We have detected problems with timing quality and metadata of the strong motion channels at DMH/GEOFON Station Naypyitaw (GE.NPW, BN* and HN* channels).
There was an error in the gain factor (factor of 2 too large, so real acceleration probably twice as large as obtained using current metadata) for all three components of the strong motion record.
There was no GPS signal, so absolute time is not reliable.
When we have corrected metadata we will provide updates here. If you have downloaded NPW metadata, you should replace it with the better version we will add here soon.
Also, real-time data from this station was unavailable for several hours following the large earthquakes of 28 March. Much of this has now been recovered and archived, and is available for download.
Our metadata for GE.NPW has been updated. You can download it as usual. Reponse-level metadata as StationXML is available from https://geofon.gfz.de/fdsnws/station/1/query?level=response&net=GE&station=NPW.
Thanks for keeping us all abreast of this and for your speedy work! This station is so valuable for understanding the event. Just to be clear, are you saying that:
(i) The broadband channels have reliable timing, but the strong motion doesn’t, and that the strong motion gain values are now appropriate
or
(ii) All channels have reliable timing and reliable responses
Looking at the arrivals at the station, it looks to be early, but since people are also saying this is a supershear rupture (based on back projection of teleseismic data) it’s not clear how early this near-fault arrival is. Given the station is right on the fault and about 240-250 km from the fault, and we can see when the rupture passes the station, because it has a displacement of about ~1.5 meters at 50-seconds after the origin. So that’s a rupture velocity of about 5 km/s (too high so too early). I’ve seen reports that the beginning of the rupture was sub s-wave rupture velocity, so my guess is that if you assume 3km/s average rupture velocity, you would expect the arrival at about 80 seconds, so that’s 30 seconds early, but maybe a bit less if you have a significant supershear section of the fault rupturing, or if the rupture jumps forward on the fault (which I’ve also seen some models showing).
You could try and use the p-wave arrivals if you have a decent velocity model to predict the time of the direct-p. When I zoom into the p-wave section I would put the p-arrival in this data at 6:21:29.9, so ~35.9 seconds after the origin time. So see what you get for the theoretical p-arrival, and use that for the timing correction.
