EarthScope Plate Boundary Observatory

 

What is EarthScope and the Plate Boundary Observatory?

In 2003, Congress appropriated $218 million to build the EarthScope instrument network, designed to be a "telescope" into the Earth. EarthScope is the largest physical science instrumentation construction project ever funded. UNAVCO, Inc., on behalf of the National Science Foundation (NSF) and EarthScope, is in the process of developing a network of permanent GPS and strainmeter stations to monitor Earth processes associated with earthquakes and volcanic activity. The network being constructed is called the Plate Boundary Observatory (PBO).

PBO is a distributed observatory of high-precision geodetic instruments designed to image the ongoing deformation of western North America. The geodetic network will extend from the Pacific coast to the eastern edge of the Rocky Mountains, and from Mexico to Alaska. Two complementary instrumentation systems - Global Positioning System (GPS) technology at about 875 sites and ultra low-noise strainmeters at 175 locations - will provide superior time resolution. A sparse GPS network at 100-200 kilometer spacing, connecting about 20 dense clusters located at active volcanoes and the most active earthquake faults, will provide complete spatial coverage. High precision GPS stations require a drilled and braced monument with a high quality geodetic antenna, equipment enclosures, solar panels and mounts, and a communications terminal (radio, VSAT, dial-up modem). Once installed GPS stations require approximately 3X3 m plot of land. Strainmeters require a 200 m (600 ft) deep borehole with an 8-inch casing, equipment enclosures, solar panels and mounts, and a communications terminal (radio, VSAT, dial-up modem). Once installed strainmeters require approximately 4X4 m plot of land.

Figure 1. PBO Network Design showing proposed GPS site locations.

Construction of GPS installations would require either handheld motorized auger and drill or a drilling rig capable of drilling to 15m depth, depending on site-specific conditions. Because of the depth involved with borehole strainmeter installations, a drill rig capable of drilling to 200m would be required. All sites would be permitted for operation for a 10-year period with the option to renew depending upon NSF funding levels.

Of the proposed 875 GPS sites, an estimated 120 could fall on BLM lands. At this time we do not anticipate locating any strainmeter installations on BLM lands.

The table below outlines the steps we plan to take in each state and BLM district. Currently PBO has provided brieifings to BLM offices in Alaska, California, Idaho, Oregon, and Washington. We plan to brief the last two large PBO/BLM states in July (Nevada and Utah).

Action/Event What? Who?
Briefing to State Realty Leads/Program A briefing on the impacted districts, schedule, NEPA compliance issues, who to deal with at the districts PBO provides briefing. State office advises districts of upcoming activity
Breifing to Districts A briefing with district realty staff and ID team represenatives

PBO provided briefing and establishes contacts with district office personnel
Pre-Application Meeting (can be combined with above briefing) PBO will bring detailed maps showing the siting tolerance for each GPS site. ID team members will help identify potential areas that may be suitable or unsuitable for siting PBO will bring maps and siting criteria to the meeting. BLM staff will provide local knowledge about site. This activity can be covered under cost-recovery.
Field Recon of potential sites PBO staff will identify sites on the ground that meet inclusionary and exclusionary siting criteria. BLM staff could accompany if available. Orange stakes will be placed at the site indicating the location of the GPS mounumnet and a second stake to indicate where the solar panles/equipment would go. A report will be prepared for each site. PBO staff prepare recon reports of sites visited in the field.
SF-299 Submittal PBO will prepare one SF-299 submission for all potential sites in a given district. BLM will assign a cost recovery category. PBO will submit a completed SF-299 application to the district
NEPA compliance BLM will indicate what if any additional NEPA compliance work is required BLM will indicate if cultural/T&E surveys are required. PBO will contract or reimburse BLM to perform.

In order to permit the GPS sites for installation on BLM lands, PBO will file SF-299 applications with each district and prepare the necessary NEPA compliance documents. EarthScope has undergone extensive peer review during the funding phase and has the broad support of the earthscience community, including the USGS, NASA and other federal agencies.

EarthScope is a major research project that will provide high accuracy GPS and Seismic data to researchers in over 100 universities and federal agencies, and to the broader GPS user community. One of the goals of EarthScope is the monitoring of natural hazards like volcanoes and fault systems and the long term benefit to Safety-of-Life and hazard prediction systems is a worthy objective that requires the cooperation of land owners.

What does a PBO GPS installation site look like and what does the facility consist of?

The PBO GPS stations require approximately a 10m x 10m temporary use construction area. Once completed the GPS site occupies approximately a 3m x 3m area. The site can be fenced if needed, painted to match the surrounding terrain, and landscaped depending on the wishes of the landowner. There will be one maintenance visit per year at most. Sites can be located away from trails and facilities if desired. Every PBO GPS station has a siting tolerance associated with it that allows for a range of location options. Typically this siting tolerance varies between 5 km and 100 km depending on the location of fault systems. PBO would prefer to locate in areas of existing development to minimize the environmental impacts. Also, the PBO GPS station could be constructed so that it is visible to the public and an interpretative display could be constructed at the site to explain to the public what EarthScope is. Once again, station location options can be discussed with BLM staff to either minimize the visibility to the public or to maximize the educational benefit to the public by having a visible station.

PBO site construction utilizes two methods. When completed, each type of GPS site looks identical. For deconstruction of the site, all above ground equipment will be removed and the brace legs will cut off at ground level.

Monument Specifications: Deep Drill Braced Monument Short Drill Braced Monument
Physical/Cultural Setting near roads and existing infrastructure remote locations or near existing infrastructure
Geological Setting alluvial material, soil, clay, fractured rock, other material unfractured bedrock
Construction Techniques track mounted drill rig, auger or percussion drilling, no drill fluids or mud hand tools
brace leg hole diameter 3" with 1" stainless steel brace rod, airspace filled with non-expansive grout 1.5" with 1" stainless steel rod, epoxied into hole
brace leg depth 10m to 15m 2m
GPS monument height when completed about 2m about 2m
days to build monument 2-3 days 1 day
data relay method cellular modem (preferred), VSAT satellite modem, or relay uplink to internet connection cellular modem (preferred), VSAT satellite modem, or relay uplink to internet connection
power system AC power where available, gel cell battery backup or solar panel array mounted on 3" pole 2m tall with gel cell battery in a metal enclosure AC power where available, gel cell battery backup or solar panel array mounted on 3" pole 2m tall with gel cell battery in a metal enclosure
Contractor Usage will utilize a contractor for drilling only, equipment installation by PBO staff all work performed by PBO staff

Figure 2. PBO Deep drill and Short drill monuments

Figure 3. Completed PBO station

 

Plate Boundary Observatory Continuously Operating (PBO) GPS (CGPS) reference stations could provide several benefits to the BLM. Benefits fall into four categories.

1. GPS surveys conducted by BLM staff could reference the PBO CGPS station to post-process differentially correct the data. This would eliminate the need for BLM to tie up equipment by running their own base station. Also, the PBO CGPS station is a high quality stable monument with known velocity vectors so data collected in the future could always be referenced and adjusted to a single known point. These benefits extend to both resource grade (1-5m accuracy) surveys and precision geodetic (0.1 cm-40 cm accuracy) surveys. In particuler, BLM survey activities related to GCDB activities could be greatly enchanced by a network of stable CGPS monuments. In addition, RTK data streams are available from every PBO station. BLM field surveyors need only bring a standard RTK broadcast radio and plug it in to use this feature. This allows real-time accuracy of 2-5cm in a radius of 5-15 km from the PBO site.

2. PBO will be providing information about plate movement and crustal deformation. In some BLM districts, this information is very relevant, for example, areas in the desert of California. PBO has an Education and Outreach component that will be able to provide information about the science of GPS based geodesy in the form of educational materials. A part of this will include locale specific information about what PBO is finding in terms of plate motion and rates of deformation.

3. One component of PBO is the GEO-Earthscope project. This component will be acquiring over $4,000,000 of LIDAR imagery and aerial photography in areas where PBO sites are located. Potential imaging targets could include BLM lands which would benefit from accurate, up-to-date imagery of the area that could be used for other resource management activities. All GEO-Earthscope data will be freely available.

4. Because PBO stations transmit data back to our Boulder facility in near real-time, there will be TCP/IP telemetry links at the majority of PBO stations. In many cases there will be extra bandwidth available for station landowners to use for webcams, gauging stations, meteorological sensors, wildlife telemetry uplinks, and other types of sensors. Each PBO station will have a router with RJ45 connections that many of these devices interface with directly. In addition, over 200 PBO stations will be equipped with meteorological sensors.

Resources for BLM Staff

PBO has prepared a "Plan of Development" document that identifies siting criteria, environmental impact mitigation strategies, and other relevant planning documents. This file is in PDF format and this example is for Alaska, however, the general concept of what we are proposing and how we plan to do it is correct for all regions.

A Powerpoint briefing on the project can be downloaded here.

An online web mapping interface that shows the location of PBO GPS sites, land ownership boundaries, and other information can be found at arcims.unavco.org .

We have identified potential sites that fall on BLM land and prepared an EXCEL spreadsheet with maps and BLM district site counts. Please click here to download.

Additional information about the project can be found at the PBO website and the EarthScope website.

For project questions, please email Dr. Michael Jackson, director, or the Permitting Coordinator, Kyle Bohnenstiehl.

Site updated 7/01/2004