Wednesday, January 6, 2021

Salt River terraces field geology exercise and updated guide

The Salt River in central Arizona has a spectactular set of fluvial terraces developed along it. I have lead a number of field trips along the Salt River for outreach and most importantly for our GLG451 Field Geology I course where we use a site along the Salt River for a mapping exercise. I have recently updated the materials associated with that exercise in anticipation of this Spring's class which will include a virtual component.

Tour from ASU to the Salt River site.
Drone overflight of the key sites for the exercise.

I built on some of the very nice writing and descriptions of Professor Pewe when I wrote up a field trip guide and ran a few field trips in the early 2000s. See this LINK. I updated that guide and it is available here: Landscape and geologic history along the Salt River near Tempe and Mesa, Arizona.

Here is the assignment with many additional links and explanations: Virtual Field Geology assignment for Salt River Field Geology I 2021.
I made a long explanation of the GIS:

These were of great interest to Professor Troy L. Pewe of Arizona State University's Department of Geology. He moved to Arizona from Alaska and converted his research from permafrost to desert processes. I was lucky to learn from him when I first came to ASU in 1995. He took me under his wing and shared with me much of what he had learned. Most importantly, he helped me to learn the field trips and field sites he had developed and discovered. I am extremely grateful to him. I recognize Brian Gootee who was a great friend of the Pewe Family and who has preserved much of the Pewe legacy at the Arizona Geological Survey.

Pictures from those early field trips with Prof. Pewe.

Thursday, December 31, 2020

Exploring diffusion for hillslope changes using a spreadsheet

I became obsessed with diffusion erosion modeling in my PhD work. It is a simple (certainly oversimplified) way to think about how hillsloopes may change over time in the absence of mass wasting, debris flow, and fluvial processes. There is a lot to say about it, but I wanted to capture a few items I recently developed.

Here is an explanation and assignment on the topic in my Computers in Geology class: Lecture 8: Exploring diffusion using Excel.

One of the challenges that I have had in some applications is that the computational "space" was too small in the spreadsheet, given that it is fixed. Of course this is not a problem if one dynamically determines the number of time steps for example based on a stability criterion and you do it with a for or while loop in something like Matlab. So, when I was helping Emily Apel with her senior thesis recently, I built her a big spreadsheet (seemed easier given the limited time that she had.

Here is the original spreadsheet with only 27 space steps and 191 time steps. It is good for teaching and quick demos: LINK to Spreadsheet.

Above is the screen cap of the main interface page where the user just changes the bold cells and watches the calculations in real time.
Above is the screen cap of the Model Calculation Space tab which shows the compuational engine with its fixed elevation boundary conditions and explicit centered in space and forward in time finite differences.

Here is the big spreadsheet with 250 space steps and 1000 time steps: LINK.

And, here is a video that I built to explain the general activity for Emily Apel, but it may be useful for others. It explains the two spreadsheets that are linked above.

One of the cirtical concepts that is accessible in both of these spreadsheets is the opportunity explore not only initial step models, but also continuously displaced scenarios.

Here are a few other blog posts and recent publications which might be of interest as well:

Tuesday, December 15, 2020

Simple computations of scalar seismic moment and moment magnitude

In my classes and for research, sometimes it is useful to calculate the scalar seismic moment (M0; basically a geometric measure of the total static energy release at a 0th order). It is a function of the area of a fault that slipped times the average slip times the shear modulus of the volume. The latter is usually assumed to be 30GPa. The main challenge (after determining the parameters) is to get the units all to be the same (dimensions of Newtons and meters):

M0= mu*Length*Width*U_bar.

And, once we have that scalar moment in Nm, then we usually want to convert it to moment magnitude (Mw):

Mw = 2/3 log10(M0) – 6.

Here is a simple spreadsheet to do this calculation: LINK
Here is a simple and older lecture I have used in introductory level geoscience courses: LINK

Sunday, December 13, 2020

New fast workstation and sUAS capability for School of Earth and Space Exploration course development


Our geoscience courses have benefited from plenty of course development, especially lately as we have moved online and virtual. I recently was able to invest SESE course fees to build out our capabilities for high resolution mapping and 3D work. Javier Colunga built a nice and fast Windows workstation, and we also purchased a Mavic Pro 2 sUAS system. The descriptions are below for reference.

Workstation description

We have been building these "gaming" style fast desktops for a while and this latest incarnation is powerful for graphics intensive and 3D work, especially structure from motion photogrammetry (e.g., Johnson, et al., 2014 and GSA short course).
Here is a short description of the hardware (cost approx. $5k):

  • CPU: Ryzen Threadripper 3970X 32-core/64-thread (with a premium cpu cooling solution)
  • Main Memory: 128GB DDR4 3600
  • Graphics Card: GeForce RTX 2080 Super
  • Storage: Samsung 1TB M.2 NVME OS drive, additional 4TB hard drive
  • Operating system: windows 10 Enterprise
  • Input: Logitech wireless keyboard and mouse
  • Monitor: HP 27 inch 1440P
Here is the main software installed:
  • Google Earth Pro
  • Matlab R2020a
  • Camtasia 2020
  • Cloudcompare
  • Agisoft Metashape
  • ArcGIS 10.7
  • QGIS
Here is more description, how to connect remotely, and a sign up sheet. LINK

sUAS description

For SESE, we have purchased a DJI Mavic 2 Pro (actually the FlyMore combo so it has a nice case and 3 batteries). This is a nice mapping and aerial documentation system.

Devin Keating has been helping to get the system into production mode. He has built a nice documentation of the system and its use. He also registered it with the FAA so we have a tail number. See this LINK. To operate it, one should have the part 107 Remote Pilot certification. And, there are ASU oversight requirements as well.

Recent course related work using this type of system (and computed on the nice workstation described above):

Warford Ranch volcano (Arizona) sUAS mapping

Virtual field geology exercises for GLG451 Field Geology I Spring 2020

Material for virtual exercises for GLG452 Field Geology II at Camp Tontozona AZ

Wednesday, November 25, 2020

Warford Ranch volcano (Arizona) sUAS mapping


We recently visited the Warford Ranch Volcano which is a low shield volcano that is part of the Sentinel-Arlington volcanic field of southwestern Arizona. It is about 3 million years old. It was a favorite field trip destination of Prof. Ronald Greeley. Shelby Cave worked on the Sentinel-Arlington field for her Ph.D. dissertation under the supervision of Prof. Greeley and after his passing she worked with Prof. Amanda Clarke.

Google maps location for Warford Ranch (NW of Gila Bend, AZ).

Professor Clarke is teaching the Advanced Field Geology course and she took the group to Warford Ranch volcano to examine its volcanology. I did some UAS-mapping to help with the documentation. This blog entry presents some of the products of the overflights with our Mavic Air and Phantom 4 Pro.

Oblique overviews

I flew the Mavic Air high to get some views over the volcano to assess its general form and the relation to adjacent landforms and geology.

View to the north. The cars are lower left are in our parking spot. LINK to jpg

View to the south-southwest. LINK to jpg

View to the south-southeast. LINK to jpg

Fissure zone on SW side of higher topography. People for scale. Not sure the purpose of the excavation. LINK to jpg

Masked and socially distanced field work. LINK to jpg

Video overflight.

sUAS mapping

Along with the free flying overviews, I flew in mapping mode (using the PX4D mapper app) over most of the volcano taking 1778 images in mapping mode. I processed those in Agisoft Metashape to produce a colored point cloud, digital elevation model, and orthophoto. The latter two can be the basis of more mapping in ArcMap.

Tour of the data and its processing in Agisoft Metashape and ArcMap.

Map downloads

Hillshade overview. 600 dpi pdf download: LINK.

Ortho image overview. 600 dpi pdf download: LINK.

Hillshade of peak area. 600 dpi pdf download: LINK.

Ortho image of peak area. 600 dpi pdf download: LINK.

Map data downloads

  • 0.1 m/pix DEM and hillshade downloads (tif): LINK
  • 0.1 m/pix orthoimage download (tif): LINK

Topographic profile

The video presented above discusses the topographic profile cut from the DEM in ArcMap towards the end. This would be the basis for the geologic cross section, preferably without vertical exaggeration.

Topographic profile location. Bent along the path of our Saturday November 22, 2020 tour. LINK to png.

Topographic data text file: LINK and MATLAB script to plot it: LINK

No vertical exaggeration. Link to png.

Vertical exaggeration. LINK to png

Friday, November 6, 2020

Thank you to the American Geophysical Union and colleagues for the Paul G. Silver Award for Scientific Service

Thank you for this great honor of the Paul G. Silver Award for Outstanding Scientific Service. Recognition from AGU’s Geodesy, Seismology, and Tectonophysics Sections adds to its heft. I am happy that Paul’s family is represented. I know we have all benefited from Paul Silver’s leadership and legacy. I was fortunate to meet him on several occasions and appreciated his wit and the spark that drove major science activities on which I was later able to contribute. I am humbled to be in the same list as those who have been awarded before. Congratulations to Doug Toomey--the other recipient this year of the award.

This recognition reflects the efforts of many of my colleagues with whom I have shared numerous projects. I know that many of you are strongly dedicated to serving your families and the communities of your private and scientific lives. I hope that this honor can lift us all as we acknowledge efforts to coordinate activity for our broader good helping others.

It has been satisfying and stimulating to help with major earth science efforts and organizations including GeoPrisms, Southern California Earthquake Center, EarthScope, AGeS - Awards for Geochronology Student Research, and OpenTopography. I share this recognition with collaborators and friends in those organizations. Colleagues in the National Science Foundation and US Geological Survey have worked mightily to sustain support.

I was inspired to serve by the example of many, including mentors Dallas Rhodes, David Pollard, and Manfred Strecker. Arizona State University’s School of Earth and Space Exploration Prof. Jim Tyburczy showed me a firm and balanced approach to leadership. My service as associate and deputy to SESE Directors Hodges, Elkins-Tanton, and Wadhwa has given me an opportunity to learn about academic administration and help students, faculty, and staff.

I want to close with a thank you to family including my sister and her husband and their daughters. Our parents--a teacher and a mechanical designer--steadfastly supported me. In their retirement, they served as the Los Ranchos (New Mexico) farmer’s market managers. Their dedicated and steady service made the market an institution. Thank you to my wife Amanda for her love and clear thinking which keeps us going in the right direction.

Here is a video of this speech: LINK

Friday, October 16, 2020

Understanding and interpreting rapidly changing Earth surface processes across a template of a rapidly urbanizing and increasingly connected world

Understanding and interpreting rapidly changing Earth surface processes across a template of a rapidly urbanizing and increasingly connected world is a major challenge. Our ability to observe and measure features on the Earth surface is increasing in quality, resolution, and temporal repeat. Thus, we have an opportunity to move understanding beyond the assumption of steadiness. It is clear that many surface phenomena occur rapidly (e.g., wildfires and the subsequent drainage network response, volcanic eruptions, earthquakes, mass movements, etc.). Each is part of a cascade of precursory and subsequent processes.

Revolutions in Earth observing and the connectedness of humanity (e.g., internet of things, social media) provide a major opportunity to characterize surface process events across the world. But they also provide a great data discovery, integration, and analysis challenge. How to bring the disparate observations into a common and quantitative 4D framework so they can be examined, and rates of change measured? For example, satellite imagery such as that available from provide a daily view of the Earth’s surface at <5m per pixel. This temporal and spatial resolution enables us to observe many phenomena at or near the spatial and temporal scales at which critical processes operate. Discovering these data is relatively straightforward, but their rapid integration with data for context, as well as with ground observations is difficult and time consuming. Integrating the synoptic view from the space-based platform with the typically less intentional but ubiquitous eyewitness views from social media posts or public image sharing platforms can provide essential ground truth, detailed observations of phenomena, and an indication of the human experience of the event.

For many events, a generic workflow can be imagined:

  1. Build on the well curated contextual geospatial data (landcover/land use, topography, imagery, 3D structures) to include (with proper geo- and temporal referencing) near real time Earth observations and compute if necessary derived products of interest (e.g., NDVI for vegetation health).
  2. Discover, locate in time and space, assess for veracity, and examine user contributed or freely posted images and videos from the ground (and maybe from UAS).
  3. Use the high geodetic accuracy of the framework to measure changes using space-based, airborne, and ground-based data. These changes may be spectral or 3D. Use the measurements to contribute to process-based models.
  4. Present predicted conditions (e.g., hazard maps and forecasts) potentially in a updating cycle defined by subsequent additional observations.
  5. Educate both in the short term (explain the event) and long term (enhance science and engineering literacy).

Several uses cases are evident:

  1. Wildfires: Map forest health using space imaging (NDVI) before, during, and after wildfire seasons. Much commercial space imaging is well configured for measuring vegetation vigor. Exposure of the built environment to the fires (and to subsequent debris flows) would be easy to explore, and hazard maps easily visualized. Including user contributed or freely posted images and videos from the ground (and maybe from UAS) during the fires and after would provide a sense of the detailed processes and phenomena.
  2. Debris flows in mixed wild-agricultural-urban environments: Flooding, especially by heavy sediment-laden flows, are hazardous and their conveyance highly sensitive to the complex 3D near surface environment which many include natural and built structures. Observations of them include larger watershed scale activation and evolution during storm events (space and airborne observations potentially combined with very high resolution 3D data from as built urban models and with on ground experiences from mobile phone picture and video). Flow simulations are available and may be useful for forecasting hazardous conditions, and also maybe updated and calibrated with detailed observations.
  3. Tsunami inundation in complex coastal environments: The 2011 Tohoku Japan earthquake and tsunami showed the very complex and rapid large scale interaction of the rising waters and the coastal Japanese environment. These were observed by some airborne and many haphazard ground-based views. Integrating those observations, and georeferencing imagery to help to measure inundation depths and flow velocities could be done with value for fluid dynamics simulations as well as for tsunamic education for coastal communities.
  4. ETC.

I wanted to capture this text that I contributed to a recent proposal and stash it here.

This is part of some ideas that I have been working on with capstone students in our capstone class. Here is a link to a presentation: LINK.