If someone mentions New Zealand, what tidbits of thoughts race through the back of your mind? Mine include ‘hobbit films location’, ‘weird landscape’, ‘two islands’, ‘south Pacific’, and ‘near Australia’. Of course, I don’t often think about New Zealand. It’s very far away, and I’m not likely to get there soon.
A couple weeks ago, I saw a headline about a recent earthquake NZ had. It took my head a couple seconds to realize, “Oh, yeah, it sits on the other side of the ring of fire.” So, just because my curiosity was aroused, I’ve been looking into the geology of NZ.
First of all, yes, New Zealand does have two large islands, but they are surrounded by a bunch of little ones. Islands tend to come in groups, right? Seems like it to me.
The south island is home of the Southern Alps, the tallest some 12,316 ft tall. These steep peaks and the deep fjords on the southwest coast indicate the glaciation that once covered the area. Makes me shiver just thinking of the ice that was once there.
The north island is not as mountainous, but does have volcanoes, which have formed a plateau. That plateau hosts that island’s highest peak (9,177 ft) and the country’s largest lake, which sits in the caldera of one of the world’s most active supervolcanoes. Okay, that’s a little too much heat for roasting marshmallows.
New Zealand is what’s left of Zealandia, a microcontinent (half the size of Australia) that long ago broke off from the super-continent Gondwana, and then slowly submerged. It also straddles the border between the Pacific and Indo-Australian tectonic plates.
The border of these plates is most evident by the Southern Alps, pushed up and contorted by the force of the 2 plates pushing against each other. In other places, the edge of one plate gets pushed beneath the other, producing deep trenches in the ocean, most notably south of NZ, east of North Island, and 2 others further north.
So, NZ has mountains and bays once scoured by glaciers, deep ocean trenches and volcanoes. What about earthquakes? Of course! It sits on a giant fault. In fact, Wikipedia says they experience 150-200 earthquakes every year that can be felt, and almost 14,000 more each year that aren’t felt.
The headline that caught my attention not long ago was about an earthquake in November of this year; a section of seabed that had been raised 6 feet above sea level on a beach. As I researched ‘New Zealand earthquakes,’ I saw another interesting headline, this one about 3 cows that were left stranded on a ‘land island’ after an earthquake. Apparently, that earthquake caused a lot of land to collapse, leaving dots at a higher altitude with sides too steep for the cows to navigate. And possibly some tourists were also trapped on similar ‘land islands’ and had to be rescued.
Just one more way New Zealand is ‘different.’