Major M 7.8 quake SW of Sumatra, Indonesia

[davenn]

The M 7.8 event was centred some 800km SW of Sumatera.
This is the largest event, world wide so far this year

Time: 2016-03-02 12:49:48 UTC
Location: 4.908°S 94.275°E
Depth: 24.0 km

A tsunami alert was released but canceled soon after.
Here is a tectonic summary from the USGS

The March 2, 2016 M 7.8 earthquake, 800 km off the west coast of southern Sumatra, Indonesia, occurred as a result of strike-slip faulting within the oceanic lithosphere of the Indo-Australia plate. This event is located 600 km to the southwest of the major subduction zone that defines the plate boundary between the India/Australia and Sunda plates offshore Sumatra. At this location, the India/Australia plates move north-northeast relative to the Sunda plate at a velocity of about 55 mm/yr. The deformation zone defining the defuse boundary between the India and Australia plates is nearby the March 2 earthquake.

Large strike-slip earthquakes are not unprecedented in the diffuse boundary region separating the India and Australia plates, southwest of the Sumatra subduction zone. In 2012, two events of M 8.6 and M 8.2 on the same day (04/12/2012) ruptured a series of oceanic strike-slip structures 650-850 km to the north of the March 2, 2016 event. On June 18, 2000, a M 7.9 earthquake ruptured an oceanic strike-slip structure about 1000 km southeast of the March 2, 2016 earthquake. The focal mechanisms of the all of these earthquakes are consistent in implying that each event could have occurred as the result of left-lateral slip on an approximately north striking fault or right-lateral slip on an approximately west striking fault. The two different orientations of strike-slip faulting are both possible under the same tectonic stress field; perpendicular strike-slip faults that are both compatible with the same stress field are called "conjugate faults". In 2012, in-depth studies of those major events showed that faults of both orientations were involved in their rupture processes, breaking a network of conjugate faults over an area of ~ 200x200 km in size in the Wharton Basin. Because of the remote locations of these oceanic earthquakes, such events rarely cause shaking-related fatalities (the 2012 M 8.6 event caused two). Similarly, strike-slip earthquakes do not typically generate tsunamis.

this event wiped out my high gain channel of the long period vertical sensor
http://www.sydneystormcity.com/seismograms.htm

more easily readable on the low gain channel of the same sensor
http://www.sydneystormcity.com/zlo1.gif

cheers
Dave

 

[jedishrfu]

We don't get too many of these here in Texas. However Oklahoma's been getting a few lately that folks believe come from oil frakking but no one will admit to it.

The last one I recall was in upstate NY around 1980, I think it was a 2 or 3 on the richter scale just a little shake. At first I thought it was the building but then heard about it on the radio. Shook up a lot of people who never felt one before.

http://earthquaketrack.com/us-ny-schenectady/recent

 

[Astronuc]

http://earthquake.usgs.gov/earthquakes/eventpage/us10004u1y#general_region

Time - 2016-03-02 12:49:48 (UTC)
Loction: Lat 4.908 °S, Long 94.275 °E
Depth=24.0 km (14.9 mi)

Distance to nearest major cities:
659km (409mi) SW of Muara Siberut, Indonesia
804km (500mi) SW of Pariaman, Indonesia
805km (500mi) WSW of Padang, Indonesia
843km (524mi) WSW of Solok, Indonesia
849km (528mi) NNW of West Island, Cocos Islands

A couple of aftershocks
5.1 Southwest of Sumatra, Indonesia 2016-03-02 15:12:08 UTC 16.4 km
http://earthquake.usgs.gov/earthquakes/eventpage/us10004u2r#general_region
5.5 Southwest of Sumatra, Indonesia 2016-03-03 00:10:50 UTC 10.0 km
http://earthquake.usgs.gov/earthquakes/eventpage/us10004u8f#general_region

 

[StevieTNZ]

I remember on the news back in 2004, the dreadful Boxing Day earthquake that took so many lives.

This is a concern: http://www.stuff.co.nz/world/asia/7...tsunami-warning-buoys-down-when-big-quake-hit

All 22 of the early-warning buoys Indonesia that were deployed after the 2004 tsunami disaster were inoperable when a massive undersea earthquake struck off the country's coast on Wednesday (Thursday NZ Time), a national disaster mitigation agency said.

The 7.8 magnitude quake did not trigger a tsunami, and there were no deaths and no major damage, but it did expose gaps in the systems put in place to prevent a disaster similar to the Indian Ocean quake that killed more than 200,000 people 11 years ago.

 

[Astronuc]

A few more aftershocks in the area

4.7 Southwest of Sumatra, Indonesia
2016-03-03 12:52:59 UTC
Location 4.837°S 94.590°E
10.0 km

4.7 Southwest of Sumatra, Indonesia
2016-03-03 12:52:59 UTC
Location 4.657°S 94.522°E
10.0 km

4.8 Southwest of Sumatra, Indonesia
2016-03-04 08:09:54 UTC
Location 4.907°S 94.593°E
13.3 km

 

[krater]

This is a concern: http://www.stuff.co.nz/world/asia/7...tsunami-warning-buoys-down-when-big-quake-hit

Also from this article:

But the buoys, which measure the force and speed of water movement, were a missing link in the chain. Authorities delayed the lifting of their tsunami warning because of the inoperable buoys, which cost around $2.3 million a year to maintain.
.
.
"Most of (the buoys) were broken by vandalism,"...

This is ridiculous. But sadly unsurprising.