AcheiUSA – What was your reaction when you heard of the seaquake that hit Asia and Africa?
Professor Marcelo Souza de Assumpção – In the beginning, I thought it was just another big earthquake. One of those that happen every three to four years and that causes a certain impact, but I didn’t thing this was nothing out of the ordinary. At the end of December 26^th, when its magnitude was given as 9 and the Tsunami had been reported to be very violent, being thousands of miles away from the epicenter I saw it was indeed an event totally out of the ordinary. It was the first earthquake of these proportions outside the Pacific Ocean. In the region of Indonesia, earthquakes of magnitude 9 probably happen once every 500 to 1000 years! 

AcheiUSA – The Hawaiian observatory registered this earthquake and the technicians knew there would be a Tsunami. What do you thing could have happened for them not to put out a warning at least to the countries that were further away from the epicenter?
Prof. Assumpção – I recently read, in the newspapers, that the Pacific Warning Center of Tsunamis had issued an “alert” but they didn’t know who to contact in the countries that would be hit. On the other hand, I checked on Tuesday (12/28/04) through the Bulletins of this center and I hadn’t found anything! The only official bulletins said that there would be no danger for the countries in the Pacific. Very frequently, those “probable forecasts” such as “there are chances of tsunamis in so and such countries”, that don’t quantify the degree of trust of these forecasts. This is only possible with very complex sensor systems and computers that are programmed to calculate tsunamis in any ocean, and there isn’t such a system in the Indic Ocean. It is very likely that some technicians made qualitative forecasts for Africa, let’s say, but they didn’t know who to inform. Another serious problem is that the time between the earthquake and the tsunami is of a little more than 2 hours and that is not enough time to have a trustful forecast.

AcheiUSA – Is there a way to map the tectonic plaques (PLACAS TECTÔNICAS) and the exact location of the flaws at the Indic Ocean?
Prof. Assumpção – Yes, there is. The EPICENTRAL region is the merging pint of the Indo-Australian PLAQUE with the Burma plaque (which is a very small one). That is a complex area composed of many plaques in many different sizes. It is believed that the Indo-Australian PLAQUE itself is gradually splitting into two smaller ones (India and Australia) very close to the epicenter. All this geography was well known. The problem was that this time the earthquake was caused by a gigantic sliding that involved all the edge of the plaque: from Sumatra, going through the Nicobar Islands to the Andaman Islands (total extension is of 1000km!) and all at one single movement. It is as if there had been 10 (ten!) earthquakes of magnitude 8, one after the other, with an interval of only 3 minutes, and each one of them generating a relatively small tsunami which generated a catastrophic result. That was the exceptional feature of this event. 

AcheiUSA – What can you tell us about the fact that no animal, excepting for the ones that were locked up, had died in the countries that were hit by the seaquake?
Prof. Assumpção – I don’t know much about the subject and I have also learned a lot from what I read. I believe that the animals have some sort of sense or an anticipating perception. In the event of a tsunami, there are no previous micro quakes as it usually happens, this could have warned the animals and made them flee. Maybe the animals are more resistant to floods. Either that or the statistics are really trustworthy. 

AcheiUSA – Don’t you think the animals ran for protection when they realized that the waves were getting near?
Prof. Assumpção – As a matter of fact, no one knows exactly how animal “predict” earthquakes. There are no scientific conclusions, and the few cases we are aware of, especially in China, are not controlled by an adequate experiment. It is believed that some animals are more sensitive than men to the previous small quakes. In Sumatra’s case, not only the animals felt it. The earthquake itself was well felt by the population. The animals might have gotten scared by the earthquake, therefore running away to safer land. But that is only my guessing. 

AcheiUSA – What is the probability of a tsunami after an earthquake in the ocean?
Prof. Assumpção – That depends on many factors such as the magnitude of the earthquake, the depth of the water at the epicenter and the kind of movement that happens. If the earthquake has a magnitude inferior to 7, a tsunami is very unlikely to happen, even if the core is located in deep water. In general, only the earthquakes with magnitudes over 8 are the ones that generate big tsunamis. Another complicating factor is that the height of the wave depends on the geometry of the bottom of the ocean through all the length of the wave and not only on the distance. Another important factor is the size of the region where the plaques slid. For example, if you have two earthquakes of magnitude 8.0, one of them with a sliding of 2m through an extension of 100km, and the other one with a sliding 1m in an area of 200km, cause different kinds of tsunamis. Those characteristics can be determined by the worldwide seismographer’s net, but one must wait an average of 30 minutes of recording to be able to calculate the correct dimension of the earthquake.

AcheiUSA – In 1975, two days before an earthquake of magnitude 7.3, the Chinese government asked the residents to evacuate the city of Haiching. What were the signs that led them to take this unique attitude?
Prof. Assumpção – In the 70’s, there was a certain optimism in the seismological area as far as predicting earthquakes. At the time (when I fist started my studies of seismology in Great Britain) people believed that in 10 years or so, predicting earthquakes would turn into a routine a lot like the weather forecast. There are many factors that can indicate the occurrence of an earthquake: an increase on the number of micro tremors in the region, small variations in the spreading speed of the seismic waves on rocks (such as electric and radioactive properties), small land deformation movements (like fractions of millimeters) and so on. The Chinese used many of those effects and they had been monitoring the area for many years before it happened. The final alert was given especially because of the increase on the micro tremors (the so called “predecessors”). 

AcheiUSA – The most incredible thing of all was that, in the following year, without any predictions, another earthquake of magnitude 7.6 hit China again, killing approximately 250 thousand people. Don’t you think this is rather incoherent?
Prof. Assumpção – This is the greatest problem of earthquake forecasts. Not all earthquakes present the same previous signs. There are many cases of earthquakes that happen without the increase on the number of micro-tremors (i.e., without “predecessors”). Another serious problem is that each region presents a different behavior, and the signs that sometimes are observed in certain places don’t necessarily happen everywhere. During the 80’s and the 90’s the seismologists realized that the Earth is a system far more complex than they had imagined before… 

AcheiUSA – With such modern technology in the world today, why can’t we predict earthquakes?
Prof. Assumpção – There are several difficulties. First of all, is to know if there is any imperfection in the CROSTA which is about to slide with an earthquake (i.e., if the tensions are in extremes and/or close to the “critical” state), extremely precise tension measurements would be necessary many miles deep in the ocean through a very big length. And that is too difficult (I would even say impossible) of being directly done. The signs that were detected before (especially in the 70’s) have proved to be exceptions and not the rule: a good part of the earthquakes happen without any previous sings that are easily detected. Nowadays, there is a branch in the seismology that believes it would never be totally possible to predict an earthquake.
There is another aspect of the problem which is how CONFIABILIDADE of a forecast. If your forecast is of a sunny day tomorrow and then it rains, there isn’t any big harm in that. But if your forecast is of a big earthquake, which caused a whole city to be evacuated for several days, and nothing happens, the economic harm caused by that can be greater than the earthquake itself! Lately, the focus of countries with a big incidence of tremors (and money), is to be well prepared to earthquakes, by studying and trying to find out which would be the places bound to have more tremors and building more resistant constructions. 

AcheiUSA – Would you live in a place that is under the forecast of an earthquake or a seaquake?
Prof. Assumpção – There is no exact “forecast” (such as the weather forecast), but there are statistically riskier areas. I would live in California or Chile, areas where the risk of dying from an earthquake is smaller than the risk of dying in an armed robbery or traffic accident in São Paulo.

AcheiUSA – What do you think when a religious person say that God, in order to punish or alert mankind, chooses a certain area for the catastrophes to happen?
Prof. Assumpção – I don’t think there’s such a thing as “chosen” areas. There are catastrophes of many different natures that can hit any part of the world (earthquakes, hurricanes, drought, hunger, and flood). There are the natural catastrophes which are very intense and fast as this one in Asia and there are the ones which are “watered down” through the years: the ones of political nature such as hunger, wars, the Holocaust that end up wearing us out until they are not first page anymore. Each person gets a different lesson out of it. My lesson is to remind the scientists that the Earth, the Universe and Life are always far more complex and harder to control that science and human techniques can ever indicate. 

AcheiUSA – Would the seismic shake that happened in southeast Asia, for instance, serve as a study source to find out more things about this phenomena?
Prof. Assumpção – Absolutely. This earthquake and this tsunami are going to motivate new studies and help us understand better the large scale earthquakes. It is very likely to gather international efforts to improve the tsunami forecast system in the Pacific and widen it to include other parts of the Globe. 

 AcheiUSA – Is it true that in the areas where tremors are frequent there’s a strong chance of large scale earthquakes?
Prof. Assumpção – In most cases, yes. There’s a relation between the number of tremors and the magnitudes. Smaller tremors are always more frequent. The areas where small tremors occur in a larger number will also have big tremors eventually. 

AcheiUSA – What is the probability of recurrent earthquakes in the areas previously affected?
Prof. Assumpção – In a long term future (hundreds of years) the large scale earthquakes hit the same areas again. That is, areas such as California and Chile where there had been large scale earthquakes in the past will once again be stage for new earthquakes in the future. In south Chile, in 1960, there was one of the greatest earthquakes ever reported (magnitude 9.5). There are still small tremors happening in that area, but another one with magnitude 9 will take many centuries to happen again. In seismic areas, in the same section of geological flaw, magnitude 8 earthquakes can happen once every 2 or 3 centuries; a magnitude 7, once every 30 to 40 years, and so on. The smaller the magnitude, the more frequent are the tremors. 

AcheiUSA – Scientist revealed in a study, published last week that when the volcano Cumbre Vieja, in the Canarian Islands erupts it may launch a huge rock over the Atlantic causing mega-tsunamis that would hit many countries. What do you have to say about this study?
Prof. Assumpção – It is a very important study to know which size of a tsunami in the Atlantic is the maximum size. Volcanoes, such as the Krakatoa in the 19^th century, have already caused bigger tsunamis than this one caused by the earthquake in Sumatra However, the possibility (probability) that the same thing happens again is extremely remote. It is not impossible to happen, but chances are so remote there’s no reason to worry.

AcheiUSA – If they are really that remote, why was it announce in details, even mentioning the countries it would hit, the size of waves and so on?
Prof. Assumpção – The work about the volcano Cumbre Vieja is a study of the biggest possible tsunami that could happen. That is: the researches calculated which would be the biggest tsunami that could be generated by the biggest eruption that would cause the biggest possible sliding of the Island shore. It wasn’t an announcement made of an upcoming danger that we should worry about. 

AcheiUSA – Is the heat in the center of the Earth anything like an erupting volcano?
Prof. Assumpção – The heat in the center of the Earth is countless times higher!!! The temperature in the center of the Earth is something close to 5000 degrees. The erupting lavas of a volcano are little higher then 1000 degrees Celsius. The lavas of a volcano don’t come from the center of the Earth, but form a depth of only 100 to 200 km caused by the fusion of rocks during a general movement in the center of the planet. 

AcheiUSA – I have heard people saying that extracting oil from the underground could be a possible cause for earthquakes. Would this theory have any kind of fundament?
Prof. Assumpção – Both the extraction of water or oil from the underground and the injection of fluid in deep wells can cause small localized tremors. But all the tremors caused by it are small and don’t offer danger. There is no connection between this and the earthquakes hat cause damage. 

AcheiUSA – Could these “small tremors” turn into a big earthquake in the future like you’ve explained a little while ago?
Prof. Assumpção – If we are talking about extraction of oil, the effect of it is a change in the internal pressure of the rock layers in a very small area around each well. In order to produce a larger earthquake, it would be necessary to have a change in the pressure of a much bigger area (hundreds of km); this is one thing that just doesn’t happen. 

AcheiUSA – What is put to replace the oil that is extracted?
Prof. Assumpção – Initially the oil is only taken out. It comes out because of sheer pressure and nothing is put in its place. Notice that this oil is not in a kind of underground pool as many people think. The oil is in the rock pores, in between the mineral grains. It is like the rocks with oil were sponges submersed in coffee. After some years, the pressure lowers and the oil doesn’t come out that easily. Form this day on, it is necessary to inject high pressure water in the wells to expel the oil through another one. 

AcheiUSA – What is the importance of the oil in the structure of the Earth?
Prof. Assumpção – If compared to the size of the Earth, the oil occupies a space and a volume relatively small. It is as if there were some spots in some of the shallower layers of the Earth.

AcheiUSA – What do you think of the bombs that are dropped on Earth, water detours, HIDROELÉTRICA constructions, atomic waste, destruction of forests and so many other interference of men in the nature?
Prof. Assumpção – It is definitely something to think about… Earthquakes have increased because of human causes and will continue to happen in unexpected times. The interference of men in the nature seems to be causing a weather change because of the increase of CO2 (EFEITO ESTUFA, etc.). On the other hand, earthquakes like this one in Asia for instance, will happen regardless of the way men has been treating the Earth. These events have the purpose of reminding us that the Earth is much stronger than we think it is, that it has its own rhythm and it is uncontrollable.

AcheiUSA – It is scientifically proved that the continents were all stuck together?
Prof. Assumpção – I think that has been proved that the continents were once together and were pulled apart several times during the billion of years of Planet evolution. During this evolution of the Earth, the continents were changing their shapes. This movement in the surface happens because of a much greater movement in the interior planet mass. The earthquakes are a consequence (and not the cause) of this movement. The movements in the inner part of the Earth cause the pieces of the “crust” (the so called Lithosphere Plaques) to move. When they rub each other or collide in when earthquakes happen. 

AcheiUSA – What are the advances on Geophysics in Brazil?
Prof. Assumpção – Geophysics, as a science, studies not only the big structures and the evolution of the tectonic plaques, but also smaller structure in search of mineral oil and underground water. Geophysics in Brazil has been growing very rapidly in what concerns oil exploitation and mining. The contributions of the Brazilian Geophysics have been very important in discovering new oil and gas fields. There are now four graduation courses in Brazil: the University of São Paulo, Federal University of Bahia, Federal University of Pará and Fluminense Federal University. 

AcheiUSA – How is the work market for our geophysics?
Prof. Assumpção – The work market has been growing a lot and virtually every student who graduates find a position without problems. Lately there is a lack of geophysics in the market. A field that is becoming more and more important for the geophysics is the study of underground pollution, especially when it comes to underground water sources due to chemical products. The bigger the population in the Earth gets, the less water we have, and this work field will be even more important for the geophysics as time goes by.

SEISMIC OCCURRENCES SHOWN ACCORDING TO THE DEPTH AND LOCATION OF THE HIPOCENTER LEGEND:
YELLOW (SUPERFICIAL) = DEPTH OF THE SPOT UP TO 25 KILOMETERS
RED (INTERMEDIATE) = DEPTH OF THE SPOT BETWEEN 26 AND 75 KILOMETERS
BLACK (DEEP) = DEPTH OF THE SPOTS BETWEEN 76 AND 660 KILOMETERS

The Article's Introduction