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Ocean bottom seismometer: design and test of a measurement system for marine seismology.

Mànuel A, Roset X, Del Rio J, Toma DM, Carreras N, Panahi SS, Garcia-Benadí A, Owen T, Cadena J - Sensors (Basel) (2012)

Bottom Line: Ocean Bottom Seismometers (OBS) have received growing attention from the geoscience community during the last forty years.In a seismic survey, a series of OBSs are placed on the seabed of the area under study, where they record either natural seismic activity or acoustic signals generated by compressed air-guns on the ocean surface.The resulting data sets are subsequently used to model both the earthquake locations and the crustal structure.

View Article: PubMed Central - PubMed

Affiliation: SARTI Group, Electronics Department, Universitat Politècnica de Catalunya, UPC.Vilanova i la Geltrú 08800, Spain. antoni.manuel@upc.edu

ABSTRACT
The Ocean Bottom Seismometer (OBS) is a key instrument for the geophysical study of sea sub-bottom layers. At present, more reliable autonomous instruments capable of recording underwater for long periods of time and therefore handling large data storage are needed. This paper presents a new Ocean Bottom Seismometer designed to be used in long duration seismic surveys. Power consumption and noise level of the acquisition system are the key points to optimize the autonomy and the data quality. To achieve our goals, a new low power data logger with high resolution and Signal-to-Noise Ratio (SNR) based on Compact Flash memory card is designed to enable continuous data acquisition. The equipment represents the achievement of joint work from different scientific and technological disciplines as electronics, mechanics, acoustics, communications, information technology, marine geophysics, etc. This easy to handle and sophisticated equipment allows the recording of useful controlled source and passive seismic data, as well as other time varying data, with multiple applications in marine environment research. We have been working on a series of prototypes for ten years to improve many of the aspects that make the equipment easy to handle and useful to work in deep-water areas. Ocean Bottom Seismometers (OBS) have received growing attention from the geoscience community during the last forty years. OBS sensors recording motion of the ocean floor hold key information in order to study offshore seismicity and to explore the Earth's crust. In a seismic survey, a series of OBSs are placed on the seabed of the area under study, where they record either natural seismic activity or acoustic signals generated by compressed air-guns on the ocean surface. The resulting data sets are subsequently used to model both the earthquake locations and the crustal structure.

No MeSH data available.


Related in: MedlinePlus

Schematic of a marine seismic refraction (controlled source) survey.
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f5-sensors-12-03693: Schematic of a marine seismic refraction (controlled source) survey.

Mentions: The signal generated by air-guns (Figure 5) may travel many of kilometers through the earth layers before it reaches the sensors, and will therefore be of low amplitude. Careful design of the experiment including the air-gun source size and ranges should ensure that the signal arriving at the sensors is greater than the ambient noise level in the sea. The geophone sensor housing is designed to couple well to the seabed, so that the full seismic ground signal is converted to geophone movement, and the resulting electrical output is maximum. The hydrophone is a piezoelectric sensor that converts pressure signals in the water into high impedance electrical signals, and these are buffered by a high input impedance amplifier. The analogue signal path between sensor and analogue to digital converter is designed so that it does not introduce additional noise; this is aided by having a high sensitivity geophone. Optional pre-amplifier gain can be inserted to ensure that the analogue signal is large compared to the bit size in order not add significant digitization noise into the signal.


Ocean bottom seismometer: design and test of a measurement system for marine seismology.

Mànuel A, Roset X, Del Rio J, Toma DM, Carreras N, Panahi SS, Garcia-Benadí A, Owen T, Cadena J - Sensors (Basel) (2012)

Schematic of a marine seismic refraction (controlled source) survey.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376630&req=5

f5-sensors-12-03693: Schematic of a marine seismic refraction (controlled source) survey.
Mentions: The signal generated by air-guns (Figure 5) may travel many of kilometers through the earth layers before it reaches the sensors, and will therefore be of low amplitude. Careful design of the experiment including the air-gun source size and ranges should ensure that the signal arriving at the sensors is greater than the ambient noise level in the sea. The geophone sensor housing is designed to couple well to the seabed, so that the full seismic ground signal is converted to geophone movement, and the resulting electrical output is maximum. The hydrophone is a piezoelectric sensor that converts pressure signals in the water into high impedance electrical signals, and these are buffered by a high input impedance amplifier. The analogue signal path between sensor and analogue to digital converter is designed so that it does not introduce additional noise; this is aided by having a high sensitivity geophone. Optional pre-amplifier gain can be inserted to ensure that the analogue signal is large compared to the bit size in order not add significant digitization noise into the signal.

Bottom Line: Ocean Bottom Seismometers (OBS) have received growing attention from the geoscience community during the last forty years.In a seismic survey, a series of OBSs are placed on the seabed of the area under study, where they record either natural seismic activity or acoustic signals generated by compressed air-guns on the ocean surface.The resulting data sets are subsequently used to model both the earthquake locations and the crustal structure.

View Article: PubMed Central - PubMed

Affiliation: SARTI Group, Electronics Department, Universitat Politècnica de Catalunya, UPC.Vilanova i la Geltrú 08800, Spain. antoni.manuel@upc.edu

ABSTRACT
The Ocean Bottom Seismometer (OBS) is a key instrument for the geophysical study of sea sub-bottom layers. At present, more reliable autonomous instruments capable of recording underwater for long periods of time and therefore handling large data storage are needed. This paper presents a new Ocean Bottom Seismometer designed to be used in long duration seismic surveys. Power consumption and noise level of the acquisition system are the key points to optimize the autonomy and the data quality. To achieve our goals, a new low power data logger with high resolution and Signal-to-Noise Ratio (SNR) based on Compact Flash memory card is designed to enable continuous data acquisition. The equipment represents the achievement of joint work from different scientific and technological disciplines as electronics, mechanics, acoustics, communications, information technology, marine geophysics, etc. This easy to handle and sophisticated equipment allows the recording of useful controlled source and passive seismic data, as well as other time varying data, with multiple applications in marine environment research. We have been working on a series of prototypes for ten years to improve many of the aspects that make the equipment easy to handle and useful to work in deep-water areas. Ocean Bottom Seismometers (OBS) have received growing attention from the geoscience community during the last forty years. OBS sensors recording motion of the ocean floor hold key information in order to study offshore seismicity and to explore the Earth's crust. In a seismic survey, a series of OBSs are placed on the seabed of the area under study, where they record either natural seismic activity or acoustic signals generated by compressed air-guns on the ocean surface. The resulting data sets are subsequently used to model both the earthquake locations and the crustal structure.

No MeSH data available.


Related in: MedlinePlus