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

Alaska Volcano Observatory GPS Network Spurr - SPCP-Spurr Crater Peak P.S.
Start: 07-Aug-2011
End: 10-Nov-2022
Freymueller, Jeffrey T., Grapenthin, Ronni, 2011, Alaska Volcano Observatory GPS Network Spurr - SPCP-Spurr Crater Peak P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5JH3JKB