Earthquakes in Japan and Lithuania
And I know how to look like the earthquake in Lithuania. Our apartment — on the fourth floor, and suddenly the house shook, swayed chandelier. In the river, the blue (against the current!) Started making waves — "tsunami" two feet in height. These were the echoes of Romanian and Kaliningrad earthquake. And what happened recently in Japan — a hundred times stronger and a thousand times worse.
It was reported that after the Japanese earthquake, even the earth's axis shifted 17 cm What is happening on the other side of the world and how it will respond to our Lithuania? Our interlocutor — Deputy Director of the Geology of the Ministry of Environment of Lithuania Jonas SATKUNAS.
— What happens to Japan? Why is it always "shakes"?
— Japan is in the so-called "Ring of Fire» (Ring of Fire), which is on the east, north-east, north, north-west and west coast of the Pacific Ocean. This area is so named because the tectonic plate is in contact with the Pacific Ocean adjacent plates, and contact areas experienced strong magnetism, volcanoes, earthquakes and mountain building. Pacific tectonic plate, which has a heavy crust, "dive" under the lighter continental plate of Eurasia. This process is called "subduction". Plates collide, and where contact is instantaneous shift of one plate to the other.
Most of the energy is converted into heat, so a shift in the submerged rocks are melted, and the energy is converted to seismic waves. The absolute velocity of the Pacific plate — 8.1 centimeters per year. At the same rate increase, for example, the nails in humans. So you can imagine how fast the plates are moving under the water, and on the plate boundary quickly accumulated tension, which must find a way out.
Earthquakes often occur within a tectonic plate in cases of "subduction", when one plate "dive" under the other, "divergence" when plates move away from each other, and "transformation" — then the plates slide against each other.
In the case of "subduction" in the Japanese islands "dive" rock slabs come in a high pressure and a high enough temperature. Rocks melt, magnetism at points of contact plate volcanism is expressed, that is formed by volcanoes, and they form the eruption of the continental crust. Thus, after the "subduction" formed volcanic field. So, by the way, there was Japan.
Movement of the Pacific plate, its collision with other plates continues thousands, hundreds of years, and this process will go on and on.
In terms of tectonics, the earthquake in Japan is not significant, but it was very strong. The final blow that caused the tsunami was the most powerful. After it happened a few hundred of weak aftershocks.
— Is it possible to pre-warn people of impending disaster?
— Earthquakes can not be predicted. We can only calculate the probability of seismic force incidents in a territory. Based on this set of seismic hazard map of the Earth. Recurrence of earthquakes in the area depends on the strain and their orientation, as well as the mode of deformation. For example, in places of "subduction" earthquakes Substantially all probability. Earthquakes occur on the continents, but the strain they accumulate slowly, so there they are rare.
— Lithuania somehow "feel" the disaster in Japan?
— In Lithuania there are four seismic stations, which are located within a radius of 30 kilometers around the Ignalina NPP. Seismic monitoring stations are owned by the system, which usually registers seismic event greater than 5 on the Richter scale. They have registered the seismic waves from distant Japan: the first strike and the subsequent strong aftershocks — clearly enough, and the weak are seen well due to high noise levels at seismic stations.
— Burning question: can we expect in our Lithuania such disasters?
— The territory of Lithuania — maloseysmichna, there have been no seismic occurrences. Although the historical records say the earthquake in 1328 in Skirsnyamunii when the earth began to tremble so violently that feared the collapse of the castle Skirsnyamunes and scared the monks were going to jump from the castle tower. In 1909, the "shocked" village Byazdonis Vilnius district.
That's about all. And then these two messages make us distrust. However, in neighboring states tremors occur frequently and on a larger scale.
On 21 August 2004, very close to Lithuania, Kaliningrad region, were recorded tremors. The first — in 14.5 in Ladushkin force 4.4 points at a depth of 10 kilometers, the second — in 16.32 in Primorsko force in 5.0 points at a depth of 10 kilometers, and the third — in 16.36, weaker force of 3 points.
In 1976 occurred underground strikes force 4.7 on the Richter scale on the Estonian island Osmussaare, in 1940, 1977, 1986 and 1990, we sunk to the ground wave of Romania, in 1904 — of the Norwegian fjords.
It should also be noted that Latvia — more seismicity than Lithuania, because through its territory is a zone fault Liepaja — Saldus. In the Kaliningrad region also has a system of faults, which "includes" and to the territory of Lithuania.
The earthquake, which occurred September 21, 2004 in Kaliningrad, force us to reconsider the previously existing opinion seismic situation of the Baltic region, including Lithuania. So far, the largest magnitude earthquake in the area reached 4.6-4.8 points, while the magnitude of the last of the Kaliningrad earthquake was 5.0 points. So the magnitude of seismic activity for the whole Baltic region is proposed that at least 5.0.
Kaliningrad earthquakes associated with the movement of blocks along South Kaliningrad fault-based in the West — the north-west and east — south-east. Seismological stations located near the Ignalina Nuclear Power Plant, fixed characteristics of seismic waves excited Kaliningrad earthquake. In addition to these shocks, the Ignalina seismic stations were marked by less powerful seismic events that have occurred in the Baltic region, including the recognized earthquake of 3.5 points, which occurred in the central part of the Baltic Sea.
Kaliningrad earthquake showed that seismic activity in Lithuania and neighboring countries as well as in the Kaliningrad region is understudied.
— But there are going to build a nuclear power plant! After a possible repetition of underground beats! Will they pose a danger to the Baltic nuclear power plant?
— We believe that an earthquake of up to 5 on the Richter scale in the area can occur, as well as on the territory of Lithuania. But this does not mean that they affect plant because, according to the research, the epicenter of the earthquake was located in 2004 in the city of Kaliningrad, and seismic zone is under it, then — under the city and our Gurievsk Prienai. Build a nuclear power station in Krasnoznamensk area — about a hundred kilometers from the fault. So that the Lithuanian side, from a geological point of view, not the neighbors' fault. "
— A Belarusian nuclear power plant, which is to be built in the city next to Astravets Lithuania?
— Ostrowiec is, one might say, not in a very favorable area. In 1908, it was in Ostrovets epicenter of the earthquake.
— And Belarusians know about this?
— Sure. We communicate with our Belarusian colleagues. Not far from the construction site near the lake Naroch equipped seismological station. Belarusians a possible repeat of tremors do not take into account, as will be building nuclear power plants with the necessary set out on such a case, the system of protection.
— Yes scary yet!
— Tremors there — a hundred years ago — were minimal, a few points. I want to emphasize that the Richter scale — logarithmic, meaning it is made up of points, but between them — the numbers — there are 30 divisions! For example, between earthquakes in 5 and 7 points difference a hundred times! So it is very important figures after the decimal point, which determine the accuracy and destructive earthquake.
— How do you comment on a nightmarish post: Earth axis bent off to the side, and the rumors went foul. Say, the Earth will turn, and we fall into the universe …
— Indeed, according to the U.S. space agency NASA, after the Japanese earthquake, the earth's axis deviated by 17 inches, and, as a consequence, the period of the Earth around its axis decreased by 1.8 milliseconds (1 second is 1000 milliseconds), — it is accelerated to a share Earth's rotation.
However, you must remember that after the earthquake in Sumatra in 2004, the axis deviated by 7 inches, and night fell by 6.8 microseconds (1 second is equal to 1,000,000 microseconds), and after last year's Chilean earthquake axis deviated by 8 inches, and the day decreased by 1.26 microseconds. Proved that the rotation of the Earth more influenced by changes in the atmosphere, the movement of air and water flow, melting, formation of ice in Greenland, the Arctic and Antarctic. Also during the year the axis position changes on the meter, which is 6 times higher than after the said earthquake. By the way, human activities can affect the position of the axis and the length of the day.
Thus, in 2008, China has completed construction of a giant hydroelectric power plant on the Yangtze River. The width of the dam — 2335 meters, width — 185 meters. For its construction consumed 200,000 cubic meters of concrete, 463,000 tons of iron and 102.6 million tons of earth! The length of the tank — 660 kilometers, width — 1,12 km. Water level — 175 meters, that is 110 meters above the normal level of the river!
According to estimates by NASA when the tank is full, the Earth's rotation slows by 0.06 microseconds, and the axis deviates by 2 centimeters. These changes are so small that they will be difficult to measure precisely, because, as I mentioned, the speed and the position of the axis is always changing. It is a natural process, and it has no effect on living organisms.
— In the wonderful film "Prisoner of the Caucasus" sounds a song about how to "rub winter bears the earth's axis." They will be able to continue as "rubbing"?
— Yes, of course.
— And the bottle on the table will not fall?
— No. Can reassure readers.
The strongest instrumentally recorded earthquake in the world occurred May 22, 1960 in Chile — 9.5 on the Richter scale. It caused in Chile, Japan, New Zealand, Philippines, Hawaii, Alaska and the Aleutian Islands tsunami. In the Chilean city of Valdivia tsunami height was 25 meters.
Table of earthquakes in the Western Baltic region
1303 Prussia. A local chronicler described the event: "… The whole earth shook Prussia. Three times the earth shook with the buildings, few of them there are not destroyed. "
October 7, 1602 Tallinn. Strong earthquake.
1607 Tallinn. Strong earthquake.
July 30th, 1616 in Latvia, Zhemgale, near Bauska. Strong fluctuations experienced people and animals living in the open air.
February 1, 1670 Estonia, 4 kilometers to the north of Parnu. Fright, land subsidence.
January 8, 1803 in Poland, Bialystok. Four strokes from evening to morning, the last — the strongest. After him, many homes Bialystok cracks.
20-21 February 1821 Latvia Koknese. Thunderous rumblings valilo people down.
February 21, 1821 Latvia Koknese. The strongest push, bells, people valilo down, cracked buildings, collapsed stone wall.
September 27, 1847 North Estonia. Noise like a passing train, floor vibrations, shocks, child fell from the bench.
February 5, 1853, Latvia, Sausne village, 20 kilometers from the knock. Two strokes, the first — the weak, the second — "terrible."
December 29, 1853 — January 5, 1854 Multiple-shock, at night especially powerful. Wake the sleeping people, glasses clinked, rumble, as of cannon fire, the cracks in the earth.
May 18, 1857. Latvia, Irbe river. Fluctuations, dropped the mirror and plates from the table, collapsed roofs of old buildings.
January 28, 1881 Russia, Narva, Ivangorod. Fall things fall off plaster, broken window panes, subterranean noise was heard.
December 10, 1887 Belarus, Borisov. Thunderous rumblings underground, many homes were broken windows.
December 28, 1908 Belarus, Bistricha. House several times and banked rocked the noise like a passing train, here and there cracks in the ground.
December 30, 1908 Belarus, Gudogi settlement. A terrible roar rattled window panes seemed to fall apart at home, animals fell to his knees.
28-31 December 1908 in Latvia, Riga. Several times, chandeliers tinkled ranged floor, there was a strong rumbling, a crack in the ground.
December 29, 1908 Latvia. Madona, Cesvaine. Wavelike fluctuations, underground explosions, the church formed a failure.
December 29th, 1908 in Latvia, Daugavpils, Kraslava. Roar like from cannons, narrow crack through fields, meadows and the house foundation.
December 12th, 1909 in Latvia, Liepaja. Explosions and crackling woke people across the area stretches crack.
May 21, 1910 Riga, Latvia. Groundwater fluctuations, before the earthquake chickens were restless.
Waldemar DOBUZHINSKY, especially for "review"