hazards -volcanic hazards

Question 1

how many volcanic hazards are there?

Answer 1

8

Question 2

what are the 8 volcanic hazards?

Answer 2

.lava flow
.pyroclastic flow
.tephra
.nuees ardentes
.ash fallout
.volcanic gases
.mudflows/lahars
.acid raid

Question 3

what are the volcanic hazards split into?

Answer 3

.primary
.secondary

Question 4

what are the primary volcanic hazards?

Answer 4

.lava flow
.pyroclastic
.tephra
.nuees ardentes
.ash fallout
.volcanic gases

Question 5

what are the secondary volcanic hazards?

Answer 5

.mudflows/lahars
.acid rain

Question 6

what is lava flow?

Answer 6

.molten rock flowing over the surface -basaltic lavas have higher temperatures and a silica content of less than 52% -means that they flow some distance before solidifying eg -on Hawaiian Islands
-andestitic lavas are more viscous so they flow slower and often solidify in the vent of the volcano, resulting in unpredictable and explosive eruptions

Question 7

what is pyroclastic flow?

Answer 7

.a mixture of hot rock, lava, ash and gases rising from a volcanic eruption that moves at a rapid speed -up to 200m/s along the ground -pyroclastic flows are more common in eruptions of acidic lava at subduction zones

Question 8

what are the temperatures of pyroclastic flow?

Answer 8

.temperatures are between 350-1000°c

Question 9

what is tephra?

Answer 9

.solid rock fragments ejected during volcanic eruptions -largest fragments can be over 1m in diameter and fall close to the volcano -potentially causing injury or death to people
.the smallest fragments -ash less than 2mm are carried by wind and travel great distances

Question 10

what is nuees ardentes?

Answer 10

.translates to ‘glowing cloud’ and is a dense, rapidly moving cloud of hot gases, ashes and lava fragments from a volcanic eruption -a type of pyroclastic flow that contains more dense material so doesn’t travel as far

Question 11

what are volcanic gases?

Answer 11

.these are dominated by steam -include carbon monoxide, hydrogen sulphide, sulphur dioxide and chlorine
.these gases are highly dangerous

Question 11

what is ash fallout?

Answer 11

.ash that is ejected high into the atmosphere and depending on prevailing winds, can cover a large area
.ash is highly abrasive and can cause breathing problems, disrupt machinery -it can also obstruct sunlight, reducing visibility and temperatures

Question 12

what are mudflows/lahars?

Answer 12

.lahars are destructive mudflows formed when ash and other volcanic material are mixed with water
.they flow at speeds of up to 60km/h and are highly erosive

Question 13

what is acid rain?

Answer 13

.volcanoes emit sulphurous gases, which can result in acidic rainwater when combined with atmospheric moisture