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AACSE - airgun
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2019
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Marcus Langseth
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Project Title: |
Alaska Amphibious Community Seismic Experiment (AACSE) - Airgun shooting supplement |
Project Status: |
Submitted |
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Principal Investigator: |
Geoffrey Abers, Cornell |
Project Institution: |
Cornell |
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Project ID: |
106286 |
Version #: |
1 |
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Date Submitted: |
9/15/2018 8:46:00 AM |
Created By: |
Geoffrey Abers |
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Date Last Modified: |
7/12/2019 1:26:00 PM |
URI Serial #: |
None |
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Funding Agencies: |
NSF/OCE/MGG - 1654568 - Funded |
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Summary of Field Work: |
We propose to collect a 3D wide-angle reflection/refraction dataset using the Alaska Amphibious community seismic experiment array. This supplementary controlled-source program will enable three-dimensional seismic imaging within subduction zone segments at the Alaska Peninsula subduction zone. The 3D P-wave velocity model will help improving the locations of the earthquakes and transients (LFE, NVT, etc.) recorded at the AASCE and permanent array, especially to compensate for the shallow structure. This project will also provide an unprecedented 3D seismic data set to be used by the community to perform joint inversions of shot and local earthquake data recorded at the same array and to develop joint inversion of 3D refraction data and ambient noise data. Acquisition of bathymetric data with a system will be very valuable to refine seismometer locations and identify geological active structures at the seafloor.
All data are being recorded on the AACSE OBSs, and will be immediately released once delivered to the IRIS DMC as with all other AACSE daa, as soon as practical after timing and other metedata corrections. |
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Summary of Facility Requirements: |
This project is a supplement to the Alaska Amphibious Community Seismic Experiment (AACSE). AACSE deployed 75 ocean bottom seismometers (OBSs) offshore Alaska last Spring and this array will remain on the seafloor for 15 months until the end of Summer 2019. We propose to use the 6600 cu.in tuned airgun array of the R/V Marcus Langseth to generate acoustic pulses that will be recorded by a subset of the AASCE OBSs and onshore seismometers. The project consists of profiles that are spaced every ~34 km and oriented approximately sub-orthogonal to the trench axis.The airgun array will be towed behind the ship at a depth of 12 m. The seismic pulses will be triggered at a pressure of 1,950 psi every 400 m (~141 s shot interval using a speed of 5.5 knots).
In addition, we will need :
- Deep-water multibeam bathymetry (EM122 multibeam bathymetry)
- Gravimeter (Bell BGM-3 gravimeter)
- Marine Magnetometer
- 3.5 kHz sub-bottom profiler |
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Summary of other requirements and comments: |
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Type of Request: |
Primary Ship Use |
Request Status: |
Submitted |
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Request ID: |
1010136 |
Created By: |
Geoffrey Abers |
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Date Last Modified: |
9/15/2018 8:46:00 AM |
Date Submitted: |
9/15/2018 8:46:00 AM |
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Year: |
2019
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Ship/Facility: |
Marcus Langseth
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Optimum Start Date:
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6/1/2019 |
Dates to Avoid: |
Cruise should happen while the AACSE OBSs are deployed, that is before the first OBS pick-up (currently August 6, on Sikuliaq). June-July is the best weather window. The shooting has highest impact if it coincides with an onshore Kodiak "nodal" deployment of c. 300 seismometers, currently planned May 15 - June 14. |
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Earliest Start Date: |
5/1/2019 |
Multi-Ship Op: |
No |
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Latest Start Date: |
7/10/2019 |
Other Ship(s): |
R/V Marcus G Langseth is necessary because the cruise requires use of the tuned airgun array. |
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Operating Days Needed: |
Science Days |
Mob Days |
De-Mob Days |
Estimated Transit Days |
Total Days |
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18 |
2 |
2 |
1 |
23 |
Repeating Cruise?
(within same year) |
No |
Interval: |
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# of Cruises: |
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Description of Repeating cruise requirements: |
Timing: the shooting needs to happen while the AACSE OBSs are on the sea floor (before Aug 6 2019). The most value-added time window is mid-May through mid-June, when an on-shore, 200-300 element Nodal seismic array will be deployed on Kodiak Island and which could record an unprecedented ship-to-shore dataset. |
Justification/Explanation for ship choice, dates,
conflicts, number of days & multi-ship operations: |
Ship choice: Only the Marcus Langseth has the airguns capable of the long offset energy proposed here. |
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Short Description of Op Area
for use in schedules: |
Alaska Penin. |
| Description of Op Area: |
South of Alaska Peninsula, Kodiak to Cold Bay, including all of shelf and extending south of trench. |
| Op Area Size/Dia.: |
160x320 nm |
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Lat/Long |
Marsden Grid |
Navy Op Area |
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Beginning
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Ending
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52° 30' N
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160° 0' W
map
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Show Degrees Minutes |
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Foreign Clearance Required? |
No |
Coastal States:
US EEZ |
 Important Info on Foreign Research Clearances
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Are you or any member in your science party bringing in any science equipment items which are regulated for export by the International Traffic in Arms Regulations (ITAR) and/or the Export Administration Regulations (EAR)?
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No |
If yes, have you applied for the necessary permits through your export control office?
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No |
| Questions about ITAR/EAR regulations?
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Comments about foreign clearance requirements or
description of any other special permitting requirements
(e.g., MMPA, ESA, IHA, Marine Sanctuaries, etc.) |
none |
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Requested Start Port |
Intermediate Port(s) |
Requested End Port |
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Kodiak, AK, USA |
None |
Kodiak, AK, USA |
Explanation/justification for requested
ports and dates of intermediate stops
or to list additional port stops |
Kodiak is directly adjacent to the data collection box and minimizes transit time. |
Important Info on Working in Foreign Ports
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Chief Scientist: |
Anne Becel, LDEO |
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# in Science Party |
10 |
# of different science teams |
1 |
# Marine Technicians to be
provided by ship operator:
(include in science party total)
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8 |
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Explanation of Science Party Requirements and Technician Requirements |
Operator-provided staff are needed for airgun operations. |
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 Dynamic Positioning | ADCP |  Multibeam | Seismic |
| Dredging/Coring/Large Dia. Trawl Wire | Stern A-frame | Fiber Optic (.681) | 0.680 Coax Wire |
| SCUBA Diving | Radioisotope use - briefly describe | NO Radioisotope use/Natural level work | Other Operator Provided Inst. - Describe |
| 0 PI-Provided Vans - briefly describe | MOCNESS | | |
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Explain Instrumentation or Capability
requirements that could affect choice
of ship in scheduling. |
need Langseth airguns - see above
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Explain Major Ancillary Facilities
Requirements and list description
and provider for "other" systems. |
OBSIC support is not needed for this leg so not a scheduling issue - there are subsequent AACSE recovery legs. |
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