The Ministry of Civil Defence and Emergency Management found itself between a rock and a hard place when a major earthquake struck off East Cape early on the morning of Friday 2nd September. Was a tsunami generated? Should people living in low-lying areas on the coast evacuate or should they stay put?
Sunday, 11th September 2016
People in a significant part of the North Island and northern parts of the South Island were woken at 4:38 on the morning of Friday September 2nd by an earthquake that seemed to go on for some time. Startled from sleep, most would have had little idea of whether the rolling motion went on for 30 seconds, a minute, or more. Some found themselves tumbling out of bed to a place of shelter, perhaps under a doorway, in the dark. To add to the confusion, electricity failed in some communities preventing them finding out about the cause of the shaking from internet websites.
The rule of thumb is, “If you are at the coast and experience a strong earthquake that makes it hard to stand up, or a weak rolling earthquake that lasts a minute or more, move immediately to the nearest high ground, or as far inland as you can.” Residents of Waipiro Bay, Hicks Bay and Te Araroa would have been able to run this through their mind, note the state of their houses, and make the decision to move. For people in Gisborne, Whakatane and places further afield, this would have been more difficult to assess. Had the rolling quake lasted a minute or more? How much of it had occurred before they woke up?
The initial magnitude assessment of the earthquake put it in the sixes, well outside the criteria for a tsunami-producing quake. However, this was quickly revised up to 7 before settling at magnitude 7.1 close to the parameters which could cause a local tsunami. By this time, MCDEM would have had reports on the shaking felt by CD officers at Te Araroa and possibly settlements nearby. The revision to magnitude 7 should have triggered the issuing of an advisory for evacuation of red zones, at the very least, between Opotiki and Tolaga Bay. The template for the advisory has been prepared and was published in the National Tsunami Advisory and Warning Plan (revised in August this year) – only the parameters relevant to Friday’s quake needed to be added.
Observations sent in by CD officers at locations near to the earthquake epicentre would then have allowed the advisory to be extended or upgraded to a warning if tsunami were observed, or cancelled altogether. There is no point in telling people to leave the coast if they feel a weak rolling earthquake that lasts a minute or more, learning that the quake was nearby and of a magnitude close to agreed thresholds, and then throwing up your hands and saying, “Aw shucks. We’re not sure.”
The National Tsunami Advisory and Warning Plan notes [page 28], “A significant source of large vertical-slip faulting exists in conjunction with the Hikurangi subduction margin off the eastern North Island. Tsunami could be generated by large earthquakes (magnitude 7.5 – 9.0) on the plate interface itself from slip between the two opposing plates, or by rupture of steeper faults that break up through the Australian plate. “ Friday’s quake was magnitude 7.1, close to that magnitude 7.5 threshold.
The plan goes on to note [page 29], “However, the March 1947 Gisborne tsunami, caused by a magnitude 7.1 earthquake, caused much larger than expected run-ups of up to about ten metres.“
Time marched on, and communities near the earthquake epicentre began experiencing aftershocks, two of which were strong in their own right. A magnitude 6.2 quake struck at 5:14 a.m. and a magnitude 5.7 earthquake at 5:36 a.m. Some communities and individuals took matters into their own hands and evacuated people to higher ground. At Te Araroa, the settlement nearest the earthquake, the fire siren was set off to alert people to take action.
The Ministry of Civil Defence and Emergency Management (MCDEM) did not issue a bulletin on the tsunami risk until 5:36 a.m., an hour after the earthquake had occurred. This was only a “potential threat” and belied the frantic activity that had been going on behind the scenes to determine the tsunami risk from the magnitude 7.1 quake. RNZ National’s Media Watch devoted a segment of its usual Sunday programme this morning to a study of MCDEM’s communications on the East Cape quake, and a review of its previous communication blunders.
During that silent hour, MCDEM had been very busy, reconciling changing estimates of the size and location of the quake with policies and procedures it had previously prepared with seismologists and tsunami experts.
MCDEM has become a victim of its own success in raising public consciousness of the tsunami hazard to New Zealand coasts. In doing so, it has created an information vacuum and, as has been shown in previous tsunami events, misinformation pours into this vacuum while MCDEM dithers about whether to make a statement. The public face of the ministry through various websites is dominated by spin, folksy language, and feel good campaigns like “Plan Stan” and “Get Ready Get Thru.” The public do not have one website to go to for information in an emergency.
This is a pity, because MCDEM’s plans, policies and procedures, rarely seen by the public, are now well-researched, well-written, and authoritative. For some reason, the very good work being done by ministry staff rarely gets past the spin-sters who manage the public image of the organisation.
What is lacking in New Zealand is a dedicated, factual website that dispenses information in the event of a tsunami threat to New Zealand. MCDEM directors keep banging on about the Pacific Tsunami Warning Centre not being the official site for information on tsunami threats to New Zealand. Media Watch quoted current director Sarah Stuart-Black as stating, “We note that some media called the Pacific Tsunami Warning Centre (PTWC) for more information, who subsequently informed there was no threat while there was actually a warning in place for New Zealand. The PTWC is not the correct source to go to for information about specific risks to New Zealand. It is important that New Zealanders have a single authoritative source to go to, and during a tsunami threat this is MCDEM and local Civil Defence Emergency Management.” Well, get on with it then.
The Pacific Tsunami Warning Centre (PTWC) often gets its initial assessment of the depth or magnitude of an earthquake wrong. Nevertheless, it has the courage to issue an authoritative statement on the event quickly, and issues updates as more information comes to hand. It is never afraid to correct its earlier assessment AND leaves all of its bulletins up on its website for later review and assessment.
Compare this with MCDEM’s website which today has no information on the debacle that occurred on the morning of Friday 2nd, even the messages that did initially appear on the website have gone – the body has been well and truly buried. Another victory for the PR minders.
There are other problems with the national civil defence plans, such as the lack of a nation-wide standard for warning sirens and their use. However, much of the core planning for seismic emergencies has been revamped and is in place.
MCDEM has come a long way in the past decade but, for some reason, it just doesn’t get the need for timely, authoritative information in an age when the public expect to be kept informed. This is the last glaring gap that will continue to be filled by supposition and misinformation until the ministry acts.