Mount Pelee is on Martinique in the West Indies. It was already active but sprang into life in April 1902. There was virtually no flow from the volcano but from within the viscous lava was pushed up like toothpaste in a tube. The dome continually grew and then crumbled away. A party of picnickers were the first to notice indications that it was about erupt. They climbed the volcano on March 23rd from the port, St Pierre, the capital of Martinique, which stood at the southern foot of the volcano, 4 miles from the summit. They reported that sulphurous vapours were being emitted from several points near the summit on the south side. When large sections of the dome of a volcano falls away exposing large area of magma its gas is released explosively resulting in a dense black cloud being formed from volcanic matter. On April 25th the eruption began with minor explosive activity that built up over the following week. In the first days of May people began to get worried because the explosions had increased in strength and volcanic ash fell almost continuously on the capital. There was also a strong smell of sulphur and volcanic gases when the wind blew from the volcano. The first disaster occurred on May 5th at the small crater lake on the south side which had become heated up almost to boiling point. New volcanic material steadily replaced the water, the crater walls gave way and a huge volume of boiling water poured down the valley (called lahar) causing an avalanche, and entered the sea about 1 mile north of St Pierre. On the way it became mixed with volcanic ash, soil and boulders, some weighing as much as 49 tons, forming a mud flow which travelled at 60 mph. A sugar processing factory lay in its path and thirty men were killed. When it hit the sea it caused a tsunami which capsized a yacht, drowning all on board and flooding some of the St Pierre shore.