Six of the most powerful earthquakes ever recorded have struck in the past 25 years.

The deadliest was the magnitude-9.1 Indian Ocean earthquake, which triggered a catastrophic tsunami on Boxing Day 2004 killing more than 220,000 people across multiple countries.

Seven years later, Japan was rocked by a magnitude-9.1 earthquake triggering a tsunami that devastated the country’s northeast and caused the Fukushima nuclear disaster.

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Chile and Indonesia have also been hit by several extraordinarily powerful events.

Since June, magnitude-seven-plus earthquakes have struck the Philippines, Venezuela, Mexico, Colombia, and Indonesia, the latest a magnitude-7.7 event in the Flores Sea earlier this month.

But does the recent succession of powerful earthquakes indicate they are becoming more frequent, or has greater global awareness, faster reporting and their impact on populated areas simply made it feel that way?

Are earthquakes becoming more frequent?

Australian National University fellow and senior lecturer Dr Caroline Eakin said the seemingly alarming cluster was not evidence major earthquakes are becoming more frequent.

Earthquakes occur around the world every day but events that strike populated areas or cause considerable destruction are far more likely to dominate international headlines.

“I’d say we hear about the earthquakes that affect people, and it just so happens that some of the larger earthquakes we’ve had a few of in the first half of this year have been damaging and have affected people in different parts of the world that make the news,” she told 7NEWS.com.au.

Eakin said scientist would expect about 15 earthquakes of magnitude seven or greater in any given year, although the number could range from 10 to 20.

Almost 300 people died in the Colombian earthquake, with hundreds missing and thousands injured. Credit: AAP

Sixteen earthquakes have been recorded during the past 12 month, placing the figure right in the normal range.

“It just so happens that, unfortunately, several of those have happened in populated areas and caused a lot of damage and distress,” Eakin said.

Scientists typically expect about one magnitude-eight or greater “great earthquake” each year, although they do not occur at regular annual intervals.

“It’s just part of the sort of natural variability of earthquakes that you’ll get some periods when there’s more, and they will appear to cluster together, and other times will appear there are not that many,” she said.

Modern technology has allowed scientists to detect an increasing number of smaller earthquakes, but the world’s most powerful events have been recorded through a global seismic network for decades.

What do earthquake magnitudes really mean?

While earthquake strength is still commonly described using the Richter scale, scientists now generally rely on what is called the “moment magnitude scale”.

“They’re roughly equivalent, but the moment magnitude scale we use is more applicable globally. It relates to a physical measurement to the size of the fault rupture and how much the rocks have slipped,” Eakin said.

“It’s a direct measure of the energy that is released by an earthquake.”

Major earthquakes that shook the world. Credit: Anadolu Agency via Getty Images

The magnitude scale is logarithmic, meaning the difference between a magnitude six, seven and eight earthquake is far greater than the numbers may suggest on face value.

“The amount of energy that is released increases by around a factor of 32 each time,” Eakin explained.

“A magnitude seven releases 30 times more energy than a magnitude six, and a magnitude eight would release around 1000 times more energy than a magnitude six.”

How an earthquake actually feels, and the destruction that it causes, depend on how close someone is to the source, the building they are inside, and the geology beneath them.

However Eakin noting a magnitude eight earthquake at the same distance as a magnitude six is going to be “a lot more destructive”.

“From a magnitude six upwards, they can be very damaging, depending on your distance,” she said.

‘Earthquakes don’t kill people, buildings do’

Magnitude alone does not determine how devastating an earthquake will be.

Its depth, distance from populated areas, the type of ground beneath a community and the quality of its buildings and infrastructure can all dramatically alter the consequences.

A shallow earthquake is generally more destructive because its energy travels to the surface more effectively.

Soft sediment can also amplify seismic waves and trap seismic energy, causing shaking to continue for longer than it would in areas built on hard rock.

But Eakin said the standard of buildings and infrastructure was “by far” the biggest factor.

“There’s a common phrase that earthquakes don’t kill people, buildings do,” she said.

Authorities launched emergency ​response ​measures after ​a quake hit China’s Sichuan province. Credit: AAP

Eakin said this made preparation and resilient infrastructure critical in areas most vulnerable to major earthquakes.

“It’s about being prepared and making sure buildings are up to code to withstand the shaking that we may expect from these earthquakes,” she said.

“Earthquakes will continue to happen. We live on an active, dynamic planet. As a society, we need to be prepared for them and build our buildings with that in mind.”

When does an earthquake become a tsunami?

Not every powerful earthquake beneath the ocean will generate a tsunami, it all depends on how the seafloor moves.

Eakin said a sudden vertical movement can displace the water above it, sending waves towards distant coastlines.

Development of a tsunami, A geologic incident on the ocean floor, at a depth of thousands of metres, causes part of the ocean floor to sink or rise. Credit: QAI Publishing/Universal Images Group via Getty

This is particularly associated with subduction zones, where one tectonic plate slides beneath another and an earthquake can abruptly lift the seafloor.

Earthquakes that mainly involve side-to-side movement are much less likely to generate a tsunami, despite potentially releasing enormous amounts of energy.

Could Australia be affected?

Australia lies away from the subduction zones responsible for the world’s largest earthquakes, meaning a magnitude-eight or greater “great earthquake” is not expected to originate within the country.

But that does not make it immune to damaging tremors. Tennant Creek was hit by a magnitude 6.6 earthquake in 1988, while a magnitude 6.5 quake struck Meckering in Western Australia in 1968.

The threat also extends beyond Australia’s shores, with active plate boundaries beneath Indonesia and near Tonga, New Zealand and Vanuatu.

Earthquakes to the north can sometimes be felt in Darwin, while major undersea events across the Pacific and Indian oceans can send tsunamis towards the Australian coastline.

A normal year for earthquake activity can still be a devastating one for the communities caught in its path.

Eakin said the best protection was to prepare for that risk, regardless of how often earthquakes made the headlines.