EARTHQUAKE ZONES

Evening Star, Issue 20779, 29 April 1931, Page 12

EARTHQUAKE ZONES

WEAKNESS IN EARTH ENGLISH GEOLOGIST’S VIEWS In striking contrast to the four months’ seismic truco in the early part of 1930 has been the world-wide series of volcanic and earthquake disasters of the end of that year and still in progress. The history of/ these disturbances traced by Professor J. W. Gregory, formerly of the University of Glasgow, and a past president of the Geological Society, who is the author of an article on the New Zealand earthquake which appeared recently in the ‘ Manchester Guardian.’ ' The middle and latter part of last year, states the professor were marked by a series of earthquakes which began in the East Indies and gradually spread westward through Burma, Northern India, Persia, and Southern Europe. This series continued to extend westward, and on January 11, 1931, caused the most violent earthquake experienced in Mexico since 1911, when the city of Oaxaca was overthrown with a loss of forty lives. This earthquake was preceded on January 2 by two submarine earthquakes under the Pacific Ocean about 1,200 miles from Oaxaca. In Europe the disturbances on this great earthquake belt were renewed by the serious earthquake at Corinth, and by a shock on January 28, which destroyed 600 houses at Kontza, in Albania. In addition, there were seven shocks on January 21 in Central Java. These earthquakes showed that some stress on the earth’s crust was producing numerous fractures on the unstable belt which runs roughly parallel to the equator and to the north of it all round the world. NEW ZEALAND ZONES. Prom this bolt three other earthquake zones branch off southward almost at right angles. Professor Gregory continues. One of these leaves the belt at Hawaii and passes through tho two remarkable rift valleys known as the Tonga Deep and tho Kermadcc Deep, and farther south on tho same line is the eastern coast of New Zealand, which is constantly disturbed by small earthquakes and is bordered by a series of great volcanoes, some still active •and others extinct. Some of the earthquakes along this coast are famous. Tho shock of January 23, 1865, near Wellington and along tho shores of Cook Strait, is well known as one of the first in which an earthquake was proved to have boon accompanied by a widespread uplift and tilting of tho land. The official surveys demonstrated that an area the size of Yorkshire had been uplifted from one to nine feet. Many of the earthquakes in Now Zealand are along fractures and are due to tho land on the one side being moved horizontally. The extent of this movement has often been shown by tho displacement of fences, which are snapped across and one side shifted several .yards. In some cases the movements produce long fissures, such as the one GO miles long and 18 inches wide formed in 1848. • “ LINE ” THROUGH DOMINION. While the inner part of tho North ■lsland has been the scene of long-con-tinued volcanic activity, the mountain chain between it and the Pacific has , been affected by numerous earthquakes,

due, no doubt, to the continuation of the processes by which the former eastward extension of the land has foundered beneath the Pacific, Professor Gregory states. Along this lino have occurred some of the most powerful of New Zealand’s earthquakes, such as the long series on the Kaikoura Ranges, where, attention was drawn to the lateral displacement of the land long before it was established by the San Francisco earthquake. This eastern series is most pronounced along a line which passes from the East Cape down tho eastern coast to Gisborne, where there was a serious earthquake in October, 1914. The line crosses Hawke’s Bay to Napier and then runs inland between the coastal Puketoi Hills and tho mountain chain which consists of the Ranknmara, Huiarau, Ruahine, and Tararua Ranges in order southward. Tho line strikes through Masterton ; which suffered earthquake damage in April, 1913, and crossing Cook Strait passes tho front of the ICaikoura Ranges and tho coast town of Cheviot, which had a severe earthquake some years ago.

REGENT HAWKE’S BAY SHOCK

Tho recent shock in Hawke’s Bay was of world-shaking severity, for it was recorded on tho seismographs at Kew and West Bromwich. Tho seismograms at each showed that it originated at so great a distance that such strong disturbances of the instruments indicated a shock of the highest intensity. Tho fact that the disaster can be correlated with the scries which has boon happening along tho West Tnclian-Mccliterrancan-East Indian bolt encourages tho hope that with an increased number of earthquake-recording stations it may bo possible to follow the stresses which creep through tho earth’s crust along the earthquake /.ones, and thus recognise tho danger spots. In tin’s earthquake, ns in so many others, much of the damage lias been due to fires which could not bo chocked because of the breaking of tho water pipes. And although foreknowledge could not lessen tho actual oscillation of tho ground it could minimise the fatalities and devastation.