Sunday, March 17, 2019

From crashing kites and Frankenmodels to efficient large-scale UAV acquisitions and beautiful shared 3D models (2018 GSA talk)

I was invited to give a presentation in a session at the Fall 2018 Geological Society of America session T60. Revolutions in Remote Sensing: Applications of UAVs to Field Mapping and Surface Analytics (organized by Dylan Blumentritt--Winona State University and Toby Dogwiler--Missouri State University). I decided to make a my presentation a bit of a reflection of how my own obsession with low altitude imaging had evolved and how far we had come. After all, I started in college working in the Fairchild Aerial Photography Collection when it was at Whittier College. So, I came up with a talk with the hopefully entertaining title of FROM CRASHING KITES AND FRANKENMODELS TO EFFICIENT LARGE-SCALE UAV ACQUISITIONS AND BEAUTIFUL SHARED 3D MODELS. I am putting links to the talks on line in case they might be useful: PPT and PDF.

The presentation shows a couple of maybe interesting things:

  1. It shows a pretty 3D point cloud (video above) from our Photogrammetric model of the Tecolote Volcano, Sonora, Mexico hosted at
  2. It spends some time talking about and making the case for the OpenTopography Community Dataspace.
  3. As part of the OpenTopography Community Dataspace discussion, I (with slides and ideas from Chris Crosby) talked about standardizing metadata for these long tail data. See for example the different styles of metadata documents ("Survey Report"): for example Almaty range front fault, Koram site or Clear Creek, Idaho post-fire debris flow erosion--note the ones I uploaded are not great examples :).
  4. Of course, one of the really nice things that the OpenTopography Community Dataspace publishing of one's data allows is to mint a DOI. That DOI allows then for a data citation. I have added a new part of my CV that has a section on data publication. Here is an example citation style:
    Arrowsmith, J R., DiMaggio, E. N., Garello, G. I., Villmoare, B. and LediGeraru Research Project (2018): Photogrammetric model of a portion of the LeeAdoyta Basin, Afar, Ethiopia (point cloud [122M points], orthophoto [2cm/pix], and DEM [25 cm/pix]). Distributed by OpenTopography. AccessedOctober 23, 2018.

The conclusions are useful to highlight as well:

  • We are part of a revolution in 3 and 4 D data collection and analysis
  • Additional needs for the community include
    • Optimized data acquisition strategies
    • Low cost and high performance computation of point clouds and models
    • Efficient and accurate georeferencing
    • High quality differencing for change detection
    • Bring the tools and data into the (outdoor) classroom; need more curriculum (c.f. GETSI - GEodesy Tools for Societal Issues (UNAVCO) at
  • OpenTopography Community Dataspace
    • Great opportunity to expand the impact of emerging topography through improved access
    • Services and existing community of users
    • Community engagement & best practices
    • Please join us and start sharing your models and ideas for how to improve

Monday, March 11, 2019

Anniversary of Great Tohoku Japan earthquake and tsunami (20110311)

Today is the anniversary of the catastrophic great Tohoku Japan earthquake and tsunami of March 11, 2011. While I am not an expert of subduction systems nor tsunamigenesis, I was of course interested in the event and prepared some lectures about it. While there are many better and newer illustrations, I wanted to share the materials.

The first presentation was at the Arizona Science Center in 2011. Here is the folder of the materials.

I prepared a lot of content for a series of lectures at IT Bandung in Java that I presented in 2013 with the help of my former student Dr. Gayatri Marliyani. There is much high quality material at IRIS (some of which I have included). The main materials are in these three folders:

Friday, March 8, 2019

Idea for an earthquake intensity exercise based on 1857 Ft. Tejon earthquake data

I was cleaning some files yesterday and I found an old exercise I had deployed when I was first teaching Introductory Geology. It was intended to help students understand earthquake intensity (vs.) magnitude. I took the felt intensities as reported by D. C. Agnew and K. Sieh (1978), A documentary study of the felt effects of the great California earthquake of 1857, Bull. Seismol. Soc. Amer., vol. 68, pp 1717-1729 and compiled some of the more easily interpreted ones into a table and then provided a simple map of California for the students to map the intensities. Here is a link to the compiled data from Agnew and Sieh. THe work of Kerry Sieh on the 1857 earthquake is seminal. I think it was an ok exercise, but there are probably more interesting and more recent datasets. For example, I like the twitter-based work that is coming from the USGS colleagues. It should be possible to take some sample tweets and do an intensity mapping.

The 1857 earthquake and its foreshocks and aftershocks are fascinating an a sobering reminder of what will happen one day in California.

This figure from Toké and Arrowsmith, 2006 shows the 1857 foreshocks and the mainshock distribution (the latter is what the exercise mentioned in the last paragraph is supposed to look like) and compares it with the historic Parkfield earthquakes.