Faces of Earth - Shaping the Planet

in September 2005 a swarm of earthquakes rattled the lowest point in Africa the afar depression in Ethiopia the earthquakes continued for 24 hours and over the next two weeks 163 more were recorded this was an unparalleled geologic event something taking place quickly and never seen before the African continent was tearing itself apart just 40 years ago a revolutionary concept plate tectonics change the way you think about earth it helped explain Earth's most violent shudders explosive forces and even what gave rise to her tallest mountain by understanding how and why the ground constantly shifts under our feet geo scientists can show us what lies ahead stress is build up and bang we have an episode you'll come look around look deep below on this episode we explore the shifting layers beneath our feet and how they alter the phases of birth the unprecedented seismic event in a far Ethiopia grabbed the attention of geo scientists around the world a 37 mile fracture had ripped open in Earth's crust at its center a 1600 foot long vent 330 feet deep scientists came to one unbelievable conclusion they were witnessing the birth of a brand-new ocean scientists rush to afar to monitor in the field what was happening Cinthia ebinger from the University of Rochester in New York and Tim Wright from the University of Leeds in England are members of one of the international teams the geoscientists I normally measure processes that happen in effect the rate that my fingernails grow over a period of about 2 to 3 weeks we had 8 meters of opening that's about 400-500 years worth of opening then that happened in a few weeks the afar depression was created by spreading of Earth's crust over the last 30 million years today it is one of only two places on earth where a spreading Ridge can be studied on land rather than the bottom of the sea the other is Iceland what geo scientists were now seeing was clearly a result of the African and Arabian plates being pushed apart along three deep rifts that are called the afar triple Junction most of what and a depth underneath the ground in the top 10 kilometers of the crust so as these two plates moved apart we actually had an injection of molten rock of magma into the crust which allowed these plates to move apart Earth's outermost shell is broken into a dozen or more plates which ride atop Earth's mantle the amount of magma that breezed in and formed this new crust in the middle of these two tectonic plates was over eighty eight thousand cubic feet enough to fill a football stadium two thousand times over afar is one of the hottest and driest places on earth this desert has little vegetation and any movement of the earth is easy to spot from the air the white bands streaking across the landscape are freshly exposed fault fractures caused by the quakes what we see when a fault has slipped is we'll see a dark band and then a white band at the bottom showing the areas where they dirt as it been sandblasted off the folks carbs so we can go to false corpse and directly measure the thickness of the white bands and directly measure the amount of offset after a three and a half hour flight into the heart of afar the scientists will set up their monitoring equipment outside a small native village the helicopter will return again at the end of the day to pick up the science team while scientific data is important to figure out what is happening in the region eyewitness accounts make this geologic event very human a delay I le one of the team members from the University of Ethiopia has been collecting firsthand stories from afar EES living here yes definitely they were very frightened by the activity and they know they were not even concerned about their goats and animals first they were worried about themselves they told that it's not going to stop at a judge the maid will judge a delay explains to the frightened Far East that the shaking and the changes to the land are going to continue indefinitely they live a simple life as nomadic herders and they live in a desert it's not just their safety the afar EES worry about it's their water supply in this desert Basin the afar EES get their water by collecting it from steam vents or bonus magma deep in earth's sub-surface heats the groundwater and the resulting steam pushes up creating the vents but now too much magma has risen up as a result of the rifting and it is boiling off their available water a delay explains to the villagers that the recent underground activity is diminishing their water supply they will have to find water elsewhere one of the tasks of the scientific team is to install a permanent reference point in the rock for a global positioning satellite antenna basically we're on the axis of the spreading grip so we're practically on the plate boundary this is a falaqa who's a surveyor from the erbium mapping authority what he's doing is positioning this tripod very very precisely on top of this benchmark down here that we've installed him I'm in the rough for the center of the tripod has to be above that point to the nearest millimeter and that controls the accuracy of the measurement it's a very delicate and somewhat time consuming process he's been doing it a long time and is very skilled at this process okay it's less here that's good nice job okay the antenna will receive precise location data from 21 satellites orbiting in space this will help scientists chart even small movements in the earth multi-grain just segments opens and another event similar to what happened last year then this point can move by several meters so this benchmark provided it survives in this location orbit will be available for future scientists as well as for our own research the authorities will watch over and maintain the monitoring equipment for the scientists until they return in several months the magma is so close to the surface that it has caused Earth's crust to literally melt stretched like taffy this thinned crust will eventually sink below sea level finally giving birth to a new ocean that's already started in the Danakil depression which goes down to getting on for 200 meters below sea level in places in order for the water to come in you need to you need to cut and make a connection to the sea and we don't know exactly when that will happen but with continued erosion and movement of water and the power of water will eventually find its way in eventually the salty waters of the Red Sea will reach the low hills to the east and spill across the depression erasing traces of what is here today and has been here for millions of years geologists predict in about 10 million years the whole 3,700 mile length of the East African Rift will be submerged and a new ocean will be born at that point Africa will have lost its horn creating yet another new profile of earth earth exists in a state of balance oceans are born twelve others die it is happening in afar and it happened 200 million years ago when the Atlantic Ocean was born why is Earth so Restless what causes the ground shake volcanoes to erupt and great mountain ranges to rise to incredible Heights the face of Earth is continually shifting influenced by a process called plate tectonics Earth's surface the lithosphere is a mosaic of many plates girdling the planet like seams on a baseball these plates drift on top of Earth's hot and slowly churning mantle over time colliding breaking apart and grinding against each other to understand tectonics scientists look back only 200 million years because earlier geologic evidence has been either recycled or hidden by Earth's processes 200 million years ago all of the continental plates we know today had collided and formed a supercontinent scientists called Pangaea the ancient paleo Pacific Ocean to the west and the Teth is sea to the east surrounded it soon after its formation Pangaea began to break apart much like what is happening in Ethiopia today a rift opened that separated North America Africa and Europe giving birth to the Atlantic Ocean that same rift now called the mid-atlantic ridge is still in motion splitting earth and widening the Atlantic how fast is it moving in your lifetime North America and Africa will be about six feet further apart than they were when you were born over the next 100 million years as the Atlantic grew in Pangaea broke-up movement of several tectonic plates closed the test to West these collisions thrust up the great mountain ranges that we still see today stretching from Spain all the way east to Indonesia they also created the eastern Mediterranean Sea the only major remnant today of the tethers see then around six million years ago Earth's climate entered one of its many cooling periods and ice sheets moved south from the Arctic trapped water in the glacial ice made sea levels fall combined with the collision of the African and European plates the waters of the Atlantic and Mediterranean were separated the collision of Africa and Europe pushed up a sill across the Straits of Gibraltar that created a barrier to the waters of the Atlantic the water in the Mediterranean began to evaporate during this time the Mediterranean dried into a group of disconnected seas some never completely dried out while other areas turned into dry wastelands covered with evaporated salts this became known as the Messenians salinity crisis dr. Maria Sita is professor emeritus at the University of Milan's department of geology dr. Sita's team was the first to discover the enormous salt deposits beneath the sea floor of the Mediterranean and figure out the impact the drying out of the Mediterranean had on the rest of the world's oceans a volume of the insults at the bottom of the Mediterranean is 1 million cubic kilometres which correspond to 6% to the salinity of the world ocean so it is quite a lot of salt trapped forever when the Mediterranean refilled this salt buried beneath sediments did not dissolve back into the water and this reduced the overall salinity of the world's oceans and raised the freezing temperature of seawater by two degrees having an impact on the formation of sea ice so this is pure halide recovered in a drill site from sicily which are related to sort exploitation it is so pure the salt sector it can be used it is just grinded besides the global impact of the Messenians salinity crisis on world oceans it also altered the climate throughout the Mediterranean Europe Africa and the Middle East it became drier and hotter this rise in temperature may have contributed to the extinction at the end of the Miocene epoch five million years ago after a million years world ocean levels rose again and the sill across the Straits of Gibraltar was finally breached refilling the Mediterranean for a second time it has been calculated that it might have taken as long as a thousand years for the Mediterranean to refill the Falls that flowed over the Gibraltar sill were more powerful than Niagara Falls today in earth time the closing of the tempest and refilling of the Mediterranean happened in an instant studying with shifting layers deep beneath the surface is difficult not only because we can't see them but also because the movements take place over millions of years scientists have discovered that Earth's movements are scaleable slow and large-scale occurrences in nature can often be replicated on tabletop models and laboratories not far from the ruins of ancient Rome is the tectonic laboratory at the University of Rome 3 Francesca Funicello has been recognized by the European Science Foundation for her geodynamic modeling today Francesca is working with two models the first shows what happened when the African plate rotated north into the Mediterranean Basin and thrust up both the Italian Eponine Mountains and the European Alps this is known as convergent mountain building Francesca uses sand in this model because at this scale it simulates the same properties as crustal rock the various layers of coloured sand represent rock formations in the subsurface every centimeters of sand is representative a one kilometer of the earth cross a motorized conveyor belt generates the tectonic energy that moves one plate into the other millions of years of geologic time are compressed into minutes you can see the topography completely deformed on the top but on the lateral view you can see also the internal structures the model shows in miniature form the same topography found in nature it reveals how the rock in the subsurface folds and deforms deep below the surface of Earth the models provide a remarkable visualization to understand how many convergent types of mountains are formed okay now we will see this duction process Francesca's second experiment demonstrates how ocean crust plunges into Earth's mantle in subduction zones it's a process where an oceanic plate slides beneath the continental plate this creates oceanic trenches and can also feed volcanoes this process is so mysterious this fuzzy image is the best scientists have been able to take of the actual subduction process in nature Francesca's model reveals more useful details of how gravity pulls a plate under this is a plate made by silicone party a slab of silicon stands in for heavy oceanic crust we will put this plate on glucose syrup a sugar syrup is the perfect substance to represent the properties of Earth's mantle so essentially the model is representative of the first 600 kilometers of Earth so the little sphere the first layer and the upper mountain once Franchesca pushes the slab a little nature takes its course time is again compressed and we watch this plate subducting mere few minutes an event that normally takes millions of years lasers scan the movement of the silicon plate providing minut details of motion and dynamics scientists then take these findings and compare them to findings taken in the field with seismic instruments creating a more complete picture when colored tracking markers are added to the experiment we can actually see how the subducting slab retreats back causing the overriding plate to be pulled forward this simple model is able to give scientists insight about the dynamics of Mediterranean subduction it's for this reason that models have become important tools thanks to the modeling we cannot think about what happened in the past the dynamic nature of plate movement around the Mediterranean will eventually alter the map in this part of the world Greece is a country in motion and it's headed toward North Africa the Mediterraneans volcanic eruption record is easily the longest of any on the planet two of the most famous incidents between humans and earth happened here the catastrophic eruption of a volcano on Santorini in 1640 BC is believed to have brought an end to the Minoan civilization on Crete some believe this eruption led to the myth of the sinking of the city of Atlantis in 79 AD Mount Vesuvius blew burying the great ancient Roman cities of Herculaneum and Pompeii in 19 hours of continuous eruption leaving an astonishing memorial of victims frozen in time today the eastern Mediterranean remains just as volatile and southern Greece is riding on top of all the action deep below the Aegean Sea for the past 10 million years the Arabian and Eurasian Plate have pushed into the small Aegean microplate that Greece is on to the west in the Ionian Sea the African plate is subducting beneath the Aegean plate stretching Greece West Greece is in the process of tearing itself away from Europe and breaking apart the video contributes elementary structures in here so wall weight you consider me Royden from MIT in Boston has come to an area northeast of Athens on the Aegean at the Gulf of Evia to observe firsthand the effects of these processes in Greece okay from space looking down on Greece it's easy to see the process that is fracturing Greece apart the successive fault lines appear as a series of north-south running lines through the landscape however on the ground and up close they look very different only half a mile from the Aegean we encounters one of the great signposts of tectonic activity in this region this is a really fantastic sports car probably one of the best xposed faults in the world certainly the best one I've ever seen it bottles in line how you've contrived by this a hundred times I've never noticed that there's this humongous fault scarp about 100 metres high sitting over here this is a normal fault normal faults are a result of the crust being stretched and young breaking into massive pieces that release tension one side slips down while the other block appears to rise up in the last 10 million years all of southern Greece has been stretched and thinned at least six miles across as a result of tectonic activity creating many normal faults well seeing this for the first time and getting up close to it what really strikes me is how incredibly smooth the surfaces looks like somebody took a floor sander to it you can also see up close these really nice small-scale lineage ins not in the surface that give you the transport direction so the upper plate just moved right down this surface paralleling these structures here there is an average of a 5.0 magnitude earthquake every two years in Greece during the last earthquake here this fault pushed up nearly 20 inches two hours to the West is Mount Parnassus which was formed much earlier in time by the same tectonic processes that have created the fault near the Aegean this fault that we're looking at in the background is one of the faults that's accommodated the rifting a part of Greece down in the far edge of that slope there's a small rounded hill which is actually a piece of the upper plate which belong up on top of Mount Parnassus and has now been brought down so there's probably at least five kilometers to ten kilometers of displacement on this fault the plate movement that gave rise to Mount Parnassus also brought deep crustal rocks to the surface marble deposits which formed several miles below the surface when we lift it up by these faults and was easy to quarry the examples of how early civilizations use this resource can still be seen throughout Greece today if the tectonic activity keeps flexing its muscles scientists think that in five to ten million years southern Greece will be pulled across the Mediterranean right up against the coast of Africa changing Earth's face again a volcanic eruption is one of Earth's most incredible sites but for people living in the volcano's shadow it is potentially one of Earth's most dangerous locations volcanoes are like ticking time bombs some remain dormant for years while others erupt with little warning in the past 400 years volcanic eruptions have killed nearly 300,000 people today for the 500 million people living near one of the 1,500 active volcanoes an effective warning system could be a lifesaver nestled in the Alps near Geneva Switzerland is CERN the world's largest particle physics laboratory where scientists study the building blocks of matter and the forces that hold them together one of CERN's unique projects uses high-powered computers to convert seismic readings from Mount Etna a volcano in Sicily and tungurahua a volcano in Ecuador into audible rumbles roars and beeps literally music to the ears of these scientists dominika vitsin Anza believes by listening to and analyzing the variations in the melodies that these musical patterns could warn of an impending volcanic eruption is it something challenging because it is the first time that people are using music as a language to describe scientific data the technique known as sonification is the acoustic counterpart of data graphic visualization letting Rao a play a piano tongue jarawa is an active volcano in Ecuador and its score was produced from data taken during a period when the volcano was relatively quiet by contrast mount etna score was produced from seismic data recorded just before an eruption what Dominico is found is that the musical intervals reflect the intensity of the seismic waves the music is smooth when the waves are small indicating that the volcano is quiet the tune becomes nervous scattering through high and low tones when an eruption is approaching domenico is now working to build a database of seismic sonograms from volcanoes around the world researchers from across Europe are helping to create the database by contributing seismic data through a public internet portal there's more than 140 University Research Center's that are contributing now because this is a real-time feature sonification is just one potential new tool that is literally keeping scientists ears to the ground in the future sonification may be able to tell us when volcanoes like Etna are about to erupt vital life-saving information for the 500 million people living in volcanic danger zones volcanoes are one of the processes that can transform the face of Earth a very different sequence of events in the far east built the roof of the world among the most dramatic and visible creations of tectonic forces are the lofty Himalayas which stretch 1,800 miles along the border between India and Tibet about 50 million years ago India separated from Madagascar and began a record-breaking race to the north normal movement for a plate would be about 1 foot every decade but the Indian plate was on a fast track moving more than 29 feet in a century the massive collision between India and Eurasia thrust up Earth's crust forming the jagged Himalaya mountain range and raised the roof of the world India pushed as much as 1,800 miles into Eurasia and continues to shove north nearly 2 inches a year this means in your lifetime it could travel 12 feet the width of a highway lane as a result the Himalayas continue to grow higher but there was a mystery afoot geologists noticed that 1800 miles of India's crust was missing scientists had always assumed that India had slid under Eurasia but the amount of uplift of the Himalayas in Tibetan Plateau couldn't account for all of that crust it's only recently the geoscientists can account for its mysterious disappearance you can see with these telegraphic techniques we can see weather has gone one of the ways geo scientists like Rob Van der hills to MIT solved the mystery is by using seismic data to generate images called tomography seismic tomography is a technique for imaging the deeper earth that was adopted for medical imaging cat scan imaging MRI imaging x-rays well it seismic waves we do the same thing we had an array of about 50 stations that we operated for about a year to get additional data for high-resolution studies in that particular region so it's about 100,000 seismographs that we actually use to construct these images this tomographic image exposes a 1,000 mile thick slice of Earth's interior the blue represents faster moving material in Earth's mantle in this case the indian plate red indicates the warmer and slower moving material of the Eurasian continent here Robb's image reveals the missing material of the indian plate bending back on itself so with the combination of cities tomographic techniques and what we know from plate reconstructions and geology at the surface we can really begin to understand how this system has changed over time so this helps us greatly to understand how India has interacted with Tibet and what actually has been driving the Tibetan Plateau the continuing collision of the Indian and Eurasian plates makes this region of the world very prone to earthquakes on October 8 2005 a 7.6 quake shook the pakistan-administered region of Kashmir on the border with India it killed 90,000 people maybe more there is also another region of potentially deadly tectonic activity on the west coast of California with every tremor and jolt the question is asked is there a way to create an effective warning system it's just another sunny day in California what could possibly go wrong the San Andreas Fault even though California experiences 10,000 earthquakes every year most of them are not felt by California's 33 million inhabitants only a handful are strong enough to get their attention the 800-mile long San Andreas Fault is perhaps one of the most worrisome examples of human tectonic interaction the boundary of the fault is formed by two plates which move side by side periodically building up tension the Pacific plate on the west and the North American plate on the east when the tension is finally released the landscape shakes and shudders the united states geologic survey center in golden colorado monitors global earthquakes in real-time the center pinpoints 12,000 to 14,000 earthquakes around the world each year about 35 per day David Wald is a seismologist at the center within a few minutes of an earthquake in the US within tens of minutes around the globe we can determine the size of the earthquake the magnitude location and from that estimate what the impacts gonna be in that area the USGS has an extensive network of seismometers keeping a watch on the San Andreas Fault when an earthquake happens data is gathered from the size monitors to create a shake map these maps show the level of shaking in specific areas within 5 minutes after an earthquake there's a number of different uses of shake map one of them is just emergency response and understand the scope of the disaster another use of these maps by federal state and local governments is to create pre response plans based on existing information for example they are an important tool used by the California Department of Transportation which is responsible for the 12,000 overpasses in California after a large quake shape maps can create an overview of the affected area showing where overpasses may have been damaged in the event of a future earthquake these maps could tell repair teams where to head first shake maps created from present and past earthquakes are also useful for future construction and determining appropriate building codes for an area that might be prone to shaking but trying to figure out where and when an earthquake might occur is tricky Richard Allen with the University of California at Berkeley is developing an early warning system using the seismometers station around the San Francisco Bay just like this one in the Berkeley Hills so we're now at the very back of the seismic vault for about 20 or 30 meters underground these are part of the network in Northern California and we're using all of those instruments to start to test whether we can do earthquake early warning in 1989 san francisco's Loma Prieta quake and the 1994 Northridge quake in Los Angeles killed 100 people and caused nearly 40 billion dollars in damages yet Californians have a way of rolling with the punches the effects that we are familiar with the Northbridge in the Loma Prieta rough quite really a very small very insignificant events when it comes to geologic processes so it's these big earthquakes which we haven't really seen that the earthquakes were concerned about efforts at earthquake early warning are going on around the world in Japan in Mexico and in Taiwan here in California is a little different we actually have millions of people living right on top of the fault we need to really push the envelope and really minimize the amount of time that we need in order to get this warning out so that we can provide warning even for people who are very close to the fault the idea of early warning is to rapidly detect the first tremors of an earthquake P waves or primary waves which are yellow are the fastest of all seismic waves and are the first to arrive at any seismic station the red shear waves travel more slowly they are the most destructive type of seismic wave generated by an earthquake we're talking about a few seconds of warning first of all so a sec total seconds to tens of seconds what you can do with that kind of times you can start to slow and stop trains and so there's less chance of the train derailing we can stop planes from landing at airports if we have some particularly sensitive highway structures such as bridges we might actually start thinking about slowing down traffic and actually stopping traffic from entering bridges to the people in Los Angeles in 1994 this kind of warning might have made a difference the San Andreas is going to continue to move northwards and is sure to generate more earthquakes for California the Los Angeles section of the San Andreas Fault is moving north faster than the San Francisco section in ten to eleven million years Los Angeles will become a suburb of San Francisco the power of tectonics is responsible for the look and shape of everything that makes up our planet after billions of years the same incredible force of energy that turns deep inside can rip earth apart erupt with unpredictability move a continent and even create a new ocean there is no one face of Earth because of the constantly shifting ground beneath our feet there have been and will always be many faces of Earth

Channel: American Geosciences Institute

Views: 142,666

Rating: 4.7922077 out of 5

Keywords: Earth, Plate Tetonics, Geology, Volcanoes, Earthquakes, Glaciers, Ice Age, North America, Documentary, American Geosciences Institute, Africa, Afar, Ethiopia, Italy, Messinian, Santorini, Greece, Tambora, Himalaya, California

Id: yWezU1P6dM0

Length: 45min 36sec (2736 seconds)

Published: Tue Feb 19 2013