Accumulating links for M6.5 earthquake 72 km west of Challis Idaho 3/31/2020 4:52 pm

An earthquake occurred in Idaho today 72 km west of Challis Idaho and about 120 km northeast of Boise Idaho. Based on the magnitude and location, I would think that it looks to be a classic Basin and Range earthquake rupturing along the mountain front south and west of Stanley Idaho (if it occurred along the Sawtooth fault--the closest active fault). But the focal mechanism is more strike-slip; we will have to wait for some updates.

The event was widely felt in the Intermontane west with light to moderate shaking in Boise. It was felt as far as Salt Lake City, Bozeman, and Spokane. The strongest ground motions appear to have been in the relatively low population Challis National Forest. Numerous aftershocks are expected.

Location of the epicenter in the Sawtooth Mountains. The yellow line to the south is the Sawtooth fault. Note the focal mechanism indicating strike-slip sense of motion

Links:

• Main USGS Page on the event
• Idaho Geological survey page on the event
• Fault map of the area from Idaho Geological Survey
• Seismogram recorded at ASU (thanks to John West, Ed Garnero, and Wendy Lin)
• Ground Motion Visualization from IRIS
• Writeup on the event from Temblor.net by Tiegan Hobbs
• UNAVCO response page
• Mapping of the area by Sotiris Valkaniotis
• Seismicity map by Jascha Polet
• Geologic map of the area (H/T Mike Bunds)
• Geomorphic pondering by Austin Elliott
• Commentary on why this would not be likely to have an effect on Yellowstone volcanic system (note that Mike Poland is an ASU Alum)--comments are for the Utah earthquake from a few weeks ago, but still generally relevant.
• Tectonic setting (from UCB Seismo Lab)

Virtual field geology exercises for GLG451 Field Geology I Spring 2020

Even before the COVID-19 crisis changed everything, I was working this semester to build some virtual options for my Field Geology I (GLG451) course. Two students are physically unable to do the field work, and then another had a crisis and missed two weekend field trips. The course has three weekend field trips and then a mini camp over spring break.

Locations of the field trips.

I decided to try to build some digital versions of the field trips using very high resolution digital elevation models and orthophotos from our SUAS systems (thanks to Tyler Scott for doing the flying and the SfM work). I wanted these to be as similar as possible to what the regular students experience so I give some initial information on the maps as well as numerous pictures from the ground and videos from the sUAS. For most of the exercises in the case of my class, I also am providing rock samples to the students of each of the mapping units.

All of the information for each of the assignments is in a long pdf which has the text assignment, links to data and images, etc. and then some explanation. It also has a topographic profile for a cross section, etc.
I am very happy to share with anyone who might find these useful. Here are the modules and the current status:

Module	Status	Link
Dreamy Draw, Phoenix Mountains, AZ	Done	LINK
Goldfields, Superstition Mountains, AZ	Done	LINK
Salt River, Bush Highway, AZ	Done	LINK
Arnett Creek, AZ	Done	LINK

Example video for the Goldfields in which we fly along the path of the introductory tour:

Here is an example of one of the explanatory tutorial videos for ArcGIS:

Here is geology tour for the Salt River mapping project:

Here is longer geology tour for the Arnett Creek Spring Break mapping project:

Accumulating links for today's southern Salt Lake Utah area earthquake (M5.65 earthquake 4km NNE of Magna, Utah: 03/18/2020 6:09:31 AM AZ time)

A M5.7 earthquake occurred this morning and it was widely felt along the northern Wasatch Front. Numerous aftershocks have occurred and will continue. Its characteristics are consistent with the crustal extension occurring in the region (Basin and Range).

I am accumulating some links here:

• Main USGS page on the event
• University of Utah Seismo lab post Site looks like it might be pretty busy here is their main page https://quake.utah.edu/
  UofU Seismo press conference
• Seismograms from AZ Broadband network (managed by SESE alum Jeri Young-BenHorin, PhD 2004)
• Seismogram plots from SESE seismologists John West and Ed Garnero
  Interpretation from Garnero: "for this earthquake we get to see some natural polarization of the surface waves, since the energy comes to ASU from due North. The Love wave is shear wave that vibrates purely perpendicular to the direction the energy comes from (thus we see something on the East-West component of motion that is not really present on the North-South or Up-Down). It is named after the mathematician A.E. Love who discovered them. In contrast, the Rayleigh wave (named after Lord Rayleigh) has P-wave and shear wave energy (that is perpendicular to the Love wave-making shear wave) combined, and it is nearly purely on the vertical and N-S components. It arrives after the love wave. We don't always see such a clear separately of the surface waves."
• Watch the seismic waves roll across North America on the USArray
• Nice graphic (updated) from Chris DuRoss on the event position relative to the projection of the Wasatch Fault
• Background from Utah Geological Survey: https://geology.utah.gov/map-pub/survey-notes/wasatch-fault-above/ (written by SESE alum Emily Kleber MS 2015; now works for Utah DNR and is out surveying the damage today)
  Nice overview of the Wasatch Fault history
• Teaching/explanatory items from IRIS (note that SESE alum Wendy Bohon PhD 2014 is one of their communications leads):
  Animation of Basin and Range extension measured by GPS
  Normal fault animation