geoscienci ia

8/13/2019 Geoscienci IA

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UGMGraduate School Gadjah Mada University, Yogyakarta Phone/Fax. (0274) 564239Website http://www.geo.ugm.ac.id, www.geoinfopasca.ugm.ac.id and

http://www.itc.nl/pub/study/programmes/joint-educations

INDIVIDUAL ASSIGNMENT

MODUL A

GEOSCIENCE AND ITS APPLICATION

LECTURER:

PROF. DR. SUTIKNO.

By:

MUHAMMAD ATHTHAAR NAZIM

(13/357422/PMU/08061)

SEPTEMBER 2013

Double Degree MSc ProgrammeGEO-INFORMATION FOR SPATIAL PLANNING AND

DISASTER RISK MANAGEMENT


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1. What are the differences between oceanic crust and continental crust, and

mention the effect of the differences?

Their main differences are in thickness, composition, density and age.

Characteristic Oceanic Crust Continental Crust

Thickness 5-10 km 20-70 km

Composition Iron and magnesium(mafic minerals)

Aluminum and silica (Felsicminerals)

Density 3.0 gr/cm3 2.7 gr/cm3

Age Over 200 million years Exceed 3 billion years

This density difference iswhat allows the continentsto float on the upper

mantle for billions of years.The oceanic crust on theother hand, can barely floaton the mantle. As theoceanic crust gets older, itbuilds up a heavy underlayer of cooled mantle rockwhich results in a two-layer

structure causing it to eventually sink into the mantle from its own weight. As itsinks, it is melted down and recycled. Due to this recycling process, the age ofthe oceanic crust is never older than 200 million years.

http://moonphases.info/the-earths-crust.html

http://www.physicalgeography.net/fundamentals/10j.html

2. What is the asthenosphere, why is it important?

The asthenosphere is the

highly viscous,

mechanically weak and

ductilely-deforming region

of the upper mantle of the

Earth. This layer lies

below the lithosphere,

between 100 and 200 km

below the surface, but

perhaps extending as

deep as 700 km (430 mi).

It is considered the

source region of mid-

ocean ridge basalt.


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It is semi solid molten metal that causing the movement of tectonic plates,

where magma is ejected from this layer during volcano. Thats way its

involved in plate tectonic movement and isostatic adjustments.

Rocks in the asthenosphere are "plastic", meaning that they can flow in

response to deformation. Even though it can flow, the asthenosphere is still

made of solid (not liquid) rock. Some observers also described the

asthenosphere as the 'lubricating oil' that permits the movement of plates in

the lithosphere

http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Asthenosphere.html

3. What would Earth be like without solar heating?

The creation and sustenance of life are depend on Solar Energy that life onEarth would not be possible without it, because of (a) the food we eat existswith sunlight falling on green plants, and the fuel we burn comes either fromsuch plants, or was accumulated by them (in the forms of coal, oil and natural

gas) long ago and (b) the Earth would probably not be fit for life. Life as weknow it needs liquid water, and Earth is the only planet to have it: without theSun, Earth would be an icy rock in space.

It was been estimated that 1,000times more energy reaches theearth surface from the sun everysingle year than could beproduced by burning all the fossilfuels mined and extracted duringthat same year.

http://www.phy6.org/stargaze/Sun1lite.htm

4. What facts make it probable that Earths core is composed of mostly iron?

During the formation of the planet, when earth was still a hot ball of liquid rockand minerals; the most dense materials would make their way to the bottom,while less dense materials (like liquid rock) would "float" on the top of thisgrowing ball of liquid metal. As iron was (and is) plentiful, and quite a dense

mineral, it makes up the majority of the Earth's core.

Based on the estimations of the density, the existence and composition ofiron meteorites, and the presence of a magnetic field on Earth possibly thatthe core must be made up mostly of iron.

http://nineplanets.org/earth.htmlhttp://web.crc.losrios.edu/~jacksoh/classes/phys_geol/homework/hw1.html


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5. Make comparison between continental drift theory, sea floor spreading theory

and plate tectonic theory.

Module No A (core 1) Geo-sciences and its application (Prof. Dr. Sutikno)

www.science.marshall.eduhttp://www.platetectonics.com/article.asp?a=18

6. Explain how plate tectonic can account for the existence of the mid oceanic

ridge and its associated rift valley, earthquake, high heat flow and basaltic

flow?

Continental DriftTheory

Sea FloorSpreading Theory

Plate TectonicTheory

Definition The continentsmove freely overEarths surface,changing theirpositions relative toone another

Hypothesis thatthe sea floor formsat the crest of themid oceanic ridge,then moveshorizontally awayfrom the ridgecrest to ward anoceanic trench

The ocean floorbegan to spreadand that thecontinents existedon plates thatmoved in responseto the changingocean floor.

The Idea Supercontinent,called Pangea thatbreak up intosmaller continentsthat drifted apartthrough thesuperoceanPanthalassa about200 million yearsago

Based onconcepts ofcontinental driftand convectioncells within themantle

Incorporatesconcepts fromContinentaldrift, Seafloorspreading andinformation ofglobal seismicity

Evidence (1) ContinentShapes, that theywould fit togethernicely, like a jigsawpuzzle.(2) Rock

Formations, ondifferent continentsthat match upbeautifully when thecontinents are putback together.(3) Fossils, foundon differentcontinents thatwould also matchup nicely.

(1) age ofseafloor (crust)increases regularlywith distance fromthe ridge axis.(2) Formation and

melting of ice onland (Ice Ages).(3) Change in thevolume of theocean basins

(1) concentrationof "tectonic"activity along plateboundaries.(2) subduction: ordestruction of old

oceaniclithosphere insubduction zones.(3) sea floorspreading: orgeneration of newoceanic crust atmid-oceanic ridges


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Earth's outer shell, the lithosphere, long thought to be a continuous,

unbroken, crust is actually a fluid mosaic of many irregular rigid segments, or

plates.There are nine large plates and a number of smaller plates. Of the nine

major plates, six are named for the continents embedded in them: the North

American, South American, Eurasian, African, Indo-Australian, and Antarctic.

The other three are oceanic plates: the Pacific, Nazca, and Cocos.

The driving force behind the process of plate tectonics is heat generated

deep inside the earths core by radioactive decay. This heat reaches the

surface primarily along the Mid-Ocean Ridge. It is a continuous range of

undersea mountains more than 12,000 feet high and 1,200 miles wide

winding through 40,000 miles of the worlds oceans. It is here, at Mid-Ocean

Ridges, that new sea-floor crust is produced and much of the earths internal

heat is released.

At Mid-Ocean Ridges, two plates are pulling apart from each other as hot

magma (liquid rock) emerges from the mantle and oozes forth as lava to fill

the crack continuously created by plate separation. The lava cools and

attaches itself to the trailing edge of each plate, forming new ocean floor

crust in a process commonly known as sea-floor spreading.

http://www.platetectonics.com/

7. What geologic processes might cause the forces that can hold a region out of

isostatic equilibrium?

Gravitational equilibrium would raised an isostatic equilibrium or balance,

between blocks of crust and the underlying mantle. There are many natural

ways on Earth that would prevent a loss of isostatic equilibrium, i.e.

mountains erode over time making them less heavy, and the particles from

that erosion often end up on the sea floor, it is a continuous cycle.


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The area to be out of equilibrium in the isostatik region should get or lose a

large amount of mass sooner or faster that the earth can put it back into

balance. For instant if at any time the ice going ice would cause the

continents to sink a bit if the continent's melting ice will rise. If the ice is

melting faster than the earth can push land upward land mass would be out of

equilibrium until it naturally regained it.

Continental collisions can also cause a region to not be in isostatic

equilibrium, other potential factors would include a large amount of mass from

space hitting the Earth, such as an asteroid.

http://www.askipedia.com/what-geologic-process-might-cause-the-forces-that-can-

hold-a-region-out-of-isostatic-equilibrium/

http://www.cliffsnotes.com/sciences/geology/inside-the-earth/isostatic-equilibrium

8. Why are there no earthquakes deeper than 670 km?

Earthquakes are relatively abundant in the first 300 kilometers (180 miles) of

a subduction zone, are scarce from 300 to 450 kilometers (180 to 270 miles),and then increase slightly again from 450 to 670 kilometers (270 to 400miles). It is possible that these deepest quakes are related to sudden mineraltransformations and resultant energy releases or volume changes.

It has been theorized that earthquakes do not occur at depths greater than670 kilometers because the subducting plate is not brittle anymore and hasbecome hot enough to flow plastically. Or in the other word the rocks are hotenough that they behave like plastic, and cannot build up enough stress tocreate an earthquake.

http://www.cliffsnotes.com/sciences/geology/earthquakes/earthquakes-and-plate-tectonics

http://answers.yahoo.com/question/index?qid=20090929070156AAO2UQB

9. Explain the spatial distribution of earthquakes and volcanoes in the world,

and in Indonesia.

The Earth's crust is broken up into pieces called plates. Heat rising and falling

inside the mantle creates convection currents generated by radioactive decay

in the core. The movement of the plates, and the activity inside the Earth, is

called plate tectonics. Plate tectonics cause earthquakes and volcanoes. The

point where two plates meet is called a plate boundary. Earthquakes and

volcanoes are most likely to occur either on or near plate boundaries.

There are three major ways that plates interact along boundaries: (1) theycan move away from each other (diverge), (2) they can move toward eachother (converge), or (3) they can move past each other, parallel to theboundary (transform). Each of these interactions produces a different andcharacteristic pattern of earthquakes, volcanic activity, and topography.


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http://www.bbc.co.uk/schools/gcsebitesize/geography/natural_hazards/tectonic_plates_rev2.shtmlhttp://www.visionlearning.com/en/library/Earth-Science/6/Plates-Plate-Boundaries-and-Driving-Forces/66

Indonesia is an area that has an interesting geological conditions. Interestingbecause cluster kepulauannya formed by the collision of tectonic plates-plate.

Indonesia is a major tectonic plate 3 meetings, namely the Indo-Australia

plate and the Pacific, Eurasia. The collision of the Eurasian plate and the

India-Australia Plate affected the western part of Indonesia (off the coast of

Sumatra, Java and Nusatenggara), whereas in the eastern Indonesia

(Maluku, North Maluku and North), two tectonic plates was struck again by

The Pacific Ocean from the East.


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Plate-tectonic plates meeting in Indonesia that produces a wide range of

natural phenomena. One example happened in Indonesia is a meeting

between the Indo-Australia and the Eurasian plate. The second meeting of

the plate produces a line of penunjaman in the South of the island of Java,

active volcanoes that line at any time will metelus along the West coast of

Sumatra, southern Java to the Lesser Sunda and the formation of the variousbasins such as North Sumatra Basin, central Sumatra, South Sumatra and

North Java Basin.

http://hanageoedu.blogspot.com/2011/12/keberadaan-dan-pengaruh-lempeng.htmlModule No A (core 1) Geo-sciences and its application (Prof. Dr. Sutikno)

10. Which one is more dangerous between earthquakes disaster and volcanic

disaster, why?

Earthquakes and volcanoes cause damage not only to humans and their

structures, but to the environment and wildlife. Earthquakes can cause

damage by shaking, tsunamis, and landslides. Volcanoes can causedamage by ash flows, release of gases, mudflows, lava flows, and landslides

Earthquakes probably the most wide spread around the world and the most

terrifying considering its massive effects. Seismic waves shake the earths

surface when two land plates collide or shift. The earthquake in itself isnt

deathly, but the aftermath effects are, to a high degree.

Depending on its magnitude, it can cause other catastrophes such as

volcanic eruptions, tsunamis, fires and explosions. The damages are

unimaginable and the degree of lives lost is one of the highest, for example

Indian Ocean Tsunami that have cost the lives of over hundred thounsand

and billion of privat and public property.

http://msnucleus.org/membership/html/k-6/pt/hazards/5/pth5_1a.htmlhttp://landarchs.com/top-10-natural-disasters/

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