Pinatubo vs. Hawaii | |
The style of volcanism at Mt. Pinatubo (Philippines) is very different from that of the Hawaiian volcanoes. While Pinatubo's eruptions are typically explosive and very violent, the ones on Hawaiian are "peaceful" and, in fact, a major tourist attraction. Eruptions at Kilauea started with spectacular lava fountains at Pu'u O'o, one of its vents, and is still going on, in 2003 though less dramatically.
This lecture explains why we find volcanoes at some places and not others and why some are violent while others are not. |
we typically distinguish between two main types of volcanoes (shield and strato volcano) and two styles of volcanism (effusive and explosive):
the style and vigor of a volcanic eruption depends on the three Vs:
Style of Volcanism | viscosity of lava | low in volatiles | high in volatiles |
effusive | low | lava flows | lava fountains |
explosive | high | small explosions | catastrophic explosions |
Type | Silica content | Volcanic | Plutonic |
silicic (or felsic or rhyolitic) | >65% | Rhyolite | Granite |
intermediate (or andesitic) | 55-65% | Andesite | Diorite |
mafic (or basaltic) | < 55%, rich in Fe and Mg | Basalt | Gabbro |