At present there are more than 500 active volcanoes but these are not scattered irregularly over the globe. It has been observed that volcanic activity is strictly confined to certain limited sectors of the crust.
They are mostly found on the marginal parts of the continents and in the littoral zones of oceans and seas they are situated within the boundaries of young tectpnically mobile mountain structures.
Thus, the distribution of the present day volcanoes are restricted mostly to the mobile-zones of the earth’s crust. Of course there are certain exceptions as for example, there are no volcanoes in the Himalayas and there is no sign of recent-folding in Iceland.
The most important belt of volcanoes is the so-called Ring of Fire or the Cicum-Pacific belt where more than 60 percent of the active volcanoes are located.
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It extends through the Andes of South America, CentrakAmerica, Mexico, the CascadeMoun tains of western U.S.A., the Aleutian Islands, Kamchatka, the Kurile Islands, Japan, Philippines, New Guinea, Solomon Islands, New Hebrides and New Zealand.Volcanoes like Cotopaxi, Katmai, Fujiyama etc. are located in this belt.
Another belt runs north-south through the Atlantic and accordingly is known as Atlantic belt. It extends, from Jan Mayen Island in the north, through Iceland, the Azores and the Canary Islands to the Cape Verde Islands in the south. Volcanoes like Mt. Pelee, St. Helena, Mt. Hekla, Mt. Helgalfel etc. are located in this belt.
Another volcanic belt is the Mediterranean Himalaya belt extending east-west from the Alps via the Apennines to the Caucasus and the mountains of Asia Minor. Volcanoes like Vesuvius, Etna, Mount Ararat and those of the Lipari Islands are located in this belt.