Thursday, July 15, 2010

A Serpentine-Inspired Rant

By this point, I don't think I need to actually outline the whole fiasco surrounding the motion to demote serpentine from its position as California's state rock. More prompt geobloggers than I have already outlined this idiocy - seriously, unless you're inhaling serpentine dust like it's oxygen, you're not going to run into an asbestos problem - and those posts (and the flurry of commentary from geotweeters) have reached the attention of national media.

The claim that serpentine is an "unhealthy" rock is ridiculous on its own, but you know what else strikes me as ridiculous about this whole issue? The fact that, suddenly, people are getting all freaked out by the mere idea that something about California's geology might be able to kill them.

Hold the phone! Stop the presses! California's geology may be hazardous to your health and wellbeing?!

This is a state sliced by a plate boundary, with the main fault and all of its subsidiary ones capable of city-destroying earthquakes. We're known for our earthquakes, are we not? This is a state where the configuration of mountains focuses, heats, and speeds up the wind like a huge bellows, and effectively creates corridors of fire. We're known for our fires, are we not? This is a state where steep slopes produce debris flows after storms or slump off after longer rains. We're known for our landslides, are we not? Not to mention the contours of the coastline that serve to magnify distant tsunamis in some cases, or the ski resorts that happen to be dormant volcanoes...

I would say those things can be pretty darn hazardous to your health. I suspect that plenty of people would agree with me: the residents of La Conchita, of Crescent City, or of Sylmar, the historians and current residents of San Francisco, those who visit and monitor Mammoth Mountain, just to name a few. I'd hazard a guess (rimshot) that these folks would find those geological threats far more pressing than some specific minerals that are one component in a rock that's more commonly found underground than in, oh, our lungs. And I suspect the other geologists pushing to keep serpentine as California's state rock would agree with me as well.

So, California's geology can be pretty darn unhealthy, for values of unhealthy ranging from "deadly due to fault surface rupture collapsing one's house on oneself" to "alive but breathing in lots of smoke." But California kind of represents us as Californians, doesn't it? Does that mean the next step is to demote California's entire landscape from representing the state?

That would be ridiculous. But isn't it, then, ridiculous to make a fuss about demoting a rock that is really only dangerous if someone throws it at you, or perhaps if you drive off a cliff with a serpentine outcrop at its base? (Because, in case you somehow missed the other blog entries, tweets, and news articles, serpentine isn't going to give you cancer!)

Aside from all that, the formation of serpentine is directly related to the forces that formed and shaped so much of California to begin with. As such, it's an excellent representative of the state. (And for any politician who knows the word "subduction" and is about to claim it's dangerous for causing quakes and volcanoes, the serpentine is a byproduct of that process, not a cause. If I wanted to be even snarkier than I already have been, I could argue that picking a rock that is dangerous might better represent California's potentially-hazardous landscape. Be glad serpentine is "just" a representative of how the land that became our state got here to begin with. Also, be glad that it's pretty. Can you find me a prettier rock that also represents California well?)

I think that's quite enough from me, at least for now. I'll leave with this note: why is state money getting spent on this issue at all? If California wants to spend money on reducing geologically-induced harm, that money would be better spent on things like seismic retrofits, zoning to avoid earthquake and landslide hazards, clearing brush between the urban-wildland interface to try and avoid fires spreading into neighborhoods, emergency response training for civilians, and general awareness and outreach.

Friday, June 18, 2010


Hello, Geoblogosphere!

I realize I should have posted a more formal hiatus in advance of all of this, but at the same time, I didn't realize I'd be quite this insanely busy.
Which is, I also realize, a ridiculous assumption, given that I was working on my Master's thesis this quarter.

That said, I am finished with it! I defended the thesis on Tuesday, to a surprisingly large audience given that it's technically summer break now. I made the minor revisions, and I officially filed the thesis with the graduate division this afternoon.

I am staying at the same school to do PhD work, and that work will be a direct offshoot of my MS work. In terms of the actual work, there's not a big cutoff or different direction, and I'm still really excited about the work I'm going to be doing next. Even with the direct continuation, there's a definite sense of accomplishment: that I wouldn't be continuing into this third (and fourth and fifth and...) year of work if I hadn't finished the Master's stuff first! So, here's to the last two years, and the next three!

The first big thing I'll be doing as a person who actually has a degree in earth science is going to a a castle in Slovakia. Seriously. It's a conference specifically on numerical modeling of earthquake dynamics, and my adviser and his other student are also attending. I will be giving a talk on my latest work. I will try to be less of a flake about blogging this than I have about the other conferences at which I gave talks.

After that, I'll be heading up to the Bay Area for July, August, and September to help with some laboratory experiments on fault friction at USGS. Needless to say, I'm beyond merely excited about this opportunity!

Another thing I really hope to do this summer is put up a series of posts on Things I Should Have Blogged About Months Ago. Because I'll be the first to say that I'm behind on this! Topics I plan on addressing are:
The trip to Hawai'i (This was in October of 2009, I am such a slacker.)
The rest of AGU (or, at least, how my talk went)
The Rise and Fall of Snow Los Angeles (purely silly, but to be blamed on a conversation at AGU)
The earthquake in Mexico, and going into the field immediately afterward!
Seismological Society of America conference in Portland
Visiting Mt. St. Helens

And I hope to be more on the ball about the Accretionary Wedge as well.

Friday, March 26, 2010

Accretionary Wedge #23: The Thing That Eats My Time

Hello, world! I realize I've failed at the day-to-day writeup of AGU that I promised back in December (eep), but what better way to come back from an unannounced work-induced hiatus than to describe the work I've been doing, hm?

I don't think I've blogged much about the research I do. I know I post about about interesting places I visit, visible and tangible fault features, and outreach, but my actual research doesn't have a field component yet at all. I do work in earthquake dynamics - the physics of how faults rupture. My method so far has been numerical modeling, specifically with both 2d and 3d finite element codes. This method divides both sides of the fault into a grid of elements of a designated size, then applies equations of motion, stress transfer, and wave propagation to each element over each timestep, then sums up the result. Each model represents a single earthquake on a fault; aside from a forced nucleation point, the magnitude and intensity of the quake are determined by the model parameters. There are many existing codes that do this, and I've been working with two of the newer ones. I've also very recently started doing some multi-cycle quasi-dynamic models. These take a fault system and put it through multiple earthquake cycles, including interseismic application of tectonic stresses. What makes them quasi-dynamic is the ruptures work by way of stress state, and don't include dynamic wave propagation.

There are a lot of fault parameters you can tweak in dynamic models, and my work focuses on the effects of fault geometry on rupture behavior and ground motion. Models investigating other parameters might use a fault that's a straight line, but straight lines almost never happen in nature. Faults have branches, bends, discontinuities, and stepovers, and they've proven to be important factors in determining where earthquake rupture stops. There's one field study of mapped surface ruptures (Wesnousky, 2008) that shows that a significant number of surface ruptures die out near a geometrical discontinuity in the mapped fault trace. On the other hand, events like the 1992 Landers earthquake or the 2002 Denali earthquake show that rupture can traverse some considerable discontinuities between faults. Understanding how rupture behaves when it encounters a geometrical discontinuity is therefore very important in determining the hazard associated with individual faults or fault systems.

I already have one fault geometry paper (which also happens to be the first chapter of my Master's thesis) in review. It's a parameter study of whether or not rupture will propagate through a bend in a fault of a given length, with a given connecting angle. Unsurprisingly, steeper angles and longer bends are more likely to halt a rupture, but exactly how steep or long varies depending on whether the step is extensional or compressional (that is, whether the bent segment is pulled apart by the fault's direction of slip, or whether it's crunched together), on the overall size of the fault system, and on the orientation of the stress field acting on the fault. That third criterion is particularly important - in some orientation, dynamic effects control the rupture far more than static ones, but in others, static effects can overcome dynamic ones. I still haven't heard from any reviewers on this paper, but I'm sure I'll post here excitedly when it goes into press.

I'm working on a second paper now, determining how fault geometry affects the intensity and distribution of peak ground motion in an earthquake. In this case, I'm using fault systems that consist of two segments with no linking segment, meaning that rupture has to re-nucleate on the second segment as opposed to just traversing an unfavorable part. I'm looking at both compressional and extensional systems here, with a varied distance between the fault segments, a variety of stress drops, a variety of rupture velocities, and a variety of different rock types. So far, I'm finding that every single one of those parameters affects the pattern and intensity of motion. The talk I gave at AGU (which I will write about, really!) was about preliminary results of this work, and I'll be giving a talk at the Seismological Society of America meeting in Portland in April about the specifics of the material contrast cases.

So that's my research - as I transition into working on a PhD, I'll start investigating more complex geometries and looking at real fault systems, as opposed to hypothetical ones. All that while still taking a bunch of classes to catch up on my background!