Originally posted by PuterMan
reply to post by westcoast
helicopter......schmellicopter. Never in a month of sundays does a helicopter make a gliding sound like that at 11 Hz. Nor does a helicopter take 6
minutes or more to do a pass, and if it was hovering the sound would not vary.
(Of course I could be wrong - nah perish the thought)
ETA: Last thought before I close down. The helicopter signal they show looks like a shortened version of the trains, which is exactly what I would
expect, and the trains sounded NOTHING like this sound. The harmonic may be from the glacier. I am not saying it is magmatic HT, but HT it is.
edit on 24/1/2012 by PuterMan because: (no reason given)
Having now spent many hours on this I have to stop and do some other stuff.
I have found this signal elsewhere. Nothing like RCS which is far and away the strongest signal, but it can be seen/heard on UW.RCM and CC.PANH and
The spread of time over the 4 stations is large – from the earliest @17:28 UTC to the latest @23:45. That is a mighty long time for a Chinook to be
flying about! I would not want the bill for that.
The times are similar but not exact and I have no idea how fast HT would travel through rock but I as guessing that it would be nowhere near as fast
as a P or S wave so I cann't make any comparison there. One set at RCM and PANH coincide timewise, but the PANH set goes on much longer. RCM is 17:46
to 17:57 and PANH is 17:45 to 18:35. RCS also comes in on this on at 17:55 to 17:58 and again from 18_07 to 18:21.
This could possibly be consistent with a helicopter flying around, but unfortunately there is not correlation at all that I can see with the other
The other problem is that for RCM to be the earliest signal @17:28 there is no way that could happen unless the aircraft came in from the SE. If the
base for the Chinook is SE of Rainier than that may prove a point except that the last appearance is @23:54 on CC.OBSR and that is NW which is not
consistent with the potential approach as to exit to base the aircraft would have to cross over the other seismos when flying SE. There is no
occurrence of the signal on RCS at the start indicating a fly over on exit to the SE
Start End Station
17:28 17:33 RCM
17:45 18:35 PANH
17:46 17:57 RCM
17:55 17:58 RCS
18:07 18:21 RCS
18:47 18:50 OBSR
19:12 19:16 RCM
21:15 21:55 PANH
21:43 21:44 RCS
22:20 22:28 PANH
22:22 22:28 RCS
22:31 22:34 RCS
23:45 23:54 OBSR
Weird sort of search pattern. Not a standard ASR Box Search.
Frequency wise they are all pretty much the same. There are some slight variations, some of which are closer to the slightly lower MSG sound.
By the way the 22.5 Hz signal seems to be consistent in the area and when cleaned is pretty much continuous.
Due to the month of Sundays just passed I am going to say that maybe it is the signal from a helicopter, in the absence of any other information, but
that the timings and apparent search pattern are all wrong for a professional search and a Chinook has to be a professional search.
I would point out that PNSN initially said "that does look strange, sometimes station noise and problems with telemetry can cause gliding spectra like
that" - in other words they did not have a clue. (And no they don't cause gliding. That is either HT or Chinook helicopters
My biggest problem with all this is that due to the virtually identical signature at MSH this calls that sound in to question. Was that also a
Chinook. Since it was June when the recording was made perhaps it was. This was just before the emergence of the first dome, that was subsequently
Of course I could be wrong - nah perish the thought
I am not convinced by their argument, but it has some merits. At the end of the day it is still harmonic tremor in the strictest sense since it
is a tremor and exhibits harmonics.
I will accept that I may be wrong in this instance as to the source which I thought was the glacier, and
in future will know exactly what this is when I see it. "It's a Chinook. Nothing to see here".
Just one final point here. Having now listened to several days of seismos - full 24 hour periods - I am convinced that there is some seismic activity
in there amongst all the other pops and bumps.
edit on 27/1/2012 by PuterMan because: (no reason given)