Yes, the stations need to be broadcasting in real-time. I didn't read the article, but have been in MANY meetings where this was discussed. Conventional seismic instruments "clip" (get flooded out) at about a magnitude 6.8 or above when near the epicenter, making them ineffective in quickly determining a true magnitude. By using the GNSS "offsets" and performing some sort of high level math (triple integration?) the magnitude (P wave?) can be calculated much more accurately in maybe 10-15 seconds, which allows for the earthquake early warning (EEW) system to issue the proper alerts over the appropriate distances.?ÿ
The Fukushima data shows that had the GNSS instrumentation been integrated into the EEW system, they would have known it was closer to a 9.0 than the much lower magnitude they thought it was when they activated the EEW system and calculated the height and inland surge of the subsequent tsunami.
i like a lot of what Yehuda Bock has written on this and related topics. See: https://www.scec.org/user/ybock
I remember his epoch-by-epoch processing approach. Smart guy.
I have worked with Yehuda for years though the CSRC and attended several meetings with him and others to brief CalOES on the importance of integrating geodetic instrumentation into a robust EEW System for California. I am currently working with him on the development of a 3D dynamic datum modeling tool (HTDP on steroids) for California, which is currently being beta tested.?ÿ
Sure makes a guy humble when running in those circles.