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