Seismic data consist of traces, which contain information about a seismic event, but in some period of time the traces may be just noise. A trace which contains seismic information, is called a seismic signal. Seismic signals consist of several typically short energy bursts, called phases, exhibiting several patterns in terms of dominant frequency, amplitude and polarisation. Amongst others, a ...

Seismic velocity changes and nonvolcanic tremor activity in the Parkfield area in California reveal that large earthquakes induce long-term perturbations of crustal properties in the San Andreas fault zone. The 2003 San Simeon and 2004 Parkfield earthquakes both reduced seismic velocities that were measured from correlations of the ambient seismic noise and induced an increased nonvolcanic trem...

We report on the installation of a long-term buried ocean-floor broadband seismic station (MOBB) in Monterey Bay, California (U.S.A.), 40 km off-shore, at a water depth of 1000 m. The station was installed in April 2002 using a ship and ROV, in a collaborative effort between the Monterey Bay Aquarium Research Institute (MBARI) and the Berkeley Seismological Laboratory (BSL). The station is loca...

Human activities have changed the acoustic environment of many terrestrial and aquatic ecosystems around the globe. Mounting evidence indicates that the resulting anthropogenic noise can impact the behaviour and physiology of at least some species in a range of taxa. However, the majority of experimental studies have considered only immediate responses to single, relatively short-term noise eve...

In [1] we present a method of signal restoration to improve the signal to noise ratio, sharpen seismic arrival onset, and act as an empirical source deconvolution of specific seismic arrivals. The method is used on the shear wave time window containing SKS and S, whereby using a Gaussian PSF produces more impulsive, narrower, signals in the wave train. The resulting restored time series facilit...

in this paper some new applications of empirical mode decomposition (emd) and hilbert spectrum in seismic ground-roll attenuation, random noise attenuation and spectral decomposition are introduced. hilbert spectrum is a time-frequency representation for hilbert-huang transform which is obtained by combination of instantaneous frequency (if) concept and intrinsic mode function of empirical mode...

S U M M A R Y Theoretical studies on ambient seismic noise (ASN) predict that complete Green’s function between seismic stations can be retrieved from cross correlation. However, only fundamental mode surface waves emerge in most studies involving real data. Here we show that Mohoreflected body wave (SmS) and its multiples can be identified with ASN for station pairs near their critical distanc...

We demonstrate with synthetic seismic data the superresolution and super-stacking properties of time reversal mirrors (TRM). Tests on synthetic data show that TRM has the potential of exceeding the Rayleigh resolution limit by a factor of more than 9. This property is accompanied by the fact that TRM has a significant resilience to strong noise. Computer tests validate these properties by accur...

The electroseismic method offers the possibility of imaging thin (much smaller than the seismic wavelength) layers in the subsurface. We have collected electroseismic data in the field using a standard seismograph outfitted with electrode pairs rather than geophones, and a sledge hammer and other seismic sources. Removal of coherent source-generated noise is an essential step in the processing ...

Transient gravity changes are expected to occur at all distances during an earthquake rupture, even before the arrival of seismic waves. Here we report on the search of such a prompt gravity signal in data recorded by a superconducting gravimeter and broadband seismometers during the 2011 Mw 9.0 Tohoku-Oki earthquake. During the earthquake rupture, a signal exceeding the background noise is obs...