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a year ago ( 18 Dec 2013) I started a thread on the first observed/confirmed recording I did of a seismic T wave from a quake off the SW tip of the South Island of New Zealand.
https://www.physicsforums.com/threads/seismic-t-waves.729045/
Since then I have recorded them on 3 other quakes from the same region. The latest was overnight last nite
this gram show the low frequency ( long period) recording of the quake an M 5.1
P wave arrival at approx. 1313 hrs T wave not really discernible in the surface wave tail at 1330 hrs
This gram is from a 4.5 Hz geophone and shows a easily identifiable burst of T waves arriving at 1330 hrs
Since that first observation a year ago, I have diligently looked at my events recorded around the New Zealand region and up towards Fiji. I have yet to see T waves from anywhere other than the area south of the South Island.
I don really see this as a distance between sensor and event issue, as there is no significant difference in distance between sensor and this region than say to the Kermadec region immediately to the north of NZ.
Yet on events from the Kermadecs, a much more active area, giving more opportunities to possibly see T wave events, they are not present.
Both region paths are all water/oceanic less the last ~ 20km from the east Australian coast to the sensor.
As yet I don't have an explanation as to why I only see then from the region immediately to the south of the South Island of NZ. I find it quite fascinating :)
regards
Dave
https://www.physicsforums.com/threads/seismic-t-waves.729045/
Since then I have recorded them on 3 other quakes from the same region. The latest was overnight last nite
this gram show the low frequency ( long period) recording of the quake an M 5.1
P wave arrival at approx. 1313 hrs T wave not really discernible in the surface wave tail at 1330 hrs
This gram is from a 4.5 Hz geophone and shows a easily identifiable burst of T waves arriving at 1330 hrs
I don really see this as a distance between sensor and event issue, as there is no significant difference in distance between sensor and this region than say to the Kermadec region immediately to the north of NZ.
Yet on events from the Kermadecs, a much more active area, giving more opportunities to possibly see T wave events, they are not present.
Both region paths are all water/oceanic less the last ~ 20km from the east Australian coast to the sensor.
As yet I don't have an explanation as to why I only see then from the region immediately to the south of the South Island of NZ. I find it quite fascinating :)
regards
Dave
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