Читать книгу A Study of Recent Earthquakes - Charles Davison - Страница 33

At nine places, Dr. Johnston-Lavis was able to make measurements of the angle of emergence, in every case from fissures in buildings, and therefore liable to sources of error already referred to. On the other hand, owing to the small depth of the focus, there would probably be less general refraction of the wave-paths than in the Neapolitan earthquake. The depths indicated by these observations vary between about 615 and 2,885 feet, a difference that is no greater than might be expected, as the size of the focus was no doubt comparable with that of the district in which observations were made. The mean depth Dr. Johnston-Lavis finds to be about 1,700 feet, or a little less than one-third of a mile.