GPS monitoring stations in the Puerto Rico Seismic Network
The permanent Global Positioning System (GPS) of the Puerto Rico Seismic Network (PRSN) operates continuously since early 2008. The network monitors movements of the earth's crust in Puerto Rico and the Virgin Islands and is funded by various agencies including the National Science Foundation (NSF), the United States Geological Survey (USGS) and the National Administration for Oceans and Atmospheric Administration (NOAA). The data is transmitted in real time from the station and are archived and processed at PRSN headquarters in Mayagüez. It has been demonstrated on several occasions recently that the fundamental basis use of this data for monitoring large earthquakes can provide the true magnitude of an earthquake by quickly using the static displacement of the stations during a seismic event.
The real time GPS (RTGPS - Real TimeGPS) includes 12 stations distributed between Puerto Rico and Virgin Islands. The PRSN NTRIP (Networked Transport of RTCM via Internet Protocol) caster provide data in the RTCM format. Access to the data in real-time is available upon request. In addition to PRSN stations, there are several other stations operated by UNAVCO, as part of the project Continuously Operating Caribbean GPS Observational Network (COCONet) , and the National Geodetic Service (NGS). An advantage of the PRSN stations is that they are being collocated with seismic and strong motion instrumentation from the PRSN. In addition to real-time transmission , each GPS receiver in the field has an internal memory that stores two types of files: (a) A data file with sampling rate of 30 seconds (two measurements per minute) , and (b) a data file every half hour with a sampling rate of 1 second (1 measurement every second or frequency of 1 Hz). These files allow for data completion in case the real-time transmission fails. The files are downloaded from the receiver via a file transfer protocol (FTP) routine and stored on a server at PRSN. Data repositories at PRSN and UNAVCO provide data availability free of charge