Vei Test Three

Front 1

Mid-ocean ridges account for ______ of the total volume of volcanic activity on Earth.

Back 1

about 75% more

Front 2

The composition of the lava erupted at mid-ocean ridges is:

Back 2

basalt

Front 3

The ocean crust has a layered structure which, from bottom to top, is

Back 3

gabbro, dykes, lava flows

Front 4

Melting of the mantle under mid-ocean ridges occurs because:

Back 4

mantle rock is rising and undergoes decompression melting.

Front 5

During circulation of ocean water through the ocean crust close to mid-ocean ridges:

Back 5

the water becomes very hot.
B) the water becomes very mineralized

both a and b

Front 6

The ecosystems that exist around hydrothermal vents/black smokers are sustained by energy from:

Back 6

chemosynthesis

Front 7

Mid-ocean ridges account for ___________ of the total energy released by earthquakes on Earth

Back 7

less than five percent

Front 8

Mid-ocean ridge earthquakes are:

Back 8

shallow focus and mostly minor (magnitude 4 and smaller).

Front 9

Which is the most common type of volcano found around the "Ring of Fire"?

Back 9

stratovolcano

Front 10

The source of the magma generated (i.e., what melts) in subduction zones is:

Back 10

peridotite of the mantle wedge

Front 11

Compared to continental volcanic arcs, in oceanic volcanic arcs there is erupted a:

Back 11

greater proportion of basalt and a lesser proportion of rhyolite.

Front 12

The difference between the compositional spectrum of oceanic arc and continental arc lavas (previous question) is because:

Back 12

B) there is a greater amount of crystal fractionation of rising magma in the continental arc setting.
C) there is interaction of rising magma with the continental crust in the continental arc setting
Both B and C

Front 13

The eruption of which Indonesian volcano in 1883 produced a tsunami that killed some 36,000 people?

Back 13

Krakatau.

Front 14

The 1902 eruption of Mt. Pelée produced a pyroclastic flow that killed some 30,000 people. Where is Mt. Pelée located?

Back 14

Caribean

Front 15

The 1985 eruption of which volcano in Colombia produced lahars that killed over 20,000 people.

Back 15

Nevado del Ruiz

Front 16

In the 1980 eruption of Mt. St. Helens

Back 16

A) the first visible sign of activity was small ash and steam (phreatic) eruptions.
B) there was about two months between the initial activity and the major, climactic eruption.
C) the major eruption produced air-fall deposits, pyroclastic flows, and lahars.
D) smaller eruptions continued for a few years after the major eruption.
E) all of A) to D).

Front 17

The major eruption of Mt. St. Helens on 18 May, 1980, was triggered by:

Back 17

a moderate earthquake (~M5) under Mt. St. Helens

Front 18

Mt. St. Helens reawakened in late 2004 and continues to erupt. The eruptive activity has comprised

Back 18

eruption of a lava dome with occasional phreatic explosions.

Front 19

How many times had Pinatubo erupted in the 2,000 years prior to the 1991 eruption

Back 19

four or five

Front 20

This first sign of activity at Mt. Pinatubo in April, 1991 was:

Back 20

earthquakes

Front 21

The 1991 Pinatubo eruption was the:

Back 21

second largest in last 100 years

Front 22

The 1991 eruption of Mt. Pinatubo injected large amounts of ash and sulphur dioxide high into the atmosphere. Over the few years after the eruption this gas and ash:

Back 22

caused a significant but small (<1°C) drop in global surface temperature.

Front 23

Montserrat is part of the ___________ island arc

Back 23

Lesser Antilles

Front 24

The continuing (1995 to present) Montserrat eruption was triggered by:

Back 24

intrusion of basalt magma into the magma chamber.

Front 25

The lava being erupted in the continuing Montserrat eruption is:

Back 25

andesite with about 60% SiO2 and 5% H2O.

Front 26

The continuing Montserrat eruption has produced

Back 26

air-fall, lahars, and pyroclastic flows.

Front 27

Of the total energy released globally by earthquakes, what percentage is released by subduction zone earthquakes?

Back 27

98 percent

Front 28

Earthquakes in subduction zones occur to as deep as 700 km, but no deeper. This is because:

Back 28

the subducting plate remains intact and does go deeper than 700 km in the mantle, but has released all of its stored stress by 700 km depth.

Front 29

The largest magnitude subduction zone earthquakes are of:

Back 29

shallow focus and occur on the boundary between the subducting and over-riding plates where there is compression.

Front 30

On the Cascadia subduction zone

Back 30

the recurrence interval for great, ~M9 earthquakes is about 500 years

Front 31

The M7.8 Tangshan, China, earthquake in 1976 was predicted, people in the area were evacuated before the earthquake because of the prediction, and hundreds of thousands of lives were saved.

Back 31

false

Front 32

In the 1995, Kobe, Japan, earthquake

Back 32

B) extensive destruction resulted from liquefaction and fires.
C) the adverse impact on the Japanese economy ran to tens of billions of dollars.
D) both B) and C).

Front 33

The 26 December, 2004, Great Sumatra earthquake

Back 33

) occurred on a segment of the subduction zone that had very few earthquakes in the previous 40 years.
and had a rupture length of over 1000km
Both A and C

Front 34

The tsunami generated by the 26 December, 2004, Great Sumatra earthquake was recorded in the Atlantic and Pacific Oceans.

Back 34

true

Front 35

The devastating M7.6 Pakistan earthquake on 8 October, 2005, was of:

Back 35

shallow focal depth and on a plate boundary thrust fault.

Front 36

On transform faults that join together mid-ocean ridge segments, the actual sense of motion is the same as the apparent (from offset of the ridge segments) sense of motion.

Back 36

false

Front 37

The San Andreas transform system:

Back 37

started to develop about 25 million years ago when the East Pacific Rise began to be subducted, and has since progressively increased in length.

Front 38

At the "big bend" in the San Andreas fault (to the east and north of L.A.) there is:

Back 38

transpression, and therefore a component of thrust faulting.

Front 39

This California earthquake is significant because it triggered a large earthquake on a nearby fault.

Back 39

1992 Landers

Front 40

The 1994 Northridge earthquake occurred on a:

Back 40

blind-thrust fault

Front 41

The 1906 San Francisco earthquake

Back 41

A) was of magnitude 7.9.
made almost 250,000 people homeless
Both A and C

Front 42

The devastation of San Francisco in 1906 mostly was the result of collapse of buildings due to ground shaking and to a lesser extent from fires.

Back 42

false

Front 43

The speed and effectiveness of the federal government response to the 1906 San Francisco earthquake disaster and the 2005 hurricane Katrina disaster was:

Back 43

much better in 1906 than in 2005

Front 44

The 1906 San Francisco earthquake was the first major earthquake disaster to which the overwhelming response was a rational one that sought to understand the natural (rather than supernatural) cause of the earthquake.

Back 44

true

Front 45

There was a very large eruption in central New Mexico just over 1 million years ago that formed a large caldera called:

Back 45

Valles Caldera

Front 46

The cinder (scoria) cone that popped up in a Mexican corn field in 1943 is:

Back 46

Paricutin

Front 47

The earthquake hazard to San Francisco and the Bay area is from:

Back 47

A) the Calaveras fault.
B) the Hayward fault.
C) the San Andreas fault.

E) All of A to C

Front 48

hi

Back 48

bye