More vulnerable than we could be

EDITORIAL

Comparisons between the potential of a mega-thrust earthquake at the Hikurangi subduction zone off our coast and the magnitude-9 quake that struck northeastern Japan in March 2011, unleashing a savage tsunami, are naturally deeply unsettling.

That double-whammy of giant earthquake and tsunami waves that surged inland up to 39 metres above sea level — and as far as 10km — killed about 18,000 people and caused damage totalling $US200 billion.

Thanks to Japan’s world-leading early warning system, people received alerts of the earthquake and tsunami warnings on their cellphones — with Tokyo residents getting the quake alert a minute before strong shaking hit the city. The tsunami warning was issued in just three minutes, well ahead of the waves’ arrival on the coast 15 minutes later.

Martha Savage, professor of geophysics at Victoria University’s School of Geography, Environment and Earth Sciences, told RadioLIVE New Zealand should be investing in more instruments on the seafloor like the 30 sensors placed on the seabed at Hikurangi in October.

“Because the subduction zone is closer to us than it is in Japan, we would have large tsunamis and we wouldn’t have as much warning — they could come in as early as six minutes,” said Prof Savage.

The proximity of the subduction zone to land, the lack of research on it (which is being addressed at last with the international study now under way) and the absence of an early warning system leaves all of us who live on the east coast in a more vulnerable situation than we would want to be when and if it does strike.

“We could do more if we had enough money, although we are constrained by the geometry,” said Prof Savage. “In Japan for instance, they are putting in a network of seismometers on the seafloor. They’re cabled together, and if we had enough money we might be able to do that and give ourselves maybe a couple more minutes’ warning.”

She also acknowledged the fact the Government “has other priorities too”, though we’re sure most readers would consider it worth spending whatever it takes.

Comparisons between the potential of a mega-thrust earthquake at the Hikurangi subduction zone off our coast and the magnitude-9 quake that struck northeastern Japan in March 2011, unleashing a savage tsunami, are naturally deeply unsettling.

That double-whammy of giant earthquake and tsunami waves that surged inland up to 39 metres above sea level — and as far as 10km — killed about 18,000 people and caused damage totalling $US200 billion.

Thanks to Japan’s world-leading early warning system, people received alerts of the earthquake and tsunami warnings on their cellphones — with Tokyo residents getting the quake alert a minute before strong shaking hit the city. The tsunami warning was issued in just three minutes, well ahead of the waves’ arrival on the coast 15 minutes later.

Martha Savage, professor of geophysics at Victoria University’s School of Geography, Environment and Earth Sciences, told RadioLIVE New Zealand should be investing in more instruments on the seafloor like the 30 sensors placed on the seabed at Hikurangi in October.

“Because the subduction zone is closer to us than it is in Japan, we would have large tsunamis and we wouldn’t have as much warning — they could come in as early as six minutes,” said Prof Savage.

The proximity of the subduction zone to land, the lack of research on it (which is being addressed at last with the international study now under way) and the absence of an early warning system leaves all of us who live on the east coast in a more vulnerable situation than we would want to be when and if it does strike.

“We could do more if we had enough money, although we are constrained by the geometry,” said Prof Savage. “In Japan for instance, they are putting in a network of seismometers on the seafloor. They’re cabled together, and if we had enough money we might be able to do that and give ourselves maybe a couple more minutes’ warning.”

She also acknowledged the fact the Government “has other priorities too”, though we’re sure most readers would consider it worth spending whatever it takes.

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