scholarly journals Report of Cruise 2010005PGC, C.C.G. Vessel John P. Tully, 22 September - 2 October 2010, SeaJade-I Seafloor Earthquake Array Japan-Canada Cascadia Experiment, ocean bottom seismometer deployment and active-source airgun refraction and reflection program

2014 ◽  
Author(s):  
G D Spence ◽  
M Riedel
Keyword(s):  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Active Source

The Alaska Amphibious Community Seismic Experiment

2020 ◽  
Vol 91 (6) ◽  
pp. 3054-3063 ◽  
Author(s):  
Grace Barcheck ◽  
Geoffrey A. Abers ◽  
Aubreya N. Adams ◽  
Anne Bécel ◽  
John Collins ◽  
...  
Keyword(s):  
Strong Motion ◽  
Seismic Survey ◽  
Absolute Pressure ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Alaska Peninsula ◽  
Outer Rise ◽  
Kodiak Island ◽  
Active Source ◽  
Seismic Experiment

Abstract The Alaska Amphibious Community Seismic Experiment (AACSE) is a shoreline-crossing passive- and active-source seismic experiment that took place from May 2018 through August 2019 along an ∼700  km long section of the Aleutian subduction zone spanning Kodiak Island and the Alaska Peninsula. The experiment featured 105 broadband seismometers; 30 were deployed onshore, and 75 were deployed offshore in Ocean Bottom Seismometer (OBS) packages. Additional strong-motion instruments were also deployed at six onshore seismic sites. Offshore OBS stretched from the outer rise across the trench to the shelf. OBSs in shallow water (<262  m depth) were deployed with a trawl-resistant shield, and deeper OBSs were unshielded. Additionally, a number of OBS-mounted strong-motion instruments, differential and absolute pressure gauges, hydrophones, and temperature and salinity sensors were deployed. OBSs were deployed on two cruises of the R/V Sikuliaq in May and July 2018 and retrieved on two cruises aboard the R/V Sikuliaq and R/V Langseth in August–September 2019. A complementary 398-instrument nodal seismometer array was deployed on Kodiak Island for four weeks in May–June 2019, and an active-source seismic survey on the R/V Langseth was arranged in June 2019 to shoot into the AACSE broadband network and the nodes. Additional underway data from cruises include seafloor bathymetry and sub-bottom profiles, with extra data collected near the rupture zone of the 2018 Mw 7.9 offshore-Kodiak earthquake. The AACSE network was deployed simultaneously with the EarthScope Transportable Array (TA) in Alaska, effectively densifying and extending the TA offshore in the region of the Alaska Peninsula. AACSE is a community experiment, and all data were made available publicly as soon as feasible in appropriate repositories.

Comparison of the S/N ratios of low-frequency hydrophones and geophones as a function of ocean depth

1981 ◽  
Vol 71 (5) ◽  
pp. 1649-1659
Author(s):  
Thomas M. Brocher ◽  
Brian T. Iwatake ◽  
Joseph F. Gettrust ◽  
George H. Sutton ◽  
L. Neil Frazer
Keyword(s):  
Nova Scotia ◽  
Continental Margin ◽  
Low Frequency ◽  
Weather Conditions ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Scotian Shelf ◽  
Ocean Bottom Seismometers ◽  
Particle Velocities ◽  
Refraction Data

abstract The pressures and particle velocities of sediment-borne signals were recorded over a 9-day period by an array of telemetered ocean-bottom seismometers positioned on the continental margin off Nova Scotia. The telemetered ocean-bottom seismometer packages, which appear to have been very well coupled to the sediments, contained three orthogonal geophones and a hydrophone. The bandwidth of all sensors was 1 to 30 Hz. Analysis of the refraction data shows that the vertical geophones have the best S/N ratio for the sediment-borne signals at all recording depths (67, 140, and 1301 m) and nearly all ranges. The S/N ratio increases with increasing sensor depth for equivalent weather conditions. Stoneley and Love waves detected on the Scotian shelf (67-m depth) are efficient modes for the propagation of noise.

An ocean-bottom seismometer capsule

1974 ◽  
Vol 64 (4) ◽  
pp. 1251-1262
Author(s):  
William A. Prothero
Keyword(s):  
Seismic Event ◽  
Field Tests ◽  
Data Interpretation ◽  
Seismic Signal ◽  
Digital Data ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Event Trigger ◽  
Analog Output ◽  
Predetermined Time

abstract An ocean-bottom seismometer capsule containing a 1-Hz vertical seismometer and triggered digital recording system has been developed and tested off the coast of San Diego. The output of the seismometer is continuously digitized at 64, 128, or 256 samples per second. The digital data is mixed with a time code and passed through a 256 sample shift register which acts as a delay line. It is then mixed with synchronization characters, serialized, encoded, and recorded on a SONY TC800B tape recorder which is turned on when a seismic event occurs. The event trigger occurs when the seismic signal jumps to at least twice the time-averaged input signal. Data are recovered using the same recorder for playback and a decoder which provides an analog output for field data interpretation or a digital output for computer analysis. The capsule itself falls freely to the ocean bottom. After a predetermined time it is released from a 150-lb steel tripod and floats to the surface. A dual timer and explosive bolt system provides a high recovery reliability. A number of seismic events have been measured in field tests and the system has proven to be extremely simple to check out, diagnose, and deploy.

Seismically Derived Ground Tilts Related to the 2010 Chilean Tsunami

2021 ◽  
Author(s):  
Jui-Chun Freya Chen ◽  
Wu-Cheng Chi ◽  
Chu-Fang Yang
Keyword(s):  
Deep Ocean ◽  
Propagation Model ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Tsunami Propagation ◽  
Ground Tilt ◽  
Tsunami Waves ◽  
The Pacific ◽  
Seismic Networks ◽  
Back Azimuth

Abstract Developing new ways to observe tsunami contributes to tsunami research. Tidal and deep-ocean gauges are typically used for coastal and offshore observations. Recently, tsunami-induced ground tilts offer a new possibility. The ground tilt signal accompanied by 2010 Mw 8.8 Chilean earthquake were observed at a tiltmeter network in Japan. However, tiltmeter stations are usually not as widely installed as broadband seismometers in other countries. Here, we studied broadband seismic records from Japan’s F-net and found ground tilt signals consistent with previously published tiltmeter dataset for this particular tsunamic event. Similar waveforms can also be found in broadband seismic networks in other countries, such as Taiwan, as well as an ocean-bottom seismometer. We documented a consistent time sequence of evolving back-azimuth directions of the tsunami waves at different stages of tsunami propagation through beamforming-frequency–wavenumber analysis and particle-motion analysis; the outcomes are consistent with the tsunami propagation model provided by the Pacific Tsunami Warning Center. These results shown that dense broadband seismic networks can provide a useful complementary dataset, in addition to tiltmeter arrays and other networks, to study or even monitor tsunami propagation using arrayed methods.

scholarly journals Exploring the submarine Graham Bank in the Sicily Channel

2016 ◽  
Vol 59 (2) ◽  
Author(s):  
Mauro Coltelli ◽  
Danilo Cavallaro ◽  
Giuseppe D’Anna ◽  
Antonino D’Alessandro ◽  
Fausto Grassa ◽  
...  
Keyword(s):  
Volcanic Activity ◽  
Structural Features ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Remotely Operated Vehicle ◽  
Bathymetric Survey ◽  
Submarine Volcanism ◽  
Historical Times ◽  
Sicily Channel ◽  
Sonar Echoes

<p>In the Sicily Channel, volcanic activity has been concentrated mainly on the Pantelleria and Linosa islands, while minor submarine volcanism took place in the Adventure, Graham and Nameless banks. The volcanic activity spanned mostly during Plio-Pleistocene, however, historical submarine eruptions occurred in 1831 on the Graham Bank and in 1891 offshore Pantelleria Island. On the Graham Bank, 25 miles SW of Sciacca, the 1831 eruption formed the short-lived Ferdinandea Island that represents the only Italian volcano active in historical times currently almost completely unknown and not yet monitored. Moreover, most of the Sicily Channel seismicity is concentrated along a broad NS belt extending from the Graham Bank to Lampedusa Island. In 2012, the Istituto Nazionale di Geofisica e Vulcanologia (INGV) carried out a multidisciplinary oceanographic cruise, named “Ferdinandea 2012”, the preliminary results of which represent the aim of this paper. The cruise goal was the mapping of the morpho-structural features of some submarine volcanic centres located in the northwestern side of the Sicily Channel and the temporary recording of their seismic and degassing activity. During the cruise, three OBS/Hs (ocean bottom seismometer with hydrophone) were deployed near the Graham, Nerita and Terribile submarine banks. During the following 9 months they have recorded several seismo-acoustic signals produced by both tectonic and volcanic sources. A high-resolution bathymetric survey was achieved on the Graham Bank and on the surrounding submarine volcanic centres. A widespread and voluminous gas bubbles emission was observed by both multibeam sonar echoes and a ROV (remotely operated vehicle) along the NW side of the Graham Bank, where gas and seafloor samples were also collected.</p>

Seismic structure of the extended continental crust in the Yamato Basin, Japan Sea, from ocean bottom seismometer survey

2013 ◽  
Vol 67-68 ◽  
pp. 199-206 ◽  
Author(s):  
Kazuo Nakahigashi ◽  
Masanao Shinohara ◽  
Tomoaki Yamada ◽  
Kenji Uehira ◽  
Kimihiro Mochizuki ◽  
...  
Keyword(s):  
Continental Crust ◽  
Japan Sea ◽  
Ocean Bottom ◽  
Ocean Bottom Seismometer ◽  
Seismic Structure ◽  
Yamato Basin
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