Friday, May 26, 2006


Greetings from Japan

I've been in Japan this past week attending a geologic workshop. I'm sorry for the delay in posting. Once I get over my jet lag I'll resume posting.

The picture is a view of Mt Fuji from the plane I took here. Unfortunately that's as close as I got to it.

Friday, May 19, 2006


Tsunami in the Pacific Northwest

Someone in the Pacific Northwest must be planning a Gay Pride parade:

Pat Robertson: Tsunami may strike Pacific Northwest

"If I heard the Lord right about 2006, the coasts of America will be lashed by storms," Robertson said May 8. On Wednesday, he added, "There well may be something as bad as a tsunami in the Pacific Northwest."

Thursday, May 18, 2006


The Other 50%

I just returned from beautiful Gunnison, Colorado, where the Rocky Mountain section of GSA is holding its annual meeting. I attended a talk in the Springs and Groundwater session by Laura Crossey from the U. of New Mexico. She spoke about Carbon Dioxide degassing from springs in the Colorado Plateau area. While not the major thrust of her talk, Dr. Crossey pointed out that commonly accepted models of natural CO2 emissions estimate that on the order of 1012 moles of CO2 are released each year along the mid-ocean ridges (the so-called Black Smokers) and an additional 1012 moles of CO2 are released from volcanoes. Thus, each of these sources is thought to provide about 50% of natural CO2 emissions. Dr. Crossey and her colleagues think that they may have discovered "the other 50%." Based on their studies of springs in the Colorado Plateau, Crossey et al. estimate that worldwide CO2 emissions from degassing of springs probably reach the same order of magnitude as emissions from either volcanoes or mid-ocean ridges (i.e., degassing of springs contributes about 1012 moles of CO2 each year). I should also note that "emissions" in this context refers to new CO2 that is being added to the carbon cycle.

For comparison, in 2002 (the latest data I could find) worldwide anthropogenic CO2 emissionss is on the order of 1014 moles per year. That is a whopping 100 times more CO2 entering the atmosphere from human activity than from natural degassing. I'm not one to rant about global warming, but according to these data the old argument that more (new) CO2 is entering the atmosphere through natural processes than through human activity has apparently been put to rest. Not only that, but according to US Dept. of Energy data you would have to go back to before the industrial revolution (1850's) to find a time when natural CO2 emissions exceeded anthropogenic emissions. Just a little food for thought.

Thursday, May 04, 2006


Simulations of earthquake ground motions

I recently went to a very interesting talk about simulating ground motion caused by earthquakes. The talk, which was archived and is available here, with JPG copies of the presentation slides here. The speaker was Brad Aagaard, a geophysicist who works with the U.S. Geological Survey in Menlo Park, California.

Aagaard, along with some other people at the USGS, created simulations of the ground motion caused by the 1906 San Francisco earthquake, the 1989 Loma Prieta earthquake, and then a few different 1906-like earthquakes. These 1906-like earthquakes were the same magnitude as the 1906 earthquake (M 7.8), but nucleated at different points along the San Andreas. The 1906 quake nucleated approximately under the Golden Gate bridge, and the rupture propagated both north and south, extending from Cape Mendocino to San Juan Bautista. Aagaard showed a 1906-like event that nucleated along the northern part of the San Andreas (Bodega Bay), and then one that nucleated along the southern part (San Juan Bautista). If you take a look at slide 82 of his talk (linked above) you can see the ground shaking intensity (using Modified Mercalli Intensities (MMI) ) in the greater Bay Area caused by the these events. A future 1906-like earthquake that nucleated near Bodega Bay would be more destructive in the Bay Area than the original 1906 quake.

The ground motion simulations require three data sets – a rupture model (how the fault moved during an earthquake), a geologic model, and then finally either recorded ground motions or MMI maps that can be used to constrain the model. For the 1906 quake, two groups of geophysicists have created rupture models (I'm not sure how these are created, so unfortunately I can't provide more detail). The geologic models are based on mapping and subsurface observations (seismic lines, boreholes, etc.). For the 1906 quake the ground motion constraints come from records of damage, reported using MMI. These data have been complied by another group of USGS geophysicists (available here). Add all those pieces of information together, and the result is REALLY impressive.

Here is a link to a video of a recreation of the 1906 event. The view is from Palo Alto looking north toward San Francisco. A screenshot is shown below:

The purple/blue in that picture show the arrival of the P-waves, and the yellow is the arrival of the S-waves. The surface waves follow shortly thereafter. It is amazing for me to watch the rupture begin underneath the Golden Gate, and then to see the seismic waves racing down the Peninsula. I should note that the ground motions in the videos have been exaggerated by a factor of 1000. The creation of these videos represents an amazing amount of work. Looking at all of them would be time well spent.

One of the goals of projects like this is to ultimately provide input to engineers so they can determine how structures will behave during an earthquake. These simulations aren't quite at that point yet because they don't include site effects (local variations in the ground motion). For example, the ground motion model of the Loma Prieta event doesn't include the liquefaction in the Marina District. Still, the models at this point do provide a lot of useful information for engineers. Below is a screenshot from a video showing how the Golden Gate Bridge would behave during a 1906-like event (the motion has been exaggerated by a factor of 100).

These recreations do a great job of making the 1906 quake (and future quakes) a lot more real. The pictures from the 1906 quake are amazing, but watching the seismic waves race along the San Andreas fault really hits me at a gut level. I'm grateful to all the people who contributed to this work, they've done an amazing job.

Wednesday, May 03, 2006


Reading List

In the last couple of weeks there was an interesting exchange on the mailing list of the ASA. Merv, the author of the first post, teaches at a Christian school (somewhere in the Midwest IIRC). Ted Davis teaches at Messiah College.

Here's Merv's post:

Our librarian (at a Christian K-12) school has asked teachers to submit titles we would like to see in our library. YEC is already well-represented there.

Do any of you have suggestions for books that would give the "other side" while being respectful to Christianity or religion in general? Or even if it was hostile towards religious thought... But the most of the books we have, hostile or not, still promote the warfare model (thought YECs wouldn't see it that way.) What suggestions would well represent the less antagonistic
strands of thought?

Here's Ted's answer:

YEC's don't mind the "warfare" view b/c they accept it in one of its obvious forms (namely, accepting modern science *does* necessitate abandoning Christian theology). Here is a very short list of books I strongly
recommend, in descending order of my recommndation for your school library.

My list is very, very short on purpose, so I'm leaving out zillions of excellent books and thus slighting none of them; and it's done with secondary school students in mind, and with their Christian convictions in mind.



Michael Poole, Beliefs and Values in Science Education. By far my highest recommendation, and ditto for home schoolers. Goes far beyond origins issues, and makes extensive use of HPS as well as basic science. Very
readable too.

Ronald Numbers, The Creationists. Extraordinarily accurate and well written history. The personal stories are revealing and often not told—but they should be.

Davis Young, Christianity and the Age of the Earth. Required reading for YEC teachers and students alike.

Guillermo Gonzalez and Jay Richards, The Privileged Planet. The DVD version gives viewers no clue that the earth and universe are old (this was a deliberate strategy when the DVD was produced), and the DVD is
popular with YECs. Having the book available to consult--and it might attract viewers if it's available--will dispell any misimpressions. Since the authors are linked with ID and the "creation-friendly" DVD, readers might be
more open to accepting the possibility of an old earth if espoused by these particular authors. And no one who reads the book will conclude that the authors believe in a young earth/universe. Thus I recommend it for your

David Hagopian, ed., The G3N3S1S Debate. A collection of three long essays, each defending a different hermeneutical approach to Genesis 1-3.
Negatives: All authors are very conservative Calvinists (and remember, I am sympathetic to much of Calvinism myself, so this is a friendly criticism),so the book does not provide much theological scope; all authors reject
evolution, so students have the impression that TE is beyond the pale; and authors of the YEC section (who actually have the gall to deny that they are YECs, saying only that a literal 24-hour view is required by Scripture) do not even try to engage science at all. Positives: the second of the 3 negatives I just listed is a positive, for this particular school's teachers
and students, allowing them perhaps more readily to consider alternatives to the "literal" view. That's really a huge positive, in this context. And the fact that the reasons given for the 24-hour view are just so weak, in the opinion of this historian (they are mainly arguments from history and tradiition, and the same arguments would readily lead one to reject heliocentrism along with evolution and an old earth), that they leave
the door wide open for the more reasonable (IMO) literary arguments of the "Framework" advocates in the third section. Hugh Ross co-authored the second section on the "day age" view, and there's a lot of good astronomy in
that part though the biology/anthropology isn't very good. Stick to the physical sciences, leave biology out of this, and many YECs can be convinced that OECs are also good Christian believers.

I'll limit myself to these five, or I'll be typing all week.


I've read Numbers' "The Creationists", and I've read a couple of other books by Davis, but the rest are new to me. I know a little about "The Privileged Planet", and I'm not favorably inclined towards it right now (honestly, I'm very skeptical of anything endorsed by The Discovery Institute). Davis thinks ID has some merit, and I'm not convinced (although to be fair, he is very unimpressed with DI-style ID). Still, I've come to respect Davis through reading his contributions to the ASA list (and some of his other material), so I'm going to track down the books on his list that I haven't read. I wanted to post the list here in case anyone who drops by this blog has read any of these books. If so, I'd love to hear your opinion.

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