lecture 10

Question 1

lava flows

Answer 1

1. pahoehoe lava flow: low viscosity lava cools with a ropy smooth surface
2. A’a lava flows: more viscous lava solidifies with rough jagged surface and holes through which gases have escaped

Question 2

ballistics

Answer 2

lava bombs (2018 KTlauea)

Question 3

shockwaves

Answer 3

atmospheric pressure waves that exceed the speed of sound and can cause minor damage

Question 4

volcanic gases

Answer 4

1986 limnic eruption at lake nyos cameroon released CO2 that had been dissolved and killed 1700 people and 3500 lifestock (asphyxiated)
Lake Kivu, Rwanda is at risk

Question 5

mount tambora

Answer 5

in april 1815 started a 4mo long eruption that is the largest volcanic eruption recorded in history
released enormous volumes of SO2 gas which oxidized into sulphate aerosal and changed the earths climate for a whole year, high food prices lead to invention of bicycle

Question 6

pyroclastic flow

Answer 6

rapid gravity current of hot pyroclastic debris and gas that travels downslope from volcano, can be triggered by;
collapse of volcanic dome, spillover from crater, direct blast from explosive eruption, collapse of plume

Question 7

Mt unzen, Japan

Answer 7

in 1991 collapse of newly formed magma dome generated a pyroclastic flow that killed 43 people

Question 8

Mt Ontake, Japan

Answer 8

phreatic eruption of mount ontake killed 63 people

Question 9

ash fall

Answer 9

weight of ash can collapse buildings and inhalation can lead to silicosis , can disrupt air travel (iceland april 2010)

Question 10

lahars

Answer 10

volcanic mudflows formed by pyroclasts mixed with debris and water
deadliest of volcanic hazards, can travel large differences (-60km away)

Question 11

how can lahars form

Answer 11

1. from pyroclastic flows that become diluted with river water or meltwater
2. from volcanic landslides that mix with water, snow or ice
3. from natural failure of a crater lake
4. from rainfall on loose tephra or from condensation directly out of an eruption column

Question 12

how do volcanic risks compare with earthquakes

Answer 12

volcanoes rarely erupt without warning which gives people a chance to evacuate, only 30,000 killed in past 50 years
earthquakes can cause damage over larger areas and collapse buildings

Question 13

volcano monitoring

Answer 13

gas- airborne and ground
remote sensing- thermal imaging, satelittle
deformaiton- tiltmeter, GPS, surveying
ground vibration- lahar and earthquake sensors

Question 14

volcano disaster assistance program

Answer 14

after 1985 nevado del ruiz columbia, USGS and USAID set up

- majority of dangerous volcanoes are still not closely monitered

Question 15

classification of volcanoes

Answer 15

active, dormant or inactive

• pressures of land availability misclassifies dormant volcanoes as inactive
  ex. Goma and Mount Nyiragongo DRC