Mark Poynting
Climate and science reporter

Image source, AFP via Getty Images

The outer layer of the Earth is divided into different sections called tectonic plates - a bit like the Earth’s puzzle pieces.

These plates move very slowly - perhaps only a few centimetres a year, which is roughly the same rate as your fingernails grow.

As they move relative to one another, parts of the plates can get "stuck", and stress builds up over a long period of time.

Eventually, this stress becomes too much and the plates jolt or slip back into place.

That releases the huge amounts of energy experienced as an earthquake.

Searches are continuing long into the night in south-western Japan, where emergency personnel are scouring the collapsed structure of the Aeon Mall.

Image source, EPA/Shutterstock

Image source, Reuters

Image source, Reuters

Chie Kobayahsi
BBC News in Japan

Two people have been found in a state of cardiac arrest and multiple people remain unaccounted for across two sites hit by the earthquake in the Kumamoto prefecture, an official has confirmed.

An official at the Disaster Management Division of Kumamoto prefecture tells the BBC that at Nippon Paper's Yatsushiro Plant, two people "were found in cardiac arrest" and nine people are still missing.

They also say that four people have been rescued from the Aeon Mall, and their lives are "not in danger".

But 10 people remain unaccounted for at the shopping centre.

The prefecture is checking reports of a gas leak, the official also says.

Video shows high-rise hotel shaken by earthquakepublished at 17:22 BST

17:22 BST

By Thomas Spencer

We have verified a video showing the moment a hotel in Kumamoto was severely shaken by the earthquake.

In the clip, the high-rise REF Kumamoto hotel can be seen rocking from side-to-side but appears to withstand the force of the tremors.

Birds in nearby trees can also be seen taking flight as the building sways.

Image source, Reuters

It's the early hours of Wednesday morning in Kumamoto, where a search operation continues at the Aeon shopping mall. Here's the latest:

• Police sources say contact has been lost with 20 to 30 employees at the Aeon Mall, reports from Japan's public broadcaster NHK suggest

• Several people are also missing at a paper factory in the region, according to NHK

• BBC Verify has been analysing footage of people leaving the mall in panic, and subsequent damage to its southern car park
• Japan's Prime Minister Sanae Takaichi earlier said rescue teams are being guided by the principle of "human life first" and will work "tirelessly through the night"
• Japan's Meteorological Agency says more than 60 aftershocks have been recorded - and residents are being warned to expect day-two tremors as they wake up on Wednesday morning

Image source, Felix Umland

Felix Umland, a German photography student in Japan was on the 13th floor of a hotel in Kagoshima, about 175km from the epicentre, when the Japan earthquake struck.

He tells BBC Newshour about the moment the earthquake started: "My phone started blaring an earthquake warning. I was just looking at my phone thinking I don't know what to do now... Five seconds later everything started shaking."

"I just heard glasses flying in the kitchen and everything in the kitchen started breaking," he says.

"There's not much you can do, it's a pretty hopeless situation. You're looking around waiting for it to stop."

Umland adds that although buildings are built to move with the Earth, "it feels like the building beneath you turns into liquid. It's a very surreal feeling".

"The solid ground just suddenly turned into a mass that was moving."

As we've been reporting today's earthquake in Kumamoto was initially recorded at a 7.1 magnitude.

And in its most recent update, the Japan Meteorological Agency lists its provisional magnitude value as 7.1.

But, the US Geological Survey, external has estimated the quake's magnitude was 6.8.

Earthquake magnitude figures are often updated as seismologists obtain and analyse new data.

As a result, it can often take days for a consensus to be reached on the best overall estimate of a quake's magnitude.

Video captures loud bang and falling pallets in warehouse storepublished at 15:58 BST

15:58 BST

By Richard Irvine-Brown

We’ve verified dramatic footage from inside the Kumamoto branch of retail warehouse chain Costco, 3.5km (two miles) to the east of the Aeon Mall.

One video starts with the sound of a small bang after which children can be seen crying and clinging to their parents as the lights flicker on and off.

People are also visibly trying to navigate pallets of goods that have fallen from high shelves. Some have been trapped by the falling items while others are seen trying to help them out.

More than 40,000 households are without power in the aftermath of the magnitude 7.1 earthquake that hit inland on the island of Kyushu, according to an update on Kyushu Electric's website.

This comes as residents in Hikawa town, which sits roughly 25 km (15 miles) south of Kumamoto City, are reporting water and electricity outages, according to Japan's public broadcaster NHK.

NHK says that the power and water outages are affecting "a wide area" within the town.

The outlet adds that Hikawa town hall is one of the buildings affected, and is without lighting or air conditioning after one of its two emergency power sources failed.

Image source, Getty Images

The Kumamoto prefecture is no stranger to earthquakes, and has been hit by powerful ones in the past.

In 2016, the prefecture was struck by a series of earthquakes. These included a magnitude 6.5 which hit the town of Mashiki on 14 April, and a magnitude 7.3 which struck the same area two days later.

According to Japan's public broadcaster NHK, 278 people were killed by those earthquakes in Kumamoto and in the neighbouring Oita Prefecture.

There were also a number of deaths linked to health problems caused by the stress of evacuation, the outlet says.

Speaking at a press conference earlier, Shinji Kiyomoto of Japan's Meteorological Agency asked the public to "remain vigilant" for additional earthquakes, referencing the events of 2016.

Image source, Getty Images

Kumamoto - where the collapsed Aeon Mall is located - is a city on the Kyushu island of Japan.

Japan doesn't have a mainland. It is made up of four primary islands, one of which is Kyushu. The other three are Honshu, Hokkaido and Shikoku.

There are also thousands of smaller islands that sit further out.

The southern island of Kyushu is the third-largest of the four main islands in Japan, and the second most populous.

Videos show extent of damage at Aeon Mall's southern car parkpublished at 14:45 BST

14:45 BST

By Richard Irvine-Brown and Yi Ma

Two videos have been verified from outside the Aeon Mall showing damage to the south side of the building.

Some of the building’s facades have been ripped apart in the earthquake while large sections of an awning have been thrown across the car park to a nearby road.

Smashed advertising boards and rubble from the shopping centre are also captured in the clips.

In one video, emergency workers are preparing a trolley near a waiting ambulance.

Tremors from today's 7.1 magnitude earthquake caused historic walls at the 17th century-built Kumamoto castle to tumble.

It isn't the first time the castle has succumbed to an earthquake, when a 7.3 magnitude quake hit the region in 2016, parts of the 400-year-old castle were also damaged when turrets and curved walls collapsed.

Image source, Reuters

Image source, Reuters

It's now past 22:00 in Kumamoto, and we're seeing rescue teams searching through the rubble of the collapsed Aeon Mall as night time sets in.

Image source, Reuters

Image source, Kyodo via Reuters

Several people are missing after a chimney collapsed at a paper factory in the Kumamoto prefecture, according to the police who are being cited by Japan's public broadcaster NHK.

Police and firefighters are investigating the scene at Nippon Paper Industries Yatsushiro Plant, which is located in Yatsushiro City in the wider Kumamoto prefecture, says the outlet.

An aerial photograph of the site obtained by Reuters news agency appears to show a broken and collapsed chimney.

People seen evacuating Japan mall after quakepublished at 14:11 BST

14:11 BST

By Richard Irvine-Brown

We’ve verified a minute-long video showing people making their way toward the exits of the Aeon Mall. Many of those seen in the footage appear to remain remarkably calm as an alarm sounds.

In the clip, one man can be seen carrying a baby and a woman can be seen with her arm around the shoulder of a child as they walk out of the building.

As the camera pans, we can see shelves hanging loose and debris scattered on the floor including tiles from the building and cups and baskets from a coffee shop.

Image source, X

The latest pictures from Kumamoto are now starting to reach us.

As a reminder, Japenese firefighters have confirmed that many people are trapped inside the shopping centre in the city on Kyushu Island.

Image source, Reuters

Image source, Reuters

Image source, Reu

Multiple people believed to be employees of the Aeon Mall Kumamoto are believed to be missing, Japan's public broadcaster NHK is reporting citing the National Police Agency.

According to the outlet, police sources say that contact has been lost with 20 to 30 employees and emergency services are working to establish if any are trapped inside the shopping centre.

Earlier, NHK had reported that Aeon employees had guided customers to evacuate outside the building before an explosion occurred.

Image source, Reuters

Jake Kwon
Seoul correspondent

We’re still grasping the scale of destruction and possible injury.

We have just heard from the prime minister, saying she had received reports of injuries and mobilised 3,600 self-defence forces to save human lives.

The place we are most concerned about is the shopping centre outside Kumamoto city. Officials say the second floor collapsed after the tremor, and many people inside are trapped. We have seen rescue workers going in.

Authorities are also warning people about the day two tremor. More than two hundred people were killed ten years ago when earthquakes struck the same island - the second tremor was more powerful than the first.

And this is why authorities are advising people to keep their eyes and ears close to the radio and television for possible take shelter or evacuation orders.

Image source, EPA

Tokyo Haneda Airport is currently experiencing several delays and cancellations because of the earthquake.

The airport, which is hundreds of miles from Kumamoto, currently has over 40 domestic and international flights delayed or cancelled.

Regional and connecting flights are affected, and passengers have been told they should check the status of the flight with their airline before travelling