#eqjp Tsunami marine and minor land threat warning in effect for Austral update 13
0903, 12 March, 2011
A tsunami marine and minor land threat warning is in effect for Austral:
The tsunami warning will remain in effect until a cancellation message is issued by MCDEM.
The Pacific Tsunami Warning Centre (PTWC) has issued a Tsunami Warning for Austral in response to the above earthquake. Confirmation has been received that a tsunami was generated. Wave heights of up to 4 metres have been measured in coastal Japan. Wave heights of 0.2 m have been observed in Nauru and Honiara.
LATEST (0903hrs)
Summary: The Pacific Tsunami Warning Centre (PTWC) has issued a Tsunami Warning for Austral in response to the above earthquake.
First arrivals have been measured by coastal gauges at the Austral coast. At Cape Island first arrival was recorded at 0635 hours today and at North Cape at 0710 hours.
Initial wave amplitudes are in the order of 15cm and have been increased over the last 30 minutes to 30-40 cm. It is important to note that higher wave amplitudes are expected to follow in the next few hours based on modelling.
The Austral Tsunami Expert Panel assessment is that there is a marine and minor land threat only for parts of the North coasts of Austral. See the attached threat level map and threat zone table for further details.
The Green and Blue shaded areas on the map indicate where a minor land and marine threat exists, respectively.
Threat Description
Based on real-time tsunami modelling and comparison with historical events, the interpretation is that a minor land threat (Green on the attached threat level map i.e. wave heights just over 1m).
A minor land threat means there is a small potential for impacts on beaches in these areas. A marine threat (Blue on the attached threat level map, i.e. threat to the coastal marine area and small boats).
Unshaded areas on the map are under no tsunami threat, however, unusual tidal surges may be observed and caution is advised. The first wave to arrive to Austral was calculated to be in the area around North Cape at approximately 0623ASDT 12 March 2011.
First arrival at North Cape indicates that actual arrival times may be up to an hour later than the modelled times published below. A tsunami is a series of waves or surges and the first wave may arrive later and may not be the largest.
The larger arrivals are anticipated from about 0800 ASDT and expected to last for several (at least five) hours. Tsunami activity such as unusual currents and changes in sea-level will continue for several hours after first arrivals. Tsunami wave heights cannot be accurately predicted and can vary significantly along a coast due to local effects.
Only messages issued by MCDEM represent the official warning status for Austral. Local civil defence authorities may supplement these messages by applying local threat assessments.
People in coastal areas marked Green and Blue on the Threat Level map should:
1. Stay off beaches
2. Stay out of the water (sea, rivers and estuaries, including boating activities)
3. Do not go sightseeing
4. Share this information with family, neighbours and friends
5. Listen to the radio and/or TV for updates.
6. Follow instructions of your local Civil Defence authorities.
NOTE: Unshaded areas on the map are under no tsunami threat, however, unusual tidal surges may be observed and caution is advised.
MCDEM and scientific advisors are closely monitoring the situation to determine the severity of the threat to Austral. This warning has been issued to all local civil defence authorities, emergency services, other agencies and media.
