NATURE OF VOLCANIC ERUPTIONS

Question 1

is a mass
of lava or molten

rocks flowing
downslope from

the vent.

Answer 1

Lava flow

Question 2

A lava characterized by
its high silica content,
resulting in lava with

high viscosity.

Answer 2

andesitic lava flow

Question 3

A lava that is usually

short and thick and often
travel down a very steep

side slope.

Answer 3

rhyolitic lava flow

Question 4

A lava characterized by
its low silica content that
generally flows in thin,

broadsheets.

Answer 4

basaltic lava flow

Question 5

They have surfaces
of rough, jagged
blocks with sharp
edges and spiny

projections.

Answer 5

AA lava flow

Question 6

They exhibit smooth
surfaces that often
resemble the twisted

braid of ropes.

Answer 6

pahoehoe lava flow

Question 7

A flow of hot, dry mass of

gases and fragments

moving rapidly down the

slopes of a volcano.

Answer 7

pryoclastic flow

Question 8

A high-velocity current

of rocks, gases, or

water.

Answer 8

pryoclastic surge

Question 9

refers to

fragmented volcanic

materials ejected into the

air during a volcanic

eruption.

Answer 9

Tephra

Question 10

A type of mudflow that

consists of water,

volcanic ash, pyroclastic
materials, and debris.

Answer 10

lahar flow

Question 11

A molten rock that has moved from a magma

chamber beneath the Earth’s surface into

surrounding rock layers.

Answer 11

injected magma

Question 12

the three theories on why volcanoes erupt

Answer 12

Buoyancy and
pressure of gases

Solubility of
dissolved gases

Injection of
new magma

Question 13

may consist of volcanic rocks and crystals with particle sizes less than 02 mn in diameer for ash, 02 mm to 64 mm in diameter for lapilli and over 64 mm in diameter for blocks or bombs

Answer 13

tephra flow

Question 14

basaltic magmas contain about ? percent silica whereas granatic magmas contain about ? silica

Answer 14

50% and 70%

Question 15

magmas that have high silica content have high ?

Answer 15

viscosity

Question 16

23 volcanoes that are in the Philippines belong to what category

Answer 16

active

Question 17

300 of these volcanos in the Philippines belong to what category

Answer 17

inactive

Question 18

Mount Apo is

Answer 18

Potentially Active

Question 19

volcanoes with broad summit and gently slopping flanks

Answer 19

shield

Question 20

the most explostive eruption is the ?

Answer 20

Pilian eruption

Question 21

When the temperature of the
magma is high, it is ?
and the magma flows easily.

Answer 21

less viscous

Question 22

When the temperature of
the magma is low, it is more

viscous and the magma
does ?

Answer 22

not flow easily

Question 23

Magma with low silica
content is less ?

Answer 23

viscous

Question 24

Magma with ?,

is more viscous.

Answer 24

high silica content,

Question 25

Lower temperature and higher silica
content: ?

Answer 25

more viscous magma and explosive eruptions.

Question 26

Higher temperature and low silica
content:

Answer 26

less viscous magma and effusive

eruptions.

Question 27

• the process in which when two plates converge, the denser plate
  sinks under the other

Answer 27

subduction

Question 28

sides of the volcano; extends to the summit

Answer 28

● Flanks -

Question 29

the apex; highest point of a volcano
○ Contains the vent

Answer 29

● Summit -

Question 30

mouth of the volcano
○ Sometimes confused with the caldera - a cauldron or cooking pot-like
volcanic feature.

Answer 30

Crater -

Question 31

found in the summit
○ An opening that allows magma to be ejected from the volcano
○ Extends to the conduit

Answer 31

● Vent -

Question 32

the pipe or the channel that conveys the magma.

Answer 32

Conduit -

Question 33

• originate from conduit

Answer 33

Secondary/ branch pipes

Question 34

reservoir-a large underground pool of molten rocks

Answer 34

●Magma chamber/