The Network of the Americas (NOTA) GNSS Network in California - Providing Reliable Data Streams for Early Warning Applications

Christian Walls, Doerte Mann, Ryan C. Turner, Shawn Lawrence, Ken Austin, Glen S. Mattioli, Tim Dittman, & Karl Feaux

Published August 14, 2018, SCEC Contribution #8591, 2018 SCEC Annual Meeting Poster #133 (PDF)

The Network of the Americas (NOTA) GNSS Network in California, funded by the NSF and operated by UNAVCO, is comprised of 599 permanent GPS and GNSS stations spanning three principal tectonic regimes. The Plate Boundary Observatory (PBO) is being federated with other NSF-funded cGNSS networks (TLALOCNet in Mexico and COCONet spanning the Caribbean) into the hemisphere-scale multi-platform Network of the Americas (NOTA). While NOTA was originally designed for tectonic and volcanic analysis using 24-hr daily files, it has proven to be of significant value to stakeholders who use real-time data streams for early warning systems (i.e. earthquake, tsunami, meteorological). 497 of NOTA stations in CA are currently streaming GPS (n=376) or GNSS (n=121) data in real-time with the majority of stations located along plate boundaries of the Cascadia subduction zone and the San Andreas Fault system. Of these stations, 44 real-time GNSS sites are located within 15 km of the west coast and benefit ionospheric studies for tsunami wave height detection and 49 stations also stream meteorological data. The 1 Hz real-time data is available from UNAVCO in BINEX and RTCM3 formats along with PPP position estimates generated for each site and broadcast in the NMEA format.

Providing complete, low-latency GNSS real-time streams from the site to the processing center hinges critically on operational equipment and reliable data telemetry. These in turn rely on a comprehensive state-of-health monitoring system that allows us to optimize station maintenance activities and equipment upgrades, prevent data loss and telemetry outages, and optimize data quality. We present an overview of the types of telemetry used in the network and performance metrics as well as the tools we use for GNSS state-of-health monitoring.

Robust GPS/GNSS real-time streams are essential for any type of GNSS-supported early warning application. For Earthquake Early Warning, high data completeness is needed to estimate peak ground displacement, depth and magnitude of an event, whereas low data latencies facilitate a rapid warning for a larger area. We present an update on our activities of incorporating NOTA GNSS stations into the Shake Alert Earthquake Early Warning System that is being developed for California, Oregon, and Washington.

Key Words
GNSS, earthquake early warning, telemetry

Citation
Walls, C., Mann, D., Turner, R. C., Lawrence, S., Austin, K., Mattioli, G. S., Dittman, T., & Feaux, K. (2018, 08). The Network of the Americas (NOTA) GNSS Network in California - Providing Reliable Data Streams for Early Warning Applications. Poster Presentation at 2018 SCEC Annual Meeting.

Related Projects & Working Groups
Tectonic Geodesy