Very strong “deep” earthquake in the greater Fiji region

Last update: September 15, 2011 at 9:46 pm by By

September 15/16, 2011 earthquake

M 7.2   7.3   2011/09/15 19:30     Depth 593.0 626 km      FIJI REGION (Tonga)
Friday, September 16, 2011 at 07:30:59 AM at epicenter
Harmless DEEP earthquake with its hypocenter in the solid hot mantle of the earth
This earthquake will probably be felt as a very weak shaking in a big radius (hundreds of km)
There is NO risk for a tsunami
GDACS earthquake report
Official NOAA statement (Alaska- California)
PUBLIC TSUNAMI INFORMATION STATEMENT NUMBER 1 NWS WEST COAST/ALASKA TSUNAMI WARNING CENTER PALMER AK
1240 PM PDT THU SEP 15 2011
…A STRONG EARTHQUAKE HAS OCCURRED BUT A TSUNAMI IS NOT EXPECTED ALONG THE CALIFORNIA/ OREGON/ WASHINGTON/ BRITISH COLUMBIA OR ALASKA COASTS…
NO WARNING… NO WATCH AND NO ADVISORY IS IN EFFECT FOR THESE AREAS.
BASED ON THE DEPTH OF THE EARTHQUAKE WITHIN THE EARTH A TSUNAMI IS NOT EXPECTED ALONG THE CALIFORNIA/ OREGON/ WASHINGTON/ BRITISH COLUMBIA AND ALASKA COASTS.
Official NOAA statement (Hawaii – Pacific)
BASED ON ALL AVAILABLE DATA A DESTRUCTIVE PACIFIC-WIDE TSUNAMI IS NOT EXPECTED AND THERE IS NO TSUNAMI THREAT TO HAWAII. REPEAT. A DESTRUCTIVE PACIFIC-WIDE TSUNAMI IS NOT EXPECTED AND THERE IS NO TSUNAMI THREAT TO HAWAII.
THIS WILL BE THE ONLY STATEMENT ISSUED FOR THIS EVENT UNLESS ADDITIONAL DATA ARE RECEIVED.
421 km (262 miles) W (263°) from NUKU'ALOFA, Tonga

UPDATE : the magnitude has been revised to 7.3 at a depth of 626 km.

Links to important maps
USGS Did You Feel It Map
Satellite map of the greater epicenter area
Historic earthquakes map
Seismic hazard map
Shaking map
Focal mechanism report
Human impact map
GDACS earthquake report
NOAA tsunami report

July 29, 2011 earthquake

UPDATE 09:15 UTC : USGS has updated his data to Magnitude : 6.7 at a depth of 522 km

UPDATE 08:31 UTC : First (also harmless) aftershocks are beginning to hit the area.

Harmless deep very strong earthquake in the Fiji, Pacific Ocean.
The hypocenter (focal depth) of this earthquake is located in the hot solid mantle of the earth.
NO tsunami warnings or advisories for the region or the greater Pacific Ocean area. (see links below)
As you can see on the map, the location of this earthquake is very common for deep earthquakes (red bullets).

 

 

 

Mantle seismic activity explanation.
The mantle is divided into sections which are based upon results from seismology. These layers (and their depths) are the following:  Moho, or base of the crust around 7 to 35 km, the upper mantle downward to 410 km), the transition zone (410–660 km), the lower mantle (660–2891 km), and in the bottom of the latter region there is the anomalous D" layer with a variable thickness (on average ~200 km thick).

The top of the mantle is defined by a sudden increase in seismic velocity, which was first noted by Andrija Mohorovičić in 1909; this boundary is now referred to as the "Mohorovičić discontinuity" or "Moho".  The uppermost mantle plus overlying crust are relatively rigid and form the lithosphere, an irregular layer with a maximum thickness of perhaps 200 km. Below the lithosphere the upper mantle becomes notably more plastic in its rheology. In some regions below the lithosphere, the seismic velocity is reduced; this so-called low-velocity zone (LVZ) extends down to a depth of several hundred km. Inge Lehmann discovered a seismic discontinuity at about 220 km depth; although this discontinuity has been found in other studies, it is not known whether the discontinuity is ubiquitous. The transition zone is an area of great complexity; it physically separates the upper and lower mantle. Very little is known about the lower mantle apart from that it appears to be relatively seismically homogeneous. The D" layer at the core–mantle boundary separates the mantle from the core. (text : Wikipedia)

Most important Earthquake Data:
Magnitude : Mw 6.6
UTC Time : Friday, July 29, 2011 at 07:42:23 UTC
Local time at epicenter : Friday, July 29, 2011 at 07:42:23 PM at epicenter
Depth (Hypocenter) : 528 km
Geo-location(s) :
365 km (226 miles) SSW of Ndoi Island, Fiji
576 km (357 miles) ESE of Ceva-i-Ra, Fiji

 

Links to important maps
Google satellite map of the greater epicenter area
PWTC Pacific tsunami warning center
Tsunami center Alaska and the US West coast

Earthquake-Report.com on twitter
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@ShakingEarth : earthquake-report.com news + automatic earthquake notifications of EMSC earthquakes of M 4.0 or higher with emphasis to earthquakes in European and Asian / Middle East sphere (4 and up) and a lot of the rest of the world (5 and up). This account was originally created to stimulate our Facebook account
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Download our (free) iPhone applications
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I have felt it Ik heb het gevoeld – Το έκανα αισθάνεται – Yo lo siento – 我的确感到了 – 私はそれを感じていました- Ich habe es gefühlt – Bunu hissediyorum yaptı – لم أشعر أنه

Comments

  1. Michael says:

    Um, USGS says it's a 7.3 upgraded from a 7.2
     
     

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