The eruption of the island of Krakatoa in 1883 was the biggest volcanic explosion of modern times and had a force roughly equivalent to 11,000 atomic bombs.

The eruption of the island of Krakatoa in 1883 was the biggest volcanic explosion of modern times and had a force roughly equivalent to 11,000 atomic bombs.

It made the loudest noise ever heard in recorded history, sent a shockwave around the world seven times and caused a cloud of dust and ash in the atmosphere that lowered global temperatures for five years.

At least 40,000 people were killed, most by an immense tsunami 40 metres high, almost three times the height of the waves that swamped Japan following the earthquake of March 2011. The effects of the tsunami were felt thousands of miles away, even causing a surge in the English Channel.

The main eruption was heard 4,500 miles away — the equivalent of an explosion in New York or Baghdad being heard in the UK.

The first inkling that the Indonesian island, then measuring 5.6 miles by 3.1, was poised to erupt came three months earlier when a German ship, the Elizabeth, reported seeing ash and smoke rising seven miles into the sky above it on May 20, 1883.

Eruptions continued for weeks — but rather than fleeing for their lives the locals gazed at them in excitement and held festivals to celebrate them.

The first serious explosion came at noon on August 26, sending debris 22 miles into the sky. The next day, starting at 5.30am UK time, came three more explosions.

These weakened Krakatoa's walls, allowing cold seawater into chambers full of magma, or molten rock. The seawater became superheated steam, and the enormous pressure caused a fourth, cataclysmic blast at 10.02am (UK time), which blew two-thirds of the island into the sea and was heard in Perth, Australia, and in Sri Lanka 4,500 miles away.

The blasts and burning debris killed around 4,500 people. Far more deadly were the tsunamis that followed as Krakatoa, once 2,667ft high, collapsed to 820ft beneath sea level.

Within an hour 130ft waves roared into the shores of Java and Sumatra at 300mph, obliterating almost everything. Some 165 towns and villages were annihilated and 132 badly damaged.

One witness said: "All of a sudden there came a great noise. We saw a great black thing, a long way off, coming towards us. It was very high and very strong, and we soon saw that it was water. Trees and houses were washed away. The people began to run for their lives. Not far off was some steep sloping ground. We all ran towards it and tried to climb up out of the way of the water.

"The wave was too quick for most of them, and many were drowned almost at my side. One after another, they were washed down and carried far away by the rushing waters."

The official death toll was given as 36,417, though it was almost certainly many more.

Five cubic miles of pumice, ash and rock were hurled into the atmosphere — 20 times as much as by the 1980 eruption of Mount St Helens in Washington State.

So much landed in the Sunda Straits near Sumatra that the sea looked solid. Relief ships could not reach stricken areas for weeks.

Huge deposits of pumice floated thousands of miles. Some washed up in Durban, South Africa, 5,000 miles away, a year later.

The massive cloud of dust and volcanic debris spread around the world, blotting out enough sunlight to lower the Earth's temperature for five years. Normal temperatures were only achieved again in 1888.

The cloud caused fantastic colours in the sky and exotic sunrises and sunsets, captured by painters of the time.

Krakatoa was one of the first disasters to be known of around the world within minutes, because undersea telegraph cables had just been laid.

The region remained quiet for years after the catastrophe. But in 1927 more volcanic activity was seen and a new island, Anak Krakatoa - "Child of Krakatoa" - began to rise.

Eighty years later, in November 2007, it too began violently erupting before going quiet.