Calibration of the Global Seismographic Network Using Tides

Temporal Variations in Global Seismic Station Ambient Noise Power Levels

“…This elevated noise also gives an explanation for why the longer-period pulsing is becoming more apparent, as we are seeing elevated power levels in the long-period band. These observations, for (IU.PET.00.LHZ), are in general agreement with the observations of Davis and Berger (2007) but not easily resolved by the methods of Ekström et al (2006b). A possible explanation for this is that the deviations are amplitude dependent and only seen in the absence of earthquakes or over long time windows.…”

“…Recent studies based on theoretical Earth models (Ekström et al 2006b;Davis and Berger 2007) suggest that broadband seismometer gain levels can vary with time. This has also been confirmed, for the STS-1 sensor, experimentally (Yuki and Ishihara 2002).…”

Common roots of modern seismology and of earth tide research. A historical overview

“…Investigation of SGs-records in the seismic band has demonstrated that they are particularly well suited for the studies of the long-period normal modes and thus are complementary to long-period seismometers (Rosat et al, 2004). At stations of the Global Seismographic Network (GSN) the earth tides will be observed (Davis, & Berger, 2007). The new very broad band seismographs, besides recording seismological signals are able to record tides of the solid earth reliably.…”

Systematic monitoring of instrumentation health in high-density broadband seismic networks

“…As methods to evaluate the instrument condition in situ, Ekström et al (2006) compared waveforms observed at GSN stations with synthetic waveform calculations based on estimated CMT solutions for M W ≥ 6.5 events and an assumed Earth's model, which indicated temporal changes in the amplitude frequency response at more than 15 stations. Ringler et al (2010) observed variations of sensor conditions in a broad range of frequencies using power levels of background noises at GSN stations, and Davis and Berger (2007) assessed published GSN response information by comparing Earth's tide observations with synthetic tides at 1-day and half-day periods. Since the latter two approaches do not depend on the occurrence of seismic events, they can be used to evaluate instrument conditions at fixed intervals, which means they could help to identify sudden instrument condition changes.…”