EARTHQUAKES.

Auckland Star, Volume LVI, Issue 180, 1 August 1925, Page 17

EARTHQUAKES.

SCIENTIFIC INVESTIGATION. HOW THEY ORIGINATE. COUNTERING THEIR EFFECTS. There was a time when people closed their eyes to tho mighty thunderbolt and were struck by it, until Franklin carried out certain investigations which showed that it could be turned aside. Fierce storms suddenly descending out of a clear sky have destroyed great numbers of vessels. When those terrible storms commenced mariners became stricken with fear, imagining the some supernatural creature was wreaking vengeance upon them for their past sins. Then by arduous scientific research a means of ascertaining the approach of a storm was obtained, and to-day ships far distant from the shore are warned of the approaching gale, so that they may prepare themselves for the danger ahead. The result of scientific investigations into the nature and origin of storms and winds generally has been to greatly diminish the perils of navigation, and consequently the preservation of many lives as well. The low-lying parts of the country may still he subject to devastation by flood waters, but whereas years ago such devastation was fairly common, to-day it is comparatively rare, because science has found a useful outlet for the excess energy and power of floods hy impounding the waters to generate power, or diverting the overflow down large channels for irrigation purposes. Science can warn the people of impending danger, and devise means for preventing disaster, and even at times it may turn Nature's excesses to profit. However, storms and flood* cannot be abolished, but their effects on mankind can be successfully mastered. In 1892 the Earthquake Investigation Committee of Japan was established for the purpose of investigating if there was any means of predicting earthquakes, and also of ascertaining what could be done to diminish the disastrous effects of earthquake shocks to a minimum by the selection of proper structures, materials and positions. Although not successful in the first object, yet in the investigation of suitable structures for the affected areas they have achieved great success. The importance of building scientifically may be best illustrated by an example. As a result of an earthquake in Italy more than three-quarters of the population of a town were killed because they had adopted the building methods of their fathers by driving heavy beams into the massive stone walls without bonds, with the result that when the walls swayed and the beams pulled out, the people were simply crushed in their sleep. Had those Italian buildings "been built scientifically, many lives would probably have been spared. Fear has prevented people from becoming intimate with the causes of earthquakes. Although earthquakes are regarded as strange phenomena, it is known that they originate on faults, and the fault is simply a break in the rocks, which are often several hundreds of miles in length. When the rocks in such faults, which have been held by friction, yield under increasing strain, they slip suddenly like an elastic spring, and send vibrations through the earth. The elastic shock thus caused is known as an earthquake. I

A low roar like distant thunder seeming to come out of the earth is usually the first indication of a serious earthquake. This roaring noise lasts for but a few seconds, and then the earth swells into a low ridge, which travels along the surface in a similar manner to a wave on the sea. People and animals are unable to stand up, and are prostrated upon the ground. The movement of the earth usually produces nausea, similar to sea-sickness. This nausea is caused also by the abominable odours of various gases which are released by the earth breaking. Whilst the earth is heaving people who have looked toward the sky declare that the clouds appear to be arrested in their courses across the heavens. Soon the awful din of falling buildings' adds to the general confusion its disquieting influence. The atmosphere then becomes thick with the dust from broken bricks, plaster and mortar, which causes an uncanny grey darkness over the affected area. But that is not all. Sometimes tlie ground opens and houses and people immediately disappear into the bowels of the earth, fn other places rivers are sucked down, and lakes vanish like magic, whilst at other points tremendous columns of water mixed ■tfith sand gush forth and flood the country. In the space of a few seconds the labours of an age have been annihilated and when the veil of grey dust is lifted the miserable inhabitants perceive their once beautiful city razed to the ground, and some of their nearest and dearest buried beneath the ruins. To the terrors of the earthquake may frequently be added those of conflagration, as happened in the Great San Francisco upheaval in 1906, and then the utter desolation and misery absolutely beggars description.

_ Earthquakes may alter the courses of rivers, and at times dry them up for all time. Instances have been given of large rivers, some of them 80 feet wide, flowing in an opposite direction for a considerable period, on account of an earthquake. Strabo, an ancient geographer, has given accounts of an earthquake in India which, on account of the shifting of river channels, destroyed more than one thousand villages. Sometimes great waves rolling over the ground have cut down forests as the sickle cuts the grass. At other times watercourses are left absolutely dry, as was the case in the earthquake of 1348 in Venice, when the Grand Canal was left dry.

Among the earth movements of the world which have caused so much suffering, probably the Lisbon earthquake of 1755 is the most terrible. Within six minutes the entire city had been thrown down, and 60,000 people perished. Day was almost immediately turned to night, and the fallen buildings caught fire, so that the horrors of a conflagration and a pillage by robbers were added to the destruction from the shocks. The sea retreated from the land, carrying numerous vessels with it, and rapidly returning in a tremendous wave 60. feet high, completed the destruction of the entire city. The records of its earthquakes are possibly more complete in Japan than anywhere else in the world. From the seventeenth century onwards its records are almost perfect, and they show that a destructive earthquake has occurred once eveiy two and a half years. One of the greatest shocks within the memory of living men occurred in the adjoining provinces of Mino and Owari in 1891, when at the.first Bhock 7000 people perished, 20,000 buildings were wrecked, and 17,000 people were seriously injured. A bamboo grove with thatched cottages and pines situated along the banks of the Shonai River

was moved en bloc 60 feet back from the embankment of the river, the trees remaining upright, and the thatched roofs falling to the ground without fracture. Thousands of peasants' cottages over the Mino-Owari plain, which is one of Japan's great gardens, and which supported 1000 people to the square mile, were completely ruined. This same earthquake shook an area of 243,000 square miles, and 82,588 after shocks recorded at Gifii during the ftve months succeeding the initial shock.

Yet another terrible earthquake occurred in 1897 in Assam, India. Within two and a-half minutes an area of 1,750,000 square miles had been shaken, and 150,000 square miles had - been devastated. The earth moved like sea waves, and an eye witness declared that it appeared "as though composed of eoft jelly."

Along the western coast of Asia Minor, and in Achaia, the sea' god Poseidon was fearfully worshipped as the earthquake god. Different people had different gods. In the early history of Japan the subterranean monster took the form of a great spider, but in modern times it has given place to a giant catfish. A gigantic mole serves a similar purpose in India, whilst the people of Mongolia prefer a hog.

As far back as 600 B.C. studies of the causes and effects of earthquakes have been made, commencing with Thales, who held the opinion that the disc of the earth was floated upon water. After several hundreds of years of patient study, the theory of the supernatural began to lose ground. Seismology has made great progress since Chi-o-Cho of China made his simple eeismoscope in the year 136 B.C. With the modern selfrecording instruments the earth may be said to have commenced the writing of its autograph. And still scientists are continuing their investigations, and are diligently exercising their minds for the purpose of devising, even more sensitive instruments than are now used, so that warnings may be given of the approach of earthquakes, thereby greatly reducing the terrible loss of life which must inevitably occur if no signal of impending disaster were to be given. Enlightened people no longer attribute the occurrence of an earthquake to any supernatural agency. Earthquakes are natural and unavoidable.