Massive earthquake Kermadec Islands

Earthquake summary : A massive M 7.6 earthquake struck in the open sea in the Kermadec Island region. The Pacific Tsunami Warning Center did issue a Tsunami alert for Tonga or New Zealand. It was later canceled without any real tsunami. To read the full story as it happened, we advise our readers to start at the bottom of the page (earthquake data) and to continue up.  It will read as a written movie of the events.
Read also :
Understanding the Magnitude 7.6 Kermadec Islands earthquake (July 6, 2011)
Read also : Massive Kermadec Islands earthquake without tsunami danger for populated islands (October 22, 2011)

UPDATE 08/07-07:45 UTC : The biggest waves reached 1.9 meter at Raoul Island, at the top of the Kermadecs  (and in the main direction of the current - ER) -- about a meter higher than normal.
Small tsunamis, not much larger than normal waves, were subsequently observed on gauges at Great Barrier Island and East Cape.

UPDATE 08/07-07:42 UTC : In New Zealand a fierce discussion is going on why NZ Civil Defence kept the Tsunami warning in place when PTWC had canceled the alert. Tsunami specialists did not understand the Civil Defense neither. They stated that the main energy of the earthquake went into a East-West direction, away from New Zealand.  Also this page has reported earlier about this. The animated image below shows very well what happened (yellow area are the highest waves). An in-depth article about the NZ tsunami alert can be found here

UPDATE 21:02 UTC : MORE GOOD NEWS FROM THE PEOPLE LIVING CLOSEST TO THE EPICENTER
Eight people on Raoul Island - right next to the epicenter - are safe and unharmed from this morning's massive earthquake. The Department of Conservation said it had four staff and four volunteers on the island. "They certainly felt the earthquake but they are fine," a DOC regional spokesman Liz Maire said. There was no obvious sign of damage and the staff had not seen a tsunami which would already have hit the island.
Maire said they were now out on the island looking for damage to tracks. She said the staff were cautious of aftershocks and were taking precautions.
Meanwhile, a Tonga police official said the quake was not felt on Tongatapu.

UPDATE 20:54 UTC : For the seismological explanation of this massive earthquake - see below. The Kermadec trench (epicenter of this earthquake) is approx. 5,500 meter deep.

UPDATE 20:32 UTC : USGS has further decreased the magnitude to 7.6 (a big difference from 7.8!). Depth also adapted to 20 km.

UPDATE 20:27 UTC : The Kermadec islands has regular strong to very strong earthquakes.  Only a handful of scientists are living on the islands and they know perfectly what to do in the case of a massive earthquake.  Luckily this massive earthquakes will be one for the scientific history books.

UPDATE 20:07 UTC :

Tsunami warning has been called off by the Tsunami Pacific Warning Center.

UPDATE 20:00 UTC : If  GDACS issues a tsunami alert for some areas, it always indicates the wave height for many places. In this case no locations have been stipulated as they  do not expect waves to reach populated islands . Nevertheless we have still the Pacific Tsunami alert in place at this time.

UPDATE 19:50 UTC :
earthquake-Report.com advise for people living near beaches in Tonga and New Zealand North Island
Safest way for coastal residents in Tonga and New Zealand is to walk for higher grounds until the Tsunami alert is called off.

UPDATE 19:41 UTC : GDACS animated tsunami image (based on theoretical models)

Kermedec Islands massive earthquake and tsunami simulation - Animated image courtesy GDACS

UPDATE 19:41 UTC : USGS has revised the magnitude to 7.7 instead of 7.8

UPDATE 19:49 UTC : Report nr. 2 from the Pacific Tsunami Center :

ESTIMATED INITIAL TSUNAMI WAVE ARRIVAL TIMES AT FORECAST POINTS WITHIN THE WARNING AND WATCH AREAS ARE GIVEN BELOW. ACTUAL ARRIVAL TIMES MAY DIFFER AND THE INITIAL WAVE MAY NOT BE THE LARGEST. A TSUNAMI IS A SERIES OF WAVES AND THE TIME BETWEEN SUCCESSIVE WAVES CAN BE FIVE MINUTES TO ONE HOUR.

LOCATION         FORECAST POINT     COORDINATES     ARRIVAL TIME

--------------------------------    ------------    ------------

KERMADEC IS      RAOUL_IS.          29.2S 182.1E    1929Z 06 JUL

TONGA            NUKUALOFA          21.0S 184.8E    2017Z 06 JUL

NEW ZEALAND      EAST_CAPE          37.7S 178.5E    2052Z 06 JUL

NORTH_CAPE         34.4S 173.3E    2054Z 06 JUL

GISBORNE           38.7S 178.0E    2059Z 06 JUL

AUCKLAND(E)        36.7S 175.0E    2200Z 06 JUL

UPDATE 19:41 UTC : GDACS tsunami wave simulation (based on theoretical models) - Based on this model, the waves will not reach New Zealand

UPDATE 19:38 UTC : The good news is that it will take a while before eventual waves will arrive on the Tonga and New Zealand Beaches :

Tonga : expected arrival time of (possible) tsunami : 20:17 UTC

New Zealand :  East Cape : 20:52 UTC

New Zealand :  North Cape : 20:54 UTC

New Zealand :  Gisborne : 20:59 UTC

New Zealand :  Auckland : 22:00 UTC

UPDATE 19:32 UTC : Summary of the below message :

Tsunami warning for Kermadec Islands (only scientific mission), TONGA and NEW ZEALAND

UPDATE 19:29 UTC : Pacific Tsunami Warning Center Bulletin 1

TSUNAMI BULLETIN NUMBER 001
PACIFIC TSUNAMI WARNING CENTER/NOAA/NWS
ISSUED AT 1912Z 06 JUL 2011

THIS BULLETIN APPLIES TO AREAS WITHIN AND BORDERING THE PACIFIC
OCEAN AND ADJACENT SEAS...EXCEPT ALASKA...BRITISH COLUMBIA...
WASHINGTON...OREGON AND CALIFORNIA.

... A TSUNAMI WARNING IS IN EFFECT ...

A TSUNAMI WARNING IS IN EFFECT FOR

 KERMADEC IS / TONGA / NEW ZEALAND

FOR ALL OTHER AREAS COVERED BY THIS BULLETIN... IT IS FOR
INFORMATION ONLY AT THIS TIME.

THIS BULLETIN IS ISSUED AS ADVICE TO GOVERNMENT AGENCIES.  ONLY
NATIONAL AND LOCAL GOVERNMENT AGENCIES HAVE THE AUTHORITY TO MAKE
DECISIONS REGARDING THE OFFICIAL STATE OF ALERT IN THEIR AREA AND
ANY ACTIONS TO BE TAKEN IN RESPONSE.

AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS

 ORIGIN TIME -  1903Z 06 JUL 2011
 COORDINATES -  29.4 SOUTH  175.7 WEST
 DEPTH       -   48 KM
 LOCATION    -  KERMADEC ISLANDS REGION
 MAGNITUDE   -  7.8

EVALUATION

 IT IS NOT KNOWN THAT A TSUNAMI WAS GENERATED.  THIS WARNING IS
 BASED ONLY ON THE EARTHQUAKE EVALUATION. AN EARTHQUAKE OF THIS
 SIZE HAS THE POTENTIAL TO GENERATE A DESTRUCTIVE TSUNAMI THAT CAN
 STRIKE COASTLINES IN THE REGION NEAR THE EPICENTER WITHIN MINUTES
 TO HOURS. AUTHORITIES IN THE REGION SHOULD TAKE APPROPRIATE
 ACTION IN RESPONSE TO THIS POSSIBILITY. THIS CENTER WILL MONITOR
 SEA LEVEL GAUGES NEAREST THE REGION AND REPORT IF ANY TSUNAMI
 WAVE ACTIVITY IS OBSERVED. THE WARNING WILL NOT EXPAND TO OTHER
 AREAS OF THE PACIFIC UNLESS ADDITIONAL DATA ARE RECEIVED TO
 WARRANT SUCH AN EXPANSION.

ESTIMATED INITIAL TSUNAMI WAVE ARRIVAL TIMES AT FORECAST POINTS
WITHIN THE WARNING AND WATCH AREAS ARE GIVEN BELOW. ACTUAL
ARRIVAL TIMES MAY DIFFER AND THE INITIAL WAVE MAY NOT BE THE
LARGEST. A TSUNAMI IS A SERIES OF WAVES AND THE TIME BETWEEN
SUCCESSIVE WAVES CAN BE FIVE MINUTES TO ONE HOUR.

 LOCATION         FORECAST POINT     COORDINATES     ARRIVAL TIME
 --------------------------------    ------------    ------------
 KERMADEC IS      RAOUL_IS.          29.2S 182.1E    1929Z 06 JUL
 TONGA            NUKUALOFA          21.0S 184.8E    2017Z 06 JUL
 NEW ZEALAND      EAST_CAPE          37.7S 178.5E    2052Z 06 JUL
                  NORTH_CAPE         34.4S 173.3E    2054Z 06 JUL
                  GISBORNE           38.7S 178.0E    2059Z 06 JUL
                  AUCKLAND(E)        36.7S 175.0E    2200Z 06 JUL

BULLETINS WILL BE ISSUED HOURLY OR SOONER IF CONDITIONS WARRANT.
THE TSUNAMI WARNING WILL REMAIN IN EFFECT UNTIL FURTHER NOTICE.

THE WEST COAST/ALASKA TSUNAMI WARNING CENTER WILL ISSUE PRODUCTS
FOR ALASKA...BRITISH COLUMBIA...WASHINGTON...OREGON...CALIFORNIA.

 

We are currently collecting data from this earthquake

If a tsunami is generated it will take hours to reach the nearest populated areas

Statement for ALASKA and WESTERN UNITED STATES :

...A STRONG EARTHQUAKE HAS OCCURRED BUT A TSUNAMI IS NOT EXPECTED ALONG THE CALIFORNIA/ OREGON/ WASHINGTON/ BRITISH COLUMBIA OR ALASKA COASTS...

 

 

 

Seismological overview
In this case it was a normal fault solution from USGS..

The subduction zone extends north-northeast from the North Island of New Zealand for over 2500 km through Tonga to within 100 km of Western Samoa. At a broad scale, tectonics of the subduction zone reflect the motion of the Pacific plate westward with respect to the interior of the Australia plate at a velocity of about 60 mm/y in the epicentral region of the earthquake. The Pacific plate subducts beneath the Australia plate at the Tonga and Kermadec trenches, and dips to the west. In detail, the eastern edge of the broad Australia plate may itself be viewed as a collection of small plates or microplates that move with respect to each other and with respect to the Pacific plate and the Australia plate interior. The location and focal-mechanism of the earthquake are consistent with it occurring as thrust faulting on the interface between the subducting Pacific plate and the overriding Australia plate (in detail, the overriding Kermadec microplate).

The interaction between the Pacific and Australia plate creates one of the most active tectonic environments in the world, with a high level of associated earthquake activity. Since 1976, a 200-km long section of the Tonga - Kermadec subduction zone that includes the epicenter of the February 18 earthquake has produced over 50 earthquakes of magnitude 6 or larger, with the largest having magnitude 7.9.

Most important Earthquake Data:
Magnitude : 7.8  (changed afterwards to 7.6)
UTC Time :  Wednesday, July 06, 2011 at 19:03:16 UTC
Local time at epicenter : Thursday, July 07, 2011 at 07:03:16 AM at epicenter
Depth (Hypocenter) : 48 km (changed afterwards to 20 km)
Geo-location(s) :
211 km (131 miles) E (95°) from Raoul Island, Kermadec Islands (NO danger)
919 km (571 miles) S (183°) from NUKU'ALOFA, Tonga

 

Links to important maps
Google satellite map of the area showing the kind of terrain the earthquake took place
USGS historic earthquakes map
USGS Seismic hazard map
GDACS GREEN earthquake report
GDACS tsunami report
NOAA tsunami report

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I did feel 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

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