What we know about the massive Russian earthquake and Pacific tsunami

A powerful earthquake has struck off the coast of Russia, triggering warnings throughout the Pacific.

The 8.8-magnitude quake hit off the Kamchatka Peninsula early on Wednesday and caused tsunami waves in Russia, Japan and Alaska, and warnings for millions of people around the Pacific.

So why are tsunamis so difficult to predict, and how big was this earthquake compared to the largest in recorded history? This is what you need to know.

LIVE UPDATES: Tsunami waves hit Hawaii

How does this earthquake compare to the most powerful in history?

The earthquake that struck Russia early on Wednesday morning was recorded at magnitude 8.8.

It currently ranks as the sixth-strongest ever recorded.

The largest in recorded history was the 9.5-magnitude Valdivia quake that struck Chile in 1960, killing more than 1600 people and leaving more than 2 million homeless.

What about the tsunami?

In the hours immediately after the earthquake, the height of the waves recorded haven't been the worst-case scenario.

Tsunami waves have ranged from as little as up to 30 centimetres tall, to up to five metres in the Russian town of Severo-Kurilsk on the Kamchatka peninsula.

As of 6.45pm (AEST) on Wednesday, the tallest waves in Hawaii reached just shy of two metres.

While still potentially damaging, these heights are far less than those seen in some of the most destructive tsunamis in recent history.

The waves that hit Tonga following the 2022 underwater volcanic eruption were estimated to have reached as high as 45 metres, while the Boxing Day tsunami waves were even bigger at 51 metres.

View gallery

First tsunami waves from Russia quake as millions under warnings

What actually is a tsunami?

Tsunamis are waves triggered by earthquakes, underwater volcanic eruptions and submarine landslides.

A tsunami isn't just one wave but rather it is typically made up of multiple waves that rush ashore like a fast-rising tide.

Some tsunamis are small and don't cause damage, while others can cause massive destruction.

READ MORE: Mushroom killer's house frozen by the state after guilty verdict

How long does it take for tsunamis to arrive?

This depends on how far the epicentre of the earthquake is from a coastal area.

It could take just minutes for waves to hit land next to the site of a major quake.

It could take hours for tsunamis to cross the Pacific Ocean.

The speed of tsunami waves also depends on ocean depth, as they travel faster over deep water and slow down in shallow water.

Is Australia safe?

The Bureau of Meteorology is currently advising there is no tsunami threat to Australia.

Why are tsunamis so difficult to predict?

Scientists can't predict when and where the next tsunamis will strike.

However, authorities can predict which earthquakes are likely to generate tsunamis and can issue warnings when they think one is possible.

Once a tsunami is detected, the warning centres use models to forecast wave height and arrival times, location and amount of flooding, and how long the tsunami will last.

READ MORE: Groom seriously injured in minibus crash on way to wedding

What is the 'Pacific Ring of Fire'?

The earthquake off the coast of Russia struck in a geologically unstable region known as the Pacific Ring of Fire.

Russia's far east, including Kamchatka, sits in this area which is prone to earthquakes and volcanic eruptions.

The ring runs from southern Chile, up the west coast of the Americas, through the islands off Alaska, down Japan to the Philippines, Indonesia and as far south as New Zealand.

Australia is not part of the Ring of Fire.

DOWNLOAD THE 9NEWS APP: Stay across all the latest in breaking news, sport, politics and the weather via our news app and get notifications sent straight to your smartphone. Available on the Apple App Store and Google Play.