and a few loitering spares, and each one transmits a very faint signal on two freqs - digital signal for hand held use and another digital carrier that is used for precision location acquisition - I'm talking centimeter-size precision here. BOTH frequencies are encrypted... they belong to the military, and for a long time the signals were deliberately "fuzzed" - this was called Selective Availability, or SA for short. If you had the key and a certain type of book-sized device, you could get very precise locations - within 10's of meters. But DOD didn't want someone else using those signals to pop an artillery round on top of one of their military outposts. Even to this day, if you try to use a receiver and go faster than a commercial airliner (as in: a ballistic missile) it won't work. It has a built-in fail-safe.

In the meantime, the rest of the world has become incredibly dependent on the GPS constellation. I could never summarize adequately all the ways and places where it is used right now.

If you are surveying - or trying to see if two points on the opposite sides of a volcano are moving apart from other (uh-oh), then you need great precision. It can now be as good as a bit over a centimeter horizontally and 2-3 centimeters vertically. In part this difference in precision is because for horizontal solutions you can subtract the atmosphere effect from two different near-horizon satellites - and triangulate better. For vertical elevations, you have only satellites in one direction (not beneath your receiver).

GPS signals all use the same frequency, but the signals are encoded to separate the satellites. Both transmitted signals from each are encoded, so you can't use one for a ballistic missile guidance system unless you own the codes. As I said, above a certain aircraft speed, GPS won't work.

Well, the Russians certainly didn't want to be dependent on something that the Americans could fuzz - or even turn off. So despite their crushing economic difficulties, they turned the best Russian minds onto building their own constellation. This is called GLONASS, and the signal is not encoded, the energy transmitted is greater, so the signal-to-noise ratio is 5 times or 15 db better. Because of this, the signal penetrates tree canopy, so I could use it in the jungle! Woo-HOO! The GLONASS system also uses 3 different frequencies, so you can reduce ambiguities and calculate better differential atmospheric corrections.

These GNSS (Global Navigation Satellite Systems) are so precise that they routinely calculate and correct for relativistic effects! There are also huge atmosphere effects that must be compensated for - dense air masses here and and ionized layers there. GLONASS even works on new American and European hand-held devices when the GPS signals are poor due to a poor view of the constellation - if you've ever been in steep canyons in Utah or New York City, you will know what I mean here.

Not to be outdone, the European Union is now experimenting with their own GNSS (Global Navigation System) called GALILEO. This is a purely civilian system with three frequencies, and is scheduled to come online in 2015 - they are testing 2 satellites in orbit right now.

For the same reasons, the Chinese have started their own COMPASS satellite GNSS system, and it likewise is coming on line rapidly - there are 6 satellites in orbit already, and thee would have been more if a recent Russian rocket system hadn't crashed. Not to be left behind, the American version of GNSS - the only one that should technically be called "GPS", is being upgraded.

All four of these GNSS systems use L-band frequencies to resolve ambiguities and increase precision - and penetrate the ionosphere. What does L-band mean? Look at your personal GPS system and the smallest dimension on it will give you an idea of the wavelength for L-band.

The navigation problem is more than just triangulation - three satellites near the horizon would serve for this; two would give you two possible location solutions, three would mean only one possible solution. But there are four unknowns, since you are measuring how long a stretch of space and air that your signal must travel. The precision of your timing thus becomes utterly critical, the speed of light being so huge (300,000 km/second), and hand-held GNSS devices cannot carry $100,000 maser clocks. Thus, you must use a 4th satellite to help solve for the 4th unknown: 3 for position, 1 for a clock reference for your receiver

There are a few more complications. You really need to use a reference ground station to get really good differential distance calculations - to do good back-corrections for the changing satellite orbits, the complex and varying atmosphere, snow cover, etc... However, during the Tohoku earthquake in early 2011, all of Japan jerked eastward, so geodesists couldn't see the whole shift with really great precision because their reference station also moved.

So how does this help volcanologists? As I said earlier, if two telemetered GNSS receivers are moving away from each other, and there is a volcano in between them (this is happening right now with Mauna Loa, the largest volcano on Earth), then you are being given a warning that something is coming.

In 1989 we didn't have such a warning before Redoubt volcano in Cook Inlet of Alaska erupted. A KLM Boeing 747 flew right into the ash cloud - and lost all four engines in rapid succession. I've got a recording of the captain's voice as she tries to guide her flight crew in Dutch and talk with flight control in Anchorage in English. Her voice rises steadily a full octave before she finally yelled "Anchorage we have lost all four engines, we are in a fall. We can use all the help you can offer." They managed to restart two of the engines, and made a rough landing at Anchorage International airport. No lives were lost - but the repairs to that Boeing 747 cost $80 million.

To put that in perspective, when I served as chief scientist for volcano hazards for the US Geological Survey, my entire science team budget was less than $20 million.

There was another interesting GNSS application that you will find fascinating - I sure did. When Mount St Helens erupted on 1 October, 2004, we had just a week of accelerating seismic racket on our network beforehand for a warning. The extrusion was first seen on October 12 - and by pure luck I got the first photo of the new "spine" from a helicopter orbiting the steaming and fractured Crater Glacier. The dacite extrusion - 700 degrees C at where it was coming up from the talus slope at its base - came out like a tube of squeezed gray toothpaste. It resembled the back of a whale, so that became its name: The Whale. It moved south through crumbling talus and ice until it hit the remaining south rim of the 1980 eruption. The geodesists wondered when it actually reached the wall - When Did The Whale Hit the Wall? A check of a GPS station on the other side, on the outside south slope of the volcano, answered the question. On November 17, 2004, that station suddenly started moving south. Was it an effect of snow on the antenna? No, because the only direction it moved was south - by about 10 cm. The entire crater wall was shoved southward by 4 inches.

I'll never forget the elation of scientists using GPS technology to answer a real question about an erupting volcano. But GNSS systems provide us more than just answers to our scientific curiosity.

In 2006 a sharp-eyed geodesist in Anchorage, Alaska, was routinely checking data from several GPS units installed on Augustine volcano in the middle of Cook Inlet, south of Anchorage. This had erupted in 1979 and nearly killed David Johnston, one of our brightest young geologists who was later killed during the 1980 lateral blast, the opening eruption salvo of Mount St Helens.

In August 2006 this geodesist noticed some differential movement apart - the first subtle inflation was starting - and notified the Scientist-in-Charge. A close checking and monitoring effort was triggered - and sure enough, the signal was real, showing above all the background noise - and it was continuing. Federal and State Emergency entities, along with the FAA, were put on notice. In Late December the first VT's started appearing on the seismometers. As they accelerated in frequency and amplitude, the USGS issued a warning: an eruption is imminent in hours or days. One day later, on January 16, 2007, Augustine erupted, and dusted Anchorage with ash. International flights were cancelled or re-routed for three days - but not a single aircraft was damaged, not a single life was lost.

Yeah! This stuff works!


25 January 2012

How do You Know if a Volcano is Going to Erupt?

As Ask-a-Geologist volunteers, we often get some really interesting questions. At least I call them interesting, anyway, because they open great doors to an interesting geology explanation. One such question follows.

How do you know if a volcano is going to erupt or not? Are volcanoes predictable?  Predictability is an important thing for humankind. If you are being shot at - by an  errant asteroid (like Tunguska, 1908), a hurricane, a tornado, an earthquake, a tsunami, or a volcano - there's some consolation if you can at least predict the event. A warning siren would be nice. This may give you enough time to collect the kids, the dog, the family photo albums, and Aunt Dottie's genealogy list - and beat it out of Dodge.

For the record, we can predict this much:

  • Asteroid impact: Something that would destroy a continent, up to 30 years' warning.
  • Asteroid impact: a "city buster" 30 to 50 meters in diameter, which could obliterate Washington, DC in seconds: hours of warning - if at all. These are very hard to detect because they are so small. They are so destructive because of the 25,000 km/hour speeds and phenomenal kinetic energy this translates into.
  • Hurricane: a week's warning that it is forming, moving towards you... and a day or two warning that you are about to get badly hammered.
  • Tornado: hours max, and perhaps as little as 5 minutes'  warning in the Midwest of the United States. And this is with the most advanced Doppler Radar network on the planet.
  • Earthquake: no warning - they are still unpredictable. You can at least know if you are in an earthquake hazard zone, and in some parts of California, you can get an actual percentage likelihood that you will get hammered in the next 30 years.
  • Tsunami: if you are in Hawai'i and the tsunami is triggered in Chile, then up to 9 hours warning. If you are in Indonesia and the tsunami is triggered by your personal subduction fault, then you get less than 20 minutes warning. Then it becomes: how fast can you run, and how far is it to the nearest high-point? The mayor of Minamisanriku, Japan, had less time than this to get to the communications tower on top of the town hall after the great Tohoku earthquake hit. Wave after wave swept over and gutted the multi-story, steel-framed building, killing all still inside - but he survived with scars on his hands from hanging onto the steel tower. Most people growing up around the Pacific Rim or Indonesian Archipelago are taught this warning from earliest childhood: if the ground shakes, run to high ground as fast as you can. 
  • Volcanoes: As much as 6 - 10 months' warning before an eruption - but many of the restive events that trigger warnings end up with a "fizzle" - it goes quiet again. For this reason, the warnings are graded, advanced in stages: Yellow, Orange, Red. If there is going to be a violent eruption, then deformation, gas, and seismic monitoring networks (if installed beforehand) can warn you with "days to weeks", and then as the signals ramp up, with "hours to days" timing, but the magnitude of the eruption is still very difficult to estimate - and with that, its consequences. The destruction of Armero, Colombia, happened about 45 minutes after the first phone-call from up the canyon towards Nevado del Ruiz volcano saying that something "sounding like 10 diesel locomotives" was passing and moving in the direction of Armero. The mayor told people not to worry. The Catholic Bishop told people to go to the cathedral for protection. But NO one can outrun a Lahar. Only the foundations of the cathedral survive. There is an elaborate acoustic flow monitor system down-stream and west of Mount Rainier in Washington State. School children routinely have evacuation drills - they must run a mile to a bridge over a busy highway to get to higher ground. They have just 45 minutes from hearing the first automated siren.


How do you know if a volcano is extinct or going to erupt again?
Rylee from Mrs. King’s class.

The 169 volcanoes in the United States and its territories are classified by USGS volcanologists as Very High Threat, High Threat, Moderate Threat, Low Threat, and Very Low Threat. There are 18 volcanoes classified as Very High Threat.

These categories were developed after many years of careful mapping, dating, and analysis. They are based on a number of criteria, including the history of the volcano - such as how recently did it erupt? How many times has it erupted in the past 10,000 years? How far out do old eruptive products reach? How many human beings are now exposed to danger in these areas if there is another eruption? Each volcano is sort of like people or bears: they each have their own unique "personalities". Some, like Kilauea volcano in Hawai'i are mostly effusive: they tend to flow lava with little explosive behavior. Others have a long and violent eruptive history, like Yellowstone. 640,000 years ago Yellowstone erupted and laid out a blanket of ash - that ash is over 20 meters (66 feet) thick hear Colorado Springs, CO - over 1,300 kilometers (800 miles) away from the volcano! I have personally pulled a camel's tooth out of the base of that off-white-colored deposit (called the Pearlette Ash Formation) where it had smothered all living things under it.

NO one can outrun a 20-meter-thick blanket of ash that reaches out and covers a continent.

A key point here is that the volcanoes and their eruption products must be age-dated. They must also be carefully mapped to see how far the eruptions reached in the past. It's pretty safe to say that if a volcano hasn't erupted in 10,000 years it's PROBABLY dormant. However, Mount St Helens last erupted in 2004-2006, and before that in 1980-1986. Kilauea volcano in Hawaii has been erupting continuously since 1982, so it's pretty safe to say that these two are DEFINITELY going to erupt again. Those are the two extremes, but a volcano called Four Peaks in Alaska erupted in 2006 after being dormant for many thousands of years... so even apparently dormant volcanoes can surprise us with little or warning - and the warning comes only if they are instrumented. Would YOU spent ~$100,000 to instrument a volcano that last erupted perhaps 10,000 years ago? Something in between Mount St Helens and Four Peaks would be Mt. Edgecumbe near Sitka, Alaska. It hasn't erupted in at least 5,000 years, so it's hard to say if it's extinct or not.

What have we done to protect the American people - and to prevent a volcanic eruption from becoming a volcanic crisis? We have put seismometers and telemetered GPS instruments on almost all of the most dangerous volcanoes. Cleveland volcano in the remote Aleutian Chain (which erupts frequently) is an exception. It has not been instrumented yet because we don't have enough funding to do so - but we watch it daily from satellites. Also, there are no towns nearby, so it was given a relatively low priority. Dangerous volcanoes close to human population centers are all instrumented in some way or another as of this year (2011). This way we will ALMOST always be able to provide some warning, even if only a few days.

When Mount St Helens erupted on October 1, 2004, we had about a week's warning from suddenly increasing micro-earthquake activity. As far as our records show, it was dead silent the day before the first volcano-tectonic earthquakes started (I was standing on the 1980-86 Dome just two months earlier). As a result, the Johnston Ridge Observatory five miles away was evacuated in time and no one was hurt. JRO was named for David Johnston, one of our PhD volcanologists who was killed by the 1980 eruption - when it erupted catastrophically while he was monitoring it. That won't happen again as long as we can keep doing our job protecting the American people.

We are, after all, the United States Geological Survey. Without funding, however, even the most dedicated scientists on the planet are helpless.


24 January 2012

CME Events - How They Affect Your Life

Let's switch briefly to the interface between Earth and Space. Specifically, the probably-novel-for-most-people idea of "space weather."

Two days ago, something not unknown, but not commonplace either, happened on the surface of the Sun. Something called a Coronal Mass Ejection (CME) event took place. These are complex phenomena, still rather poorly understood, but involve the Sun's powerful magnetic field and the huge energy being generated by hydrogen fusion. The result is a huge ball of ionized material shooting off into space. This particular one was aimed at Earth and Mars. It is the space equivalent of a Category 5 hurricane.

The Solar Dynamics Observatory satellites first picked up this solar flare erupting from the sun on January 22, 2012. Almost immediately there was a large burst of radiation, higher levels than have been measured since 2005. The highly energetic ionized particles erupted from the sun as part of this CME traveled well above the speed limit - at roughly 2,200 kilometers per second - and hit Earth on January 24 around 10am US Eastern Time.

Why would you possibly care?

Because there are some amazing side effects from one of these events that can directly affect you.

The huge ion bomb, when it strikes Earth's protective magnetic field, is partially deflected towards the poles. Auroras sometimes reach the mid-continental United States during these events. They set up huge telluric currents in the Earth's surface - these are short-circuited by the oceans, but the shallow continental crust is resistive to varying degrees. Basic physics says that if current is flowing, there must be a voltage difference causing it. Electrical power grids generally transmit electrical energy at very high voltages (in the 100,000 range and higher) in three "phases" - in other words, the power on each of the three lines held up by transmission towers is at 60 Hz (in North America; 50 Hz in Europe and the British Commonwealth), and each line's alternating signal is out of phase from the other two by 120 degrees. Think of a wheel turning through 360 degrees for each cycle, then each cycle will peak at 4 o'clock, 8 o'clock, and 12 o'clock in sequence.

But the power transmission system is never perfectly insulated - electrical charge inevitably "leaks", and for this reason each tower and power substation has a fourth electrical line called a "ground" to take care of that leakage. This is the fat round opening on the bottom of most electrical sockets. In our homes, we only "see" two phases and a ground after the voltage is stepped down by transformers to 220 volts and 110 volts. The assumption underlying all grounds is that the Earth is all at the same base voltage - the same reference point. However, if there is a large telluric current (this word means an electrical current flowing through the ground), then the voltage of each tower's "ground" and each substation's "ground" is going to be different. Inevitably something will become unstable - a ground-loop is set up - and an excessive voltage at some point is going to lead to an "arcing" or jump of current to someplace where it shouldn't be going. It's not unusual for transformers the size of a car or an SUV to explode violently when this happens. This is commonly seen in video of a city skyline as a tornado approaches: the transformers "pop" with a flash, one by one.

How could this affect you? The Canadian provinces of Quebec and Ontario experienced a huge and long-lasting blackout due to a CME event back in 2005. In mid-winter, if electricity is your source of heat, this could be a life-threatening event. If you survive, your water pipes will freeze and burst, and you will have heck to pay when it warms up again.

What else happens? The huge telluric currents overwhelm the carefully-designed electrical corrosion protection on oil and gas pipelines. Most readers are aware of the fiery inferno that happened in San Bruno, California two years ago when a corroding pipeline leaked natural gas that somehow ignited. Whole neighborhoods were consumed in a raging fire that took hours to subdue.

Death by fire, death by flood.

Do you use GPS in your car? You can expect that the GPS satellites, which are designed to withstand this sort of event up to a point, might malfunction. Some satellites can go off-line for awhile or even permanently if the damage is too severe. I hope you are aware that any commercial airliner you fly in depends on GPS. Same holds for weather and communication satellites. American Idol? You may miss an episode, but that may not necessarily be a bad thing...

Death by boredom. Are you starting to feel a pinch now?

Large and turbulent changes in the ionosphere during geomagnetic storms triggered by these CME events interfere with high-frequency radio communications... just what your pilot is using to communicate with the control tower. As of today (24 January) Delta Airlines has started re-routing pole-crossing international flights away from the poles, where the dipolar nature of the Earth's magnetic field allows these huge ion-storms to penetrate deeply into our Earth's protective atmosphere. This is why the auroras will be so bright and far-reaching tonight.

What about our astronauts in the International Space Station? They have a protective "safe room" to retreat to, but this is a partial mitigation at best. As I write this, all six astronauts in the ISS are being severely irradiated. The highly energetic particles during solar events like this cause temporary operational anomalies, damage critical electronics, degrade solar arrays, and blind optical systems such as imagers and star trackers. The latter are necessary to keep the solar arrays correctly oriented, and to keep one side of the ISS from broiling while the other side freezes.

For the vast majority of us, there will likely be no manifestation of anything unusual. But then, when Hurricanes Andrew (1992), Isabel (2003), Katrina (2005) and Felix (2007) struck the eastern United States, most of the rest of us felt nothing... until the forced immigrants began to arrive. When fire engulfs vast neighborhoods in southern California, and floods destroy homes in the Dakotas, and Tornadoes destroy Joplin, Missouri yet again... what are your obligations? If it's not already obvious, I can suggest several books to read...


22 January 2012

Lava Tubes

If you've never walked through a lava-tube, you are in for a Bucket List experience. There are many in Hawai'i (of course), but there are others in the Pacific Cascades of America and even in Idaho. I have a permanent dent in my forehead, a trophy obtained while climbing through Upper Ape Cave, on the south side of Mount St Helens, in Washington, State.

WEAR HELMETS. Do as I say, not as I did.


I’m writing a sci‐fi novel and would like to know what kind of rock makes up a lava tube? As far as I can tell with my feeble mind, it’s basaltic rock, is this right? I’ve tried searching the internet and can’t find a definite answer. Can you help me?
Thanks ahead, J.R.M.

A: Yep, you're right. Higher-silica lava like rhyolite and dacite don't make tubes - but crusty domes instead. It helps if you understand how lava tubes are formed. I've walked through lava-tubes in Hawai'i and Mount St Helens, and you can see that everything - even the "bathtub rings", is basalt. At Pu'u O'o, part of the East Rift Zone of Kilauea, a friend used a police speed-gun to clock the yellow-glowing basalt magma at 40 kph (25 miles per hour) as it shot through the active tube past a skylight. As lava pours down a slope, it finds the natural drainages (or makes its own) and follows them. The lava on the edges of these flowing, yellow-red rivers starts to cool, and then starts to crust over. When the cover is complete, you have a lava-tube that is now insulated from the (relatively) cold air, and liquid lava can now maintain its heat and travel farther. After the the hydraulic pressure stops from above, the tube drains, empties out, and cools off. The inside isn't perfectly smooth, either; there are lots of irregularities, and these are fascinating. They give subtle insights on how magma flows - and "paints" and drips and leaves "bathtub rings" in the walls of the tube.

The roof can be up to 7 meters tall, and boulders and cold lava in the hot lava path get incorporated into the flow or partially dam it. There are parts of the roof that break off - exposing skylights - and these slabs travel down as solid chunks (at least for awhile) in the lava. I have a permanent dent in my right forehead from making a right turn into one of these lava "blades" hanging out of a roof in the Ape's Cave lava tube at Mount St Helens. In my office I have a USGS cap soaked in dried blood from this experience: sort of a trophy, and a reminder to be more careful.


14 January 2012

Higgs and the Need for New Physics

WARNING: This entry has a LOT of background stuff in order to make the story a complete one. If you are patient, you will learn a lot... but dinner will be late.

The Higgs boson is sometimes called the God Particle (said with a deep, sonorous voice). That title irritates most physicists, who view it as a classic example of media hyperbole. The Higgs is the theoretical particle manifestation of the theoretical Higgs Field, which theoretically gives elementary particles mass. Theoretically, anyway. The graviton is something different, and like the Higgs has also never been seen, but is proposed by high-energy physicists to be the gauge boson - the force carrier - that conveys the force of the gravity field on all that mass.

You can quit here, but if you continue on you will be able to answer all your friends' questions about the Whichness of the Why. 

Like... why is the Higgs being talked about so much in the media? Among other things, it has led to the multi-billion-dollar funding and construction of the largest and most technically sophisticated machine in the history of humankind: the Large Hadron Collider. The LHC is the source of worship of at least one atheist Harvard physics professor. It is a giant underground ring full of monster magnets, 27 kilometers (17 miles) in diameter, straddling the Swiss-French frontier.

But first, what's a hadron, anyway? A hadron is a heavy particle, made up of three quarks, the fundamental building blocks of the universe. A proton and a neutron are perhaps the best examples of a hadron. It's sort of like saying "siblings" instead of "brother," or "sister."

Uhhhh.  Then what is a quark? For more than 30 years, the particle zoo called elementary particle physics has been more or less, well sort of, explained by something called the Standard Model. Let's see if this helps: twist electromagnetism with the Strong (nuclear) Force and tweak the Weak (nuclear) Force and you get... a lot of strangely-named particles and six different characteristics including mass, spin, "up-ness" and flavor. Among other things, gauge bosons are particles that carry or transmit the different forces between particles like hadrons.

Except mass and gravity. Since the 1960's, some of the sharpest minds on the planet have tried - and failed - to bring mass and gravity into the Standard Model. They wanted a Grand Unified Theory, or GUT for short. A Theory of Everything. String Theory is just one of many attempts at a GUT, and because it is mathematically elegant, it has seduced much of the physics community into its clutches. Just a few problems: String Theory is not testable, not falsifiable - so it's not even remotely scientific. It also has 10 to the 500th power (10^500) possible solutions; I could use it to predict the existence of Extreme Moosetracks Ice Cream. After the fact, of course.

I once took a graduate physics course called Group Theory and Quantum Mechanics; the idea was to predict still-unseen particles by building a sort of association matrix. An incomplete symmetry - an empty box in the matrix - might mean some particle physicists haven't seen yet. There were a lot of different particles in the high-energy zoo even at that time, and this approach eventually became Super Symmetry.

However, even with Super Symmetry no one has ever been able to figure out how to fit gravity and mass into all this. You know: the force and physical property that order the entire macro universe, cause galaxies to spin, bend light... 

To explain the next part, we need to go back a century in history. Particle physics really got its start with Ernest Rutherford in 1911: he started out by stripping electrons off hydrogen atoms - leaving naked protons - and shooting a stream of these protons at a patch of gold foil. The first thing he noticed was that the protons were only very rarely deflected backwards. Mostly the beam passed through the foil with some electromagnetic repulsive bending. So: atoms and matter were mostly empty space. If one increases the energy of the beam, sometime protons would hit actual nuclei and stick - and new elements came into being, along with exotic particle fireworks in the original cloud chambers. The alchemist dream was finally realized: elements were converted to something else. The exotic particles that would go flying off would often last for just tiny fractions of a second and then break down into yet something else.

You can rivet the attention of a lot of over-sized children for a long time with a toy like this. But a tiny fraction of the great early experimental physics discoveries led to something with real-world consequences: a single bomb that could destroy an entire city.

Perhaps a residual benefit of having invented the nuclear bomb is that physicists can still wangle billions of dollars out of entire national governments to build bigger and better... proton smashers. Keeping in mind the basic Einstein equation of E=mc2 that equates matter with energy, the thinking goes like this: a bigger cyclotron, a bigger synchrotron, a bigger linear collider, a bigger Tevatron... and you can generate more energy when you shoot particles at each other. More energy means heavier particles pop up, however momentarily, in collisions. That generally means more new things, particles that hadn't been seen before.

Some more background: Let's talk a bit about electron-volts. This is the amount of energy gained by an electron moved across an electric potential difference of one volt. Technically, it's not even an SI unit, but it IS measurable, and equivalent to about 1.6 x 10^(-19) Joules. About 1 Quintillionth of a fly push-up. BTW: that ^(- symbolism means you move the decimal place 19 digits to the LEFT - in other words, you put a lot of 0's between the decimal and in front of that 1. That's pretty tiny; to put it in perspective, the power to run a 100 watt light bulb for one second is about 6 x 10^(+20) eV. That's six times ten to the twentieth power: moving the decimal point all the way back - and multiplying by another 40 besides.

But remember that matter and energy are interchangeable by that E=mc2 equation. In that case, the entire resting mass of the electron is equal to about half a million electron-volts, or 0.5 MeV, if converted to pure energy. The proton is heavier - more mass - so it's mass converted to pure energy is slightly under a giga-electron-volt, or GeV. The neutron is slightly heavier than the proton, so it comes out as slightly more than 1 GeV... or 1,008 MeV to be four-decimal-places precise. Maybe you see where this is headed by now.

As an aside, a photon of visible light has about 1.6 to 3.4 electron-volts, depending on its wavelength. And yes, if that photon has enough energy and hits something like a tiny electron, it will likely knock it around - even kick it out of its rest-state atomic shell. This is called ionization: there is a free electron floating around somewhere, and an atom or a molecule left with an excess of one positive charge. When the electron drops back down again to its rest state, it re-emits a photon of a precise wavelength that can be correlated with that particular atom. If you do it right, you can use this behavior to chemically analyze a molecule for its constituent atoms.

But heck: it all keeps coming back to gravity. It just won't fit in. Physicists have thought for at least TWO generations that gravity must just be another force - hey, it pulls masses together sort of like electromagnetism pulls two charged objects to each other (or pushes like charges away: SAYYYY... can there be an anti-gravity?). But where is the particle exchange that makes the force work between two masses? The gauge boson, the force carrier? For that matter, what gives rise to mass in the first place?

The Higgs would solve a big chunk of this problem... if it exists.

If you notice the very tiny numbers earlier, and then start thinking about the masses of galaxies with 100,000,000,000 suns in them... well, there is a lot out there that we know virtually nothing about. Intuitively, you might think that the Higgs boson must be something pretty bohonkin' huge. One rather mundane reason for this supposition is that it hasn't been found yet using smaller 'tron machines. So if it exists at all, it has to be out of reach of everything up until now except the LHC, right? That means a boson with a rather huge mass.

As I write this, no one has yet detected the Higgs boson. The science teams working at the LHC have been giving broad hints for a long time that they are seeing some "statistical" things that hint at its existence. However, that is a very, very long way from anything that anyone would call proof - and has a lot more to do with making sure that European governments don't suddenly pull all their LHC funding as the Euro goes down the tubes. These broad hints to the media are sort of like: your cousin knows a guy who heard from a neighbor that... Some theoretical studies have suggested that the Higgs might be in the energy range of 115 - 130 GeV. Not more, not less. For reference, 125 GeV is about 133 proton masses.

Hey, wait... the particle that gives rise to "mass" is ~133 times heavier than a proton?!?? 

If that sounds illogical, then give yourself three stars. And that isn't even HALF the problem.


Finally, we arrive at the recent history: Physicists gathered all the goodwill they could find, world-wide, and pooled enough tax-payer money (the U.S. Congress politely but firmly declined) to build the Large Hadron Collider at the CERN facility on the Switzerland-France border. This monster first came online in 2010. A lot of hope, and at least one atheist's faith, is pinned on that huge, spectacular machine.

History is being ignored again of course: every time something bigger is built to answer a question, new things pop up that need a bigger machine to answer... ad infinitem. Some people consider this an old con-game. In fact, the US Congress put a foot down in 1993, and cancelled the half-built American Superconducting Super Collider in Texas. It was a Texas-politician-boon-doggle with massive and growing cost over-runs, so this call was a no-brainer decision. This infuriated particle physicists, of course - but gave hope to most of the rest of the American science community that all their research funding wouldn't be gobbled up by a single gigantic foo-ball project.

So that's the story, right? I wish. 

An article in a recent issue of Nature, by physicist John Ellis of the UK, titled "The Need for New Physics", makes these points:

  • Whether or not the Higgs exists, there must be physics beyond the Standard Model: 
  • If the Higgs weighs in at less than 130 GeV, then all the calculations for the lowest energy state of the universe are totally wrong, totally unlike our current universe. A "mass-giving" particle that weighs 140 times the mass of a proton, really did seem a bit fishy, didn't it?
  • What if the LHC results do NOT confirm a Higgs boson? Well, we could try to look at a particle heavier than 600 GeV... but that would take something bigger and far more expensive than the multi-billion-dollar LHC. We're talking about costs up in the range of another Iraq War (roughly calculated at $1 Trillion). But it's worse than even that: a heavier Higgs would require a host of new particles and particle interactions... and the interactions in the Standard Model become infinite at higher energies. The universe blows up. Since I'm writing this right now, that just can't be true.

Ellis has a number of even more arcane arguments, but the rather blunt bottom line is this:

Physicists don't know jack. We may think we're real smart, but we really know almost nothing.


If you got this far, you know more than The 99%You deserve five gold stars on your forehead. And my thumb aches from teaching Jujitsu yesterday and today and hitting the space bar one too many times.


05 January 2012

Why Mars Lost its Air

Last year NASA approved a new orbiting satellite mission to Mars, called Mars Atmosphere and Volatile Evolution, or MAVEN for short. There is growing evidence that Mars once had water on its surface - and water cannot exist if there is no atmosphere, because it would evaporate quickly. There are unmistakable rivulet marks on rocky Martian slopes, evidence of sedimentary layering in giant Martian basins, minerals detected by various means that can only form in the presence of water - all discovered by orbiters and semi-automated rovers like Sojourner, Spirit, and Opportunity.

If Mars once had an atmosphere, then where did it go? More important: WHY did it go? Planetary scientists speculate that Mars lost its atmosphere when it lost its magnetic field.


Most people have no idea how important our Earth's magnetic field is. If you've seen videos of the Northern Lights, you have seen our planet's magnetic field at work: it traps the huge CME (Coronal Mass Ejection) blasts that come out of the Sun during the more active times of the Solar Sunspot cycle. The magnetic field bends these highly energetic charged solar particles until they come into the atmosphere near the magnetic poles.Those beautiful shimmering curtains of light you see are highly energetic particles literally tearing up the upper atmosphere.

Dr. Robert Brown was my adviser at Berkeley when I was a young student there. He was a great guy, and never hesitated to stop whatever he was doing to answer the physics questions I always had. His own experiments as a physicist concerned sending balloons into the troposphere to collect some of these energetic solar particles. They were so energetic, he told me, that he had actually captured iron nuclei with so much energy that all the electrons had been stripped off! That sort of stuff does terrible things to soft tissue - it's a burn that goes far beyond a simple sunburn. It is hard ionic radiation, and it kills.

Without our planet's magnetic field, the latitudes humans live at would be constantly blasted by CME's. Without the atmosphere, those deadly high-energy particles would blast right down to the ground, killing all life, sterilizing the planet's surface like the Moon.

So how are the magnetic field and the atmosphere related? If the magnetic field is turned off, the CME's would not be deflected, but would scour our atmosphere unimpeded and blast it off the face of the planet into interstellar space, instead of just nibbling at the atmosphere around the poles. Point a blow-torch at something and what happens? You've got the picture. That's what scientists believe happened to Mars sometimes in its ancient past: as its smaller core cooled, its magnetic field died, and the solar wind and CME's stripped the atmosphere away.

Let's go a little deeper - literally. If the interior of the planet cooled, convective movement of the hot liquid material inside would slow and stop - and with it, the magnetic field created by that conductive fluid dynamo. Interestingly, our Earth's magnetic field might or might not have something to do with radiation. Heavy radioactive minerals, that sank to the mantle and core of the Earth during planetary formation, will still decay. The heat has to go somewhere, and geomagnetic specialists believe this sets up convection like what you see in your kitchen: heat rises because hotter materials expand and have lower density.

Much if not most of the original heat in the inner Earth probably comes from gravitational collapse during the formation of the primordial Earth, however. There is also compositional convection thought to be going on in the core itself as it cools: metallic iron plates out onto the solid mostly-iron inner core, leaving lighter materials to float up towards the mantle. The Earth's magnetic field is a complex thing made up of a dipolar field and a secular field: a big, steady north-south magnetic dipole, and something added on top of this that "drifts" the north magnetic pole westward about 0.2 degrees each year.

An interesting aside from my days as a high-pressure solid-state physicist: rocks that are resistive at room temperature generally become highly conductive and plastic when heated and pressurized (even diamond), and the moving conductor that results is what generates the Earth's magnetic dynamo.

Perhaps we can also look farther out. Gene Shoemaker, my great friend and the brilliant father of Astrogeology, felt very strongly that life exists on Earth also in large part because of Jupiter. Yes, Jupiter. As the largest planet by far, it has a huge gravity field - as proven by the impact of Comet Shoemaker-Levy 9 in 1994. The dark blots that SL9 caused in Jupiter's banded atmosphere were as large as the planet Earth! Jupiter and the Sun drag comets coming in from the Oort Cloud to themselves, and away from the inner worlds - the Sun by itself would just draw more bombardment to the inner solar system if it was by itself. Gene actually thought that the Drake Equation - which is an estimate of the probability of life outside of the Solar System - should be modified to include a factor he called Fj - the Jupiter factor. Like a big brother on the playground, Jupiter protects the Earth from the Oort bullies.

So we are alive because of heat, perhaps some of it due to radioactive decay - and a Big Brother planet orbiting outside of the inner solar system.