Particle motion and pressure relationships of ocean bottom noise: 3900 M depth; 0.003 to 5 Hz

Barstow, N.; Sutton, George H.; Carter, Jerry A.

doi:10.1029/gl016i010p01185

Cited by 22 publications

(12 citation statements)

References 11 publications

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“…Assuming that the particle motion of double‐frequency microseisms and microtremors (which are mainly composed of Rayleigh waves) are elliptical and that the medium is azimuthally isotropic, then the wave should have a rotational motion in a vertical plane oriented in the azimuthal direction (i.e., in the direction of wave propagation) (Barstow et al 1989; Bromirski and Duennebier 2002; Tanimoto, Ishimaru and Alvizuri 2006; Bonnefoy‐Claudet et al 2006b). If, for example, the wave is actually a Love wave then the motion will be transverse to this.…”

Section: Particle Motionmentioning

confidence: 99%

Low‐frequency passive seismic experiments in Abu Dhabi, United Arab Emirates: implications for hydrocarbon detection

Ali

Berteussen

Small

et al. 2010

Geophysical Prospecting

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Low‐frequency passive seismic experiments utilizing arrays of 3‐component broadband seismometers were conducted over two sites in the emirate of Abu Dhabi in the United Arab Emirates. The experiments were conducted in the vicinity of a producing oilfield and around a dry exploration well to better understand the characteristics and origins of microtremor signals (1–6 Hz), which had been reported as occurring exclusively above several hydrocarbon reservoirs in the region. The results of the experiments revealed that a strong correlation exists between the recorded ambient noise and observed meteorological and anthropogenic noises. In the frequency range of 0.15–0.4 Hz, the dominant feature is a double‐frequency microseism peak generated by the non‐linear interactions of storm induced surface waves in the Arabian Sea. We observed that the double‐frequency microseism displays a high variability in spectral amplitude, with the strongest amplitude occurring when Cyclone Gonu was battering the eastern coast of Oman; this noise was present at both sites and so is not a hydrocarbon indicator. Moreover, this study found that very strong microtremor signals in the frequency range of 2–3 Hz were present in all of the locations surveyed, both within and outside of the reservoir boundary and surrounding the dry exploration well. This microtremor signal has no clear correlation with the microseism signals but significant variations in the characteristics of the signals were observed between daytime and nighttime recording periods that clearly correlate with human activity. High‐resolution frequency‐wavenumber (f‐k) spectral analyses were performed on the recorded data to determine apparent velocities and azimuths of the wavefronts for the microseism and microtremor events. The f‐k analyses confirmed that the double‐frequency microseism originates from wave activity in the Arabian Sea, while the microtremor events have an azimuth pointing towards the nearest motorways, indicating that they are probably being excited by traffic noise. Results drawn from particle motion studies confirm these observations. The vertical‐to‐horizontal spectral ratios of the data acquired in both experiments show peaks around 2.5–3 Hz with no dependence on the presence or absence of subsurface hydrocarbons. Therefore, this method should not be used as a direct hydrocarbon indicator in these environments. Furthermore, the analyses provide no direct evidence to indicate that earthquakes are capable of stimulating the hydrocarbon reservoir in a way that could modify the spectral amplitude of the microtremor signal.

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Section: Particle Motionmentioning

confidence: 99%

Low‐frequency passive seismic experiments in Abu Dhabi, United Arab Emirates: implications for hydrocarbon detection

Ali

Berteussen

Small

et al. 2010

Geophysical Prospecting

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“…Haubrich & McCamy 1969; Cessaro 1994; Schulte‐Pelkum et al 2004) and on ocean bottom stations (e.g. Barstow et al 1989; Webb 1998).…”

Section: Microseismic Noise In French Polynesiamentioning

confidence: 99%

Characterizing swells in the southern Pacific from seismic and infrasonic noise analyses

Barruol

Reymond

Fontaine

et al. 2006

Geophysical Journal International

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International audienceA temporary network of 10 broad-band seismic stations has been installed in French Polynesia for the Polynesian Lithosphere and Upper Mantle Experiment (PLUME). All the seismic stations were installed either on volcanic islands or on atolls of the various archipelagos of French Polynesia in a manner which complements the geographic coverage provided by the regional permanent stations. The primary aim of PLUME is to image the upper mantle structures related to plate motion and hotspot activity. However, because of its proximity to all sites, the ocean is responsible for a high level of noise in the seismic data and we show that these data can also be used to analyse ocean wave activity. The power spectral density (PSD) analyses of the seismic data recorded in French Polynesia show clear peaks in the 0.05– 0.10 Hz band (periods between 10 and 20 s), which corresponds to swell frequencies. Clear peaks in this frequency band are also observed in infrasonic data recorded on Tahiti. Ground motion analysis shows that the swell-related seismic noise (SRSN) is linearly polarized in the horizontal plane and its amplitude decreases rapidly with the distance from the shore. The microseismic and the infrasonic 'noise' amplitudes show very similar variations from station to station and both are strongly correlated with the swell amplitudes predicted by the National Oceanic and Atmospheric Administration (NOAA), wind-forced, 'WaveWatch' models. The swell direction can be estimated from SRSN polarization analysis but this has to be done with care since, for some cases, the ground motions are strongly controlled by the islands' anisometric shapes and by swell refraction processes. We find cases, however, such as Tahiti or roughly circular Tuamotu atolls, where the azimuth of the swell is in good agreement with the seismic estimates. We, therefore, demonstrate that the SRSN and the infrasonic signal observed in French Polynesia can be used in such cases as a proxy for swell amplitude and azimuth. From the continuous analysis of the data recorded in 2003 at the permanent seismic station PPTL in Tahiti, transfer functions have been obtained. This could provide a way to quantify the swell activity during the last two decades and, therefore, assist in the investigation of climate changes

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“…Although broadband seismic and pressure measurements had been made on the seafloor [ Auld et al , 1969; Barstow et al , 1989; Dozorov and Soloviev , 1992; Latham and Sutton , 1966; Sutton and Barstow , 1990; Webb and Schultz , 1992; Webb , 1988; Webb et al , 1994], the issue of what could be gained by placing a sensor below the seafloor was unresolved prior to the OSNPE. It is convenient in our discussion to define “broadband” as frequencies between 0.001 Hz and 100 Hz; ULF (Ultra Low Frequency) as the band from 0.001 to 1Hz; and VLF (Very Low Frequency) as the band from 1 to 100 Hz.…”

Section: Introductionmentioning

confidence: 99%

Ocean Seismic Network Pilot Experiment

Stephen

Spiess

Collins

et al. 2003

Geochem Geophys Geosyst

104

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[1] The primary goal of the Ocean Seismic Network Pilot Experiment (OSNPE) was to learn how to make high quality broadband seismic measurements on the ocean bottom in preparation for a permanent ocean seismic network. The experiment also had implications for the development of a capability for temporary (e.g., 1 year duration) seismic experiments on the ocean floor. Equipment for installing, operating and monitoring borehole observatories in the deep sea was also tested including a lead-in package, a logging probe, a wire line packer and a control vehicle. The control vehicle was used in three modes during the experiment: for observation of seafloor features and equipment, for equipment launch and recovery, and for power supply and telemetry between ocean bottom units and the ship. The OSNPE which was completed in June 1998 acquired almost four months of continuous data and it demonstrated clearly that a combination of shallow buried and borehole broadband sensors could provide comparable quality data to broadband seismic installations on islands and continents. Burial in soft mud appears to be adequate at frequencies below the microseism peak. Although the borehole sensor was subject to installation noise at low frequencies (0.6 to 50 mHz), analysis of the OSNPE data provides new insights into our understanding of ocean bottom ambient noise. The OSNPE results clearly demonstrate the importance of sediment borne shear modes in ocean bottom ambient noise behavior. Ambient noise drops significantly at high frequencies for a sensor placed just at the sediment basalt interface. At frequencies above the microseism peak, there are two reasons that ocean bottom stations have been generally regarded as noisier than island or land stations: ocean bottom stations are closer to the noise source (the surface gravity waves) and most ocean bottom stations to date have been installed on low rigidity sediments where they are subject to the effects of shear wave resonances. When sensors are placed in boreholes in basement the performance of ocean bottom seismic stations approaches that of continental and island stations. A broadband borehole seismic station should be included in any real-time ocean bottom observatory.

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Particle motion and pressure relationships of ocean bottom noise: 3900 M depth; 0.003 to 5 Hz

Cited by 22 publications

References 11 publications

Low‐frequency passive seismic experiments in Abu Dhabi, United Arab Emirates: implications for hydrocarbon detection

Low‐frequency passive seismic experiments in Abu Dhabi, United Arab Emirates: implications for hydrocarbon detection

Characterizing swells in the southern Pacific from seismic and infrasonic noise analyses

Ocean Seismic Network Pilot Experiment

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