Download Volcanic Hazards Exam Q&A: Lahars, Avalanches, and Eruption Dynamics and more Exams Advanced Education in PDF only on Docsity!
ERTH 111 - Exam 3 With
Complete Solution
Lahars move downslope under the force of _________________. - ANSWER gravity
The difference between a mud flow and a lahar is _________________. - ANSWER Nothing, they are the same thing
Lahars move downslopes like a fast moving river of _______________. - ANSWER Wet concrete
Lahar deposits have __________________ supported clasts. - ANSWER Matrix
Lahar deposits grade upward from the base from ___________ clasts to _____________clasts. - ANSWER small, large
Lahars can cause fatalities for years after an eruption since all you need to produce them is basically a mixture of _______________ and __________________. - ANSWER ash, water
The source of water for lahars can be ______________________. - ANSWER hydrothermal, rain, snow, lakes
The town of Armero is in ______________________. - ANSWER Colombia
Deadly mud flows destroyed the town of Armero when an eruption melted some of the snow and ice at the summit of ________________________ volcano. - ANSWER Nevado del Ruiz
The death toll was higher than normal in Armero since the mudflows
_____________________. - ANSWER Happed at night
Rescue of the injured in Armero was complicated because land vehicles _________________. - ANSWER Couldn't cross the mud
The death toll from mudflows in Armero was approximately ______________ people. - ANSWER 20,
No lives would have been lost in Armero if people had _____________________________. - ANSWER Been warned, had an evacuation plan, moved a short distance out of the river valley
Debris avalanches were brought to the attention of scientists after the eruption of ______________ volcano. - ANSWER Mt St Helens
Debris avalanches move downslope under the force of _________________. - ANSWER Gravity
The town of Weed in California is built on a large debris avalanche from ______________ volcano. - ANSWER Mt. Shasta
Debris avalanche deposits are recognized primarily by their _______________ topography. - ANSWER Hummocky
The two depositional facies seen in debris avalanche deposits consist of ____________ and ______________. - ANSWER block, matrix
Debris avalanches can be triggered by____________________. - ANSWER Phreatic explosions, earthquakes
A debris avalanche triggered the eruption of Mt St Helens in ________________. - ANSWER May 1980
The eruption of Mt St Helens killed 56 people primarily because
The curve showing the number of volcanoes active per year oscillates up and down over time. because of ____________________. - ANSWER A. Normal variations in volcanic behavior
B. Overlooked eruptions due to humans distracted by other events like wars and famine
C. Extra notice paid to eruptions after periodic large, catastrophic eruptions
The curve showing the number of eruptions per year that had an eruptive volume greater than 0.1km3 does not vary with time like the curve for all volcanic eruptions because _____________. - ANSWER B. Large eruptions have always been consistently identified
The magnitude of an eruption is ______________________. - ANSWER D. Its size/volume
The frequency of an eruption is ______________________. - ANSWER B. How often it erupts
On the plot showing the magnitude versus the frequency of eruptions during the last 12,000 years there is a consistent relationship between ______________ and _____________ eruptions. - ANSWER C. Many small and few large
The reason for the linear behavior curve between the magnitude and frequency of eruptions is ______________________. - ANSWER Consistent magma volume production with time due to plate tectonics
When eruption repose times are longer than human history _________________. - ANSWER B. This is normally bad for human populations because they are not prepared
Since 1700, there have been over ______________non-famine deaths due to volcanic eruptions. - ANSWER 270,
Since 1800, 480 volcanoes have had 7886 eruptions. ______________of these eruptions produced fatalities - ANSWER 400
_________ of the 21 largest historical eruptions occurred at volcanoes without a previous historical eruption. - ANSWER 17
The proximity of ______________ to volcanoes is a fundamental component of risk. - ANSWER Humans
The spatial proximity of humans to volcanoes is increasing. The population today is approximately ________ times what it was in 1800. - ANSWER 5
Approximately __________ percent of the world population lives within _________km of an active volcano. - ANSWER 20, 200
Worldwide, population density _____________with radial distance from the volcanoes summit. - ANSWER decreases
C. Respiratory problems
The primary risk due to volcanic gases is normally _________________. - ANSWER A. Respiratory problems
The primary risk due to ash flows is normally _________________. - ANSWER A. Loss of human life
B. Property and infrastructure damage
C. Respiratory problems
The primary risk due to mud flows is normally _________________. - ANSWER A. Loss of human life
The primary risk due to debris avalanches is normally _________________. - ANSWER A. Loss of human life
The primary risk due to tsunamis is normally _________________. - ANSWER A. Loss of human life
The type of hazard(s) depends on the type of volcano which is strongly linked to ______________________. - ANSWER B. Plate tectonics
The recurrence interval of eruptions effects the impact of hazards because __________________ so this causes human to forget or ignore the risk. - ANSWER D. Very large eruptions only happen after very long periods of inactivity
Short repose times mean __________ eruptions happen ____________ leading to____________ risk. - ANSWER C. Small, often, low
Long repose times mean __________ eruptions happen ____________ leading to____________ risk. - ANSWER D. Large, infrequently, high
The geographic location of a volcano influences the impact of hazards since _______________ effects the distribution of ash. - ANSWER D. Prevailing winds
The geographic location of a volcano influences the impact of hazards since _______________ controls the number of potential eruption casualties. - ANSWER D. Population density
The geographic location of a volcano influences the impact of hazards since _______________ controls the possibility of tsunamis. - ANSWER C. Proximity to an ocean
Resources available to reduce risk
The risk formula is _________________________. - ANSWER C. Risk = (Hazard x Value x Vulnerability) / Capacity
Risk can be mitigated by _________________________. - ANSWER A. Communication
B. Timely application of good science
C. Building codes
The risk for human fatalities has been reduced at Lake Nyos in Cameroon by ______________. - ANSWER A. Pumping water from deep depths to remove the buildup of gas
The risk for human fatalities in the town of St Pierre on the island of Martinique could have been reduced by ______________. - ANSWER C. The government promptly announcing warnings of impending eruptions
The best way to reduce risk to humans living near a volcano is to _______________ the volcano. - ANSWER Monitor
__________________________ compares multiple radar images to construct a series
of fringes that record inflation or deflation of the ground surface. - ANSWER INSAR
What natural but unrelated phenomena occurred simultaneously to increase the severity or impact of the Mt Pinatubo eruption on the local population?. - ANSWER D. A typhoon
The most effective monitoring method is _________________. - ANSWER Seismology
The _________________ satellite was developed for weather mapping but can identify ash and other aerosols in the atmosphere too. - ANSWER GOES
The US government had a considerable stake in whether Mt Pinatubo erupted since _______________ and _______________were very close by. - ANSWER B. A naval base, an airbase
At the same time Mt Pinatubo was getting ready to erupt another volcano tragedy occurred in Japan at Mt ______________ where 43 people were killed when an unexpected dome collapse produced a very large pyroclastic flow. - ANSWER Uzen
On June 15th Mt Pinatubo serves up the "main course" and sends ash
B. Conventional survey techniques
C. Differential GPS
After the initial seismometer was placed on the mountain by Philippian scientists, it recorded over ______________ earthquakes in two days. - ANSWER 400
When studying seismicity it is important to know the _________________ before the eruption cycle begins since no two volcanoes are alike. - ANSWER A. Background levels
Mt Pinatubo erupted in __________________. - ANSWER 1991
The initial evacuation at alert level 4 was everyone within _________ miles of the mountain. - ANSWER 12
The initial word that Mt Pinatubo was becoming active was delivered to the Philippian authorities in Manilla two days after the initial explosions by ____________________. - ANSWER D. A nun
The sighting of a _________________ at the vent convinces the scientists to go to alert level 3 which means an eruption is expected within two weeks. This was
ultimately a false alarm. - ANSWER Magma dome
Some of the least expensive but best techniques for volcano monitoring are _________________ and ______________ since a volcano without historical activity is likely to do what it has done in the past. - ANSWER D. Mapping, sampling
When Dave Ewert saw the deposits around Mt Pinatubo he compared it to another famous volcano in Alaska that had erupted large volumes of ash flows they saw out the window when the team was flying to the Philippines. He ultimately said, "this is bad...this is real bad"...which volcano did he compare Pinatubo to?. - ANSWER Katmai
At the time Mt Pinatubo erupted, it had been the largest eruption in __________ years and was almost 10 times larger than the eruption at Mt St Helens. - ANSWER 80
In the field of volcano seismology, a _______________ sends a signal to the _______________, which it records it as a __________________. - ANSWER A. Seismometer, seismograph, seismogram
__________________ was originally developed to look at SO2 emissions from power plants. - ANSWER COSPEC
