Seismic exploration‐scale velocities and structure from ambient seismic noise (>1 Hz)

Abstract

[1] The successful surface waves retrieval in solid-Earth seismology using long-time correlations and subsequent tomographic images of the crust have sparked interest in extraction of subsurface information from noise in the exploration seismology. Subsurface information in exploration seismology is usually derived from body-wave reflections > 1 Hz, which is challenging for utilization of ambient noise. We use 11 h of noise recorded in the Sirte basin, Libya. First, we study the characteristics of the noise. We show that the bulk of the noise is composed of surface waves at frequencies below 6 Hz. Some noise panels contain nearly vertically traveling events. We further characterize these events using a beamforming algorithm. From the beamforming, we conclude that these events represent body-wave arrivals with a fairly rich azimuthal distribution. Having body-wave arrivals in the noise is a prerequisite for body-wave reflections retrieval. We crosscorrelate and sum the recorded ambient-noise panels to retrieve common-source gathers, following two approaches-using all the noise and using only noise panels containing body-wave arrivals likely to contribute to the reflections retrieval. Comparing the retrieved gathers with active seismic data, we show that the two-way traveltimes at short offsets of several retrieved events coincide with those of reflections in the active data and thus correspond to apexes of reflections. We then compare retrieved stacked sections of the subsurface from both approaches with the active-data stacked section and show that the reflectors are consistent along a line. The results from the second approach exhibit the reflectors better.Citation: Draganov, D., X. Campman, J. Thorbecke, A. Verdel, and K. Wapenaar (2013), Seismic exploration-scale velocities and structure from ambient seismic noise (> 1

Application of Seismic Interferometry in Crystalline Rocks - A Case Study From the Lalor Mining Area, Canada

“…To create virtual shot gathers from ambient noise, the Green's function is estimated by crosscorrelating noise for each possible pair of receivers (Draganov et al, 2013) in each hourly segment (i.e., about 110000 calculation/segment for a total of 33 million calculations in the survey). The results from all hourly segments are spatially summed to generate the final shot gathers.…”

“…Recently, impulse responses (Green's functions) have been retrieved from ambient seismic noise to determine exploration-scale velocities and structures (e.g. Draganov et al, 2013).These results suggest that interferometry could also help address some of the challenges related to wave propagation in the crystalline rock environment (e.g., cost, scattering, surface wave velocity) and may offer a valuable imaging complement to traditional exploration methods.…”

Retrieving virtual reflection responses at drill‐bit positions using seismic interferometry with drill‐bit noise

“…Night-hour ambient-noise recordings (Draganov et al 2007), patterns of geophones (Draganov et al 2009), and selected parts of the noise (Panea et al 2014) are utilized for such suppression in order to retrieve reflections using ambient noise. Draganov et al (2013) and Xu et al (2012) show examples of extracting exploration-scale velocities and structures from ambient-noise recordings. Cross-coherence is another approach to apply SI using noise sources, and Nakata et al (2011) retrieve both surface waves and body waves from traffic noise by cross-coherence SI.…”

Feasibility of Retrieving Time-lapse Reflection Signals Using Ambient-noise Seismic Interferometry at Ketzin, Germany

“…By cross-correlating body-wave-dominated ambient-noise records, passive seismic interferometry retrieves an estimate of the reflection response as if from a source at the position of receivers (Draganov et al, 2009(Draganov et al, , 2013. We refer to this technique as ambient-noise seismic interferometry (ANSI).…”