Earthquakes & Volcanoes Exam 3 Review

super volcano eruptions with mag 8 or above occur how much?

very infrequently (more than every 100 years)

Volcanoes are NOT common along what plate boundaries

transform

Time duration between distinct eruptions generally increases or decreases with the size of the eruption

increases

what are the most dangerous of effects accompanying volcanoes because of the speed of the process and the density of the materials

lahars

intraplate volcanoes

passive in nature and usually produces catastrophic effects

are hot spots in the mantle fixed or moving relative to the movement of the plates

fixed

can lahars occur on volcanoes that are snow/ice capped

yes

flood basalts

CAN cover large areas and aren't thin

Gas and aerosols released during volcanic eruptions lead to

acid rain

Mount Pinatubo activity

was not active for many years prior to its catastrophic eruption in 1991

Rocks associated with the volcanism in the Cascade Mountains of Washington and Oregon are primarily what type of mineral

andesitic

Hawaiian volcanic activity is characterized by magma's with what levels of volatiles

small levels

The Yellowstone eruption 630,000 years ago distributed ash how far

beyond 1000 miles

VEI measures what

height of the plume, distance traveled by ejecta, duration of blast, and volume erupted

what rock is composed of minerals with a higher level of polymerization than the minerals that make up basalt

rhyolite

polymerization

linking together of atoms in minerals that make up volcanic magma

does the degree of polymerization have a relationship to the explosive nature of volcanoes

yes

The increase in viscosity from basaltic to andesitic magma is on the order of

100 - 1000

Caldera formation can follow what eruption

ultraplinian

what type of rock is granite

intrusive, igneous rock

is silica the most abundant element in the earth

no

what net charge do cations have

positive; less electrons than protons

what net charge do anions have

negative; more electrons than protons

95% of all crustal rocks are what type

igneous or metamorphic

what is the first silicate mineral to crystallize out of a cooling silicate magma

olivine

what can rock texture tell you

the history of the rocks

are Isotopes stable or unstable atoms

unstable

The degree of polymerization in a mineral can affect what

how it appears to the naked eye

pumice flows

collapse of the eruption column

Pumice flows are more/less energetic than nuee ardentes due to lava dome collapse

less energetic

tephra

airfall pyroclastic materials from a volcano

aa

type of lava flow having a rough, fragmental surface found in Hawaii

lahar

volcanic mudflow

pahoehoe

basalt volcanic rock formed as hot an fluid magma solidifies often showing a ropey structure indicative of the flow in the magma as it solidified

welded tuff

hard pyroclastic rock compacted and formed by high internal heat when deposited and possibly pressure of overlying materials if it becomes buried

Hawaiian volcanism

minimal crustal contamination of magma; low viscosity magma; associated with an oceanic hot spot; effusive eruptions

Cascade/Andean volcanism

significant crustal contamination of magma; intermediate viscosity magma; associated with a convergent plate boundary; explosive eruptions

mercalli

type of eruption, materials erupted and height of eruption - visual appearance

magnitude

total volume or mass of erupted material

dispersive power

area covered by tephra fall

intensity

rate of magma or ash output

explosivity index

integrated measure involving height of plume, distance traveled by ejecta, duration and volume erupted

Mount St Helens

1980 .24 cubic miles; VEI 4.9-5

Mount Pinatubo

1991 2.4 cubic miles; VEI 6

Yellowstone

630,000 years ago 240 cubic miles; VEI 8

Hawaiian eruptions

basalt w/ lowest amount of volatiles; 100's meters

Strombolian eruptions

basalts w/ slight more volatiles; discrete bursts of magma w/ 10-30% volatiles but no sustained eruptive column; 1 km

Volcanian eruptions

andesitic; brief explosive eruptions of intermediate viscosity material and accompanied by an eruptive column; 10-20 km

Plinian eruptions

dacitic to rhyolite; sustained eruptions, sometimes leading to caldera formation; 35 km+

pyroxene

single chain silicate

feldspars and quarts

3d framework silicate

amphibole

double chain silicate

mica

sheet silicate

olivine

isolated individual silicates

granite

intrusive with the highest % of silica as a result of being composed of the minerals that are made up of silica tetrahedron that are linked into 2-3d patterns

peridotite

intrusive with the lowest % of silica as a result of being composed of minerals that are made up primarily of isolated silica tetrahedron

basalt

extrusive with the least silica and lowest viscosity

rhyolite

extrusive with the highest polymerization of silica tetrahedra and the highest viscosity

olivine igneous

simple silicate mineral that is made up of isolated silica tetrahedral

reflection

wave encounters a discontinuity in geology; anytime it encounters a change in velocity or density in the rocks

refraction

wave encounters a change in rock type, which is characterized by a velocity of propagation change; some of the energy in the wave will propagate into the new material after the direction of the wave is bent