First seismic T-Phase events for 2015

[davenn]

hi everyone,
Well we are into a new year and into new discoveries and observations

Yesterday morning, Jan 6th, 0548NZST ( 05 Jan 1748UT) there was a reasonable quake in the mountains of the central South Island of New Zealand M 6.0 GNZ ( M 5.6 USGS). Now the quake itself isn't unusual, NZ is prone to regular quakes because of its location straddling the Indo-Australian Plate and Pacific Plate boundary.
What was unusual is that this is the first time I have seen/recorded T-phase waves from an inland event.
All previous events have been under the seafloor, see previous thread ... https://www.physicsforums.com/threads/seismic-t-waves.785155/

This first image is of the long period seismogram to show the overall quake. The T-phase is not identifiable in this image as it is buried in amongst the surface waves

This second image shows the P wave arrival at 1752UT and the T-Phase arriving at ~ 1810UT
Note its amplitude is much larger than either the P or S arrivals ( actually the S wave arrival cannot be seen)

The surprises that this subject of seismology is still coming up with :)

cheers
Dave

 

[Bystander]

I was going to ask about that. Been on the news for hours, and no post, I was starting to wonder.

 

[davenn]

It was out in the middle of nowhere. Arthur's Pass would have been about the closest community, maybe Cass. I have not heard of any damage reports. Tho many closer in probably did have crockery off shelves etc