United States of America
Alaska North Slope LiDAR
High-resolution light detection and ranging (lidar) elevation data were acquired along the north coast of Alaska between 2009 and 2012. The lidar acquisition, from Icy Cape, Alaska to the United States/Canadian border, comprised approximately 11,000 km2. The airborne lidar data were acquired in support of the U.S. Geological Survey...
Filtering of Elevation Difference Mask to Identify True Topographic Changes
The output of the differencing and thresholding procedures described above was a set of pixels with elevation differences large enough to be judged significant. Ideally, these differences would represent the set of true topographic changes that could then be used for further analysis. In reality, this was not the case, as the selected differences included areas that clearly did not reflect...
Significant Change Thresholds
The next step in the data processing procedure was to threshold the difference grids to isolate areas of significant change. This procedure is commonly done in the image differencing method of change detection, and the threshold is often based on the standard deviation value of the differences. As implemented for this study, the thresholding approach incorporated the inherent absolute vertical...
What if the ShakeAlert Earthquake Early Warning System Had Been Operating During the M6.9 1989 Loma Prieta Earthquake?
How will ShakeAlert® likely perform now on a large earthquake impacting a major urban area? How much warning will you get? To answer this, let’s do a thought experiment...
Ecosystems: EXPRESS
The continental shelf and slope offshore California, Oregon, and Washington are home to deep-sea corals, chemosynthetic communities, and other sensitive habitats that could be impacted by the development of energy and mineral resources. The EXPRESS campaign will map and...
Resources: EXPRESS
Along the U.S. west coast, the Pacific Ocean, ocean floor, and winds above contain potentially vast energy and mineral resources. Developing these resources safely and wisely requires detailed information for each area of interest. One goal of EXPRESS is to inform ocean...
Hazards: EXPRESS
Marine geohazards including earthquakes, landslides, and tsunamis lie offshore of densely populated areas of California, Oregon, and Washington. One goal of EXPRESS is to improve assessments of these hazards.
Earth As Art 6
As always, our newest collection of Earth As Art relies on the interplay of visible and invisible light across the electromagnetic spectrum made possible by satellite sensors. The stunning views seen in Earth As Art 6 carry on that two decade tradition, but also include high-resolution imagery captured by Unmanned Aircraft Systems - commonly referred to as drones - for the first time. ...
Beavers Impacting Tundra Ecosystems (BITE)
The range expansion of the North American beaver (Castor canadensis) has implications for water quality, aquatic ecosystems, and fisheries in Arctic streams.
California Seafloor Mapping Program
The California Seafloor Mapping Program (CSMP) is a cooperative program to create a comprehensive coastal/marine geologic and habitat base map series for all of California's State waters. The California Ocean Protection Council (COPC) authorized funds to establish the CSMP in 2007 (...
Accuracy Assessment of Elevation Data
The thresholding approach (described below) used to distinguish significant differences from the raw difference grids requires a measure of the absolute vertical accuracy of each input elevation dataset. The NED and SRTM data were compared to an independent reference geodetic control point dataset from NGS. These points have centimeter-...
Southern California / Channel Islands - Topobathymetric Elevation Model of the Channel Islands
Located in the Pacific Ocean off the coast of California, the Channel Islands are a chain of eight islands where years of isolation has created unique fauna, flora, and archeological resources. Five of the islands are part of Channel Islands National Park (Anacapa, Santa Cruz, Santa Rosa, San Miguel, and Santa Barbara), and the waters surrounding these islands make up the Channel Islands...