Twelve minutes to the maunga: an evacuation plan that has to work for everyone

The arithmetic

• Required average speed to cover 1.4 km in 12 minutes: 1.4 km ÷ 0.2 h = 7.0 km/h.
• Fastest group: 1.4 km in 13 min = 1.4 ÷ 0.217 h ≈ 6.5 km/h - already slower than required, before any assembly time.
• Slowest group: 1.4 km in 26 min ≈ 3.2 km/h, which is a normal pace for 5–7 year olds in a group. Implied time: about 26 minutes, more than double the available window.
• The bus: 320 students at 45 per trip = 8 trips. At 14 minutes each, that is about 112 minutes - nearly ten times the window. The bus is only viable if reserved for the six students who cannot walk, which is one trip.

Plus the plan's own delays. 'Assemble on the court' adds several minutes of standing still, and 'wait for a civil defence warning' adds an indefinite delay - in a near-field tsunami the wave can arrive before any official warning is issued.

Assumptions inside the 12 minutes

• It is a model output for one rupture scenario at high tide, not a guarantee; other scenarios give different times, and the true figure could be shorter.
• It measures wave arrival at the shore, not the time the water reaches the school, and does not include any safety margin.
• It assumes the single-lane road is clear. In a real event it will be shared with evacuating whānau and cars.

Judgement: the current plan cannot work. No group can reach the maunga in 12 minutes even at full pace, and assembly plus a warning wait makes the gap larger.

1. Replace 'wait for a warning' with immediate action. The recognised rule is Long or Strong, Get Gone: if the shaking is longer than a minute or strong enough to make standing difficult, evacuate at once. Justification: a 12-minute window and the likelihood that no official warning will precede a near-field wave. 2. Abolish the court assembly. Each class leaves from its own room along a pre-assigned route, with the roll taken at the top rather than on the field. Justification: the fastest group needed 13 minutes of walking alone; any stationary assembly time is unaffordable. 3. Move the trigger point closer. Identify the lowest point on the route that is above the modelled inundation zone (a contour or a marked line) and treat that as 'safe enough', rather than the summit. Justification: the full 1.4 km climb is what breaks the 12-minute budget; shortens the distance for the youngest and slowest. 4. Dedicate the bus to the six mobility students and their adults, and roster drivers. One trip of 14 minutes is feasible for that group; eight trips are not. Justification: 320 ÷ 45 = 8 trips ≈ 112 minutes, so general busing cannot work. 5. Practise the real thing. Termly drills, including one with no notice, timed and recorded, with the slowest group's time reported to the board. Justification: the existing practice produced the 13- and 26-minute figures - that data is only useful if it drives change and is re-measured. 6. Whānau plan. Publish the maunga as the reunification point and teach the Long or Strong rule to families, so parents do not drive to the school gate during an evacuation and block the single-lane road. 7. Interim vertical evacuation. If a suitable multi-storey building exists within a few minutes' walk, assess it as a nearer option while the route is improved.

For

• The school is 380 m from the beach with only 12 minutes and 1.4 km of single-lane road to safe ground. A platform on site removes the travel problem entirely - the strongest argument in a near-field event where the wave may arrive before any warning.
• It serves the six students with mobility aids and the youngest children, who currently cannot make the distance.
• It is usable in every scenario, including a night event or one where the road is blocked by traffic, fallen trees or liquefaction.

Against

• Cost and opportunity cost. $450,000 is substantial for a school of 320; the same money could fund route improvements, a second evacuation vehicle, and community education, which may protect more people more often.
• Engineering under load. A platform must survive the earthquake itself, aftershocks, debris impact and buoyancy from the wave, and must have safe, rapid access for 320 young children. Whether the existing roof structure can carry that is unknown.
• Vertical evacuation still needs time. Getting 320 children up onto a roof is not instant; if it takes 15 minutes it fails for the same reason the walk does.
• Risk of false comfort. A platform could discourage the immediate evacuation that is still the best option when there is time to use it, and it may complicate the message the school teaches whānau.

Information needed before deciding

1. Modelled wave heights, flow velocities and arrival times at the school site for several scenarios, including a near-field rupture.
2. A structural engineering assessment of whether any existing building could be upgraded, and to what standard.
3. A measured drill time for 320 students to reach and ascend the proposed platform, compared with 12 minutes.
4. Cost–benefit against alternatives: a closer high-ground route, a second vehicle for mobility students, and a community vertical-evacuation building shared with the wider suburb.
5. Clarity on whether official guidance for this coast treats vertical evacuation as a primary or last-resort measure, since the plan should align with it.