What Caused the M 7.5 Earthquake in Central New Guinea?

[davenn]

very large event had my seismometer hitting the stops for some time

and the low gain channel so things could be seen more clearly

Location map with aftershocks

USGS Data for the event

M 7.5 - 89km SSW of Porgera, Papua New Guinea
Time: 2018-02-25 17:44:44 (UTC)
Location: 6.149°S 142.766°E
Depth: 35.0 km

Dave

 

[berkeman]

Holy smokes!

 

[davenn]

An update as the aftershocks continue to roll in the two largest ones have been a 6.0 and a 6.3
As can be seen on the updated even map below, the events stretch out in a line. With the main 7.5 shock located roughly in the middle of the events it shows a really nice bi-lateral rupture sequence ( where the fault ruptures in both directions along the fault line)

This line is the front of a large fold and thrust fault zone (Highlands Fold and Thrust Belt) along the southern edge of the mountains.

The moment tensor data clearly shows a thrust fault motion for this event
with the dip-slip to the north east and this agrees with the plate motion arrows in the previous map
The amount of plate motion is indicated by the length of those arrows and for the area of the quake, the convergence is around 50mm / year

Fault motions and "beach balls"
The 3rd one down relates to the thrust motion of this 7.5 quake

cheers
Dave

 

[davenn]

Large aftershocks are continuing for this event

a M5.8 and 6.0 last weekend and this morning a M 6.7

my live seismograph is here ...

http://www.sydneystormcity.com/seismograms.htmDave