Deep Underground Earthquake Observation: Small to Moderate Earthquakes and Microearthquakes Identification
摘要
Affected by amplification and attenuation of the site effect, SNRs of records at the surface appear to be significantly frequency-dependent. For earthquakes with small magnitudes and epicentral distance, high-frequency S-wave and surface wave are easily identified in the underground records, and their SNRs are normally higher than the surface records. For remote earthquakes with main wave mode of low-frequency surface wave, SNRs of the surface records are higher because of amplification of the site effect. But for remote earthquakes excited by deep sources, as the main wave mode is confirmed as P-wave with frequency above 1 Hz, the underground records show as higher SNRs. Synchronous observations in HDUL show advantages in identifying small to moderate earthquakes and microearthquakes, especially the high-frequency signals above 1 Hz.