NICARAGUAN QUAKE IS EXPLAINED BY SCIENCE

Explaining the difference between the earthquake which recently shook New York State and the one in Nicaragua on Friday, April 10, which caused a great deal of damage. Dr. L. Don Leet, Seismologist-in-charge of the Harvard Seismograph Station, said "The earthquakes which occur in New England and vicinity are surficial, seldom extending to a depth of more than 200 feet, whereas the earthquakes which are typical of Central America, the Western coast of the United States, and Japan, are deep-seated, continuing from the surface to a depth of 25 miles.

Indications of Rising Land

"Earthquakes in New England are minor affairs, resulting from isostatic adjustment, or elastic recovery, of the land which was greatly depressed during the Great Ice Age 10,000 years ago. That the land was depressed is an established fact, for old sea-beaches have been located along the St. Lawrence valley which are 600 feet above sea-level, and similar beaches, ranging in a regular order from 600 feet above sea-level to sea level, have been located east of the St. Lawrence, indicating the regular emergence of the land from the sea after the withdrawal of the ice sheet.

"There have been a few earthquakes in New England of considerable violence within historic time, but it is extremely improbable that there will be any recurrence. Earthquakes of great force, such as the one which occurred in Nicaragua, are the result of great mountain-making movements, involving the forces of millions of tons of rocks. The cause of these movements is unknown, but it is believed that they are a form of reaction from previous stress."