The photograph shows a group of scientists from the U. Austral de Chile excavations in the area of \u200b\u200bMaullín, on the coast of Valdivia, where there are sedimentary debris tsunamis of 1960 and earlier. Effects
Great Design for
was held yesterday in Valparaiso a successful simulated earthquake and tsunami. To Conception authorities still have not kept a similar exercise.
By Nello Rolleri Veloso.
Five thousand people took part yesterday in a successful simulation of earthquake and tsunami in the towns of Valparaiso and Concón. Concepción
has not planned a massive activity similar, although the city has been devastated by tsunamis repeatedly during its history. In fact, its current location due to a transfer from Penco after the tsunami of May 25, 1751.
The director of the Onemi, Carmen Fernandez, said this is the first drill with a lot of people. "We tried to be as least invasive as possible, since the massive over-drill eventually cause an emergency in itself. We are committed to work by way of modeling behavior, ie, to generate a model for other sectors ", which would repeat this experience in other areas of the country, Talcahuano and Concepción.
However, the usefulness of these exercises and the way the city is prepared to face such a phenomenon, including the definition of "risk areas" which appear in the master plans should be reviewed in the light new discoveries scientists on the issue and has required revisions to the December 2004 disaster in Asia Pacific. One of the Chileans who has been recognized by the international scientific community for their contributions to the subject is the researcher of the Pontificia Universidad Católica de Valparaíso, Marco Cisternas Vega, who has studied with scholars of the Center of the U. Eula
de Concepción.
Tanks is one of the authors of an article in the prestigious British science journal "Nature" on 15 September last year, entitled "Predecessors of the giant earthquake in Chile in 1960." This article questions
models used to date to identify and classify the earthquakes "giants" which are those whose energy released escapes the Richter scale and that exceeded magnitude 9.
rather unexpected happened
Sumatra-Andaman event rethink the phenomenon does
Valparaiso
The drill was followed with great interest worldwide, because the issue is sensitive for all coastal countries, especially the Pacific Ocean . This
after the global shock caused by the earthquake and tsunami in Sumatra-Andaman occurred on December 26, 2004, which left 187,000 dead and 43,000 missing persons in Indonesia, Sri Lanka, India and Thailand.
This movement had a magnitude 9.3, being the second strongest recorded in the history of measurement instruments. The first worldwide
it still ranks the 1960 Valdivia earthquake with a magnitude 9.5.
New theories have not been well received in Chile, especially after they were based on National Geographic for a documentary "The last earthquake, which simulates an earthquake and tsunami in Valparaiso.
Although the program has not been broadcast by television Chile (cable only), enough to know the outline (available on Youtube), with the virtual images of the giant waves entering the Marga-Marga estuary and coastal buildings collapsing, so that the authorities should hit the roof and threatened with lawsuits by a "brand damage" in the city. Cisternas
said it had nothing to do with the National Geographic documentary and says its studies on paleosols buried by prehistoric tsunamis say nothing if the lifts and the Municipality of Valparaíso product will fly a giant wave shock.
What happened in Sumatra-Andaman was supplemented unexpected.
Nobody says Cisternas, expected a giant earthquake, about magnitude 9 in the area of \u200b\u200bthe planet, so it took a shock to seismologists, as assumed in that area of \u200b\u200bthe planet the plates were too old and slow to generate an earthquake of that magnitude.
The great "moral" of this disaster is that "never underestimate the subduction zone where you are."
theories are under construction
Conception is located in buffer zone to "mega-earthquake"
The discovery helps explain the large amount of stored energy was released in 1960 and increases the period between a giant earthquake and another 130 years to over 300 years.
This explains Tanks, means good and bad news for Chile. The good news is that Valdivia should not expect a mega-earthquake and tsunami to the 24th century.
The bad news is that the northern and central where there is no record of a phenomenon of this magnitude, they might be in a dangerous area.
consulted by Design, replied that the city is in a buffer zone on the edge of the plate energy released in the "mega-earthquake" of 1960. To delve deeper into this question, in the excavations carried out here next summer.
What is clear, he warns, is that the current state of science does not predict least one earthquake or tsunami. However, to produce a tidal wave it is necessary that occurred before a strong earthquake in the seabed, with a magnitude greater than 8.
Unfortunately for Chile, the most affected area in the world for this phenomenon is the Pacific Ocean.
One of the characteristics of a tsunami, the sea withdrew several hundred meters in a swift tide. There is evidence that this happened in Valdivia in 1960. Since that time, until it reaches the main wave can spend 5 to 10 minutes.
But how can scientists prove that the sandy sediment on land there were traces of a tsunami?. Marco Cisternas
explains that there are several tests. One is that the mantle of sand is wider at the edge of the sea and inland thins, unlike what happens with fluvial deposits. Another way is by studying the fossils, corresponding to marine organisms and no fresh water.
* SOUTH, Wednesday November 1, 2006.
0 comments:
Post a Comment