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Broadband Ocean Bottom Seismometer

Broadband Ocean Bottom Seismometers provide characterization of seismicity/earthquake activity along tectonic plate boundaries where two key phenomena can occur: large-magnitude subduction zone earthquakes and seismicity associated with migration of melt (magma) beneath the seafloor at underwater volcanoes. The array of OOI broadband seismometers are primarily installed to detect earthquakes along the subduction zone of the Oregon margin and at Axial Volcano. Because the seismometers are cabled and, hence, connected directly to shore, they can provide detection of earthquakes in real-time.

The sensors are in a titanium housing, and in sedimented areas (Slope Base, Southern Hydrate Ridge, and at the base of Axial Seamount), the seismometers are buried beneath the seafloor sediments in 60 cm deep X 60 cm diameter caissons (cylindrical retaining structures filled with silica beads) to obtain the highest quality resolution of seismic waves. At the summit of Axial Seamount, there is little sediment, and therefore the broadband seismometer was installed on basement rock, and surrounded by gravel-filled bags.

Instrument Specifics: The broadband seismometers are manufactured by Guralp, instrument model Guralp CMG-1T  360s-50Hz with CMG-5T Strong Motion, DM24/7-EAM Digitizer/Interface + Low Frequency Hydrophone (HTI-90-U). They have an Ethernet (10/100) interface, and are synced to pulse per second timing.

Data Products

This instrument measures the following data products. Select a data product's name to learn more.

Data Product Code DPS
Broadband Ground Acceleration GRNDACC DPS
Broadband Ground Velocity GRNDVEL DPS

The algorithm code used to generate data products for this instrument is also available in the ion-functions GitHub repository.

Algorithm Code

Instrument Models & Deployed Locations

The OOI includes the following instrument makes and models for this instrument type. Follow the links below to find out where in the OOI this instrument has been deployed. You'll also find quick links for each instrument to Data portal, where you can plot and access data.

Series Make Model
OBSBBA Guralp CMG-1T/5T

A seismometer (in titanium sphere) and low-frequency hydrophone (red tripod) being lowered towards the seafloor. Photo credit: NSF-OOI/UW/CSSF; Dive R1751; V14. Creative Commons License

Primary Science Discipline
Geological

A seismometer (in titanium housing) being lifted towards the caisson for burial, which enhances coupling to the seafloor, providing better resolution data. A low-frequency hydrophone (red tripod) is on the platform to the right, and will be deployed nearby. Photo credit: NSF-OOI/UW/CSSF; Dive R1751; V14. Creative Commons License

A seismometer (in titanium housing) sitting in the caisson just prior to burial in silica beads, which enhances coupling to the seafloor, providing better resolution data. Photo credit: NSF-OOI/UW/CSSF; Dive R1751; V14. Creative Commons License