Lava flows from volcanoes are rarely a threat to human life as the flow moves slowly enough to move away. Extensive lava fountaining can produce ash and tephra which can fall on grazing land or collapse roofs. Gas released from lava can cause air pollution and gas explosions from flows can be dangerous if you stand close enough. The main losses come from property and communications. Pahoehoe and aa-aa lavas present the most lava flow hazard whereas dacitic,andesitic and rhyollitic lavas present the more explosive eruption risk.
The rate at which lava flows is dependent on .
- Type of lava ,low silica basic lavas such as basalt have a low viscosity and produces pahoehoe. High silica and lavas such as dacite and rhyolite produce domes rather than flows.
- Terrain and slope steepness
- Whether the lava is channeled in a tube or channel
- How fast the lava is produced from the vent.
Hawaii:Kilauea lava flows
In 1990 and 2010 a lava flow from Kilauea engulfed and consumed the settlement of Kalapana.Between 1983 and 1998 lava flows from Kilauea also covered 13km of the southern coastal road to a depth of 25m in places. This eruption from the Pu oo oo vent is still continuing.