Storm Australian Severe Weather Forum
Severe Weather Discussion => General Weather - all topics not current severe weather. => Topic started by: Colin Maitland on 28 February 2010, 04:35:38 PM
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Due to the severe earthquake magnitude 8.8 occurred at 4:34 PM EST on Saturday 27
February 2010 near THE COAST OF CENTRAL CHILE (latitude 35.320S longitude72.930W ) and the following tremors, the Pacific area has been placed on alert, I have received an EWN warning as some of you may have also. Here is the report.
NSW is also on alert with much the same message except for localities.
MEDIA:
No use of the Standard Emergency Warning Signal (SEWS)
TOP PRIORITY FOR IMMEDIATE AND FREQUENT BROADCAST
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TSUNAMI WARNING NUMBER 2 FOR QUEENSLAND
Issued by the Joint Australian Tsunami Warning Centre (JATWC) at
8:44 PM EST on Saturday 27 February 2010
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TSUNAMI THREAT TO THE MARINE ENVIRONMENT
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SUMMARY:
Tsunami warning for the marine environment for QUEENSLAND.
Threatened areas extend from Point Danger to Double Island Point, Moreton
Bay.
Possibility of dangerous waves, strong ocean currents and foreshore flooding
for several hours from 08:15 am (EST) Sunday.
Sea level observations HAVE confirmed a tsunami has been generated.
For further details visit the Bureau web site www.bom.gov.au (http://www.bom.gov.au).
Next update due by 10:14 PM EST on Saturday 27 February 2010
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DETAILS:
Tsunami waves are more powerful than the same size beach waves, with the first
wave not always the largest. First tsunami effects are expected as follows:
Coolangatta after 08:15 am (EST) Sunday
Maroochydore after 09:00 am (EST) Sunday
Brisbane after 09:15 am (EST) Sunday
Do not go to the coast to watch the tsunami. Check that your neighbours have
received this advice.
Boats in harbours, estuaries or shallow coastal water should return to shore.
Secure your boat and move away from the waterfront. Vessels already at sea
should stay offshore in deep water until further advised.
Do not go to the coast to watch the tsunami, as there is the possibility of
dangerous, localised flooding of the immediate foreshore.
For emergency assistance, call EMERGENCY MANAGEMENT QUEENSLAND on 132 500
Maps showing the affected areas are on the Bureau web site
www.bom.gov.au/tsunami (http://www.bom.gov.au/tsunami). For a repeat of this warning call 1300 TSUNAMI (1300
878 6264).
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TSUNAMI SOURCE:
An undersea earthquake of magnitude 8.8 occurred at 4:34 PM EST on Saturday 27
February 2010 near THE COAST OF CENTRAL CHILE (latitude 35.320S longitude
72.930W )
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Luckily the Tsunami doesn't appear too big, and here in Sydney we are protected by NZ. From the Joint Tsunami Warning Centre update issued about 15 minutes ago....
AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS
ORIGIN TIME - 0634Z 27 FEB 2010
COORDINATES - 36.1 SOUTH 72.6 WEST
DEPTH - 55 KM
LOCATION - NEAR COAST OF CENTRAL CHILE
MAGNITUDE - 8.8
MEASUREMENTS OR REPORTS OF TSUNAMI WAVE ACTIVITY
GAUGE LOCATION LAT LON TIME AMPL PER
------------------- ----- ------ ----- --------------- -----
EASTER CL 27.2S 109.5W 1160Z 0.44M / 1.4FT 08MIN
ANCUD CL 41.9S 73.8W 0838Z 0.62M / 2.0FT 84MIN
CALLAO LA-PUNTA PE 12.1S 77.2W 1029Z 0.36M / 1.2FT 30MIN
ARICA CL 18.5S 70.3W 1008Z 0.94M / 3.1FT 42MIN
IQUIQUE CL 20.2S 70.1W 0907Z 0.28M / 0.9FT 68MIN
ANTOFAGASTA CL 23.2S 70.4W 0941Z 0.49M / 1.6FT 52MIN
DART LIMA 32412 18.0S 86.4W 0941Z 0.24M / 0.8FT 36MIN
CALDERA CL 27.1S 70.8W 0843Z 0.45M / 1.5FT 20MIN
TALCAHUANO CL 36.7S 73.4W 0653Z 2.34M / 7.7FT 88MIN
COQUIMBO CL 30.0S 71.3W 0852Z 1.32M / 4.3FT 30MIN
CORRAL CL 39.9S 73.4W 0739Z 0.90M / 2.9FT 16MIN
SAN FELIX CL 26.3S 80.1W 0815Z 0.53M / 1.7FT 08MIN
VALPARAISO CL 33.0S 71.6W 0708Z 1.29M / 4.2FT 20MIN
LAT - LATITUDE (N-NORTH, S-SOUTH)
LON - LONGITUDE (E-EAST, W-WEST)
TIME - TIME OF THE MEASUREMENT (Z IS UTC IS GREENWICH TIME)
AMPL - TSUNAMI AMPLITUDE MEASURED RELATIVE TO NORMAL SEA LEVEL.
IT IS ...NOT... CREST-TO-TROUGH WAVE HEIGHT.
VALUES ARE GIVEN IN BOTH METERS(M) AND FEET(FT).
PER - PERIOD OF TIME IN MINUTES(MIN) FROM ONE WAVE TO THE NEXT.
EVALUATION
SEA LEVEL READINGS CONFIRM THAT A TSUNAMI HAS BEEN GENERATED
WHICH COULD CAUSE WIDESPREAD DAMAGE. AUTHORITIES SHOULD TAKE
APPROPRIATE ACTION IN RESPONSE TO THIS THREAT. THIS CENTER WILL
CONTINUE TO MONITOR SEA LEVEL DATA TO DETERMINE THE EXTENT AND
SEVERITY OF THE THREAT.
A TSUNAMI IS A SERIES OF WAVES AND THE FIRST WAVE MAY NOT BE THE
LARGEST. TSUNAMI WAVE HEIGHTS CANNOT BE PREDICTED AND CAN VARY
SIGNIFICANTLY ALONG A COAST DUE TO LOCAL EFFECTS. THE TIME FROM
ONE TSUNAMI WAVE TO THE NEXT CAN BE FIVE MINUTES TO AN HOUR, AND
THE THREAT CAN CONTINUE FOR MANY HOURS AS MULTIPLE WAVES ARRIVE.
FOR ALL AREAS - WHEN NO MAJOR WAVES ARE OBSERVED FOR TWO HOURS
AFTER THE ESTIMATED TIME OF ARRIVAL OR DAMAGING WAVES HAVE NOT
OCCURRED FOR AT LEAST TWO HOURS THEN LOCAL AUTHORITIES CAN ASSUME
THE THREAT IS PASSED. DANGER TO BOATS AND COASTAL STRUCTURES CAN
CONTINUE FOR SEVERAL HOURS DUE TO RAPID CURRENTS. AS LOCAL
CONDITIONS CAN CAUSE A WIDE VARIATION IN TSUNAMI WAVE ACTION THE
ALL CLEAR DETERMINATION MUST BE MADE BY LOCAL AUTHORITIES.
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.
AUSTRALIA HOBART 43.3S 147.6E 2105Z 27 FEB
SYDNEY 33.9S 151.4E 2146Z 27 FEB
BRISBANE 27.2S 153.3E 2310Z 27 FEB
GLADSTONE 23.8S 151.4E 0101Z 28 FEB
CAIRNS 16.7S 145.8E 0159Z 28 FEB
MACKAY 21.1S 149.3E 0251Z 28 FEB
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JTWC and BOM have now placed the much of the east Coast of Australia, from Mackay to Tasmania on alert.
Although the wave heights do not appear too big from the a list that has been generated by JTWC and posted below, it is important to remember that these heights are taken from Ocean Bouys and are measured by "Half peak to trough value".
Tsunamis have a small amplitude (wave height) offshore, and a very long wavelength often hundreds of kilometers long, which is why they generally pass unnoticed at sea, forming only a slight swell usually about 300 millimetres above the normal sea surface. They grow in height when they reach shallower water, in a wave shoaling process.
In shallow water and parallel depth contours, non-breaking waves will increase in wave height when following a wave packet as it moves from one location towards another location with less water depth. This is for instance particularly important with respect to the devastating effects of tsunamis when they reach the coast.
Take care if near coastal waters.
PAPEETE TAHITI 17.5S 149.6W 1810Z 0.16M
RIKITEA FRENCH POLYNS 23.1S 134.9W 1559Z 0.15M
DART MARQUESAS 51406 8.5S 125.0W 1531Z 0.18M
CALDERA CHILE 27.1S 70.8W 0843Z 0.45M
TALCAHUANO CHILE 36.7S 73.4W 0653Z 2.34M
COQUIMBO CHILE 30.0S 71.3W 0852Z 1.32M
CORRAL CHILE 39.9S 73.4W 0739Z 0.90M
VALPARAISO CHILE 33.0S 71.6W 0708Z 1.29M
IQUIQUE CHILE 20.2S 70.1W 0907Z 0.28M
ANTOFAGASTA CHILE 23.2S 70.4W 0941Z 0.49M
ARICA CHILE 18.5S 70.3W 1007Z 0.94M
DART 32412 18.0S 86.4W 0941Z 0.24M
SAN FELIX CHILE 26.3S 80.1W 0815Z 0.53M
VALPARAISO CHILE 33.0S 71.6W 0708Z 1.29M
EASTER ISLAND 27.2S 109.5W 1205Z 0.35M
BALTRA GALAPAGOS IS 0.4S 90.3W 1452Z 0.35M
RARATONGA, COOK IS 21.2s 159.8E 1930z 0.35M