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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

Geophone structure and transversal section where the space for the sensors can be seen. The contours in the base are to improve coupling with seabed mud. Based on a design by Carrack Measurement Technology.
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f9-sensors-12-03693: Geophone structure and transversal section where the space for the sensors can be seen. The contours in the base are to improve coupling with seabed mud. Based on a design by Carrack Measurement Technology.

Mentions: Main sensors in the OBS are the hydrophone, which is sensitive to pressure fluctuations within the near seabed water column, and the geophone that responds to movement of the seabed itself. The geophone has three perpendicular components; it has been designed from small, robust and high sensitivity magnetic velocity sensors (SM-6 with 28.8 V/m/s from Input-Output Inc. Stafford, TX, USA. and GS-11 with 85 V/m/s from OYO GeoSpace Technologies, Houston, Texas, USA). This sensor contains a magnetized seismic mass surrounded by a coil—movement of the mass causes the magnetic field lines to cut the coil, which induces an electric current through the coil (Figure 8). The signal is amplified and is proportional to the velocity of movement of the surface in the direction of the sensor axis where the geophone is placed. The geophone housing contains the three geophones. It has been designed using 3-D finite element software (COSMOS) to work down to a seawater depth of 6,000 m, (Figure 9). The design is based on the use of aluminum alloy 3005-H18.


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)

Geophone structure and transversal section where the space for the sensors can be seen. The contours in the base are to improve coupling with seabed mud. Based on a design by Carrack Measurement Technology.
© Copyright Policy
Related In: Results  -  Collection

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

f9-sensors-12-03693: Geophone structure and transversal section where the space for the sensors can be seen. The contours in the base are to improve coupling with seabed mud. Based on a design by Carrack Measurement Technology.
Mentions: Main sensors in the OBS are the hydrophone, which is sensitive to pressure fluctuations within the near seabed water column, and the geophone that responds to movement of the seabed itself. The geophone has three perpendicular components; it has been designed from small, robust and high sensitivity magnetic velocity sensors (SM-6 with 28.8 V/m/s from Input-Output Inc. Stafford, TX, USA. and GS-11 with 85 V/m/s from OYO GeoSpace Technologies, Houston, Texas, USA). This sensor contains a magnetized seismic mass surrounded by a coil—movement of the mass causes the magnetic field lines to cut the coil, which induces an electric current through the coil (Figure 8). The signal is amplified and is proportional to the velocity of movement of the surface in the direction of the sensor axis where the geophone is placed. The geophone housing contains the three geophones. It has been designed using 3-D finite element software (COSMOS) to work down to a seawater depth of 6,000 m, (Figure 9). The design is based on the use of aluminum alloy 3005-H18.

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