Swarming Quakes: The End is Nigh

December 30, 2008

Some strange fowl flock to swarming earthquakes. Among the odd birds that have flown into my virtual windshield today are folks with theories about the ongoing unusual swarm of small earthquakes at Yellowstone National Park. Everything from an inexplicable connection between the swarm and changes in Earth's magnetic field to warnings that the swarm is heralding a titanic eruption and the end of the world. 

I spoke briefly this morning with the University of Utah's Robert Smith, the geophysicist who literally wrote the book on Yellowstone. He's also been pulling a series of all-nighters since the quake swarm began a few days ago. Smith says he gets "a whole lot of email from a wide range of perspectives." But Smith is being extremely polite here. Fact is, some of these perspectives fall under the heading "wacko." Forgive me for being less polite.

The most likely cause of the quake swarm -- though it remains to be shown for certain -- is that a 20-year trend in the rising ground in the area near the quake swarm is about to reverse. It's all the product of all the residual heat in the crust from the last genuinely giant eruption there about 640,000 years ago. The last time they had a similar swarm, says Smith, is when another portion of the caldera had been rising, then began to subside back in 1985. A couple of other things to clear from the air:   

Q: Is this connected to some global changes in the Earth?

A: "We can say that it's a very localized effect," Smith told me. That said, there have been some interesting cases where earthquakes in Yellowstone have been triggered by distant larger quakes. It's almost as if Yellowstone is extra sensitive and sometimes has a hair-trigger when it comes to shooting off small earthquakes. There's not, however, any scientific reason to connect this particular swarm of quakes to anything happening globally.

Q: Does this herald a giant eruption?

A: Nope. Despite the fact that we have never seen the run-up to a caldera (a.k.a. "Supervolcanic") eruption in historic times, we can extrapolate from what we know about smaller volcanoes that have been observed before and during eruptions. These tell us that no reason to believe this swarm of mostly very small quakes is a precursor to a big blowout, Smith explained. For lots more about this and other info about the science of Yellowstone works, check out this Yellowstone series I wrote a couple of summers back.

Big Quakes on Camera

December 05, 2008

What's a 8.4 magnitude earthquake feel like? Hard to convey over the Internet, but we have some exclusive footage here of a duo of  8.4 and 7.9 quakes as they rumbled through the island of Siberut, off the coast of Sumatra on Sept. 12, 2007. This is near a section of the same gigantic, super-active fault that gave is the Great Indian Ocean Tsunami and its monster megathrust quake. It's also a place that might be ready to unleash another such monster. The videos were taken by John Galetzka, a field geodesist, who was deploying GPS stations at the time these earthquakes struck, and supplied to Discovery Channel by Caltech seismologist Jean Philippe Avouac.

In the first part shown here Galetzka gives us an idea how the locals responded to the heavy shaking. People raced for the highest ground they could find -- a very wise decision even if no tsunami came. In places like Sumatra, where tsunamis can reach land just minutes after a quake, there is no better alarm system than a quake itself. Feel a jolt? Bolt!

Next we see how Galetzka is so caught up in recording the second 7.9 quake for science that he momentarily forgets about the danger of tsunamis. When he finds himself alone on the beach, self preservation kicks in and he follows the locals and heads for high ground. He even from higher and probably more stable ground (perhaps the reason he thought the later and lesser quake is more powerful -- since it was felt on a sandy beach).

Finally we see through Galetzka's eyes as he records the 8.4 quake.  Always the scientist, Galetzka tries to estimate the periods of the seismic waves and even lies down on the ground to get a better feel as the shaking subsides. In this video you can also see Galetzka's GPS equipment, in particular the solar panels in the background. The GPS stations he deployed help geoscientists study how the crust is being contorted in this very active part of the planet (for more on this see this slideshow).

Earthquake: The Sequel

November 15, 2008

Here's a waaaaay scarier earthquake simulation than the one below (if you can, for a moment, look past my poor quality video copy). It shows the shaking intensity ramping up as the seismic waves roll west across the Los Angeles basin and into the Watts area. I've never seen a better representation of how the solid ground moves like the sea with seismic waves. Of course, these simulated waves are here exaggerated 1,000 times for the sake of making them visible in this simulation. If the real ground rolled like this we'd build boats instead of buildings.

The immensely superior original simulation, along with many others from other vantage points in Southern California are available in low and high res, and even HD resolution at this US Geological Survey website. Please forgive my hacked copy of the USGS QT movie. I lack QT Pro to save the orginal, so I used my webcam to shoot a low res copy. This ought to be enough to whet your appetite, however.

Earthquake: The Movie

November 09, 2008

Here's a fun, if a little scary, movie showing a simulated 7.8 earthquake propagating up the San Andreas fault in Southern California. The quake starts at Salton Sea and then later saturates California's most populated area with powerful ground motions. The time counter in lower left corner counts the seconds that elapse after the earthquake starts. For the much higher res original movie and more info visit here.

God in the Quake

July 30, 2008

I'm way out here in Maryland this week, far from my native land of California and my home in New Mexico, and what's everyone talking about? Yesterday's quake in California, of course. By a native's measure, anything under a 6.0 magnitude shaker is considered minor. It's really more of a kindly reminder from

God (or Chance or whichever universal force you prefer) that we are not really in control and need to check our hubris at the door (as well as check the straps holding the water heater to the wall). So why all the media hoopla? Simple: We're in the middle of the annual summer news drought. I was joking about this last night with a colleague and even suggested that this is the time of year when something totally inconsequential like a three-headed calf has no trouble making headlines. About 10 minutes later, I was talking with Discovery News producer Sarah Goforth and she mentioned an AP story now making the rounds about a six-legged deer. Bingo! When there is little other news people care about, it's time for the freak show to begin. No matter how far we get from Nature in our daily lives, the six-legged deer or less than six-magnitude quake will always have it's place in our hearts. God bless'em.

Quake Saves the Chinese Cousin?

June 02, 2008

An aspect of the Sichuan Earthquake tragedy that's starting to make headlines is the plight of parents who lost their only children to the collapsing buildings. These folks are really feeling the sting of China's one-child policy. Some are hoping to at least adopt earthquake orphans and cobble together new families in the wake of the disaster -- growing something new and hopeful out of their shared losses.

Some people are suggesting that the loss of so many children could be the beginning of the end of the one-child policy. As a father of two, I have to admit that I like the sound of that. On the other hand, it's worrisome to envision. I seriously doubt our planet could support a much larger Chinese version of America's mid-20th century Baby Boom.
What really interests me about this one-child policy, however, is what it does to cousins. Think about it. Without brothers and sisters, there can be no nephews and nieces either. After a few generations of single-child families, first cousins will no longer exist. It makes me wonder if cousins are already becoming more rare in China today.

The loss of cousins just saddens me. I have something like 34 first cousins of my own (if I remember the count my Dad and brother Dan made a few years back). So I feel sentimental about cousins. I have many fond memories of cousins. Life without them would seem starker, more lonesome and isolated. Yes, I know, I know. This is hopeless sentimentalism. The real question is: Can the world handle more cousins -- of any nationality? I'm sure I just don't know.

Cousins tree chart from Wikimedia Commons, by Matt Leidholm

Closer Look at Sichuan

June 01, 2008

Real quick: There's already some science coming out of the 8.0 magnitude earthquake in China. This map showing the rupture zone and some seismic data comes from a presentation slide at the American Geophysical Union meeting underway in Ft. Lauderdale, Florida. The following is the text for the slide:

 

"12/5/2008 Sichuan Mw 8 earthquake, 3D modeled (0.5Hz) velocities (m/s) synthetics (Chavez et al, in preparation). Fatalities: >80,000, $ Looses:10Billion US dollars (Modified from Lab. Geologie, ENS, 2008)."

Chavez is the author. They have also created a movie of the ground motion that I'm still trying to run. Gotta get the right unzipping software.

You don't need to be a seismologist to get something from this picture. For instance, notice that the time of the blip that signals the quakes arrive later and later at stations more distant from the epicenter. Then there is the topography: The near-linear fault where the basin meets the mountains all along the rupture zone.

Why Sichuan Shakes

May 27, 2008

One of the enduring myths about earthquakes is that they are random events, occurring anywhere and at the whim of an angry god, lesser gods or perhaps underworld demons. It's a logical enough way to look at it when you lack any other explanation. I use a similar idea to calm my four-year-old son about thunder ("It's just that thunder giant up there hammering the tops of the clouds, shaking all the rain and hail loose. Nothing to worry about.")

Luckily, modern geoscience has taught us that there is no need to sacrifice virgins to volcanoes. Earthquakes can happen anywhere, but they are certainly more common in some settings, and in these places they usually leave plenty of evidence of their frequency. In China's Sichuan Basin, for instance, there was a study just last year of the landscape there that identified plenty of signs of previous major earthquakes.

Why there? It turns out that Sichuan Basin is the side yard of the same collision zone that created the Himalaya Range -- where the Indian and Eurasian tectonic plates smashed together and raised the Tibetan Plateau about three miles (5 km), without either plate saying "uncle." (See it on the right side of the tectonic velocities map, from the webpage of Peter Molnar). In other words, tectonically it's a real happ'ning place. You dig? The recent deadly earthquake happened beneath the Dragon's Gate Mountains, which are steeper than the Himalayas because of a lot of recent -- and usually seismogenic -- uplift. In such a place there's a worldwide geological truth that rises to the surface more often: That civilizations survive at the whim of geological forces.

Quake makes lake

May 20, 2008

The NASA's Earth Observatory just posted this amazing series of satellite images of a river that has been turned into a lake by the recent earthquake in China. Here's some of their text:

"Within days of the magnitude 7.9 earthquake that shook China’s Sichuan Basin, floods became a real hazard. The earthquake and its aftershocks sent earth and rock tumbling down mountains into rivers, creating natural dams behind which lakes quickly built up. As of May 19, 2008, 21 lakes had formed throughout the basin, said China Daily. This series of images, captured by Taiwan’s Formosat-2 satellite, shows the formation of one such lake (Yansai Lake) in Beichuan County, one of the most severely affect quake regions.

"Acquired on May 14, 2006, the top image shows the region under normal spring-time conditions. Two tiny villages flank the river, the man-made surfaces regularly shaped and bright. The towns are connected by light-colored roads, which line the river on both sides and merge at a bridge where the river narrows on the right.

On May 15, 2008, three days after the initial earthquake, both the bridge and the roads it connected have disappeared under murky water. Some sections of the villages remain above the waterline, as do portions of the roads leading to the villages. The tops of trees, perhaps on slightly higher ground, form tiny islands near the shores of the growing lake...."

China's Earthquake

May 14, 2008

The devastation in Sichuan is, again, a reminder of the old seismological truism: Earthquakes don't kill people. Buildings kill people.

Good earthquake engineering and strict building codes are the reasons so few people die in earthquakes in California and Japan. No earthquake engineering and/or poor enforcement of codes is the reason lots of people die in China, Turkey and elsewhere. Unfortunately humans get complacent -- even those residing along the San Andreas Fault. When years go by without a major quake, the political will to spend more money to make safer buildings gets diluted. One of the things I always like about feeling an earthquake is how it reminds me, to the very core of by being, that despite our very significant effects on this planet,  we humans are still not in charge.