Palu supershear quake/tsunami Sept 2018

[jim mcnamara]

Popular article: https://www.nationalgeographic.com/...hquake-supersonic-supershear-speed-indonesia/
Nature.com paywall/abstract:
https://www.nature.com/articles/s41561-019-0308-8

After analysis of the quake centered near Palu Indonesia that killed 2000+ people, it was determined that the velocity at which the tremor propagated the tear in the earth, this was "no ordinary earthquake". It is termed a supershear event.

Supershear refers to the velocity of propagation of the rupture. These are rare. This one had lots of seismogaphs listening. Maybe our @davenn can point out this phenomenon using his output as recorded on his machine.

 

[davenn]

Supershear refers to the velocity of propagation of the rupture. These are rare

They must be ! ... Supershear is not a term I have heard of before

This one had lots of seismogaphs listening. Maybe our @davenn can point out this phenomenon using his output as recorded on his machine.

Hmmm, not sure how these would be manifest on a seismogram.
My initial thought would maybe a higher frequency of the P ( and maybe also the S) waves due to the higher velocity of the propagation of the rupture.

I would have to try and see if there is a difference in P wave frequencies of that event compared to others with a similar distance from my recorder.

Dave

 

[jim mcnamara]

If you can access Nature Geoscience, then I assume there is methodology in the primary article.

[guess]The idea is that the point of emanation of the S-waves would be moving really fast relative to one station. It also mentions "bunching up" of multiple waves onto the wavefront.[/guess]

So possibly it takes multiple stations to discern a rapidly moving location. The pop sci article mentions 9300 ft/s.

 

[BillTre]

Here is a Science mag news article on this.