Conferencia (o xerrada) : "Tectònica Global: La dinàmica d'un planeta actiu"

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1 Conferencia (o xerrada) : "Tectònica Global: La dinàmica d'un planeta actiu" El progrés dels darrers anys de les tècniques de geofísica i d'adquisició de dades mitjançant satèl lits han revolucionat la visió que tenim de la Terra i del paradigma de la Tectònica de Plaques. En aquesta xerrada es farà una introducció a la dinàmica interna de la Terra des d'un punt de vista multidisciplinari, i que ens permetran millor comprendre el vulcanisme, l'activitat sísmica, la generació de tsunamis o els processos que generen el relleu de la Terra. Taller: Explorant la Terra: Recursos en xarxa GeoMapApp es una aplicació que permet l'exploració i visualització de dades de l àmbit de les Ciències de la Terra. Per aquest taller ens centrarem en l'exploració de la dinàmica interna a partir dels catàlegs de terratrèmols (localització, magnitud i profunditat dels epicentres), dades de geofísica (magnetisme, gravetat, perfils de reflexió sísmica), batimetria/ topografia i geologia (litologia, geoquímica, geocronologia). L'objectiu és mostrar la versatilitat de l'aplicació i les seves possibilitats a nivell docent o el desenvolupament de projectes de batxillerat. El taller també es centrarà en la lectura Don't provoke the planet! per Richard Fischer (New Scientist, Setembre 2009, 8-9 pp.) on es discuteix com el canvi climàtic pot influir en la dinàmica interna de la Terra (terratrèmols, vulcanisme).

2 Us deixo una sèrie de petites lectures i material sobre aspectes d actualitat de la Tectònica de Plaques.. 1) El canvi climàtic afecta a l activitat sísmica i volcànica del planeta? Lectura Don t provoke the planet de Richard Fisher, 3-4 pp. Richard Fisher, Don't provoke the planet, The New Scientist, Volume 203, Issue 2727, 23 September 2009, Pages 8-9 2) Va ser el 2010 (o el 2011) una any apocalíptic a nivell de terratrèmols? Quina conclusió és pot extreure a partir de les dades? Recent Eartquake Activity is not Unusual, scientists say 3) La relació entre volcanisme a Islàndia i l expansió del fons oceànic. Iceland Volcano Could continue Erupting fore moret han a month, Researcher says 4) L enigmàtic terratrèmol de magnitud 6.3 a Granada, 11 d Abril de Per què? Quines implicacions es poden deduir?

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5 1 de 2 07/05/ :40 Web address: htm ScienceDaily (Apr. 15, 2010) China's tragic magnitude 6.9 earthquake on April 13 and the recent devastating earthquakes in Haiti, Chile, Mexico, and elsewhere have many wondering if this earthquake activity is unusual. Scientists say 2010 is not showing signs of unusually high earthquake activity. Since 1900, an average of 16 magnitude 7 or greater earthquakes -- the size that seismologists define as major -- have occurred worldwide each year. Some years have had as few as 6, as in 1986 and 1989, while 1943 had 32, with considerable variability from year to year. With six major earthquakes striking in the first four months of this year, 2010 is well within the normal range. Furthermore, from April 15, 2009, to April 14, 2010, there have been 18 major earthquakes, a number also well within the expected variation. "While the number of earthquakes is within the normal range, this does not diminish the fact that there has been extreme devastation and loss of life in heavily populated areas," said USGS Associate Coordinator for Earthquake Hazards Dr. Michael Blanpied. What will happen next? Aftershocks will continue in the regions around each of this year's major earthquakes sites. It is unlikely that any of these aftershocks will be larger than the earthquakes experienced so far, but structures damaged in the previous events could be further damaged and should be treated with caution. Beyond the ongoing aftershock sequences, earthquakes in recent months have not raised the likelihood of future major earthquakes; that likelihood has not decreased, either. Large earthquakes will continue to occur just as they have in the past. Though the recent earthquakes are not unusual, they are a stark reminder that earthquakes can produce disasters when they strike populated areas -- especially areas where the buildings have not been designed to withstand strong shaking. What can you do to prepare? Scientists cannot predict the timing of specific earthquakes. However, families and communities can improve their safety and reduce their losses by taking actions to make their homes, places of work, schools and businesses as earthquake-safe as possible. or share this story: More Story Source: Adapted from materials provided by United States Geological Survey. Need to cite this story in your essay, paper, or report? Use one of the following formats: APA MLA

6 These plots and this map show the temporal and spatial distribution of earthquakes with a magnitude of M 8 since On the global map, earthquake locations are denoted by red stars; the largest five are labeled with their location names and year of occurrence. Below this map, earthquakes are displayed in graphic format; first as a bar graph of earthquake magnitude through time, and next as cumulative energy release (seismic moment) through time. For correspondence with the global map, the largest five earthquakes are also labeled on the bar graph.

7 1 de 2 07/05/ :43 Web address: htm ScienceDaily (Apr. 18, 2010) The airspace over much of northern Europe remains shut and the Norwegian Prime Minister, Jens Stoltenberg, is stranded in New York City because of the threat from a volcanic ash plume being belched out of Iceland. How long will the eruption of the Eyjafjallajokull volcano continue and what other kinds of activity can we expect? A volcanologist at the Norwegian University of Science and Technology (NTNU) who has worked extensively in Iceland says a month-long eruption would not be out of the question. But the eruption could also continue for a year or more, he says. Professor Reidar Trønnes, who was a research scientist at the University of Iceland's Nordic Volcanological Institute from 2000 to 2004, says as eruptions go, the Eyjafjallajokull volcano is not that large. Nevertheless, concerns about the effects of volcanic ash on jet engines led to a range of airport closures in northern Europe on Friday. Volcanic ash, which is made up of tiny glass shards that are carried aloft in a foamy mix of steam, can damage jet engines by melting right inside them and causing them to seize up. " enlarge Iceland's volcanic activity is linked to its position on the Mid-Atlantic Rift, where the Eurasian plate and the North American plate are pulling apart. The Eyjafjallajokull volcano is in the cluster of volcanoes at the southern edge of the island, on the Eastern Rift Zone. Residents from a number of central Norwegian cities reported the smell of sulphur in the air, and some residents in northern Norway reported finding volcanic ash on their automobiles. Trønnes says that the ash gets shot high into the air as magma that was once deep in the Earth comes to the surface and is depressurized. Any water that has dissolved in the magma comes boiling out when the magma is no longer under pressure, much the way that CO2 bubbles out of your selzer water when the cap is removed, he says. The plume coming out of the Eyjafjallajokull volcano also contains a good deal of steam because the intensely hot magma is melting the ice cap that blankets the volcano, he adds. While the Eyjafjallajokull volcano's eruption is highly dramatic, most volcanologists like Trønnes are watching the volcano's much larger neighbour to the east, Katla. This volcano, buried under the Mýrdalsjökull glacier, Iceland's fourth largest ice sheet, usually erupts twice a century, Trønnes says, but has erupted just once in the last 100 years -- in "Katla has had two large eruptions every century since Iceland was settled 1,100 years ago," he said. "It is long overdue -- or it could mean that Katla has changed its behaviour." Trønnes said that a number of large volcanic eruptions over the last several decades may have helped drain the vast magma reservoirs that would feed any eruption of Katla. These include eruptions as far back as one that created the island of Surtsey in and one that took place on nearby Heimaey in

8 2 de 2 07/05/ : "The fact that we have had these two large eruptions in the 1960s and 1970s may have relieved the pressure in the Katla reservoir, although this is just speculation," he said. The Eyjafjallajokull volcano now appears to have released enough pressure that Trønnes does not expect any large-scale explosions, but the melting of the glacier caused by lava flows will continue to pose risks of potentially large and devastating floods, such as one that caused Icelandic officials to evacuate 800 people from their homes on Wednesday, April 14, he said. or share this story: More Story Source: Adapted from materials provided by The Norwegian University of Science and Technology (NTNU), via AlphaGalileo. Need to cite this story in your essay, paper, or report? Use one of the following formats: APA MLA The Norwegian University of Science and Technology (NTNU) (2010, April 18). Iceland volcano could continue erupting for more than a month, researcher says. ScienceDaily. Retrieved May 7, 2010, from /releases/2010/04/ htm Note: If no author is given, the source is cited instead.

9 Deep Earthquake In Spain Something of An Enigma In environmental news, something of a seismic anomaly occurred yesterday in Spain. A magnitude 6.3 earthquake struck deep beneath Granada. While no damage or even significant ground shake were noted, the depth at 616 kilometers is a little enigmatic even according to the USGS. Deep quakes in this region have been recorded in the past, but this is 2010 a time for anomalies. Seismologists in Spain, and at the USGS associate this very deep seismic activity with a powerful earthquake which struck Spain in Besides that magnitude 7.1 event, earthquakes at this depth, in this region, are not all that common. One Spanish geologist, Spanish Geologist Luis Eugenio Suarez, predicted a month ago that a quake like that which devastated Chile would strike this region of Spain. If you look at the occurrence map (above) from the European-Mediterranean Seismological Centre you can see, not only is yesterday s quake the largest in recent days, but it occurred deeper and a little outside other significant events. The depth being the most interesting variable. Several studies (PDF) have been conducted with regard to very deep, high magnitude quakes in the Mediterranean basin. Counting yesterday, there have only been 4 such quakes in something like the last 125 years. Other experts negated his theory based on the fact the Chilean event occurred in a high seismic occurrence area. However, the same geologists noted that Spain is struck about every 100 years or so with a forceful event. The last was over 120 years ago. So far no aftershocks have been felt by the people in the region, or registered at monitoring stations. We will keep you appraised via our USGS notification alerts. Fig. 1 Mapa de la localització de la sismicitat al sud de la peninsula Ibèrica. Els colors indiquen la profunditat, mentre l estrella vermella indica el terratremol de magnitud 6.3 d Abril References United States Geological Survey (2010, April 11). Preliminary Earthquake report.

10 Distribució de la sismicitat amb profunditat a la zona dels Andes Central. Font USGS