Exciting news! We're transitioning to the Statewide California Earthquake Center. Our new website is under construction, but we'll continue using this website for SCEC business in the meantime. We're also archiving the Southern Center site to preserve its rich history. A new and improved platform is coming soon!

Dating of alluvial fans by surface reflectance imaged with AVIRIS and EMIT spectroscopy

Chris Anthonissen, Robert Zinke, & James F. Dolan

Submitted September 10, 2023, SCEC Contribution #13227, 2023 SCEC Annual Meeting Poster #085

Alluvial fans are sediment deposits found throughout arid regions, and are commonly used to measure and date past movements of earthquake faults. Offsets of these fan surfaces are readily measured, while the dating of these fans, using methods like luminescence or radiometric isotope dating are costly and time consuming.

The reflective properties of these surfaces change over millennial time scales through the development of iron-oxides and clay mineral on the surface, and studies using multi-spectral data (e.g., D’Arcy et al., 2018) have shown that that it may be possible to use remote sensing data to quantify these changes and determine fan ages. We use freely available Hyperspectral data, specifically the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and newly launched, ISS-mounted Earth Surface Mineral Dust Source Investigation (EMIT) imaging spectrometer, to quantify the spectral properties of multiple alluvial fan surfaces at two sites in the Mojave Desert, along the Garlock fault in Southern California. We use published ages of fan surfaces and new Infrared-luminescence (IRSL) fan ages and compare these to the spectroscopic data from these Hyperspectral sensors to determine an age dependent relationships.

Sites were selected to have homogenous granitic source material, ensuring that changes in reflective properties are a function of time and not of source lithology.

A marked decrease in the reflection of short-wavelength radiation (at ~500 nm) and increases in the reflection of infra-red radiation (at ~800 nm) are observed on older, increasingly weathered fan surfaces, and hyperspectral data here are used to quantify diagenetic minerals like hematite and Al-OH minerals, all believed to be proxies for fan age.

The exceptionally high spectral resolution of the data allows us to apply several statistical and mineral based approaches to find age-reflectance proxies that may be applied to alluvial fan mapping and earthquake studies more generally. The low-cost of this approach further ingratiates this as a tool to supplement datasets with limited age controls.

Anthonissen, C., Zinke, R., & Dolan, J. F. (2023, 09). Dating of alluvial fans by surface reflectance imaged with AVIRIS and EMIT spectroscopy. Poster Presentation at 2023 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Geology