Effects of Lithologic Heterogeneity on Landscape Evolution in the Canyons of the Colorado Plateau

Courtney StarlingKelin Whipple

Andrew Darling

Arizona State University

Brian Clarke

2014-2015 Arizona Space Grant Symposium

April 18, 2015

OutlineObjectives: Characterize

lithologic heterogeneityMethod: Seismic refraction studyAnalyze field findings using

seismic softwareCompare p-wave field velocities

to lab core sample velocities.

Seismic Refraction Field StudyP-wave – Propagates parallel to

particle motion.

Measure p-wave velocities using Geophones and seismographs.

Animation courtesy Larry Braile, Purdue University

Geophones: 24 spaced ~2m for 48m~9 shots, along entire length (~every

6m)

Seismic Refraction Time vs Distance

Animation courtesy of Craig Lippus, Geometrics Inc.

Field Set-upSeismic HammerSeismic PlateGeophonesMeasuring Tape

Photo Courtesy of Marina Bravo Foster, ASU

Find Field P-wave velocityUse Seisimager software -

PickwinMake first picks

P-wave velocity at depthAs depth increases p-wave velocity

increases

Figure courtesy of Brian Clarke

Esplanade 5 Formation

• Ray paths from geophones– Determines depth of model

Esplanade 5 Formation• Surface Velocity: 0.6-0.9 km/s– Weathered rock at surface to Soil

• Velocity at Depth: 2.0-2.2 km/s

Other Tomographies

Hermit 2-Elevated Formation- Slow Velocities

Navajo 1-Longest survey

Claron 2-Fast Velocities at Depth

ConclusionsField Velocities confirm earlier

observationsFormations with outcrops of bedrock-

faster field velocities.Future work – Compare Field to Lab

Velocities

11

Survey NameMinimum Velocity

Maximum Velocity

Minimum Velocity

Maximum Velocity

Kaibab5 0.3 0.9 1.6 2.3 3.62Esplanade5 0.6 0.9 2 2.2 3.72Esplanade4 0.8 2.5 2.5 2.5+ 2.86Claron1 0.5 1.2 2.2 2.4 5Claron2 0.5 1 2.4 2.5 5.11Navajo1 0.4 0.5 1.1 1.3 9.24Hermit 2 0.3 0.5 1.4 1.4 5.71

Data Depth

(m)

Surface Velocity (km/s) Velocity at Depth (km/s)

Thank You

Acknowledgements:

Dr. Kelin WhippleDr. Brian ClarkeAndrew Darling

Marina Bravo Foster