Review of the Tsunami Evacuation 2017

All sirens (except one) sounded when they were activated on 14 November. The one malfunctioning
siren (located in New Brighton) did not in any way impact on the alerting system because the other
sirens are loud enough to compensate. It failed to sound because it had no mains power for weeks so
the battery was not charged. Council was aware of this issue and had liaised with its siren installation
contractor to reactivate the mains power. This matter has since been rectified.
When the sirens were installed, it is believed that the residual current device (“RCD”) switches were
faulty. Prior to 14 November, Council had requested the installation contractor to replace all the RCD
switches. This is to ensure that the power supply to the batteries is not compromised. The switches
had not been replaced by 14 November but this did not impact on the integrity of the sirens. The
switches are in the process of being replaced.
The sirens are scheduled to be serviced this year. This will enable functionality issues to be identified,
including whether use of the sirens for a long period of time on 14 November has damaged the life of
the batteries.
Recommendations
Educating residents on the need to evacuate without waiting for sirens in an earthquake which could
produce a local source tsunami is fundamental. Reliance on sirens sounding to indicate that an
evacuation is necessary puts residents at significant risk. Furthermore, education on how the siren
alerting system will be used (i.e. it will not sound continuously and the evacuation remains in place
until otherwise notified) is required to minimise confusion and frustration.
In order to minimise risks that the sirens do not sound when activated, it has been proposed that a
separate radio will be located in the Justice and Emergency Precinct (Precinct). This will enable the
system to have a backup radio (on Pages Road) which is located in a different location to the main
radio (in the Precinct). The Council should ensure that this proposal proceeds and another radio is
installed within the Precinct.
Council should impress on the siren installation contractor the need to respond urgently to issues that
may impact the integrity of the siren alerting system. If possible, specific service levels should be
included in the contractual arrangements. These levels should stipulate the exact timeframe within
which the contractor must action the service requirement. The immediate need is for the contractor
to replace the faulty switches.
CDEM staff should activate the sirens themselves without the need to contact a third party. This would
shorten the time taken to activate the sirens and minimise the risk of delay. Regular training and
refresh of the activation process should be undertaken to ensure that staff are familiar and confident
with activating the sirens.
The time taken to activate the sirens could be further shortened if the need to log into VPN was
removed from the process. Council staff should explore the pros and cons of logging into the system
via VPN to ensure that the activation process is as streamlined as possible.
The scope of this review did not extend to determining whether the current siren module continues to
be fit for purpose. Council staff, with input from residents and Christchurch Police, should consider the
pros and cons of the various modules available – in particular whether voice capability should be
added. Discussion with other local authorities who use different modules may provide useful analysis.
The Tsunami Warning Sirens Technical Standard produced by MCDEM should be taken into account
when determining the use of sirens.
There is a need for CDEM to consider how to communicate an evacuation if the sirens cannot be
activated (due to a mechanical failure) or if there is no telecommunication coverage. Alternative
methods of communication should be included in the Procedure and communicated to residents. This
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