M 6.1 northern territory, australia

[EMSC]

Magnitude M 6.1Region NORTHERN TERRITORY, AUSTRALIADate time 2016-05-20 18:14:02.8 UTCLocation 25.71 S ; 129.66 EDepth 2 km



More... (http://www.emsc-csem.org/Earthquake/earthquake.php?id=507606)

[Wind]

Was just wondering where another quake would hit, certainly was feeling it in my bones.

Magnitude 5.9 quake hits central Australia at 10km depth – USGS (https://www.rt.com/news/343821-australia-quake-alice-springs/)

"The current quake is one of the strongest to hit mainland Australia since August 1997, when a 6.3-magnitude earthquake was recorded off Collier Bay on the far north coast of West Australia."

https://cdn.rt.com/files/2016.05/original/573f5e3cc461884c068b45a0.jpg

[Daniel Duxfield]

Something about this strikes me as a bit odd.
Now, I'm no geologist but does Australia have any fault lines running through that area?
Aus is a largely flat stable continent on the Australasian plate, very unlike New Zealand (where I live) which has hundreds of fault lines running through it, so we get little shakes quite often. So that's why I'm surprised that an earthquake occurred in the centre of the continent.

Of particular interest to me is that Pine Gap is located close to where the earthquake occurred. Can anyone elaborate on my line of thinking here?

[KiwiElf]

Australia has no major fault lines where that quake struck Daniel (it might have, now!! ;)), minor ones quite possibly, & yeah, it is VERY weird (initially being shown as a 6.1M at less than 10 km deep - (about 3km!) That makes it the largest global quake in the last 24-hrs.

Pine Gap is just a few km west of Alice Springs, so the quake struck a long distance well to the West of that. Tennant Creek had a fairly large one a few days back, but thats about 500 km north of Alice.

Here's some data about Australian faultlines:
https://cooberpedyregionaltimes.wordpress.com/2008/09/26/faultlines-weaving-their-way-across-southern-australia/

Perhaps Bob or Herve can shed some light on it?

[bluestflame]

https://www.google.com.au/maps/place/25°31'48.0"S+129°48'36.0"E/@-25.4338175,125.3152845,6z/data=!3m1!4b1!4m5!3m4!1s0x0:0x0!8m2!3d-25.53!4d129.81

¤=[Post Update]=¤

https://www.google.com.au/maps/place/25°31'48.0"S+129°48'36.0"E/@-25.4338175,125.3152845,6z/data=!3m1!4b1!4m5!3m4!1s0x0:0x0!8m2!3d-25.53!4d129.81

[Fairy Friend]

Earthquakes can occur anywhere. They don't have to be on fault lines. Australia has movement all around it.

[KiwiElf]

Two after shocks since then, same area:

4.2 Northern Territory, Australia 2016-05-21 21:08:36 UTC+12:00 10.0 km
4.4 Northern Territory, Australia 2016-05-21 20:46:19 UTC+12:00 10.0 km

[Bob]

Australia has no major fault lines where that quake struck Daniel (it might have, now!! ;)), minor ones quite possibly, & yeah, it is VERY weird (initially being shown as a 6.1M at less than 10 km deep - (about 3km!) That makes it the largest global quake in the last 24-hrs.

Pine Gap is just a few km west of Alice Springs, so the quake struck a long distance well to the West of that. Tennant Creek had a fairly large one a few days back, but thats about 500 km north of Alice.

[..]

Perhaps Bob or Herve can shed some light on it?

Some background -


Here's some data about Australian geology:
https://upload.wikimedia.org/wikipedia/commons/3/3b/Ausgeolbasic.jpg

https://upload.wikimedia.org/wikipedia/commons/thumb/3/30/IBRA_6.1_MacDonnell_Ranges.png/1146px-IBRA_6.1_MacDonnell_Ranges.png

Looks like this is called the MacDonnell Range of mountains, valleys, gorges.


The ranges are composed of many rock types, but are most famous for their red quartzite peaks and gorges. Other rock types include granite, limestone, sandstone and siltstone.

Some of the valleys of the range contain fossil evidence of the inland sea that once covered central Australia.

reference: Hema Maps (1997). Discover Australia's National Parks. Milsons Point, New South Wales: Random House Australia. pp. 242—246. ISBN 1-875992-47-2 and
"Rangelands - Overview - MacDonnell Ranges". Australian Natural Resources Atlas. Department of the Environment, Water, Heritage and the Arts. Retrieved 2009-11-17

Link: http://www.ga.gov.au/earthquakes/searchQuake.do?selectedPage=2&isNewSearch=false&region=2&stateTerritory=&regionSelect=&westLon=110.0&eastLon=157.0&northLat=-7.0&southLat=-45.0&magnitudeMin=0.0&magnitudeMax=9.9&startDate=22%2F05%2F2015&startTime=00%3A00&endDate=22%2F05%2F2016&endTime=23%3A59&depthMin=0&depthMax=1000&allEarthquakes=true&tsunamigenicEarthQuakes=false&significantEarthQuakes=false&sortAttributeName=utcdate&sortType=desc&rowsPerPage=25&paging=true

When the link is opened click the mousey drag left then you can center on Australia, and keep hitting the "+" to get closer.. You can expand to what looks like a 20 foot spacing.. And there are quite a few quakes, both shallow and deep in that area.. The link to the Australian geological society has what looks like 10 recent pages of quakes in Australia..

Some of those showing up at 1 kilometer sure seems interesting such as the land is shifting under some strain..


http://chanlo.com/images/oz-1.jpg

Going a few days back in May, you can see the large distribution of quakes in Australia (scroll thru the Link's pages to see the recent historical). You can track which days had the largest and widest spread of quakes. I didn't see any injection wells with a quick cursory view of the one discussed in the OP tho.. which could be a good source for seismic stimulation.

[KiwiElf]

@ Bob: What are your thoughts about it being so shallow? (ie originally posted @ approx 2 km deep (first post) - USGS changed it to 10km!)

[Bob]

@ Bob: What are your thoughts about it being so shallow? (ie originally posted @ approx 2 km deep (first post) - USGS changed it to 10km!)

From the geological society, and GeoScience Australia, there is some good background information on large and small quakes in Australia -

Stress buildup in the interior, and then a release happens. Depths of these releases can happen from surface landslides, to shallow depths.

(source link (http://www.ga.gov.au/scientific-topics/hazards/earthquake/basics/where))

Here is a quote with some background:


Large shallow earthquakes also happen where two plates are pulling apart with the creation of new oceanic crust along mid-ocean ridges and on the transform faults that intersect them.

Shallow intraplate earthquakes occur in the relatively stable interior of continents away from plate boundaries. They are less common and do not follow easily recognisable patterns. This type of earthquake generally originates at shallow depths.

Although Australia is not on the edge of a plate, the continent experiences earthquakes because the Indo-Australian plate is being pushed north and is colliding with the Eurasian, Philippine and Pacific plates.

This causes the build up of mainly compressive stress in the interior of the Indo-Australian plate which is released during earthquakes.

Here is a locational map up till 2011 for Australia and the surrounding regions showing the magnitude and location - (depth reports can be researched on their website, link mentioned in post #8 above)

http://www.ga.gov.au/__data/assets/image/0020/14474/GA20737.jpg


Australia's largest recorded earthquake was in 1988 at Tennant Creek in the Northern Territory with an estimated magnitude of 6.6.

It occurred in a sparsely populated area.

A magnitude 6.5 earthquake at Meckering in 1968 caused extensive damage to buildings and was felt over most of southern Western Australia.

Earthquakes of magnitude 4.0 or more are relatively common in Western Australia with one occurring approximately every five years in the Meckering region.

and

"An average 80 earthquakes of magnitude 3.0 or more in Australia each year. South Australia is being slowly squeezed in an east-west direction by about 0.1mm/yr. "

Stress relief for instance can be triggered by tidal forces. Faults can be lined up and under tension, not having released for many years. The action can be like the triggering on a "mouse trap" for instance - held back until the trigger point is touched with a light tap.

Underground caverns can cave in, for instance if water has been withdrawn continually, an finally the surface features crack, and shifts happen. It is known that the tidal forces on water create large volume shifts of water. Tidal forces affect land and water. We mostly recognize the tides as they are obvious to sight. We normally don't pay attention to water movement underground.

[Bob]

@ Bob: What are your thoughts about it being so shallow? (ie originally posted @ approx 2 km deep (first post) - USGS changed it to 10km!)

On the question of initially posted shallow then corrected..

I believe the automated system comes up with a trip point where the recording systems analyze the data from numerous recording stations. "Resolution solution finalized" is the statement made when the data from many recording stations are in, processed and then displayed (and reported).

Waiting for a bit, maybe a day or so, allows for time for data to come in from numerous locations. And stations further away could "see" the depths of the quake events clearer. Time of Arrival of the seismic wave is used as well as the slant angle (useful for depth analysis). The types of sensors provide different indications too.. Different recording stations may not have the same type of sensors.

Some sensors monitor UP down movement, others east west, and others North South movements.

So it is not unusual for reporting depth to change as different sensor data is used.

Mapping:




Locating Earthquakes One station gives distance to E.Q. but not direction Plotting distances from 3 stations on a map, as circles with radii equaling the distance from the quake. Point where 3 circles overlap locates the earthquake epicenter Depth of focus beneath Earth’s surface can also be determined –Shallow focus 0-70 km deep –Intermediate focus 70-350 km deep –Deep focus 350-670 km deep

Here's 4 key images to understand the reporting network and quakes:

http://chanlo.com/images/quake-1.jpg

http://chanlo.com/images/quake-2.jpg

http://chanlo.com/images/quake-3.jpg

http://chanlo.com/images/quake-4.jpg

The full presentation is available HERE (LINK) (http://slideplayer.com/slide/5214361/) and such discusses the background on earthquakes, what types of waves are generated, what their speeds are, and how there is a world-wide monitoring network used in computation.

[Bob]

Lastly, Geosciences in Australia - the monitoring of earthquakes.

The determination of the initial data and its posting is supervised by the "Duty Seismologist".

Here is HOW IT WORKS: *from data-gathering to analysis to reporting*


How Geoscience Australia monitors earthquakes

Geoscience Australia monitors seismic data from more than 60 stations on the Australian National Seismograph Network and in excess of 300 stations worldwide in near real-time, 24 hours a day, seven days a week.

Most of the 40 samples per second data are delivered within 30 seconds of being recorded at the seismometer to Geoscience Australia’s central processing facility in Canberra through various digital satellite and broadband communication systems.

Seismic data are also provided by overseas Governments which have national seismic networks.

Geoscience Australia uses data provided by the Governments of New Zealand, Indonesia, Malaysia, Singapore and China and has access to data from global seismic networks provided by the USA, Japan, Germany and France. The Comprehensive Nuclear Test Ban Treaty Organisation’s External site link International Monitoring System also provides seismic data for tsunami warning purposes.

The seismic data are collected and analysed automatically and immediately reviewed by Geoscience Australia’s Duty Seismologist.

As part of the Joint Australian Tsunami Warning Centre (JATWC), Duty Seismologists also are responsible for analysing and reporting within 10 minutes of the origin time, on earthquakes which have the potential to generate a tsunami. An earthquake alert is then sent to Geoscience Australia’s partner in the JATWC, the Australian Bureau of Meteorology, to determine tsunami advice and publish tsunami bulletins.

The parameters of all other earthquakes with a magnitude greater than 3.5 are generally computed within 20 minutes.

The analysis includes its magnitude, origin time and date of the earthquake and the location of its hypocentre.

Smaller earthquakes that are not detected by many seismometers are difficult to locate in real-time and, consequently, are located by Seismic Analysts using computer programs.

(Link (http://www.ga.gov.au/scientific-topics/hazards/earthquake/capabilties/monitoring#heading-3))

[Rocky_Shorz]

Australian Politicians have told all of you, fracking is completely safe... for bankers...


http://www.youtube.com/watch?v=NvJAKVnK4qM

[TigaHawk]

That would be caused by Fracking.

Australia has no fault lines. It sit's smack bang in the MIDDLE of a huge plate.

http://www.aph.gov.au/~/media/05%20About%20Parliament/54%20Parliamentary%20Depts/544%20Parliamentary%20Library/BriefingBook44p/EnergyResources.gif?la=en

Fracking is the cause of these quakes. And shall only intensify.

We are starting to get sink holes too.

I cannot find the picture i was looking for but our government has just OK'd an expansion of the CSG sites. The area that they are now allowed to frack in is extremely scary. We're about to kill ourselves here due to poisoning the land with fracking.

Why the *** am i still on this planet? Its depressing.

[KiwiElf]

More info here, but no definitive cause, fracking or otherwise.

http://www.stuff.co.nz/world/australia/80239921/magnitude-59-earthquake-recorded-in-central-australia

http://www.abc.net.au/news/2016-05-21/earthquake-hits-outside-alice-springs/7434196

[Bob]

There is no fraking at the location of the quake listed in the OP.

There are no "injection wells" at the location mentioned in the OP

Injection wells ARE the DOCUMENTED cause of earthquakes in Oklahoma - I have very detailed threads on that situation, the earthquakes in Oklahoma. And why fraking is not the cause of those quakes.