Volcanic Eruptions - VOLCANIC HAZARDS AND NOTABLE DISASTERS Flashcards
The way in which humans respond to potential volcanic threats depends on several factors, in particular, the ______ and the _____
frequency at which eruption occur ; availability of habitable living space
some of the primary hazards near a volcano
violent eruption and lava flow
secondary hazards of volcanoes that can reach considerable distances
mudflow, lahar, suspension of volcanic ash and toxic gases into the atmosphere, tsunamis and landslides
occurs whenever magma reaches the surface and begins to move across the landscape
lava flows
how fast and how far a lava flow will travel is largely determined by
slope of land surface;
volume of lava;
viscosity of lava
t or f: lava flows are very common in hawaii
T
t or f: gas poor magmas can generate large steam explosions should the magma suddenly come in contact with a significant volume of groundwater or seawater
T
what are the most common hazards from explosive eruptions?
pyroclastic material and hot gases
the ____ during an explosive eruption pulverizes rocks making up the volcano into smaller fragments, hurling them upward and at great speed along with superheated gases and blobs of lava
shock wave
example of a lateral eruption
Mt. St. Helens, 1980
a volcanic eruption which is directed laterally from a volcano rather than upwards from the summit
lateral eruption or lateral blast
pyroclastic flow is a dry avalanche consisting of ______, _____, and ____, all rushing down the side of a volcano at great speed
hot rock fragments, ash, and superheated gas
a typical pyroclastic flow consist of two parts:
a tumbling mass of large rocks;
overlain by
a turbulent cloud of finer material
t or f: pyroclastic flow can form during explosive and nonexplosive eruptions
T
t or f: pyroclastic flow are almost always associated with SiO2 poor magma
F (SiO2 rich)
how far was Mt. Peele from the City of Pierre
7km
two most famous examples of pyroclastic flow
Mt. Vesuvius, Italy (79 AD)
Mt. Peele, Martinique (1902)
jagged rock and glass fragment less than 2mm in diameter
volcanic ash
volcanic ash are transported by ____ at considerable distances prior to disposition
wind
hazardous effects of volcanic asg
a.) respiratory conditions
b.) destroy crops
c.) contaminate surface water
d.) increasing severity of flooding
e.) damage to mechanical property
f.) trigger global cooling
volcanic ash can damage mechanical and electrical equipment because of its
abrasive property
Mt. Pinatubo temperature drop by:
0.25 degrees celsius
Mt. Tambora temperature drop by:
3 degrees celsius
when was the year without summer
mount tambora eruption (1815)
two types of mass wasting on volcanoes
volcanic landslide and volcanic mudflows
also called as debris avalanche
volcanic landslide
occurs whenever a steep flanks of volcano become unstable and results in rapid downslope movement
volcanic landlside
volcanic landslide is often triggered by
earthquake and heavy rains
______ and _____ within a volcano can breakdown _____ rocks into much weaker _____, thereby making slope more prone to volcanic landslide
corrosive gases;
groundwater;
feldspar-rich;
clay minerals
also called a lahar or debris flow
volcanic mudflows
is an indonesian term, and is a mixture of ash, rock, and considerable amounts of water
lahar
ash and rock in volcanic mudflows may comprise _____ by weight, and may resemble a river of wet concrete
60 to 90%
speed of volcanic mudflows
35-60 km/hr
t or f: volcanic mudflows are more destructive than ordinary river floods
T
volcanic gas is mainly composed of:
water vapor (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2)
H2O, CO2, and SO2 together account for ____ of all volcanic gases
over 95%
volcanic gas cloud is hazardous to humans simply because it contains _____
no free oxygen (O2)
forms when volcanoes explode violently in an oceanic setting and may subsequently strike coastal communities far from the volcanoes itself
tsunamis
t or f: volcanic landslides may also generate large tsunamis
T
what was the major secondary hazard during the Mt. Tambora volcanic eruption in 1815
volcanic ash and short-term climate change (starvation from crop failure)
what was the major secondary hazard during the Nevado del Ruiz, Colombia eruption in 1985?
mudflow
what was the major secondary hazard during the lake nyos, cameroon eruption in 1986
gas asphyxiation (CO2)
