2.b. volcanic eruptions generate distinctive hazards

lava flows

impacts dependent on type of lava. basic/ basaltic lava is free flowing and can run for considerable distances. Hawaii july 2015: lava flow extended for 20km before stopping and in august the same year a flow was reported to have covered about 800m a day. acidic lavas such as rhyolite are thick and pasty so do not flow easily. everything in the path of lava will be either burned, bulldozed or buried. although they destroy infrastructure, property and crops lava rarely causes injuries or fatalities

pyroclastic flows

combination of very hot gases- 500^oc+, ash and rock fragments travelling at high speed-100km/h. they follow the contours of the ground and destroy everything in their path. the inhalation of such hot and poisonous gas and ash causes almost instant death. the roman town of Pompeii was overwhelmed by a pyroclastic flow from mount vesuvius in 79 AD

tephra

describes any material ejected from a volcano into the air. it ranges in size from very fine ash to large volcanic bombs- greater than 6cm across. it also includes lighter debris such as pumice. potentially very hazardous, burying farmland in layers of ash and destroying crops. transport can be disrupted both on the ground and in the air. the eruption of Iceland’s volcano in april 2010 led to the cancellation of 100,000 flights. buildings

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