Selwyn District

humidity

Longshore current has moved Tom parallel to the shore. What has caused the greatest changes in sea level in the past 3000 years? A longshore sand bar might cause a wave to break well before it meets the shoreline. A longshore sand bar parallels the coast.

In New Zealand, several towns and cities could be underwater in just 30 years’ time.

The sinking is being caused by catastrophic subsidence from groundwater being pumped out from below, often through unregulated wells for homes, factories and farms.

From the Paris Agreement period alone—between 2015, when the agreement was signed, and 2030, when the stated commitments end—the world will have caused enough warming to drive sea levels about 4.5 inches higher in the future. That’s just from that 15-year stretch.

NZ’s landmass overall is rising slowly with an average GIA of around 0.3 mm/year of relative sea level.

New Zealand lies at the edge of both the Australian and Pacific tectonic plates. To the northeast of New Zealand, and underneath North Island, the Pacific Plate is moving towards, and being subducted below the Australian Plate.

If two tectonic plates collide, they form a convergent plate boundary. Usually, one of the converging plates will move beneath the other, a process known as subduction. The new magma (molten rock) rises and may erupt violently to form volcanoes, often building arcs of islands along the convergent boundary.

Modern tectonic setting and earthquakes New Zealand is currently astride the convergent boundary between the Pacific and Australian Plates. Through most of the South Island, the plates slide past each other (Alpine Fault), with slight obduction of the Pacific Plate over the Australian Plate, forming Southern Alps.

New Zealand experiences large numbers of small earthquakes, in a well-defined belt stretching from Fiordland to East Cape and the Bay of Plenty. This pattern is part of the ‘Ring of Fire’, the almost continuous belt of volcanoes and earthquakes rimming the Pacific Ocean.

New Zealand is the site of one of the world’s youngest subduction zones, where the Pacific Plate of Earth’s crust dives beneath the Australian Plate. New Zealand is the site of one of the world’s youngest subduction zones, where the Pacific Plate of Earth’s crust dives beneath the Australian Plate.

New Zealand has volcanoes because it sits on a convergent continental plate boundary. The North Island’s Taupo Volcanic Zone is one of the most active volcanic regions in the world.

Many of the major rivers in the North Island still carry large amounts of this pumice when in flood. Most importantly, Taupo shows no signs of being finished—it is extremely likely to erupt again and the timing and scale of its next episode cannot be predicted.

The eruption was New Zealand’s deadliest, killing at least 120 people and burying settlements and villages.

It is part of the larger Central Volcanic Region that extends further westward through the western Bay of Plenty to the eastern side of the Coromandel Peninsula and has been active for four million years. The Taupo Volcanic Zone is widening east–west at the rate of about 8 mm per year.

Whakaari/White Island

The Taupo Volcano roared back into life 1800 years ago, when it erupted again.