Langseth (Pacific):
1. Mar. 19: Sail from P.C. to SW end of Line 1W
2. Mar. 20-21: Deploy streamer & guns
3. Mar. 21-22: Shoot Line 1W for MCS/Refteks
4. Mar. 22-23: Shoot Line Osa for OBS/MCS
5. Mar. 23-24: Shoot Line CR-Serp for OBS
6. Mar. 24-25: Shoot Nicoya MCS lines
7. Mar. 25-26: Shoot Line 1W for OBS
8. Mar. 26-29: Contingency; wait for OBS recoveries
9. Mar. 29-31: Shoot Geomar MCS lines
10. Mar. 31 – Apr. 2: Shoot Line Serp for OBS
11. Apr. 2-3: Shoot line Anis-1
12. Apr. 3-4: Shoot line Anis-2
13. Apr. 4-5: Shoot line Anis-3
14. Apr. 5-7: Shoot anisotropy circle
15. Apr. 7-11: Contingency
16. Apr. 11-12: Recover guns & streamer
17. April 12-13: Steam to Puerto Caldera
New Horizon (Pacific):
1. Mar. 19-20: Sail from P.C.; deploy OBS, Line Osa
2. Mar. 20-21: Deploy OBS, Line CR-serp
3. Mar. 21-23: Deploy OBS, Line 1W
4. Mar. 23-29: Recover OBS, Lines Osa, CR-Serp, 1W
5. Mar. 29-31: Deploy OBS, Line Serp
6. Mar. 31 – Apr. 2: Deploy OBS, Lines Anis 1-3
7. Apr. 2-4: Contingency/CTD
8. Apr. 4-8: Recover OBS, Lines Anis 1-3
9. Apr. 8-12: Recover OBS, Line Serp
10. Apr. 12-16: Contingency; steam to Puerto Caldera
Our project aims to address these questions by determining the structure, volume, and origin of the volcanic rocks of Costa Rica with a seismic imaging study. Sound sources from the R/V Marcus Langseth 's airgun array will be recorded on onshore seismometers, ocean-bottom seismometers, and the Langseth's own hydrophone array to create a tomographic image of the crust across the volcanic arc (akin to a medical CAT-scan). By operating the Langseth in both the Atlantic and Pacific Oceans and recording the sound on an array of seismometers deployed in Costa Rica, we will create an image of the entire subduction system, including the downgoing Cocos Plate, the subduction trench, the forearc, the volcanoes, and the back-arc. This image will provide an unprecedented view of the Central American volcanic system.
The research cruise we will undertake in 2008 represents the second stage in a two-stage project. During January, February, and July of 2005, we successfully conducted a large onshore seismic survey of the volcanoes, using explosive sources in deep boreholes. The data from that part of the project will constrain the shallow (upper-crustal) structure of the volcanic arc in Costa Rica. The data we will acquire in 2008 are a critical supplement to the earlier work, as they will provide the deeper crustal data that will enable us to construct a complete mass balance for the volcanic arc.
Types of samples and data |
Methods to be used |
Instruments to be used |
Ocean Bottom Seismometers (OBS) will record displacement of the seafloor produced by earthquakes. These components are contained within pressure vessels and are recovered at the end of the experiment. |
Deployment of OBS's |
Instrument consists of a seismometer that detects displacement, a data logger that records digital data on a computer hard drive, an acoustic unit that is used to communicate between the surface-ship and the instrument, and a battery pack to provide power. |
Sea Water (Temperature, salinity, nutrients, carbon, CFC, trace metals) |
Water sample analysis |
CTD and bottle rosette |
coordinates for Pacific Side:
-83.47225 10.62843 #BOL 1E
-82.33989 11.72036 #EOL 1E
>
-82.69744 9.79653 #BOL LIMON
-83.66033 11.08347 #EOL LIMON
>
-84.60279 9.50358 #BOL 1W
-85.84955 8.29457 #EOL 1W
>
-87.79292 11.19933 #EOL SERP
-85.19353 8.44008 #BOL SERP
>
-82.52859 11.21633 #BOL HESS
-83.50069 12.20142 #EOL HESS
>
-84.77851 9.54814 #BOL OSA
-83.73554 8.77494 #EOL OSA
>
-83.38405 11.80764 #BOL NICRISE
-82.21713 13.74454 #EOL NICRISE
>
-83.88197 8.52066 #BOL CR-SERP
-85.86316 9.18963 #EOL CR-SERP
>
-88.00283 10.70076 #BOL ANISOT-1
-86.66069 10.70076 #EOL ANISOT-1
>
-86.90661 11.03725 #BOL ANISOT-2
-87.81943 10.29938 #EOL ANISOT-2
>
-87.32759 10.10534 #BOL ANISOT-3
-87.32759 11.34587 #EOL ANISOT-3
> |
