Tsunami risk: More needs to be done

Abstract

New Zealand has just had a ‘near miss’ with a major off-shore earthquake event. Media covered how at 4.37 am on Friday 2 September a magnitude M7.1 earthquake struck 100kms off the coast of Te Araroa. Around 15 minutes later a sea level gauge registered a 30cm tsunami on the East Coast. Ironically earlier in the week the Civil Defence Emergency Management community had just undertaken Exercise Tangaroa, a simulation of a M 9.1 earthquake further offshore in the Kermadec Trench. So the team would have been in a high state of readiness. The media were relatively restrained in their treatment of the confused sequence of events that followed. In brief – the magnitude of the earthquake did not meet the thresholds for a default tsunami warning, subsequently only an advisory about the earthquake was issued at 5:10 am. Later, at 5.55 am a tsunami warning for marine and beach areas was issued. The latter was nearly 1 hour 20 minute after the earthquake and 1 hour 5 minutes after the arrival of the first wave. Meanwhile the Pacific Tsunami Warning Center was providing contrary advice.