Geoscience Australia says a strong earthquake that rocked Japan did not trigger a smaller event off NZ.
The Pacific ‘Ring of Fire’. Picture: Wikipedia
NO PLACE on Earth is safe from the force of Mother Nature but countries on the “Ring of Fire” are certainly most vulnerable.
The Ring of Fire is a horseshoe-shaped band of fault lines that circles the Pacific Basin and is prone to frequent earthquakes and volcanic eruptions. It is the most seismically active zone on the planet.
The Ring of Fire extends 40,000km and includes 452 volcanoes, stretches from the southern tip of South America, up and along the west coast of North America, across the Bering Strait and down through Japan and then south to New Zealand. It also takes in Vanuatu, the Solomon Islands, Papua New Guinea, and Indonesia, where the Indo-Australian Plate collides with the Eurasian Plate.
The most catastrophic earthquakes have taken place around the Ring of Fire, including the strongest one on record, a magnitude 9.5 in Chile in the 1960s.
UTS Geotechnical and Earthquake Engineering senior lecturer Behzad Fatahi said the Ring of Fire “looks like broken eggshells”.
“The borders of a lot of tectonic plates meet in the Ring of Fire, they move away from each other and push each other, it’s one of those very active areas,” Dr Fatahi said.
This week has seen significant seismic activity along the belt, particularly in Japan and New Zealand.
Yesterday, a 6.9-magnitude earthquake struck off the Japanese coast of Fukushima prefecture and tsunami waves soon followed.
Books are scattered on the floor at a library in Iwaki, Fukushima prefecture after a strong earthquake on November 22, 2016. Picture: Kyodo News via APSource:AP
A magnitude 6.9 earthquake struck at 11.4km depth, 35km from Tomioka, Fukushima Prefecture, Japan. 5:59am local time.Source:AAP
Hours later, New Zealand was rocked by an earthquake with a preliminary magnitude of 6.1 to 6.3. The quake hit the nation’s North Island on Tuesday morning, centred off the coast almost 140km from Palmerston North at a depth of 37km.
The earthquake came less than a week after a powerful tremor centred in the upper South Island rocked the country and killed two people. Thousands of aftershocks have been registered since a 7.8 magnitude quake struck near Christchurch in the early hours of November 14.
New Zealand has endured more than its fair share of earthquakes. New fault lines emerged there as recently as September 2010 when Christchurch was struck by a powerful 7.1-magnitude earthquake. The quake smashed buildings, cracked roads, twisted rail lines and ripped a new 3.5 metre wide fault line in the earth’s surface.
Dr Fatahi said “the earthquakes in Japan and New Zealand occurred because they are on the borders of Pacific plates”.
“Right under these tectonic plates there’s magma,” he told news.com.au.
“When these plates move away, slide and compress together there’s the chance of earthquakes and volcanoes.”
A landslide covers a section of State Highway 1 near Kaikoura after a powerful earthquake hit New Zealand on November 14, 2016. Picture: David Alexander/SNPA via APSource:AP
A convoy makes its way to deliver Civil Defence support in Kaikoura, South Island, New Zealand, after the November 14, 2016 earthquake. Picture: AAP Image/New Zealand Defence Force, Defence Force Affairs, LAC Chad SharmanSource:AAP
Dr Fatahi said Japan was particularly vulnerable because it was in “a very complex area” where four major tectonic plates meet.
“The edges of the Eurasian, Pacific, North American and Philippine Sea plates all meet in Japan,” he said.
“The earthquake that hit Japan today looks like it happened when the North American and Pacific Plate collided.
“The North American Plate is huge — much bigger than the Pacific Plate.”
In 2011, entire towns were swamped after a 10m tsunami slammed into Japan’s Pacific coast following a massive 8.9 magnitude offshore earthquake, the largest in 140 years.
“The earthquake in Japan in 2011 was above a magnitude 8 and caused a tsunami and the melting down of the nuclear power plant and so on,” Dr Fatahi said.
“If something of that scale happens it’s really devastating.”
Volcanic eruptions are also common in Japan. The country suffered its deadliest eruption in almost 90 years when Mount Ontake blew its top in September this year, killing more than 60 people.
Indonesia, an archipelago of 240 million people, is another one of our neighbours prone to earthquakes and volcano eruptions because it sits along the Pacific Ring of Fire.
On February 2, 2013, the Lokon volcano spewed its thick, hot smoke 2000 metres into the air in a spectacular eruption. Picture: AFPSource:AFP
Peru, also on the Ring of Fire, was struck by a magnitude 7.9 earthquake on August 15, 2007. Its epicentre was on the central coast, just west of the major city of Pisco. It killed 595 people.
In August this year, a moderate 5.3-magnitude earthquake in Peru killed at least four people including a US tourist and left 68 injured, crushing villagers under rubble and blocking roads. The quake knocked down about 50 homes and cut off roads and power in the southern Arequipa region.
“It was tragic. They got wounded people out as best they could,” said John Rivera, a resident of Yanque, a hard-hit rural village of mud huts.
There is an earthquake every minute, according to Dr Fatahi. But it’s mostly those stronger than a magnitude 6 that tend to cause significant destruction and loss of life. For every number higher, the earthquake is 30 times stronger, he said.
EARTHQUAKE EXPERT PREDICTED DISASTERS
Dr Behzad Fatahi warned it was only a matter of time until more high magnitude earthquakes would strike, when he spoke to news.com.au in August.
“There are a lot of magnitude 6-plus earthquakes overdue in the Middle East, India, China, Japan and the US,” Dr Fatahi said at the time.
“There are some fault lines that have not released their energy for a while.
“There are at least 5-10 that are overdue, but we don’t know when they’re going to happen.
“The question is not will they be activated. The question is when.”
Dr Fatahi said there was a “return period” for earthquakes and those that didn’t strike within the expected time frame only came back stronger. He said an example of this was the 7.8 magnitude earthquake in Nepal that left more than 8000 people dead in April last year.
“You expect a particular fault line will be activated every 100 years or 500 years,” he said.
“If the period is longer we expect higher magnitude earthquakes … looking at the history of some of those major fault lines, some are very overdue.
“The return period has passed but the earthquakes haven’t happened.
“So we are just waiting for them to happen.”
MAJOR FAULT LINES
Earthquakes claim tens of thousands of lives all over the world each year.
“The crust has several pieces,” Dr Fatahi said.
“The line between each of these pieces is called a ‘fault line’.
“The most dangerous fault lines are those where two tectonic plates collide.”
That was the case in central Italy, when a 6.2 magnitude earthquake struck the region in August this year. More than 257 people died and many more were injured.
“The Eurasian Plate and African Plate both have a very big fault line where they meet somewhere under Italy … this is what caused the (Italy) earthquake (in August),” Dr Fatahi said.
Tectonic plates are giant slabs of rock that make up the earth’s upper crust (lithosphere) and move, float, and sometimes fracture, causing continental drift, earthquakes, volcanoes, mountains, and oceanic trenches.
The San Andreas Fault line in California is the longest in the world. It sits between the Pacific and North American plates and measures 1300km. The depths of these collision zones can range from 0-700km.
While scientists can’t predict the timing or location of an earthquake it’s a safe bet that the next disaster will happen somewhere along the Ring of Fire.