Earthquake in South Pacific, NE of Australia

[fresh_42]

They set a tsunami warning. Seems to be several.

http://geofon.gfz-potsdam.de/eqinfo/seismon/globmon.php
http://earthquake.usgs.gov/earthquakes/eventpage/us20007z8m#region-info

 

[StevieTNZ]

Yup, we have a warning issued for NZ, of a potential tsunami.

http://www.stuff.co.nz/world/south-pacific/87378899/81-magnitude-earthquake-hits-solomons--usgs

The earthquake has been revised to 7.8mag, despite the URL saying 8.1.

The US Pacific Tsunami Warning Center said tsunami waves were forecast to be less than 30cm for New Zealand.

 

[davenn]

yeah a massive 7.8
68km WSW of Kirakira, Solomon Islands
2016-12-08 17:38:46 (UTC)
41.0 km

my seismo has only a short time ago stopped hitting the stops ... I was still sleeping when the event occurred and the seismic waves arrived at my location
so I couldn't do a screen save before it started overwriting itself

long period hi gain channel

medium period low gain channel

http://www.sydneystormcity.com/seismograms.htm
Dave

 

[davenn]

Ohhh I discovered that buried in the huge signal of the 7.8, there is a M 6.5 off the coast of northern California
Its P wave arrival is at 15:20 UT. where as the P arrival of the 7.8 is at 17:44 UT

so some calc's ... Calif quake origin time 14:50UT ( to nearest minute) and arrival in Sydney Australia at 15:20 (to nearest minute)

P travel time = 30 minutes x 60 = 1800 sec
across Earth's surface distance (from google Earth) 11,834 km

11834 / 1800 = 6.57 km / sec which fits pretty well with the standard models Dave

 

[fresh_42]

And a 6 in China. The total list is pretty long, even within the last 24h. Is it true, that media nowadays only report those > 6.8? Did this change in comparison to say, the 80's?

 

[davenn]

And a 6 in China. The total list is pretty long, even within the last 24h. Is it true, that media nowadays only report those > 6.8? Did this change in comparison to say, the 80's?

I did record that M5.9 (6.0) in China yesterday, it was a pretty small signal

The media usually only cover those that were felt / caused damage. There's many significant events that go unreported ( in media) because of their remote location. The media do report a lot more than in days gone by, mainly because global media coverage has improved so much over the last 30 years.
It has the effect of making people think that there are more big quakes than there used to be. But that isn't the case.
On avg ( world wide) per year ...

1 x M8.0 +
18 x M 7.0 - 7.9
~120 odd x M 6.0 - 6.9
~ 800 x 5.0 - 5.9

and these figures haven't changed in the last ~ 150 years of systematic written records. ~ 100 years of instrument recordsDave

 

[StevieTNZ]

http://www.stuff.co.nz/world/south-pacific/87426995/magnitude-7-earthquake-hits-near-solomon-island

A magnitude 7 undersea earthquake has hit near the Solomon Islands, just a day after a 7.8 earthquake destroyed homes and triggered a tsunami warning on the island nation.

Saturday morning's earthquake hit at 6.10am (8.10am, NZT) off Rennell Island.

EDIT: now revised to 6.9 mag.

 

[davenn]

http://www.stuff.co.nz/world/south-pacific/87426995/magnitude-7-earthquake-hits-near-solomon-island

EDIT: now revised to 6.9 mag.

Yup, the largest aftershock to date :)