Tsuami siren sounding timing increased to better gauge reach

Tsunami sirens installed at Amberley Beach and Leithfield Beach late last year will be sounded for six minutes next week – not as a warning – more of a precaution.

The sirens, installed on poles outside the community centres in the beach communities, are being tested at midday on Friday April 3rd, 2011.

The testing is part of a bi-annual regime, Emergency Management Officer, Allan Grigg, says will help confirm the sirens effectiveness in the event of an emergency.

“For the council and residents to truly appreciate the value of the sirens it is critical we understand just how the sound will travel under different weather conditions to confirm the sirens are performing as required.

“That’s why it is important we repeat the test every six months to gather the data to help provide us with a real time picture of how the sirens are likely to perform and how effective they would be under a variety of conditions.”

During the April 3rd test, the siren will sound for double the amount of time of the original sounding – two minutes, instead of one for each of the three soundings.

“We know last time the wind did affect the direction the sound travelled in, but because the original soundings were just one minute each, we weren’t able to precisely determine the impact of the nor-wester on the siren’s reach.

“Doubling the soundings should not only give the sirens enough time to wind up to full noise but also allow us to better gauge the way the sound travels to provide a more accurate picture of where the siren is and is not being heard.”

During the test three different sounds will be heard with a 15 second pause between each one: ALERT (dash-dash-dot-dot), EVACUATE (dot, dot, dot, dot) and ALL CLEAR (on long continuous tone).

Residents are being urged to complete a post-sounding survey, sent to all households, including providing their street name and number to help the Council more accurately plot the sounding.

The sirens, the first in Hurunui, were installed last October and Allan Grigg acknowledges they have provided a degree of reassurance to the residents, but he warns, they should not come to rely on them alone.

“While they will be a valuable way to communicate an early warning of a potential surge generated by a distant or regional earthquake to the two beach communities, the simple fact is there is unlikely to be enough time to activate them in the event of a local source tsunami.

“A regional tsunami will be between one and three hours away, while a local tsunami – the most dangerous – may only give a few minutes warning. That’s why it is important residents of coastal areas continue to brush up on their emergency planning and know what to look for and what to do, without being prompted by a siren.”

He urges all households to develop a Household Emergency Plan and prepare an Emergency Survival kit to provide necessaries for three days or more, and plan their escape route to the nearest higher ground if necessary.

Anyone at the coast who feels a strong earthquake or sees the sea bubbling, receding (the waterline moving away from the shore), or making a roaring sound, should IMMEDIATELY MOVE to higher ground at least 35 metres above sea level or at least 1km inland – and not return to the sea until they have been told it is safe to do so (this could be 24 hours or longer).

For further information contact:

Allan Grigg


Management Officer

Hurunui District Council

03 314 0024