VOLCANIC HAZARDS

LAVA

lava flow can be PREDICTABLE which can REDUCE loss of life

however, it can DESTROY everything in its path such as property and infrastructure

there are LOCALISED economic costs

1990 - kilauea in hawaii burned down houses and buries the village of kalpana

PYROCLASTIC FLOW

lethal MIXTURE of superheated gases, hot ash and rock fragments

associated with SUBDUCTION zone volcanoes

it is DENSER than the surrounding air and moves close to the ground

the high SPEED and TEMPERATURE of the flow witll destroy everything in its path

over 29000 people in the town of ST PIERRE were killed in 1902

ASH AND TEPHRA

these form when magma is GRAGMENTED by explosions

the finest ash can be carried HIGH into the atmosphere and is carried by PREVAILING winds over large areas

it can affect world weather PATTERNS and present a HAZARD to aircraft

ICELAND 2010 - caused major travel disruptions throughout europe

when ash falls back to earth it can cause LOSS OF LIFE as roofs collapse under the weight

ash can also contaminate local FRESHWATER supplies in rivers

VOLCANIC GASES

they are often HOT and TOXIC (sulpher dioxide)

1996 - Lake Nyos - over 1700 people died of CO2 poisoning as a heavier than AIR cloud rich in CO2 was expelled from a volcanic lake. people 23km away died in their sleep

IJEN volcano - miners only live to age 35 due to sulpher dioxide poisoning

LAHARS

SECOND most destructive hazard

MUDFLOW of volcanic material

ash and debris MIX with water and move RAPIDLY over long distances usually over LOW LYING areas

this mixture can BURY the environment and drown people

1985 - nevado del ruiz eruption resulting in a lahar flowing at 100km an hour with 20,000 people dying as they were buried by hot mud