Another Megathrust event in Indonesia tonite

davenn

hi gang

2 hrs after the event started to roll in on my seismograph, here in Sydney Australia, I am still recording a significant signal.

The quake is off the NW coast of Sumatera with almost an identical epicentral point as the 2004, Mw9+ event.
Tonite's event was initially listed as a Mw8.7 by the USGA and ~ an hr or so later was revised down to a Mw8.6.
I havent seen any specific reports as yet other than comments to the effect that a tsunami was generated (USGS)

Dave

davenn

This has been followed by another major event in the same area

a Prelim Mw 8.2 aftershock. Im finding it hard to see as the initial event is obscurring the signal a lot.
here is a compressed screen shot from my analysis program of the initial event.....



cheers
Dave

Attached Thumbnails

 

meidan

another earthquake this time in Mexico 7.0...

davenn

latest data has it downgraded to a Mw6.5, still a respectable event
I didnt record it here in Australia, its usually got to be M7.0 and greater when from the western Americas ( USA down to Chile).
Its a real balancing act for me, I live in the suburbs with lots of manmade noise from clothes washing machines bouncing around on spin cycle to much heavy traffic on the road.

Keeping the gain of the system a bit lower can be a blessing in disguise as in the big events of last nite. Even at only 4500 km from the event, The M8.6 still maxed out my 14bit A to D converter ( time for a 24bit one haha). But not as bad as some of my fellow recording stations in the USA who's systems, with their much higher gain, were maxing out from almost the start of the event, even tho they were 4 x the distance from the epicentre as me.

cheers
Dave

davenn

Well it looks like Sumatera and the surrounding region really dodged a bullet last nite.
Both the events were a bit to the west of the downward thrusting slab of the Indo-Australian Plate. Their Centroid Moment Tensor solutions revealed that they were on strike - slip faults. This pretty much allieviated the possibility of any significant tsunami being generated. Everyone breathes a sigh of relief :)

Its still amazing that after 8 years, a Mw9.2 and a Mw8.7 (some months later), that so much stress was still pent up in the region.

Dave

Evo

It's great to have you here Dave.

davenn

awww thanks Evo :)

The subject is a bit of a passionate hobbyhorse of mine haha
has been for many years

I hope general discussion of events etc, like above, is within the guidelines of the forum rather than always just being specific question/answer type threads

cheers
Dave