Although spectacular lava fountains and substantial cinder cones are common products of basaltic eruptions, these eruptions are normally dominated by lava flows. As is the case in Hawaii, the large volume of lava that accumulates forms wide volcanoes with gently sloping sides, known as shield volcanoes. As basaltic magmas are normally low in volatiles and are less viscous than magmas of other compositions, volcanic eruptions that occur at these locations tend to be less dangerous than those occurring at convergent margins. The viscous lava released at convergent margins, combined with the high volatile content, can cause pressure to build in the volcano. This causes explosive eruptions.
Eruptions tend to consist of large amounts of fragmented material released into the atmosphere.
Most of the fragments fall back to Earth in the region of the eruption. In many regions of the world, you can be sure of the presence of a convergent margin by the line of stratovolcanoes that marks it. All rights reserved.