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Cascadia forearc
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2021
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Oceanus
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Project Title: |
Cascadia submarine forearc structure from multiscale controlled-source seismic data combining regional and focused large-N nodal arrays of multicomponent OBSs |
Project Status: |
Submitted |
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Principal Investigator: |
Juan Pablo Canales, WHOI |
Project Institution: |
WHOI |
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Project ID: |
106396 |
Version #: |
3 |
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Date Submitted: |
2/8/2019 8:00:00 PM |
Created By: |
Juan Pablo Canales |
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Date Last Modified: |
3/16/2021 11:41:00 PM |
URI Serial #: |
None |
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Funding Agencies: |
NSF/OCE/MGG - 1929545 - Funded |
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Summary of Field Work: |
We propose to conduct a marine wide-angle seismic reflection/refraction survey of the Cascadia submarine forearc encompassing most of the length of the margin from southern Oregon to northern Vancouver Island. This survey will consist of the deployment of multicomponent OBSs and large-N ocean bottom nodal arrays that will record the controlled-source airgun signals of an NSF-funded seismic reflection survey of the Cascadia margin planed for Summer 2021 onboard R/V Langseth. The instrumentation will be deployed along ~half of the planed 2-D MCS profiles in advance of the Langseth MCS cruise, and recovered after the MCS cruise. The OBS and OBN arrays will sample the wavefields at different spatial scales, thus providing a multi-scale seismic dataset that is optimal for obtaining seismic P- and S-wave velocity models of the Cascadia forearc, from the abyssal plain near the deformation front to near the coast, at three complementary scales:
1. A margin-scale model (~100-km lateral resolution) encompassing most of the length of the subduction zone, from southern Oregon to northern Vancouver Is.
2. Regional, intermediate-resolution models ((~10-km lateral resolution) across 10 transects from the abyssal plain to the continental shelf evenly spaced along the full length of the margin.
3. Local, high-resolution models (hundreds-of-meters lateral resolution) across 3 transects representative of distinct forearc deformation regimes and known structural heterogeneities.
The survey we propose to conduct will consist of: (1) deployment and recovery (using a 3,000-m ROV from Pelagic Research Services) of 350 short-period, 4-component ocean bottom nodes leased from a commercial provider (inApril) at a nominal instrument spacing of 500 m along 3 profiles 30-90 km in length offshore Oregon; (2) deployment (free-fall) and recovery of 60 short-period, 4-component OBSs from the national instrumentation pool (OBSIC) at a nominal instrument spacing of 10 km along 6 profiles 70-150 km in length offshore Oregon; and (3) deployment (free-fall) and recovery of 55 short-period, 4-component OBS from the national instrumentation pool (OBSIC) at a nominal instrument spacing of 10 km along 4 profiles 100-130 km in length offshore Washington and Vancouver Island. |
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Summary of Facility Requirements: |
1 Leg on RV Oceanus (4 mob + 28 science + 2 demob days: May 19-June 21, 2021) with ROV capabilities for node deployment/recovery. Deck space for ROV vans, and deck and wet lab space for node storage.
1 Leg on RV Oceanus (1 mob + 22 science + 1 demob days : June 22-July 15, 2021) for OBS deployment/recovery. Deck space for carrying 60 OBSs and over-the-side OBS deployment/recovery capabilities. Deck/lab space for 60 OBSs from OBSIC.
1 Leg on RV M.G. Langseth (2 mob + 5 science + 1 demob: May 22-29, 2021) for OBS deployment. Deck space for carrying 60 OBSs and over-the-side OBS deployment/recovery capabilities. Deck/lab space for 60 OBSs from OBSIC. |
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Summary of other requirements and comments: |
Scheduling of each leg will have to be coordinated with R/V Langseth's schedule for Summer 2021 for their MCS project (PI S. Carbotte).
Node (OBN) Deployments
We propose to deploy 350 ocean bottom nodes (OBNs) leased from inApril, a commercial provider of ocean bottom node-based seabed seismic surveys (inapril.com).
Due to its small, compact size, the units are not buoyant and lack anchor and self-release mechanisms, and therefore cannot be deploy by free-fall as the OBSIC OBSs do. Thus OBN deep-water surveys are routinely conducted using a remote-operated vehicle (ROV). Pelagic Research Services (PRS) will be providing the ROV support for this project.
We will conduct 1 deployment of 350 ocean bottom nodes:
- 179 nodes at 500-m spacing along a 89-km-long transect.
- 107 nodes at 500-m spacing along a 53-km-long transect.
- 64 nodes at 500-m spacing along a 32-km-long transect.
We propose a RV Oceanus 28-day cruise to deploy and recover the nodes using PRS' ROV. During the first 14 days we will deploy the 350 units in 10 ROV dives. The ROV will be fitted with a skid with capacity for 32 units, lowered to the seafloor, and towed at speed of 0.6 knots at an altitude of 5-10 m over the seafloor between deployment sites. After the 32 units have been deployed, we will retrieve the ROV, reload the skid with another 32 units, and send it back to the seafloor to continue the deployment. Nodes on the seafloor will start to record the Langseth airgun signals soon after deployment.
The last 14 days of the cruise will be to recover the nodes, following the same strategy.
OBS Deployments
We will conduct 2 deployments of short-period OBSIC instruments, resulting in a total of 115 drops:
(1) One deployment of 60 OBSs to instrument 6 transects offshore Oregon at 10-km spacing.
(2) A second deployment of 55 OBSs to instrument the 4 transects offshore Washington and Vancouver Is. at 10-km spacing.
The instruments to be used in these deployments will be short-period OBSs from the Ocean Bottom Seismograph Instrument Center (OBSIC). The OBSs will record the Langseth’s airgun shots.
OBS deployment/recoveries will be conducted in 2 separate legs and different ships:
- We are requesting the use of RV Langseth for a 5-day cruise to deploy 60 OBSs.
- We are requesting the use of RV Oceanus for a 22-day cruise to recover the 60 OBSs, re-deploy 55 OBS along the northern transects, and then recover the 55 OBSs. |
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Type of Request: |
Primary Ship Use |
Request Status: |
Submitted |
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Request ID: |
1010291 |
Created By: |
Juan Pablo Canales |
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Date Last Modified: |
3/16/2021 11:41:00 PM |
Date Submitted: |
2/8/2019 8:00:00 PM |
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Year: |
2021
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Ship/Facility: |
Oceanus
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Optimum Start Date:
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5/19/2021 |
Dates to Avoid: |
Weather window: summer. |
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Earliest Start Date: |
5/19/2021 |
Multi-Ship Op: |
Yes |
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Latest Start Date: |
5/19/2021 |
Other Ship(s): |
Instruments deployed from this ship will record airgun signals from an MCS survey with R/V Langseth. Thus scheduling of the legs of this cruise will have to be coordinated with Langseth's Summer 2021 MCS survey off Oregon and Washington (PI S. Carbotte). |
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Operating Days Needed: |
Science Days |
Mob Days |
De-Mob Days |
Estimated Transit Days |
Total Days |
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50 |
5 |
3 |
0 |
58 |
Repeating Cruise?
(within same year) |
Yes |
Interval: |
0 |
# of Cruises: |
2 |
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Description of Repeating cruise requirements: |
We need a two-leg RV Oceanus cruise:
- one 28-science-days leg to deploy and recover ocean bottom nodes using PRS ROV
- one 22-science-days leg to recover/deploy/recover OBSIC’s 60 short-period OBSs
Ship needs to go back to port in between legs to demob the ROV and nodes, and mob the OBSs. |
Justification/Explanation for ship choice, dates,
conflicts, number of days & multi-ship operations: |
Instruments deployed from this ship will record airgun signals from an MCS survey with R/V Langseth. Thus scheduling of the legs of this cruise will have to be coordinated with Langseth's Summer 2021 MCS survey off Oregon and Washington (PI S. Carbotte).
We need a two-leg RV Oceanus cruise:
- one 28-science-days leg to deploy and recover ocean bottom nodes using PRS ROV
- one 22-science-days leg to recover/deploy/recover OBSIC’s 60 short-period OBSs
Ship needs to go back to port in between legs to demob the ROV and nodes, and mob the OBSs. |
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Short Description of Op Area
for use in schedules: |
West coast |
| Description of Op Area: |
Offshore Oregon, Washington, and Vancouver Is. |
| Op Area Size/Dia.: |
475 nm x 180 nm |
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Lat/Long |
Marsden Grid |
Navy Op Area |
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Beginning
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42.1833° N
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124.25° W
map
42° 10.998' N
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124° 15' W
map
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Ending
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50° 0' N
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128° 30' W
map
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Show Degrees Minutes |
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Foreign Clearance Required? |
Yes |
Coastal States:
Canada, 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.) |
Permits are being coordinated by Holly Smith at NSF in conjunction with permits for the RV Langseth Cascadia MCS survey |
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Requested Start Port |
Intermediate Port(s) |
Requested End Port |
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Newport, OR, USA |
Newport, OR, USA |
Port Angeles, WA, USA |
Explanation/justification for requested
ports and dates of intermediate stops
or to list additional port stops |
For Leg 1, we request Newport-Newport as start/end port, very close to operations area.
For Leg 2 we request Newport, OR, to Port Angeles, WA, as start/end ports. Ending in Port Angeles would facilitate transitioning OBSIC personnel and equipment to their next cruise and accommodate their covid-19 mitigation procedures. |
Important Info on Working in Foreign Ports
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Chief Scientist: |
Juan Pablo Canales, WHOI |
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# in Science Party |
15 |
# of different science teams |
2 |
# Marine Technicians to be
provided by ship operator:
(include in science party total)
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2 |
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Explanation of Science Party Requirements and Technician Requirements |
Leg 1 (nodes): Chief Sci. J.P. Canales. 5 science + 8 PRS + 2 Oceanus Techs
Leg 2 (OBSs): Chief Sci.: N. Miller. 2 science + 5 OBSIC + 2 Oceanus Techs |
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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. |
The ship needs to be adequately equiped for ROV operations.
The ROV has to be able to conduct operations up to 3,000 m depth.
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Explain Major Ancillary Facilities
Requirements and list description
and provider for "other" systems. |
We are requesting the use of PRS' ROV to deploy/retrieve 350 ocean bottom nodes (OBNs) leased from inApril. |
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