Upload
281095
View
498
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Bahan ajar Geologi Dasar Fakultas Teknologi Mineral UPN "Veteran" Yogyakarta
Citation preview
Module 12Module 12
VolcanoesVolcanoes
The gods of volcanoes doing their taskThe gods of volcanoes doing their task
A A volcanovolcano is a is a ventvent or or fissurefissure in the Earth’s crust in the Earth’s crust through which molten magma, hot gases, and through which molten magma, hot gases, and other fluids escape to the surface of the land or to other fluids escape to the surface of the land or to the bottom of the seathe bottom of the sea
Volcanoes may be classified broadly into:Volcanoes may be classified broadly into: Central TypesCentral Types: the products escape via a single : the products escape via a single
pipe (vent)pipe (vent) Fissure TypesFissure Types: the products escape from a : the products escape from a
linear vent or cracklinear vent or crack
VOLCANOESVOLCANOES
Vent positionsVent positions
Central EruptionCentral Eruption
Fissure EruptionFissure Eruption
Side EruptionSide Eruption
Vent positionsVent positions
Earth’s GeothermEarth’s Geotherm
GEOTHERMGEOTHERM: increase in : increase in temperature with depth in the temperature with depth in the earthearth
GEOTHERMAL GRADIENTGEOTHERMAL GRADIENT is is the rate of change of T with the rate of change of T with depthdepth
In upper 100 km, average In upper 100 km, average geothermal gradient = 30geothermal gradient = 3000C C kmkm-1-1
Heat source is decay of Heat source is decay of radioactive elementsradioactive elements
This heat causes melting of This heat causes melting of rocks to form Magmarocks to form Magma
Composition of MagmaComposition of Magma
Variation in magma properties include:Variation in magma properties include: SILICA CONTENTSILICA CONTENT
varies from 45% to 75% varies from 45% to 75% VOLATILES (GAS CONTENT)VOLATILES (GAS CONTENT)
most common gases: H most common gases: H22O vapor,O vapor, CO CO22, SO, SO22, H, H22SS
TEMPERATURE OF ERUPTED MAGMATEMPERATURE OF ERUPTED MAGMA varies from 1200 varies from 120000C to about 800C to about 80000CC
Variation in magma properties affect Variation in magma properties affect VISCOSITYVISCOSITY of of the magmathe magma
VISCOSITYVISCOSITY refers to the thickness or fluidity of a refers to the thickness or fluidity of a liquidliquid Liquid with HIGH viscosity are very thick, Liquid with HIGH viscosity are very thick,
stickysticky Liquid with LOW viscosity are very fluidLiquid with LOW viscosity are very fluid
Effect of various properties on magma viscosity:Effect of various properties on magma viscosity: TemperatureTemperature: HIGH temperature = LOW : HIGH temperature = LOW
viscosity (viscosity (i.e.i.e. very fluid) very fluid) Silica ContentSilica Content: HIGH silica = HIGH viscosity: HIGH silica = HIGH viscosity Volatile ContentVolatile Content: HIGH volatiles = LOW : HIGH volatiles = LOW
viscosityviscosity
(However, (However, high gas contentshigh gas contents contribute to contribute to explosiveexplosive eruptions) eruptions)
Viscosity of MagmaViscosity of Magma
Types of VolcanoesTypes of Volcanoes
Types of VolcanoesTypes of Volcanoes
Shield VolcanoesShield Volcanoes
Shield VolcanoesShield Volcanoes
Shield VolcanoesShield Volcanoes
Shield VolcanoesShield Volcanoes
Shield VolcanoesShield Volcanoes
Shield VolcanoesShield Volcanoes
HOT SPOT
Shield VolcanoesShield Volcanoes
Cinder Cone VolcanoesCinder Cone Volcanoes
Cinder Cone VolcanoesCinder Cone Volcanoes
Strato VolcanoesStrato Volcanoes
Strato VolcanoesStrato Volcanoes
Strato VolcanoesStrato Volcanoes
Strato VolcanoesStrato Volcanoes
Strato VolcanoesStrato Volcanoes
Strato VolcanoesStrato Volcanoes
Lava Dome VolcanoesLava Dome Volcanoes
Dome VolcanoesDome Volcanoes
Caldera VolcanoesCaldera Volcanoes
The formation of The formation of CalderaCaldera
Caldera VolcanoesCaldera Volcanoes
Eruption TypesEruption Types
HAWAIIAN-HAWAI
Eruption TypesEruption Types
STROMBOLIAN - ANAK KRAKATAU
Eruption TypesEruption Types
VULCANIAN DOME - MERAPI
Eruption TypesEruption Types
VULCANIAN - SURTSEYAN
Eruption TypesEruption Types
VULCANIAN - PAPANDAYANGAMALAMA
Eruption TypesEruption Types
PELEEAN - ST HELLENS
Eruption TypesEruption Types
PLINIAN PINATUBO
Eruption TypesEruption Types
PLINIAN - TAMBORA
Eruption TypesEruption Types
Global Distribution of VolcanoesGlobal Distribution of Volcanoes
Most Most subduction zones are in the “Ring of Fire” (so-calledsubduction zones are in the “Ring of Fire” (so-called because of volcanism of the Pacificbecause of volcanism of the Pacific))
from
: htt
p://
ww
w.g
eo.ls
a.um
ich.
edu/
~crl
b/C
OU
RS
ES
/270
Distribution of VolcanoesDistribution of Volcanoes
Volcanism & Plate TectonicsVolcanism & Plate Tectonics
Volcanism in continentalVolcanism in continental
Volcanism in islands arcVolcanism in islands arc
Pacific Ocean
Volcanism & Plate TectonicsVolcanism & Plate Tectonics
Volcanism in Volcanism in Mid Oceanic RidgeMid Oceanic Ridge
Volcanism & Plate TectonicsVolcanism & Plate Tectonics
Hot Spot VolcanismHot Spot Volcanism
Classification of Volcanic EnvironmentClassification of Volcanic Environment
Types and Zones of VolcanismTypes and Zones of Volcanism
VOLCANIC NECK
COLUMNAR JOINT
Finally . . . Finally . . . Rest in PeaceRest in Peace
Major Volcanoes of IndonesiaMajor Volcanoes of Indonesia(with eruptions since 1900 A.D.)(with eruptions since 1900 A.D.)
Distribution of Magmatic Arcs of IndonesiaDistribution of Magmatic Arcs of Indonesia(source: Carlile & Michell, 1994)(source: Carlile & Michell, 1994)