The following information obtained from UNAVCO's online DOI system:
(https://www.unavco.org/data/doi/search/search.html)

Rio Grande Rift GPS Network - RG18-RG18TwLakeCO2007 P.S.
Start: 31-May-2007
End: 27-Aug-2020
Sheehan, Anne, 2007, Rio Grande Rift GPS Network - RG18-RG18TwLakeCO2007 P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5SX6BFH