One year ago, an earthquake rocked the eastern coast of New Zealand’s South Island, leaving a trail of death and devastation in its wake. Now scientists are taking a closer look at what caused it – and what they’ve discovered could have terrifying implications.
Just after midnight on November 14, 2016, residents in the small town of Kaikoura, New Zealand, were shaken from their beds by a massive earthquake. Starting some 37 miles southwest of the town, the quake lasted around two minutes. It registered a sizeable 7.8 on the Richter scale.
When the dust settled, the quake’s devastating impact became clear. Just outside of Kaikoura, a well-known homestead had collapsed, killing a man trapped inside. Elsewhere, a woman died from a fatal head injury sustained during the disaster.
Meanwhile, bridges, roads and railway lines were severely damaged, cutting off parts of the island for several days. Even the capital, Wellington, some 150 miles from the epicenter, lost a number of buildings to the quake. And in the far northeast, the peninsula of Cape Campbell rose permanently by around three feet.
Once measured, the Kaikoura quake was determined to be the most violent that New Zealand had ever seen. In order to better understand the phenomenon, scientists began taking a closer look at the geology surrounding the island nation. And, shockingly, their research has revealed that the worst might still be to come.
Located in the southwest of the Pacific Ocean, New Zealand sits on top of a number of fault lines. Essentially cracks in the Earth, these faults form when sections of rock slide against each other. Often, this movement has little effect. But if there’s a large build-up of pressure, big shifts in the rock can occur – causing earthquakes like the one that hit Kaikoura in 2016.
According to scientists, New Zealand’s largest fault line is the Hikurangi subduction zone. Beginning just east of Gisborne on the country’s North Island, the fault runs all the way to the South Island’s tip, some 280 miles away. And if recent research is correct, it could pose the biggest threat yet.
Forming part of the earthquake hotspot known as the Pacific Ring of Fire, the Hikurangi fault marks the spot where two of the Earth’s tectonic plates meet. As the Pacific plate moves underneath the Australian plate, it creates a volatile region known as a subduction zone.
According to experts, the Earth’s subduction zones are where the planet’s mightiest earthquakes take place. Known as megathrust quakes, they occur when the edge of one plate thrusts upwards, creating upheaval that often registers near the top of the Richter scale.
Megathrust earthquakes also disrupt the seabed, bringing about giant tsunami waves. Together, these twin threats can cause unparalleled devastation around the world. In fact, they have been responsible for hundreds of thousands of deaths in the 21st century alone.
On December 26, 2004, a megathrust earthquake was caused when the Burma plate slid underneath the Indian plate off the western coast of Sumatra. Although the quake itself caused minimal damage, the resulting tsunami waves caused as many as 280,000 people to lose their lives in one of the worst natural disasters ever.
Seven years later, another megathrust quake struck off the coast of Tōhoku in Japan. As powerful tremors damaged buildings, tsunami waves reaching over 130 feet in height traveled as far as six miles inland. In the ensuing chaos, at least 15,800 people lost their lives.
Now people in New Zealand are pondering the unthinkable. Could an earthquake of equally devastating strength be waiting to strike off the coast of their country? Apparently, scientists had previously believed that the Hikurangi zone was dormant, as seismic activity had historically been absent in the region.
But now, in the aftermath of the Kaikoura quake, it’s clear that things are on the move. And if a megathrust earthquake occurs, the country could see a devastating disaster on a par with Sumatra or Japan. In fact, it would make last year’s incident seem like a mere rumble by comparison.
At a November 2017 conference in Blenheim on New Zealand’s South Island, scientist Ursula Cochran suggested that locals should prepare for the worst. “We need to think Japan 2011, basically,” she explained, “because if our whole plate boundary ruptured it would be a magnitude-9 earthquake.”
Crucially, Cochran insists that the 2016 quake was merely a taste of what could be in store. “One thing about reflecting on from the Kaikoura earthquake,” she continued, “is we don’t want people to think this is the big one.” Indeed, a quake of that scale could cause chaos on a level that New Zealand has never seen.
Aside from the obvious dangers of the quake itself, a magnitude-9 event could see a deadly tsunami wave engulf large swathes of the North and South islands. And, frighteningly, it could happen before residents have time to escape.
“We know from tsunami modeling from a hypothetical earthquake from the Hikurangi subduction zone that the travel time could be very short to the coast,” Cochran explained, “so seven minutes for some of the south Wairarapa coast.”
Given the speed at which a tsunami wave could engulf coastal communities, some experts have suggested that residents should have an evacuation plan in place. “I would encourage people to say, ‘Look, I’m gong to measure how much time it takes me to get from my place to higher ground,’” Caroline Orchiston from the University of Otago told the conference.
Meanwhile, a team of 30 scientists has embarked on a mission to study the Hikurangi zone off the Gisborne coast. But as they learn more about the volatile region, will they be able to prevent future loss of life? If a megathrust earthquake hits New Zealand in the years to come, we can only hope that the country is prepared.