ch 03 ejemplos en imágenes

8/15/2019 Ch 03 Ejemplos en Imágenes

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VulcanismoVulcanismo


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The Nabro volcano in northeast Africa


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Until last weekend, the Nabro volcano in northeast Africa looked like it does in the imageabove. Then, on the night of June 12, 2011, the stratovolcano eruted for the first time inrecorded histor!. "t sewed ash and large amounts of sulfur dio#ide gas$the highest levelsever detected from sace, according to reliminar! estimates from researchers at NA%A&s'oddard %ace (light )enter.Astronauts on the "nternational %ace %tation snaed this digital hotograh of Nabro inJanuar! 2011, when all was still *uiet. The horseshoe+shaed caldera stretches kilometers -

miles/ in diameter and oens to the southwest. Two smaller calderas lie within the larger one.'ullies and channels scar the outer flanks, signs of man! !ears of runoff. The inner edge ofthe caldera has stee cliffs, some as high as 00 meters.ocated in ritrea near the border with thioia, Nabro is art of larger double+calderastructure with the 3allahle volcano to the southwest. 4oth volcanoes were built, like5iliman6aro, from trach!te lavas, and later filled b! erutions of ignimbrite. 8esearch suggeststhat both calderas ma! have formed around the same time. The volcanic range has been

9virtuall! undocumented,: according to researchers.As of June 1, the volcano was still eruting, though less effusivel! than a week ago. The ashcloud has eriodicall! disruted air traffic in North Africa and arts of the eastern3editerranean. Ash lumes were reorted as far as the )entral African 8eublic, "srael, andTurkmenistan.

http://flexiblelearning.auckland.ac.nz/rocks_minerals/rocks/trachyte.htmlhttp://flexiblelearning.auckland.ac.nz/rocks_minerals/rocks/ignimbrite.htmlhttp://flexiblelearning.auckland.ac.nz/rocks_minerals/rocks/ignimbrite.htmlhttp://flexiblelearning.auckland.ac.nz/rocks_minerals/rocks/trachyte.html


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ritrea;s Nabro


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after nearl! a week of e#losive activit!, ritrea;s Nabro ,?00 meters/, according to the Joint Air(orce @ Arm! eather "nformation Network. The shrinking lumerevealed a 1+kilometer -=.B+mile/ lava flow, visible in this thermalinfrared, false+color image.The Advanced %aceborne Thermal mission and 8eflection 8adiometer

-A%T8/ aboard the Terra satellite observed Nabro on the evening of

June 1=. Cot areas are bright, and cold areas are dark. Thermal infrareddata were combined with a shaded relief image to show the terrain. Thewhite feature e#ending to the northwest is an active lava flow. A high+altitude lume, likel! rich in water vaor, is nearl! black, and obscures theeruting vents. A diffuse, ash+rich lume to the southwest of Nabroaears urle.4ecause the volcano is located in a remote, hard+to+access region, satelliteimages rovide valuable insight into the nature of the erution. The lavaflow fans out in the flat lain, roviding a clue that it is robabl! basalt

lava, which is thinner -less viscous/ than other t!es, sa!s volcanologistric 5lemetti in his anal!sis of the image.4asalt lava can travel long

distances before cooling, thus covering a wide area.Drior to June 12, 2011, Nabro had not eruted in recorded histor!. "t is

unknown when the volcano last eruted. The volcano is one of man! alongAfrica;s 'reat 8ift


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The Aurora+4odie volcanic field Nevada includes a series of small lava flows

and scoria -cinder/ cones that range in age from about 100,000 !ears -lateDleistocene/ to more than 1 million !ears old. "t is art of the4asin and 8ange rovince, an area of e#tensive crustal stretching across the

western United %tates.The volcanoes of the Aurora+4odie field eruted lavas ranging fromrelativel! fluid basalt to more viscousa ndesite. These erutions roduced

distinctive thick and bulbous lava flows such as those of the 3ud %rings

kilometers from the small vent near the southeastern end of the volcano.This natural+color satellite image was ac*uired b! Eigital 'lobe;s

orldview+2 satellite on Jul! , 200. The dr! Nevada climate has largel!reserved the dark lava surface of 3ud %rings, even though it is about

110,000 !ears old. "ndividual trees are visible on flat areas, as well as on thesurrounding, older volcanoes. The basin floor surrounding the volcano islargel! barren.3ost of the erutions from Aurora+4odie have been small, with an averageerutive rate of 200 cubic meters er s*uare kilometer -20,000 cubic feeter s*uare mile/ er !ear since about B.? million !ears ago. This low rate ofactivit! is evidence that the Aurora+4odie volcanoes are fed b! remelted

basalt from the lower crust, rather than a stable magma chamber in theuer crust.

http://volcanoes.usgs.gov/images/pglossary/scoria.phphttp://geomaps.wr.usgs.gov/parks/province/basinrange.htmlhttp://volcanoes.usgs.gov/images/pglossary/basalt.phphttp://volcanoes.usgs.gov/images/pglossary/andesite.phphttp://www.digitalglobe.com/http://www.digitalglobe.com/index.php/88/WorldView-2http://www.digitalglobe.com/index.php/88/WorldView-2http://www.digitalglobe.com/http://volcanoes.usgs.gov/images/pglossary/andesite.phphttp://volcanoes.usgs.gov/images/pglossary/basalt.phphttp://geomaps.wr.usgs.gov/parks/province/basinrange.htmlhttp://volcanoes.usgs.gov/images/pglossary/scoria.php


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D!roclastic flows are some of

the most fearsome haFardsosed b! eruting volcanoes.These avalanches ofsuerheated ash, gas, and rockare resonsible for some of themost famous volcanic disastersin histor!. 3ore recentl!,

!roclastic flows from3ount 3erai in "ndonesia

caused most of the casualtiesduring the volcano;s 2010erution.The intense heat$over 1,000G )the terrific seed$u to >20kilometers er hour$and the

mi#ture of to#ic gases allcontribute to the deadl!otential. D!roclastic flows canincinerate, burn, or ash!#iateeole who cannot get out ofthe flow ath.This false+color satellite imagefrom theAdvanced %aceborne Thermal

mission and 8eflection 8adiometer-A%T8/ on the Terra satellite

shows the remnants of a large!roclastic flow on the sloesof %hiveluch


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The %an (rancisco 00 s*uare kilometers, the volcanic fieldconsists of volcanoes and lava flows, including %D )rater. The Advanced and "mager -A"/ on NA%A;s arth

Ibserving+1 -I+1/ satellite catured this natural+color image on Aril 1>, 2010.

%D )rater is a cinder cone, a conical structure made u of volcanic fragments, often glass! rocks containingbubbles of traed gas. )inder cones often form around or downwind from volcanic vents. hen lava eruts fromthese structures, it fre*uentl! flows out of breaches on the side, and that aears to be the case at %D )rater.ike most volcanoes in this field, %D )rater is a basalt cinder cone. 4asalt has low resistance to flow, so basalt lavaflows tend to travel fairl! far from the erution source.(orming a aisle! attern, the dark volcanic rocks north of %D )rater result from lava flows. -This image has beenrotated and north is at right./ The hardened lava e#tends some miles -? kilometers/ from the cinder cone, and isabout 100 feet -B0 meters/ thick. Eifferent dating techni*ues have laced the age of this lava between ,000 and>1,000 !ears old.

According to the U.%. 'eological %urve!, more than ?00 volcanoes occur in the %an (rancisco


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(ree of vegetation, the gra! and white lava+covered eak of the Ubinas


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"n far eastern 8ussia, north of the 5amchatka Deninsula, lies An!u!ski!


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(ar out in the central Dacific Icean, thousands of miles from an! large landmass, hotmolten rock from dee in the arth;s core bubbles u and eriodicall! recreates thelargest volcano in the worldK 3auna oa on the 94ig "sland: of CawaiLi. 3ost of thesurface of the volcano is covered b! lava flows that have been laid down in the last10,000 !ears, although geologists believe the volcano is robabl! between ?00,000 and1 million !ears old."n this andsat image from (ebruar! , 2000, the rivers of hardened lava make darkbrown etchings across the massive volcano;s flanks. The eak reaches u = kilometersfrom the ocean floor, e#tending to an altitude of ,1>0 meters. In the northeast andsouthwest sides of the 3oku;aweoweo caldera at the summit are two rift Fones, from

which fountains of lava eriodicall! erut. The trails of lava from the last erution of3auna oa, in 1=, snake down from the northeast rift Fone into the green vegetationof the lower sloes. At bottom right of the image is 5ilauea


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(ar out in the central Dacific Icean, thousands of miles from an! large landmass, hot moltenrock from dee in the arth;s core bubbles u and eriodicall! recreates the largest volcano inthe worldK 3auna oa on the 94ig "sland: of CawaiLi. The Dacific coastline of much of )entralAmerica is marked b! a line of active and *uiescent volcanoes known to geologists as the )entralAmerican


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The Tibesti 3ountain 8ange in northern )had is one of the world;s least+studiedvolcanic regions. A look at the area from sace, however, must intrigue

vulcanologists. Ine of the Tibesti 3ountain;s features is Tarso ToussidO. Thisimage is a comosite of images ac*uired b! the nhanced Thematic 3aer Dlussensor on NA%A;s andsat satellite on Januar! 22, 2001, and (ebruar! 1, 2000.ooking like the result of a giant inkwell tied on its side, Tarso ToussidOunderwent a violent erution in the recent geologic ast, and the remains ofthat erution have stained the ground black. The volcanoe6ectedtehra, fragments of rock and volcanic glass, lava, and ash. Tehra doesnot last on the landscae as long as consolidated volcanic rocks such as tuff orlava, so the resence of tehra suggests fairl! recent activit!. "n the middle ofthe field of dark tehra is Dic ToussidO, a lava dome oking out of the currentcaldera.


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4asalt cliffs along the northwest edge of the 3eseta de %omuncura lateaunear %ierra )olorada, Argentina show an unusual and striking attern of erosion.%tereoscoic observation hels to clarif! the landform changing rocesses activehere.

3an! of the cliffs aear to be rock staircases that have the same color asthe lateau&s basaltic carock. Are these the edges of lower la!ers in the basalt, orare the! a train of slivers that are breaking off from, then sliding downsloe andawa! from, the carockS The! aear to be the latter.

)lose insection shows that each stair ste is too laterall! irregular to be acontinuous sheet of bedrock like the carock. Also, the stes are not flat but

instead are little ridges, as one might e#ect from broken, tilted, and sliding slicesof the carock. %tream erosion has cut some gullies into the cliffs and greenvegetation shows that water srings from and flows down some channels, butlandsliding is clearl! a ma6or agent of erosion here.

andsat satellites have rovided visible light and infrared images of the arthcontinuousl! since 1=>2. %8T3 toograhic data match the B0+meter -==+foot/satial resolution of most andsat images and rovide a valuable comlement for

stud!ing the historic and growing andsat data archive. The andsat > Thematic3aer image used here -to image/ was rovided to the %8T3 ro6ect b! theUnited %tates 'eological %urve!, arth 8esources Ibservation %!stems -8I%/Eata )enter, %iou# (alls, %outh Eakota.


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Dlate tectonics, volcanism, landslides, erosion and deosition$and their interactions$are allver! evident in this view of the )rater Cighlands along the ast African 8ift in TanFania. Theimage shows landforms using color and shading. )olor indicates height, with lowest elevationsin green and highest elevations in white. %hading shows the sloe. The vertical relief has been

e#aggerated b! a factor of 2 to reveal greater detail about the landscae. The image isoriented as though !ou were looking from the north toward the southwest.ake !asi is in blue at the to of the image, and a smaller lake occurs in Ngorongoro )rater.Near the image center, elevations eak at B,? meters at 3ount oolmalasin, which is southof la Naibori )rater. 5itumbeine -left/ and 'elai -right/ are the two broad mountains risingfrom the rift lowlands. 3ount ongido is seen in the lower left, and the 3eto Cills are in theright foreground.The ast African 8ift is a Fone of sreading between the African -on the west/ and %omali -on

the east/ crustal lates. Two branches of the rift intersect here in TanFania, resulting indistinctive and rominent landforms. Ine branch trends nearl! arallel to this southwesterl!view and includes ake !asi and the ver! wide Ngorongoro )rater. The other branch is welldefined b! the lowlands that trend left to right across the image -below center, in green/.


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The arid climate of 4a6a )alifornia limits the amount of vegetation covering the ground andallows the dramatic volcanic features of the landscae to stand out in this natural+color imagefrom the andsat satellite on Ictober , 2000. The landscae is a atchwork of lava flows andthe hardened remains of !roclastic flows$hot clouds of volcanic ash, dust, and rock fragmentsthat race down the sloes of a volcano like an avalanche.

In the eastern coast of the eninsula, facing the 'ulf of )alifornia, is the massive a8eforma )aldera. The outer rim of the caldera is defined b! dark+colored rocks made out ofver! fluid lava. A dome of rock in the center of the caldera is a resurgent dome. A resurgentdome is formed as the floor of the caldera is heaved uward b! the movement of magma belowground. The lavas surrounding the caldera date to about 1 million !ears ago.

est of a 8eforma is a line of three connected volcanoes. a


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A%T8&s abilit! to sense fine+scale heated surfaces is roviding never+before seenviews of active volcanic erutions. These observations rovide a detailed look intothe erutive histor!. ava flows, hot mudflows, and other details of erutionactivit! that cannot be seen using other techni*ues are revealed. 3ichael 8amse! ofthe Universit! of Dittsburgh will resent initial observations of the recent hasesof two ongoing erutions in the )aribbean -3ontserrat/ and 8ussia -4eF!miann!/.


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This view of northern Datagonia, at Los Menucos, Argentina shows remnants ofrelativel! !oung volcanoes built uon an eroded lain of much older and contortedvolcanic, granitic, and sedimentar! rocks. The large urle, brown, and green&butterfl!& attern is a single volcano that has been deel! eroded.

arge holes on the volcano&s flanks indicate that the! ma! have collased soon aftererution, as fluid molten rock drained out from under its cooled and solidified outershell.At the uer left, a more recent erution occurred and roduced a small volcanic coneand a long stream of lava, which flowed down a gull!.At the to of the image, volcanic intrusions ermeated the older rocks resulting in a

chain of small dark volcanic eaks.At the to center of the image, two halves of a tan ellise attern are offset fromeach other. This feature is an old igneous intrusion that has been slit b! a right+lateral fault. The aarent offset is about ?.? kilometers - miles/. )olor, tonal, andtoograhic discontinuities reveal the fault trace as it e#tends across the image tothe lower left. Cowever, !oung unbroken basalt flows show that the fault has notbeen active recentl!.

This cross+e!ed stereoscoic image air was generated using toograhic data fromthe %huttle 8adar Toograh! 3ission, combined with an enhanced andsat > satellitecolor image. The toograh! data are used to create two differing ersectives of asingle image, one ersective for each e!e. "n doing so, each oint in the image isshifted slightl!, deending on its elevation. hen stereoscoicall! merged, the resultis a verticall! e#aggerated view of the arth&s surface in its full three dimensions.


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)erro DicWn eufW)erro DicWn eufW

)erro 3arucho)erro 3arucho

Anticlinal DicWn eufWAnticlinal DicWn eufW

)hacaico+)harahuilla)hacaico+)harahuilla

4asamento4asamento


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