A powerful 7.8 magnitude earthquake – the biggest experienced in the Shaky Isles for 80 years – occurred in southern New Zealand during the early evening of July 15th last. Had you owned a Seismograph, you might have known about it virtually straight away.
The earthquake fortunately struck in a very remote part of the South Island (Dusky Sound-Fiordland) and damage was minor, with no injuries or deaths.
Few Kiwis in the more populous North Island even felt it! However as a tribute to the massive power of the event, it transpires that this NZ region has been measurably twisted slightly out-of-shape.
Once the shaking settled, the net result in that region has been a land raising of about a metre, along with a sideways shift westward approximating a handspan. Yes – NZ is now (fractionally!) closer to Australia.
With memories of the Boxing Day 2004 magnitude 9.3 Indian Ocean tsunami still painfully fresh, Australian east coast alerts (and even some precautionary Lord Howe Island evacuations) promptly developed.
Thankfully these concerns proved a false alarm, as only mere surges – no higher than normal ocean waves – eventuated trans-Tasman.
However, closer to the quake source, waves of 1m high were experienced, and even in remote Hawaii handspan-high rough water was noted. The event served as an excellent test run of the Australian Tsunami Warning System (ATWS) and as a reminder that devastating earth movements can strike at any time, with no warning.
New Zealand sits above an area of the earth’s crust where the Pacific and Australian tectonic plates collide and earthquakes are a regular occurrence.
Kiwis reckon lots of small quakes (to relieve pressure) are better than a single large rumble! The Dusky Sound quake was certainly no mere pebble splash however and it has triggered renewed interest in earthquake monitoring overall, perhaps even with an eye on the holy grail of eventual prediction.