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May 30, 2014

GPS in the Eastern Sierra, Year Six (and Counting)

At the end of May, I made my annual pilgrimage to SNARL, the Sierra Nevada Aquatic Research Lab, at the base of Mount Morrison in the Eastern Sierra. Big heart. The purpose: teaching Indiana University undergrads about GPS. The bonuses, starting with the drive down: mountain views.

[Stormy weather all the way from Reno to the field station, four hours' drive south.]

[A dry winter for California, but unseasonal snow in the spring this year.]

[Maybe the stormy weather didn't last quite the whole way. I had to detour up to check out this valley. How could I not, with that lighting?]

[The Eastern Sierra: Mountains and moraines.]

This is my sixth year helping out with the class, which has been going for I think 12. I get grandmothered in as GPS instructor/engineer, which actually fits my current job quite well. The class is taught by my Indiana University master's advisor, Michael Hamburger, and John Rupp, from the Indiana Geological Survey. They are helped out by an Associate Instructor and together hold court over 15 students for a California mountain adventure.

[The view from SNARL: Mount Morrison and its moraines, on a stormy day.]

What I love about this class (other than the amazing scenery): Unlike most geology field courses, it is an *intro* course, open to non-majors. This year, there were three geology majors, a history and political science major, a few biology majors, an environmental management major, and a speech pathology major, among others. And because it's Indiana University, in the heart of the midwest, many of these students have never seen these mountains before. Some have never really seen *any* mountains before. So every day is a wonderful new discovery. They get to ride a gondola for the first time, up Mammoth Mountain. They glissade for the first time, they see Death Valley for the first time, they soak in hot springs for the first time. And, they eat Linda's cooking for the first time. (Linda's been doing the catering since the beginning or almost the beginning of the course some twelve years ago, and it's an amazing thing. Don't come with any expectation of losing weight. The hiking is more than balanced out by Linda's desserts. Sigh.)

[Walking to our lunch spot at the top of Mammoth Mountain.]

[Every last person in the group did the optional glissade this year. So proud.]

[This is generally their new favorite lunch spot... until their next favorite lunch spot. It changes almost daily.]

[Happy students. A really, really good crew.]

Oh, and they do GPS for the first time! (The most important thing, right?) One day of the course is surveying day, and we measure a line of survey markers up and across a fault using leveling (old school) and GPS (new school), so they can compare the techniques. The fault is the Hilton Creek fault, but we measure its displacement across McGee Creek, just a hair south of the field station where we stay. (Turns out faults don't care about their namesakes when they rupture).

[Interpreting the geology of McGee Creek before heading over to survey.]

[Not just for geo majors. Getting down and into it here: Becky, English/History/Contemporary Lit, and Amelia, Chem/Geo.]

This is how the day is supposed to go:
"Wow, we spent a lot of time trying to located these (small, hidden) survey markers amidst the sage brush and scrubby trees, and even though the written directions from years past seem pretty good it took forever. But that GPS stuff—WOW! It got us right to the point!"

[And they're off!]

[I love watching the students struggle—and prevail—with this particular setup. Is that bad?]

To explain: We use what's called real-time kinematic methods, or RTK, which means we have a base station (GPS) that communicates with our rover (also GPS) via radios. We tell the base station where it is. No, base station, even if you think you're over there, you're not! You're right here! And so it can actually calculate the errors in its position. Because our rover and base are close together (a few km at most), they share the same error sources. Mainly, the satellite signals are going to travel through the same slice of atmosphere to reach our instruments, which means they're going to be delayed by the same amount to our base and rover, and that error essentially cancels out. It's convenient. And I program in the locations of the survey points beforehand, so *theoretically* we can navigate right to the points. And by "right to," I mean we should get within 2-3 centimeters, or about an inch. It's cool when it works.

[We break the students up into groups of 3-5 and cycle them through the different activities so everyone gets their hands on the equipment.]

And it *would* have worked this time if I had just chosen good coordinates. I happened to use coordinates from a year where the survey was bad for some reason. I had maybe eight years to choose from, and two were bad, and I used one of them. So in the field we were off by one meter, then two, then five. Not very impressive. But that was only a side goal of the survey. The main goal was to re-measure the positions of the markers to see if they'd changed.

[GPS is funny.]

[I like to teach one student in each group how to run the controller, and then they teach the next person, and so on, until everyone has used it to measure a marker. When possible, I have the old group teach the new group when we switch off. They always do great.]

And, the students seemed to like it. Some of them were totally grooving on it. The first group I had helped me set up the base station, and they were waaaaaay into it. A couple of the students even matched the equipment.

[Morgan, polisci/history with a geo minor, and Max, geo.]

The idea of the survey is that we'll see motion on the fault, if there is any between surveys. So far, no luck. But I feel like we did a good job of surveying this year, so if there had been any motions, we'd have seen it. Michael and I manage to almost-but-not-quite work our way out of the tangle of data every year to make some sense of it, but with one or two days and an Excel spreadsheet and undoubtedly small motions, if any at all, we've never really had a "wow" product to show the students. By the next day they're on to the next thing, anyway, so I don't think they mind. But it would be really nice to show some real, meaningful results from the survey.

As it is, I attempt to entertain them with a few lectures—one to show how GPS works and what makes our fancy high-precision stuff different from the GPS in their smartphones, and another to show applications of GPS. Earthquakes! Volcanoes! Even hurricanes, snow depth, soil moisture, drought, and glaciers! And I show off about the Plate Boundary Observatory, which includes several sites within almost spitting distance of the field station where we stay.

[Leveling. More precise in the vertical, but it *only* gives the vertical. Plus, we cruise right past them once we're set up. Plus, we can navigate right to the markers...usually. Still, if there are changes, but the changes are very small, leveling might be the way to go.]

And then, at the end of the exhausting days, we eat Linda's food and soak in those hot springs and giggle in the "executive suite" dorm room like we're in... well, college. Or maybe junior high.

And maybe, just maybe (it's not uncommon), one or two of the students who weren't geology majors decide to study geology, or a student ends up in something else with an Earth science or environmental focus. One went on to study environmental law. The 2008 group started a Facebook page, and posts still show up periodically about the ecology or geology of the Eastern Sierra. We have yet to rope in a geodesist. But I like to think that the students at least have a better idea of what technology can do for us when it comes to understanding and mitigating hazards.

[Are these the folks you want doing your future hazards assessments?]
[Answer: Yes!]


A major bonus for ME is getting to hang out with my dear friend Anne Hereford, who helped teach the class for six years and still comes out to visit. Here, we're taking Sunday afternoon off to hike up Convict Creek after lunch on the lake with the class. AMAZING geology. Just plain beautiful, whether you understand the folds or not. And the company was pretty darn okay, too.

[The wonderful Ms. Anne Hereford.]

[Wow. The Eastern Sierra.]

[It was hard to turn back, presented with a valley like this. Hard enough that we were late for dinner. Okay, we might have missed it...]

[Sooo many options for a caption here...]


Epilogue Part 2:

The drive back north is almost as nice as the drive back south, except the destination is not quite as nice. Hope to see you next year, Sierra class.

[Another geological wonder, Mono Lake, on the drive back up to Reno.]

Posted by beth at May 30, 2014 12:33 AM

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