An estimated 500 million people live near active volcanoes - some even build homes on their slopes. Despite the danger, volcanoes provide some of the most fertile land in the world, a cooler climate because of their height and, in many cases, a lucrative draw for tourists.

About 20 volcanoes are erupting at any one time in the world. Although improved disaster planning and monitoring of many volcanoes have saved thousands of lives since the 1980s, the mountains of fire remain a constant threat to homes and livelihoods.

When the Tungurahua Volcano in Ecuador erupted in 2006, it killed just five people after thousands were evacuated from the area. But it also destroyed villages, buried homes and fields under tonnes of ash and rained lava and hot rocks on the surrounding region. In all 300,000 people were affected.

Most explosive volcanoes are on the margins of the Pacific Ocean in the so-called "Ring of Fire", which runs from Latin America up to Alaska, across to Russia and down through Japan and Indonesia.

50-70 volcanoes erupt each year	(Source: Global Volcanism Program)
Indonesia has the world's largest number of active volcanoes	(Source: U.S. Geological Survey)
More than 80 percent of the Earth's surface is of volcanic origin	(Source: USGS's Miscellaneous Volcanic Facts)