AGU 2017, Day 2

The second full day of the American Geophysical Union conference is always an interesting one, as the exhibit hall opens. Vendors, funding agencies, publishers, universities, and other organizations are present at booths, filling a huge hall. It’s a great place to go to see the latest and greatest technology, such as the 4 meter long flume table from Emriver. I took a picture, but forgot to bring my card reader so I have no way to transfer it off of my camera. It shall have to suffice for now to say that it was stunning.

In addition to some very interesting discussions with people at posters, I went to the Volcanology, Geochemistry, and Petrology award lectures. The second lecture, by Craig Manning, was a fairly clear discussion about the inadequacies of previous thinking about thermodynamics in hot (900–1100 °C), high-pressure (5–10 kbar [I think I have that pressure right]) hydrothermal systems (e.g. subduction zones) and some new experimental results and conceptual models which seem to fit better.

My mind was blown fairly early in the talk when he pointed out that under those temperature and pressure conditions, neutral pH for water is around 4. I also haven’t thought enough about ionic liquids (e.g. molten sodium chloride), or the ternary phase diagram of H2O, CO2, and NaCl, particularly not under high temperature/pressure. However, in the thermodynamic sense these systems do have some predictable behaviors when thought of this way, and the data seem to fit those predictions. The fluids have a tendency to become quickly rich in silica (SiO2), which gives rise to the quartz veins commonly found in metamorphic rocks. In these models it is not hard to then transition from silica-in-salt-solution toward partial melting of a type found in metamorphic and volcanic rocks.

The afternoon held interesting talks on isotope systems of relevance to volcanic measurements (estimating sulfur emissions and speciation), as well as good discussions with people I met in the hallways or poster sessions. Later in the afternoon I came across a former labmate, and it was good to catch up with her for a while and discuss the various challenges of being an early-career scientist. Dinner, debrief, and further discussion of early-career issues with my conference buddy capped off my day.

Tomorrow has yet more interesting talks and posters, and there are a few people on my to-talk-with list who I will need to track down.

AGU 2017, Day 1

The American Geophysical Union fall meeting is always an interesting conference, in part because of the diversity of topics covered. I started off the day learning about the effects of the solar eclipse on the ionosphere. From there it was off to posters, where I had some interesting conversations about polar atmospheric chemistry and met some grad school friends I hadn’t been expecting to see here.

Unfortunately, the wifi at the convention center was very poor, so it looks like it will be difficult to tweet this conference, at least from the scientific side.

After lunch, I went to a few more posters that had been on my to-see list, mostly related to glaciers, glacial melt, and glacial retreat. Some of the education talks looked quite interesting, so I saw a few of those before running across grad school friends and joining them for the big Planetary Science lecture, on the Juno mission to Jupiter.

Dinner with some grad school friends was good, as was the after-dinner expedition for beignets (French donuts, except with no holes). We had some very interesting discussions about working in science, both in academia and in industry, as well as on some of the challenges facing early-career researchers.

AGU 2017, Day 0

This week is the American Geophysical Union’s fall meeting, which is taking place in New Orleans, Louisiana. AGU is a big conference, which recently has been drawing 20K-25K attendees each year. With the conference scientific program beginning tomorrow, many people are arriving today.

Getting 20,000 scientists together in one city when they mostly arrive on one day takes up quite a bit of the inbound capacity on transportation. My flight from Minneapolis today, for instance, was probably more than 50% meeting attendees—many of whom are are recognizable by their poster tube decked out in NASA, USGS, and other Earth science related stickers.

The community is also weirdly small. On the plane was a visiting professor from my undergraduate institution, and when I got in line for the downtown hotel shuttle, two alumni (each one year apart from me) were on either side of me.

Upon reaching the hotel, I settled in and started the process of figuring out what talks, posters, and events I should get to this week. Thursday morning will be my poster, which I’m very excited for. There are some sessions on Wednesday related to my doctoral work (and co-chaired by my doctoral adviser) which look very interesting. Several networking events will be happening as well, with varying degrees of field specificity.

Eventually I’d had enough of scheduling and decided it was time to eat food. I walked over to the French Quarter and, having again crossed paths with the prof I’d met in the Minneapolis airport, found one that had good jambalaya. A long walk and some further scheduling later, and it’s now time for bed. Tomorrow is a big day, with lots of networking to do and cool science to go learn about!

Heard Island Poster at the 2017 American Geophysical Union Fall Meeting

Glacial ice on the beach at Corinthian Bay, Heard Island. Image credit: Bill Mitchell (CC-BY).
Glacial ice on the beach at Corinthian Bay, Heard Island. Image credit: Bill Mitchell (CC-BY).

In three weeks I will be attending the American Geophysical Union (AGU) fall meeting, and on Thursday morning I will be presenting a poster about the Retreat of Stephenson Glacier, Heard Island, from Remote Sensing and Field Observations.1,2 I am very much looking forward to it, and if you will be at the meeting I hope you will stop by. There is likely to be a journal article forthcoming on this work, and the conference will be a great opportunity to discuss my project with glaciologists and get feedback on it—exactly what poster sessions at conferences are for, from what I understand.

Although my analysis is pretty much done, there is still quite a bit of work to go. Most importantly, the poster needs to be created. For that, I’ll start with a list of graphics and figures that will be needed for the poster:

  • Map of the world, showing the location of Heard Island
  • Map of Heard Island, showing the location of Stephenson Glacier
  • Satellite image(s) of Stephenson Glacier, showing the retreat
  • Field photo(s) of Stephenson Glacier from the Heard Island Expedition3
  • Graph showing the area of the glacier over time
  • Other maps/graphs as needed

From that graphical outline will follow a minimal amount of text to guide a reader through the project with introduction, methods, results, and discussion sections. Once all that gets put together, it gets reviewed, sent to my co-author for further review, then changes are made until we’re satisfied and it’s sent off to the printer.

Following the conference, I hope to get a more detailed manuscript written. When it is ready for submission, I expect it will go to EarthArxiv, a new Earth science pre-print server, as well as an appropriate journal with open-access options.

Publication of that article would be the final step for this project, but there are quite a few new project ideas which have sprung up while I’ve been preparing this poster and article. One of the great things about using openly available data is that there are so many projects which could be done relatively simply and at little cost. Of course, a few other ideas have come to mind—and are perhaps more interesting—that would need further field studies.

Notes:

  1. Poster C41B-1222.
  2. Unless the affiliation is “Unaffiliated” for the lead author, it is incorrect. I have tried to get it corrected, but apparently the system can’t handle that.
  3. During the Heard Island Expedition, although I was close to Stephenson Glacier I was unable to travel to that part of the island. Fortunately my co-author and several other expedition members did get there and took lots of photographs among other sampling and documentation efforts.

Mapping the Eclipse for a Citizen Science Project

Map of the continental United States showing the amateur radio grids and path of the eclipse.  Image credit: Bill Mitchell (CC-BY).
Map of the continental United States showing the amateur radio grids and path of the eclipse. Image credit: Bill Mitchell (CC-BY).

During the solar eclipse next week, I will be at the Science Museum of Minnesota with a citizen science project studying the effects of the eclipse on radio propagation. While there are many radio-related projects going on—the most accessible being a study of AM radio reception—I will be using amateur radio to make contacts and provide reception reports during the eclipse. One of the important pieces of information that will be exchanged with other amateur stations is a “grid”, which is a shorthand for rough latitude and longitude.

Amateur radio grids are 2° longitude by 1° latitude, and represented with pairs of letters and numbers. For instance, the Science Museum of Minnesota is located in EN34. Fields (20°x10°) are designated with letters, and increase from -180 longitude and -90 latitude (AA) to 160 longitude and 80 latitude (RR). Fields are further subdivided into grids using numbers, which increase from 00 at the southwest corner to 99 at the northeast. Looking again at our example, the first character, E, indicates a location between 100° and 80° W longitude, and N indicates a location between 40° and 50° N latitude. The numbers provide further refinement on that range. The 3 means the longitude is between 6° and 8° east of the west edge of the field (i.e. 94°–92° W), and the 4 after it means the latitude is 4°–5° north of the south edge of the field (i.e. 44°–45° N). Further letters (A-X) and numbers can be used to specify locations more precisely in a similar fashion. Longitude is always indicated first, and increases west-to-east; latitude is indicated second, increasing south-to-north.

For the event, I want to have a map of the continental US and southern Canada with the grids outlined on it. During the event as we hear which grid other stations are in, we can mark their location on the map. Unfortunately, I was not able to find a map that I wanted to use for this purpose, so I decided to make my own with QGIS.

For my eclipse map, I needed to gather a few datasets. First and foremost, I needed a US state map. Canadian provinces were also a high priority. Once I had those, I was still missing Mexico and other North American areas, so I found a world map as well. That covered the basics, but as long as I’m making a special map for the eclipse, I wanted to have the path of totality, which I found from NASA. I unzipped each of those files into a folder for my eclipse grid map project.

In QGIS, I loaded all the datasets (vectors). The Canadian provinces were in a different projection, so I saved (converted) it to the projection I wanted (EPSG:4269), which is a simple latitude-longitude projection. I found that the Canadian provinces included detailed coastlines and islands, so I simplified it (Vector | Geometry Tools | Simplify Geometry) using a tolerance of 0.01 or something like that. The islands cleaned up a little, but the overall shapes didn’t change much.

With the datasets loaded, I needed to make my field and grid boundaries. Using the grid tool (Vector | Research Tools | Vector Grid) I created the field grid (xmin=-180, xmax=180, ymin=-90, ymax=90, parameter x=20, parameter y=10) and the fine grid (same except parameter x=2, parameter y=1).

I looked up the coordinates for the Science Museum of Minnesota, and put them into a CSV text file. By loading in that CSV file, I put a star on the map where I will be located.

From that point, it was just a matter of adjusting colors and display properties. I gave reasonable, light colors to the US and Canada, and thickened the borders for the US states. I used a dashed line for the field lines, and a lighter grey dotted line for the smaller grids. The eclipse path I made a partially-transparent grey.

That’s about all there was to it! In the print composer I added in some of the labels for a few grids to help demonstrate the letter/number scheme.

Results (PDF): 8.5″x11″, 11″x17″.

Heard Island Landslide!

Landslide on Compton Glacier, Heard Island, 2017-07-21.  Image credit: processed by Bill Mitchell (CC-BY), using USGS/Landsat 8 data.
Landslide on Compton Glacier, Heard Island, 2017-07-21. Image credit: processed by Bill Mitchell (CC-BY), using USGS/Landsat 8 data.

On July 21, 2017, the Landsat 8 satellite imaged a fresh landslide on Heard Island, seen in the picture above. The slide occurred in the northeast portion of the island, on top of Compton Glacier, and I have annotated it for clarity in the image below.

Satellite image of Heard Island with annotation marking the region where the landslide is present.  Image credit: processing and annotation by Bill Mitchell (CC-BY), data from USGS/Landsat 8.
Satellite image of Heard Island with annotation marking the region where the landslide is present. Image credit: processing and annotation by Bill Mitchell (CC-BY), data from USGS/Landsat 8.

This landslide is quite easy to spot because of the relatively clear conditions over Heard Island and the very high contrast between the dark, presumably-basaltic rocks and the white snow of the glaciers. Given that it is presently austral winter and Heard Island is located south of the Antarctic Convergence, the rate of snow accumulation should be quite high. It will be interesting to see how long it takes to be covered by snow.

I am fairly convinced that this is a rock- or landslide rather than an eruption. The head of the flow is along the top of a steep ridge, and the infrared imagery shows no thermal anomaly in this part of the island.

What’s interesting to me is that this slide appears to have eroded some snow on top of the glacier which then caused a secondary avalanche from a north-facing slope. I’ve annotated this in the image below.

Region of secondary avalanche.  Image processing and annotation: Bill Mitchell (CC-BY), data from USGS/Landsat 8.
Region of secondary avalanche. Image processing and annotation: Bill Mitchell (CC-BY), data from USGS/Landsat 8.

This landslide has a run-out of about 2.5 km, an elevation drop of ~750 m, and a total affected area of ~0.8 km2. Several flow tongues are evident in the close-up image, even though the satellite imagery resolution is a modest 15 m/pixel.

Close-up of landslide on Compton Glacier, Heard Island.  Several flow paths of dark rock are evident here.  Image processing: Bill Mitchell (CC-BY), data from USGS/Landsat 8.
Close-up of landslide on Compton Glacier, Heard Island. Several flow paths of dark rock are evident here. Image processing: Bill Mitchell (CC-BY), data from USGS/Landsat 8.

From this image, it looks like the rockfall mostly happened in the portion running west-to-east, then as it turned the corner to head northeast, transitioned to a surface flow. In many ways, this reminds me of the Mt. Dixon (New Zealand) rock avalanche in 2013 (coverage by Dave Petley here and here, among others). The video below is from the Mt. Dixon (NZ) rock avalanche, but is likely similar to what occurred on Heard Island.

A fly-over after the Mt. Dixon (NZ) rock avalanche provided more video of the rock avalanche scar.

I look forward to seeing more images of this slide as they come in. Heard Island is imaged roughly every 8 days by Landsat 8, which as far as I can tell is the only publicly available high-resolution imagery for the island now that EO-1 has been decommissioned.

Capitol Rock Close-Up

Close-up outcrop photograph of Capitol Rock, viewed from the north-northeast.  Image credit: Bill Mitchell (CC-BY).
Close-up outcrop photograph of Capitol Rock, viewed from the north-northeast. Image credit: Bill Mitchell (CC-BY).

Two years ago, I came tantalizingly close to Capitol Rock, an outcrop in southeastern Montana (45.572189, -104.087964) just a few miles over the border from Camp Crook, SD. Unfortunately, I did not have an opportunity at that time to explore the outcrop from any closer than about a quarter mile, but I did find the Ekalaka Quadrangle 30’x60′ (pdf) geologic map.

Recently, I was out in the area again, and this time made sure to have time to take some pictures and see some of what was to be seen. Let’s start with the quarter-mile view, which is roughly equivalent to what I saw last year.

Wide view of Capitol Rock from the east.  Image credit: Bill Mitchell (CC-BY).
Wide view of Capitol Rock from the east. Image credit: Bill Mitchell (CC-BY).

Capitol Rock has three major parts to it: an easily eroded base, a laminated sandstone middle, and a massive sandstone top. A handy turn-out from the forest service road leads right to the base of the outcrop.

The easily eroded base is made of fine, chalky, white sediment sediment, and it remains in horizontal orientation. In several places, this unit is at least superficially porous. Surprisingly, there are occasional chert clasts in the otherwise fine sediments—I’m not quite sure how those would have been deposited or formed here.

Basal unit of Capitol Rock.  Foot for scale.  Image credit: Bill Mitchell (CC-BY).
Basal unit of Capitol Rock. Foot for scale. Image credit: Bill Mitchell (CC-BY).
Cherty clast in the basal sediments at Capitol Rock.  Foot for scale.  Image credit: Bill Mitchell (CC-BY).
Chert clast embedded in the basal sediments at Capitol Rock. Foot for scale. Image credit: Bill Mitchell (CC-BY).

Above the basal unit is a somewhat more resistant, coarser-grained set of beds. These strata are finely bedded, and have a tendency toward spheroidal weathering. Occasionally interbedded with the spheroidal beds are 1–3 cm thick, well-cemented strata of a white or pink color [discoloration?].

Spheroidal weathering of finely-laminated strata.  Hand for scale.  Image credit: Bill Mitchell (CC-BY).
Spheroidal weathering of finely-laminated strata. Hand for scale. Image credit: Bill Mitchell (CC-BY).
Laminations in the unit displaying spheroidal weathering.  Hand for scale.  Image credit: Bill Mitchell (CC-BY).
Laminations in the unit displaying spheroidal weathering. Hand for scale. Image credit: Bill Mitchell (CC-BY).
Non-spheroidal bed 1–3 cm thick and slightly orange-pink in coloration, within the spheroidal beds at Capitol Rock.  Hand for scale.  Image credit: Bill Mitchell (CC-BY).
Non-spheroidal bed 1–3 cm thick and slightly orange-pink in coloration, within the spheroidal beds at Capitol Rock. Hand for scale. Image credit: Bill Mitchell (CC-BY).

The spheroidally-weathered unit also seems to have one or more channels within it.

Contact between spheroidally-weathered strata (above) and easily-weathered basal unit (below).  Possible channel cut at right.  Outcrop height in image is ~10 m.  Image credit: Bill Mitchell (CC-BY).
Contact between spheroidally-weathered strata (above) and easily-weathered basal unit (below). Possible channel cut at right. Outcrop height in image is ~10 m. Image credit: Bill Mitchell (CC-BY).
Contact between spheroidally-weathered strata (above) and easily-weathered basal unit (below).  Possible channel cut at right has been annotated.  Outcrop height in image is ~10 m.  Image credit: Bill Mitchell (CC-BY).
Contact between spheroidally-weathered strata (above) and easily-weathered basal unit (below). Possible channel cut at right has been annotated. Outcrop height in image is ~10 m. Image credit: Bill Mitchell (CC-BY).

The upper unit at Capitol Rock has more massive sandstone (see wide view above). I didn’t notice many channels in this unit, although I didn’t get very close. A butte just to the north of Capitol Rock provided a good photograph (below).

Massive unit of Capitol Rock, seen in the butte immediately to the north of Capitol Rock.  Cliff is ~30–40 m tall.  Image credit: Bill Mitchell (CC-BY).
Massive unit of Capitol Rock, seen in the butte immediately to the north of Capitol Rock. Cliff is ~30–40 m tall. Image credit: Bill Mitchell (CC-BY).

Although I have those observations, I don’t have much for interpretation of them. The depositional environment seems to be relatively low-energy (give or take the chert clasts), evidenced by the flat strata, fine grain sizes, and relatively few cross-beds. Changes in the rock types would suggest changes in the sediment sources or the depositional environment (or both). There may be post-deposition alteration effects as well, such as cementation of the spheroidally-weathering strata.

View SSE from the butte just north of Capitol Rock.  Truck for scale in pull-out near Capitol Rock.  Image credit: Bill Mitchell (CC-BY).
View SSE from the butte just north of Capitol Rock. Truck for scale in pull-out near Capitol Rock. Image credit: Bill Mitchell (CC-BY).

Capitol Rock is an interesting outcrop, and if you’re in the area, I’d recommend a stop. The rocks are interesting, there are US Forest Service campgrounds nearby, and the view is quite nice. These units can probably be correlated to the Slim Buttes in South Dakota (~45 miles east).

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