Be Prepared Month: What are the odds part two (or “More crystal ball gazing”)

In the last episode, we asked if New Zealand was becoming more vulnerable to earthquakes. There was a bit of debate on this on our Facebook page, but looking at 12 years of data our answer is “probably not”.

And, as if their ears were burning, GeoNet posted this helpful tweet on Monday:

None of this, of course, means there’s no risk – events in Canterbury have proven that beyond doubt. It is however one of several challenges this beautiful little island nation potentially faces. Here’s a few more to be prepared for:

 

Tsunami

Last weekend, Christchurch tried out its new tsunami warning system. 22 sirens, costing $550,000 each, went off at 11am. Chances are you didn’t know about this, because not many people heard them.

Local man struggles in vain to hear tsunami sirens.

There may be up to 79 more sirens set up along the entire coast. Hopefully, with the 101 sirens combined, people will notice and act accordingly. Incidentally, your author has a similar set up in his bedroom using alarm clocks.

This all stems from 2004’s massive global tsunami, after which our government decided to find out what would happen had the wave hit us too.

The subsequent report contained a surprise for many: we have had 40 tsunamis since 1840. So clearly it’s the Treaty’s fault, right? No, actually, they worked out most of the causes too:

  • 14 were triggered by global/distant earthquakes (regions outside the South Pacific),
  • Seven were from regional earthquakes (the South Pacific region and south of New Zealand),
  • Nine were from local earthquakes (self-explanatory),
  • Four were from local earthquakes accompanied by coastal landslides,
  • One was a spontaneous landslide,
  • Eight others were from unknown sources, one of which was possibly a submarine landslide.

Our one tsunami-related death in this period came in 1868, from a 10+ metre high wave triggered by a South American shake.

Since then, of course, there has been a great deal more population growth and coastal development. A similar tsunami today would equal more damage and more fatalities.

So what are the chances? I found the following diagnosis on page 104:

“The ongoing risk from tsunami in New Zealand is significant, possibly rather higher than many people may realise… the damage to property from tsunami is about twice what we expect from earthquakes… and the deaths and injuries are many times more. A caveat here is that the projected deaths and injuries numbers will drop if it is felt appropriate to assume an effective warning system exists for tsunami of distant origin, but they will still be substantially greater than for earthquakes in places such as Wellington where the major threat is from locally generated tsunami.”

So that warning system in Christchurch will be a big help once beefed up, right? Says the local Council website, “the sirens will not be used for a local source tsunami as there will not be sufficient time before the tsunami reaches land.” Well, fiddlesticks.

 

Volcano eruption

In last Friday’s blog we politely asked New Zealand not to have any volcano eruptions at least until this blog was published.

“Challenge accepted” said Mt Tongariro, and promptly upped its seismic activity. Whereas the area was lucky to have two small earthquakes a year, last week saw at least twenty of them, and GNS accordingly upgraded its alert level to one. There has also been reports of volcanic gases being detected.

Realistically a level of one means little more than “we’re keeping an eye on things”. Ruapehu and White Island, our most restless cones, have been sitting at one for a few years now. The alert system defines this as showing signs of possible unrest, with no eruption threat at this time.

Mt Tongariro

Quiet, you. That’s not a challenge.

Ruapehu’s most recent eruption was a seven-minute outburst in 2007, which spewed ash, rocks and lahar over the summit and Whakapapa ski field. The worst we’ve seen in modern times was the 1886 Mt Tarawera eruption. This event started the great kiwi tradition of terrace desecration, which reached its peak during the 1999 Super 12 final at Carisbrook.

Other than the occasional rush to the head by Ruapehu and White Island, the other area of focus is Auckland and its approximately 53 volcanoes. The good news is, they’re not planning on blowing their top again for a long while.  On average, according to the Auckland Museum, Auckland has a problem every 2500 years – and the last big eruption was Rangitoto 600 years ago.

This doesn’t mean they won’t surprise us, mind you. What we do know is, whether Auckland blows early or Tongariro decides it’s not all talk, our best science people are monitoring the situation all the time, and Get Thru has a list of what to do if, or when, an eruption happens.

 

Flooding

This is an easy one. Floods happen in New Zealand all. The. Time.

In just the past week we’ve seen roads closed in the Waikato and Coromandel and 30 Levin residents cut off by a rain-induced landslide. Earlier this month flash floods caused havoc in Auckland. Heck, last Christmas even the sunshine capital of New Zealand got swamped, with over 200 slips and more than 100 homes red-stickered.

Flash flooding on the North Shore.

So if you’re going to mentally and physically prepare yourselves for anything, do it for this. Now, aren’t you glad you read all the way to the conclusion?

 

Conclusion

What I’ve learned in the last hour is this: predicting what the earth will do next is almost as hard as writing a conclusion. With the former we suggest you stock your kits, draw up a plan and live your life without worry, knowing you’re as well prepared as you can be for something so unpredictable.

As we said last time, “It might be that you’ll never need your emergency kit or plan; alternatively it might be the smartest thing you ever did.” So stop reading this and go get prepared. Or if you’d rather stick around, how about leaving us a comment below or on our Facebook page? We’d love to read your thoughts.

4 thoughts on “Be Prepared Month: What are the odds part two (or “More crystal ball gazing”)

  1. Pingback: Be Prepared Month: What are the odds? | Open2view

  2. Impressed, more infomation here than i have found any where, most important it is relevant to where we live and not a global thing, thanks and keep up the good work.
    Steve.

  3. Pingback: Be Prepared Month: That’s a wrap (up) | Open2view

  4. Pingback: July’s NZ Property Report in short | Open2view

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