Some earthquakes are accompanied by such devastating waves that they sometimes devastate entire coasts and cause more damage than the earthquakes themselves. These disastrous waves are now called the common term "tsunami", which comes from the Japanese word for "a big wave that floods the bay." Much is said and written about tsunamis and their terrible destructive power, but it is rather difficult for land inhabitants to imagine these cool-headed waves crowned with foamy crests in reality.
Tsunami waves are so long that they are sometimes not perceived as waves: their length ranges from 150 to 300 kilometers. In the open ocean, tsunamis are not very noticeable, since their height (that is, the vertical distance from the crest to the depression) is only a few tens of centimeters. The maximum is a few meters. But having reached the shallow shelf, the wave rises and soon becomes like a moving wall. Entering shallow bays, it becomes even higher, slows down and, like a giant shaft, rolls onto the land.
The tsunami is spoken of in the biblical book “Exodus”: “And the children of Israel went out in the middle of the sea on dry land: the waters were a wall to them on the right and on the left” (Exodus 14:22). Modern Bible scholars believe that the Israelites did not cross the "dry land" of the Red Sea, but the "Sea of Reeds," a freshwater lagoon east of the Nile Delta.
One of the first to describe the tsunami was the tireless explorer of Kamchatka S. P. Krasheninnikov. In October 1775, he observed an earthquake on the Shumshu island and wrote in his diary: “On the first Kuril island, called Sumchshu, the earthquake was as follows. On October 6 in the afternoon, at the third hour of midnight at first the earth shook so violently that many booths fell from it, and it was impossible for people to stand, and this lasted for a quarter of an hour. And when the shaking ceased, the waters around from the sea with a great noise of three fathoms arrived, which again immediately went far into the sea. After the water escaped, another time the earth shook, only very lightly, and then again the water from the sea came back to the same place where it had been for the first time."
Charles Darwin also left a description of the tsunami when, during his trip on the Beagle ship on February 20, 1835, he felt a catastrophic earthquake in Chile. “Shortly after the shock, a huge wave was seen three to four miles away. She was approaching and in the middle of the bay was smooth, but along the coast she was tearing down houses and trees and rushing forward with irrepressible force. In the depths of the bay, it crashed into a series of fearsome white breakers, which soared up 23 feet … The force of the breaker must have been enormous, since in the fort a cannon with a carriage weighing four tons was pushed inward fifteen feet. A schooner was stuck in the ruins two hundred yards from the shore. The first wave was followed by two more, and many of the wrecked skeletons of ships and boats were washed away by their return movement. At one end of the bay, the ship was washed ashore, then washed away,again thrown ashore and again carried away by the wave."
The study of the tsunami began relatively recently, although this disaster is as old as the world. Soviet scientists A. E. Svyatlovsky and B. I. Silkin noted that “during excavations near the present Arab settlement of Ras Shamra in Syria, a whole library of clay tablets was found dating back to the second millennium BC. Archaeologists managed, having deciphered the cuneiform script, to read on them a mournful story about how a wave of unprecedented heights unexpectedly hit the flourishing capital of the ancient state Ugarit that once stood here, almost completely destroying it.
In a Hellenistic chronicle under 358 AD, you can find a record that in August of this year a huge wave rolled over the eastern Mediterranean Sea, covered "headlong" many low islets, and in Alexandria threw ships on the rooftops."
In October 1746, several water shafts, the height of which reached 20-25 meters, swept off the face of the earth the seaport of Callao and the city of Lima on the Pacific coast of South America. Scientist Manuel Audriosola wrote about this disaster as follows:
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“After the earthquake that destroyed all buildings in the port, the ocean receded, but no one can say how far. Soon the ocean waters began to return with a terrible roar; there was a giant wave that hit the embankment. Everything was swept away.
There were 23 ships at the pier in the port; most of them were broken and sank. The four largest ships, including the 34-gun frigate San Fermin, were lifted by the wave and carried inland, where they were stuck after the wave subsided. The ocean retreated again and again collapsed on the coast, and this was repeated several times.
Landslides can be another cause of tsunamis. They can occur on the seabed in loose sedimentary rocks and cause disturbances in the water mass. A similar disaster occurred in southeastern Alaska. Here is Lituya Bay, which is part of the Glacier Bay National Park in Alaska. A long narrow isthmus connects the bay with the open space of the Gulf of Alaska, and the far coast of the bay runs along the Fairweather seismological fault.
Geologist D. Miller drew attention to the difference in the age of trees on the slopes of the hills surrounding the bay. From the annual rings on the trees, he determined that the last hundred years in the bay four times there were waves of great height. At first, the conclusions of the scientist were reacted with great distrust, but a new catastrophe confirmed the correctness of his assumptions.
On July 9, 1958, a massive earthquake at the Fairweather Fault caused a landslide on the side of a mountain above Lituya Bay. A huge mass of ice, rocks and earth (about 300 million cubic meters in volume) rushed down from the glacier, exposing the mountain slopes. The earthquake destroyed numerous buildings, cracks formed in the ground, and the coast slipped. The moving mass fell on the northern part of the bay, filled it up, and then crawled to the opposite side of the mountain, tearing off the forest cover from it to a height of more than three hundred meters. The landslide generated a giant wave, which literally carried the Lituya bay towards the ocean. The wave was so great that it swept over the entire sandbank at the mouth of the bay.
Lituya Bay is a favorite fishing spot and three fishing boats were there when the wave broke. So the eyewitnesses were people from ships that dropped anchor in the bay. A terrible shock threw them all from their beds, and in front of the shocked fishermen, a huge wave rose and swallowed the foot of the northern mountain. After that, a wave swept across the bay, stripping trees from the slopes of the mountains. Where there used to be a dense forest, now there are bare rocks, and such a picture was observed at a height of up to six hundred meters.
One longboat was raised high, easily carried over the shallows and thrown into the ocean. At that moment, when the launch was carried across the sandbank, the fishermen on it saw standing trees under them. The wave literally threw people across the island into the open sea. During a nightmarish ride on a giant wave, the boat pounded on trees and debris. The longboat sank, but the fishermen miraculously survived and were saved two hours later. Of the other two longboats, one safely withstood the wave, but the other sank, and the people on it were missing.
Japan is the most affected by the tsunami, especially its harbors along the northeastern coast of Honshu Island (also called the Sanriku coast). Therefore, Japan, one of the first countries in the world, hosted the Tsunami Service. Thanks to her, it has already been possible to preserve large material values and prevent the death of many people. But not always …
In May 1983, as a result of a strong underwater earthquake in the Sea of Japan, a tsunami occurred, which killed 105 people. Including a group of schoolchildren who have just gathered for a picnic near the city of Akita. In past centuries, the rebellious sea element behaved much more belligerent. On New Year's Eve 1703, about 100,000 inhabitants of the Japanese islands died. Four times, giant water walls attacked the coast, penetrating deep into the land, bringing death and destruction. The residents of the Sagami, Oshima, Musashi and Katsuza districts were particularly affected.
September 1, 1923 for Japan became one of the most tragic in its history. Then a strong earthquake occurred at the bottom of Sagami Bay. The sea immediately responded to him: two huge waves rushed to the coast of the bay. As a result of this disaster, 143 thousand people were killed and eight thousand ships sank. The city of Ito was particularly affected.
N. A. Ionina, M. N. Kubeev