Geology topics

Russell P. Rykhus

Publications and source records attributed to Russell P. Rykhus.

6 recordsLinked to original sources

USGS2014

InSAR detects possible thaw settlement in the Alaskan Arctic Coastal Plain

Satellite interferometric synthetic aperture radar (InSAR) has proven to be an effective tool for monitoring surface deformation from volcanoes, earthquakes, landslides, and groundwater withdrawal. This paper seeks to expand the list of applications of InSAR data to include monitoring subsidence possibly associated with thaw settlement over the Alaskan Arctic Coastal Plain. To test our hypothesis that InSAR data are sufficiently sensitive to detect subsidence associated with thaw settlement, we acquired all Japanese Earth Resources Satellite-1 (JERS-1) L-band data available for the summers of 1996, 1997, and 1998 over two sites on the Alaska North Slope. The least amount of subsidence for both study sites was detected in the interferograms covering the summer of 1996 (2-3 cm), interferograms from 1997 and 1998 revealed that about 3 cm of subsidence occurred at the northern Cache One Lake site, and about 5 cm of subsidence was detected at the southern Kaparuk River site. These preliminary results illustrate the capacity of the L-band (24 cm) wavelength JERS-1 radar data to penetrate the short Arctic vegetation to monitor subsidence possibly associated with thaw settlement of the active layer and (or) other hydrologic changes over relatively large areas.

Canadian Journal of Remote Sensing↗

USGS2011

Satellite imagery maps Hurricane Katrina-induced flooding and oil slicks

In the early morning of 29 August 2005, Hurricane Katrina made landfall near Buras, Louisiana, as a Category 4 hurricane. With wind speeds of about 233 kilometers per hour, a storm surge of 8.5 meters, and heavy rains, Katrina pounded the U.S. Gulf Coast states of Alabama, Louisiana, and Mississippi with lifethreatening flooding and destruction. Katrina's high winds and storm surge breached the levees protecting New Orleans, a city located below sea level, and flooded approximately 80% of the city. Katrina also caused major damage to the region's oil and natural gas production and refining capabilities. On 2 September 2005, the Associated Press reported that Katrina had damaged 58 oil platforms, 30 of which were reported lost; one damaged platform had been blown nearly 100 km from its original location.

Eos, Earth and Space Science News↗

USGS2006

Thickness distribution of a cooling pyroclastic flow deposit on Augustine Volcano, Alaska: Optimization using InSAR, FEMs, and an adaptive mesh algorithm

Interferometric synthetic aperture radar (InSAR) imagery documents the consistent subsidence, during the interval 1992–1999, of a pyroclastic flow deposit (PFD) emplaced during the 1986 eruption of Augustine Volcano, Alaska. We construct finite element models (FEMs) that simulate thermoelastic contraction of the PFD to account for the observed subsidence. Three-dimensional problem domains of the FEMs include a thermoelastic PFD embedded in an elastic substrate. The thickness of the PFD is initially determined from the difference between post- and pre-eruption digital elevation models (DEMs). The initial excess temperature of the PFD at the time of deposition, 640 °C, is estimated from FEM predictions and an InSAR image via standard least-squares inverse methods. Although the FEM predicts the major features of the observed transient deformation, systematic prediction errors (RMSE = 2.2 cm) are most likely associated with errors in the a priori PFD thickness distribution estimated from the DEM differences. We combine an InSAR image, FEMs, and an adaptive mesh algorithm to iteratively optimize the geometry of the PFD with respect to a minimized misfit between the predicted thermoelastic deformation and observed deformation. Prediction errors from an FEM, which includes an optimized PFD geometry and the initial excess PFD temperature estimated from the least-squares analysis, are sub-millimeter (RMSE = 0.3 mm). The average thickness (9.3 m), maximum thickness (126 m), and volume (2.1 × 10 7 m 3 ) of the PFD, estimated using the adaptive mesh algorithm, are about twice as large as the respective estimations for the a priori PFD geometry. Sensitivity analyses suggest unrealistic PFD thickness distributions are required for initial excess PFD temperatures outside of the range 500–800 °C.

Alaska↗

USGS2003

Studies of Alaskan volcanoes using synthetic aperature radar and Landsat imagery

Approximately 10 percent of the world’s active volcanoes are located in the Alaskan Aleutian arc and produce about 3-4 explosive eruptions per year. Even with this high amount of volcanic activity, the remote locations and harsh environments of the Aleutian volcanoes conspire to keep them among some of the most poorly studied volcanoes in the world. Space-borne remote sensed imagery can play a significant role in improving our understanding of activity at these volcanoes. Synthetic aperture radar (SAR), Landsat imagery, and Digital Elevation Models (DEMs) derived from SRTM and the National Elevation Database (NED) are used to study several Alaskan volcanoes. Interferometric SAR (InSAR) techniques with ERS-1 and ERS-2 SAR imagery are used to measure ground-surface deformation, which enables the construction of detailed mechanical models that enhance the study of magmatic and tectonic processes. The 30-year historical archive of Landsat data is used to study land cover change, visualize the ash plumes of Aleutian volcanic eruptions, and to map the extent of lava flows. Differencing two DEMs that represent volcano topography before and after an eruption makes it possible to calculate the volume of extruded materials. This paper provides a progress report on how InSAR, Landsat imagery and digital elevation data can be used to better understand the volcanic processes at three Aleutian volcanoes.

Alaska↗

USGS2003

Deriving rangeland structural attributes using Landsat ETM+, ERS-1/ERS-2

The purpose of this study is to determine if Synthetic Aperture Radar (SAR) can be used independently, or in conjunction with Landsat Enhanced Thematic Mapper Plus (ETM+) to improve the classification accuracy of structural attributes of rangeland vegetation, particularly percent shrub cover and top shrub canopy height. Such information, if mapped accurately, can be used in models to better characterize fuel conditions and fire regimes, as well as to evaluate fire hazard status, called for by the U.S. National Fire Plan. The input datasets utilized in this investigation included eighteen bands of Landsat ETM+ path 38 / row 32 (three image dates, six bands each), backscattering and interferometic data derived from tandem ERS-1/2 SAR image pairs (C-band), and extensive field point data. The results showed the use of SAR data provided no significant improvement over the ETM+ data for estimating percent cover or shrub canopy height. The lack of improvement in classification accuracy is possibly due to the influence of topography on the radar backscattering signal. Additional results demonstrated improved model accuracies when a 3x3-averaging filter was applied to the eighteen bands of ETM+ imagery.

Conference Paper↗

USGS2002

Synergistic use of FIA plot data and Landsat 7 ETM+ images for large area forest mapping

FIA plot data were used to assist in classifying forest land cover from Landsat imagery and relevant ancillary data in two regions of the U.S.: one around the Chesapeake Bay area and the other around Utah. The overall accuracies for the forest/nonforest classification were over 90 percent and about 80 percent, respectively, in the two regions. The accuracies for deciduous/evergreen/mixed and forest type group classifications were around 80 percent and 65 percent, respectively, and were consistent in the two regions. These results suggest that use of FIA plot data together with satellite imagery and relevant ancillary data may substantially improve the efficiency, accuracy, and consistency of large area forest land cover mapping.

Conterminous United States↗