GPS monitoring data from spider units on the post-disaster 2014 Oso landslide, Snohomish County, Washington

Data in this release record ground-surface positions obtained during post-disaster emergency response following the 2014 catastrophic Oso (SR 530) landslide, Snohomish County, Washington. Global Positioning System (GPS) data were collected using three USGS GPS-seismometer spider units deployed adjacent to (OSO1), upslope of (OSO2), and on (OSO3) the landslide (see image for locations) for about five weeks. Details of the post-disaster response as well as the spider units are described in the accompanying publication. Positions were determined in near real-time relative to a base-station GPS receiver (OSO0) located on stable ground less than 2 km from the landslide using static, differential GPS processing techniques. The spider positions over time were computed using GPS L1-only data collected every 15 seconds and processed about every 10 minutes using the previous 3-hour periods of data. Data are presented as latitude, longitude, and ellipsoid height in the World Geodetic System 1984 (WGS 84) coordinate system with times in Coordinated Universal Time (UTC). Horizontal coordinates are also presented as converted into Universal Transverse Mercator (UTM) values. Differences in horizontal and 3D positions over time, relative to the initial spider locations, are included. Time gaps in the data sets indicate that insufficient GPS data were available to obtain fixed ambiguity, high quality, static solutions during the gap time periods. Details of the GPS processing techniques are further described in the Procedure section of the FGDC Metadata. Seismic data from the same spider units are available through IRIS. This data release includes: 1) image showing locations of the three GPS-seismic spider units relative to the Oso landslide, 2) initial positions (WGS 84) of the three spider units and the reference base station, OSO0, and 3) three files containing ground-surface positions and horizontal and 3D movement amounts for OSO1, OSO2, and OSO3 spiders over the monitoring period.