Title of research project: High-resolution Seismological Observations of Ultra Long-period Earth Motion
Reference number of grant: MBZ000
Period of performance: 1994 to 1996
Principal Investigator: Dr. Yu. Kolesnikov
Total funds: US$ 12,479
Considerable progress in the study of deep earth structure and the inderstanding of physical processes in the mantle and in the Earth's core can be expected due to resolution improvement of long-period seismological data. The main factor which restricts the signal-to-noise ratio in long-period domain is environmental fluctuations of air pressure and temperature. In the fravework of the project we conducted experimental investigations of ultra-long period ground motion by means of a new kind of high-resolution and great dynamics range instruments. These sensors are protected against the direct influence of oressure fluctuations on vertical component and have a considerably decreased sensitivity of the horizontal components to the ground tilts. Precise measurements by these instruments of simultaneous oscillations of the Earth and pressure (with special microbarograph) provide experimental basis for solving the following problems: - Investigation of detectability of fundamental modes and their multiplets with regard to pressure-ground interaction. - Detailed experimental study of ground motion in the range of eigenfrequencies of the Earth core (T=60-180 min). - Search for 'silent' earthquakes with anomalously slow rupture velocity which are usually hidden in the noise of the conventional instruments.