Vestnik Otdelenia nauk o Zemle RAN VOL. 4, NZ1001, doi:10.2205/2012NZ000110, 2012

Subvertical congestions of the earthquake hypocenters – seismic "nails"

V. N. Vadkovsky

Moscow State University, Moscow, Russia.


The spatial distribution of earthquake hypocenters in the Japanese islands region for 1983–1990 according to the Catalog of Japanese Meteorological Agency (JMA) was investigated. Almost vertical, isometric in the plan, short-living congestions of the earthquake hypocenters, named seismic "nails" are detected. They consist, mainly, of the weak earthquake focuses with magnitude 2–3 on used in JMA scale of magnitudes MJMA. Vertical extension of "nail" is from 10 to 50 km, depth of formation doesn't exceed 90 km. Epicentral projection of "nail" measures 5–10 km in diameter. It is not established a preferable direction (upwards or downwards) of "nail" formation eventually. The earthquake hypocentres equiprobably fill all body of "nail" as it is formed. "Nail" formation occurs in time from several days about one month. It is not observed direct correlation of "nails" with strong earthquakes with MJMA > 5.0 and with a modern active volcanism. Compactness of "nails", their almost vertical arrangement in the range of depths of 0–100 km and short time of formation allow to assume participation in this process of fluids. Similar congestions of the earthquake centers are discovered as well in other regions.

Received 20 December 2011; published 5 February 2012.

Citation: Vadkovsky V. N. (2012), Subvertical congestions of the earthquake hypocenters – seismic "nails", Vestn. Otd. nauk Zemle, 4, NZ1001, doi:10.2205/2012NZ000110.

Copyright 2012 by the Geophysical Center RAS