(June 26 - July 2, 2017)

POS515 CALVADOS - 

CALabrian arc mud VolcAnoes: Deep

Origin and internal Structure,

June 18 – July 13, 2017,

Dubrovnik - Catani

Lipschultz, B.

Hutchinson, I.

Bombard, B.

Wan, A.

Riedel, Michael

OceanRep

  POS515  CALVADOS  CALabrianarc mud VolcAnoes: Deep Origin and internal Structure  June 18 – July 13, 2017 Dubrovnik - Catania    Weekly Report2 June 26 – July 2, 2017   Despite our initial hopes to run a complete 3D survey with the P-cable system across Venere mud volcano, a problem with quickly increasing current-leakage occurred on Sunday (June 25) afternoon,forcing us to abandon the P-cable survey. All gear was recovered and we switched to 2D survey mode. A single 150 m long streamer made from twelve sections was quickly put together. The 2D streamer consists of 96 channels in total yielding high quality seismic images. We acquired over the course of the entire week a set of 84parallel 2D lines, which can be combined to form a pseudo 3D data volume. On board processing of the 2D data included streamer- and gun-navigation for calculating common-mid-point geometry, followed by stacking, and Stolt time-migration. The complete set of lines was then uploaded into the interpretation software to create time-slices through the data volume for a first data quality check (Figure 1). Seismic surveying at Venere mud volcano ceased Sunday morning at 06:00, followed by a quick recovery of the airgun and our 2D streamer. We then recovered our twelve OBS within a record time of 5 ½ hours. However, due to high winds and seas, we are unable to collect additional seismic lines, connecting the Venere mud volcano with our next target, the Poseidon mud volcano chain. At 13:30 we started our transit to the new study site, where we intend to re-deploy the twelve OBS in the morning hours of Monday, July 3rd. From our initial onboard data QC/QA of the streamer and OBS data, we are very pleased with the outcome of the survey, despite the disappointing P-Cable issues; however, all initially defined scientific objectives at this prominent mud volcano have been met. We have collected seismic data along a distance of ~640 nautical miles (or equivalently ~1180 km) and look forward for additional processing and interpretation of this huge but rewarding data set.  Throughout the week, weather has been mostly cooperative,though some unusual high winds often occur over night, creating a choppy swell for a short period of time during the morning hours. However, towards the afternoon, the winds usually calmed down and sea state was overall < 1m.   (a)  (b)  (c)  (d)   Figure 1: First glimpse of the pseudo-3D analyses  generated from 84 parallel lines acquired across Venere mud volcano: (a) time slice at 2.32 seconds (two-way time) through the pseudo-3D data volume showing a ring of low-amplitude mud-flows sharply truncated from the surrounding high reflectivity sedimentary layers, and three examples of the parallel 2D reflection lines: (b) #1062 at the southern limit of the survey zone, (c) #1027 across the two peaks of Venere, and (d) line #1071 at the northern limit of the survey area showing three distinct stratified sedimentary units with the middle unit of reduced reflection amplitude intruded by mud flows.    Michael Riedel, July 2, 2017 on behalf of all involved in the project CALVADOS 

2. Wochenbericht POS515 CALVADOS

DSpace@MIT

Electric probes in plasmas

(3. Jui - 9. Juli 2017)

POS515 CALVADOS - 

CALabrian arc mud VolcAnoes: Deep

Origin and internal Structure,

June 18 – July 13, 2017,

Dubrovnik - Catani

  POS515  CALVADOS  CALabrianarc mud VolcAnoes: Deep Origin and internal Structure  June 18 – July 13, 2017 Dubrovnik - Catania    Weekly Report 3 July3 – July9, 2017  After we successfully recovered all our OBS instruments at ‘Venere’ mud volcano (Figure 1a), we completed a transit of ~30 nautical miles to the next study region: a chain of mud volcanoes with the most prominent structure called ‘Poseidon’. However, due to high winds (7 – 8 Bft) and sea (3.5 m), we were unable to collect any seismic lines between the two study regions. In the morning of Monday, July 3, we started to re-deploy the set of 12 OBS instruments, after all data from the previous deployment had been secured from the recorders, batteries were exchanged, and all units had been re-programmed. The deployment went swiftly and with a favorable weather window ahead, we deployed the 2D streamer and GI gun to acquire two long refraction seismic profiles across the OBS. However, at 19:30 in the evening, weather had steadily declined forcing us to abort the seismic survey.    Figure 1a: Recovery of an OBS at Venere mud volcano (D. Heßelmann, M. Keller, F. Schrage)  Figure 1b: Preparing P-Cable for deployment (J. Bialas, F. Beek, M. Riedel, F. Schrage, V. Bähre, S. Muff)  We used the down-time to assess the data we collected across the ‘Poseidon’ mud volcano chain, as well as the nearby mud volcano ‘Sartori’. In contrast to the ‘Venere’ mud volcano, where we saw deep seismic stratigraphy well below the root of the main structures, seismic imaging around ‘Poseidon’ proofed difficult. With few seismic reflections and no deep targets, we decided to turn our eye to ‘Sartori’ mud volcano, which (from the one line acquired) offered much more favorable structures for 3D imaging.  After weather had improved, we started to deploy our airgun system and 2D streamer again on Tuesday afternoon (16:00) for more reconnaissance work and to obtain more 2D seismic profiles across the OBS instruments in order to augment our post-cruise seismic velocity analyses. Since our 3D target had moved, the OBS no longer are required to stay on the seafloor until the end of the survey. Thus, we decided to recover these instruments on Wednesday (July 4) morning, which we completed within 6 ½ hours. During the OBS recovery, a second team worked on dismantling the 2D streamer and rebuilding the P-Cable system. At shortly after 3 o’clock in the afternoon, we were ready to deploy the P-cable system (Figure 1b). After a short glitch in the system caused by a broken shackle and a swift repair with great support by the ship’s crew, all gear was re-deployed and the ‘Sartori’ 3D P-Cable survey officially started on July 4th, at 22:00. Since Wednesday night, we had completed about 75% of the survey grid by Sunday afternoon, with only few minor recording issues. However, we can easily interpolate between those missing pieces of information with no major impact on the outcome of the 3D data. While the P-Cable survey is ongoing, the scientists continue with data management: all data have been secured, data quality checked. As well, OBS equipment no longer required for the remainder of the cruise is put back into shipping crates. We also start to prepare for arrival in Catania and work on the logistics for offloading and trucking of all gear backto Kiel. With the end of cruise coming closer, much work completed, people start to look forward returning home; yet some heavy work load still lies ahead of us. However, spirits of all crew and scientists are still fine, especially after the sea state has declined by mid-week to almost lake-like conditions.  Michael Riedel, July9, 2017 on behalf of all involved in the project CALVADOS 

3. Wochenbericht POS515 CALVADOS

POS515 CALVADOS - 

CALabrian arc mud VolcAnoes: Deep

Origin and internal Structure,

June 18 – July 13, 2017,

Dubrovnik - Catani

  POS515  CALVADOS  CALabrian arc mud VolcAnoes: Deep Origin and internal Structure  June 18 – July 13, 2017 Dubrovnik - Catania   Weekly Report 1 June 19 – June 25, 2017   The project CALVADOS is a cooperative study between GEOMAR (M. Riedel, J. Bialas), the University of Bremen (G. Bohrmann) and OGS Trieste (S. Ceramicola). The study is focused on determining the interactions of geological, physical, and chemical processes at mud volcanoes by observing ongoing changes and reconstructing past evolution in order to improve estimates of gaseous and dissolved methane emissions over time. Investigation of the temporal progression of individual mud flows at different mud volcanoes will be used to constrain a model for mud volcano genesis within different zones of the Calabrian accretionary complex. The project aims in achieving these goals by collecting 3D seismic data with the P-Cable system and simultaneous recordings of the airgun acoustic signals on a grid of Ocean Bottom Seismometers (OBS). After departure from Dubrovnik in the afternoon of June 19, we completed the transit to our first study area at Venere mud volcano within 1.5 days. During this time we progressed with preparations for seismic operations around the mud volcano area and installing all gear required on deck and in the laboratories. A total of twelve OBS were prepared by building anchors, programming the recorder units and acoustic releasers. We will use these OBS instruments to determine the seismic velocity field around the mud volcano and attempt 3D imaging of the structures with a special processing technique called mirror imaging, which utilizes the first multiple reflection of the acoustic signals recorded on the OBS’ hydrophone. After a successful test of our acoustic releasers at the first OBS drop position, we started the sequence of instrument deployment. All twelve OBS were laid out in a 1 km grid pattern within ~4 hours. This was followed with deck-preparations of the P-cable and airgun system. During the night from Wednesday, June 21, to Thursday, June 22, we collected our first 2D seismic reflection lines using a 210 in3 (3.4 L) GI airgun and a short streamer made from four P-cable sections. Data quality was excellent and we use these sections as guide for future P-Cable data acquisition.  After this successful first start, we continued preparing the P-Cable system all of Thursday, Friday, and Saturday. A second attempt in collecting 2D seismic data on Friday evening was not successful due to GI gun problems.  On Sunday, June 25, the 3D P-Cable system was finally fully operational, and we deployed a total of 14 parallel streamers by 13:45. The GI airgun is also operating well, and we started the first shot into the P-cable spread at 14:15. Currently we are turning onto the first profile and officially starting the 3D data acquisition across Venere mud volcano. An introduction science meeting was held in the evening of June 21, which was used for discussion on deployment procedures andoverall science plans. Additionally, information about gas venting around the caldera and ring-faults of the Venere mud volcano from previous work by scientists from the University of Bremen and OGS Trieste was discussed.  The entire week, weather has been cooperative and the long sunny days are quite a change from the usual weather in Kiel. All crew and scientists are well and despite the continued P-Cable issues, in good spirits.  Michael Riedel, June 25, 2017 on behalf of all involved in the project CALVADOS Dateiname:  POS515_CALVADOS _ weeklyreport1_V2.docx Verzeichnis:  C:\Users\mheinitz\AppData\Local\Microsoft\Windows\Temporary Internet Files Vorlage:  C:\Users\mheinitz\AppData\Roaming\Microsoft\Templates\Normal.dotm Titel:   Thema:   Autor:  PosFL Stichwörter:   Kommentar:   Erstelldatum:  24.06.2017 19:47:00 Änderung Nummer:  10 Letztes Speicherdatum: 25.06.2017 15:56:00 Zuletzt gespeichert von: PosFL Letztes Druckdatum:  26.06.2017 13:08:00 Nach letztem vollständigen Druck   Anzahl Seiten:  2   Anzahl Wörter:  484 (ca.)   Anzahl Zeichen:  3.055 (ca.)  

1. Wochenbericht POS515 CALVADOS

(10. Juli - 13. Juli, 2017)

POS515 CALVADOS - 

CALabrian arc mud VolcAnoes: Deep

Origin and internal Structure,

June 18 – July 13, 2017,

Dubrovnik - Catani

  POS515  CALVADOS  CALabrianarc mud VolcAnoes: Deep Origin and internal Structure  June 18 – July 13, 2017 Dubrovnik - Catania    Weekly Report 4 July 10 – July 13, 2017   With the overall end of the cruise in view, we successfully finished data acquisition on Tuesday (July 11) of the ‘Sartori’ 3D P-cable cube. The last few profiles were acquired to fill smaller holes in the 3D coverage. Tuesday afternoon at ~16:00 we ended the survey, recovered the P-Cable and GI gun. However, with one more target in view, we quickly switched four streamer sections to form a short, 50 m long, 2D streamer. We wanted to investigate one additional mud volcano, which is situated strategically on the way to Catania. After a short transit of ~3 hours, we deployed the GI gun and Streamer starting data collecting around 20:30 in the evening.  Over the course ofthe night, we accomplished acquiring ten additional profiles ending our survey at 6:00 am on Wednesday morning (July 12). We did acquire quite some spectacular data and the ‘Cetus’ mud volcano looks in no way similar to all the previously imaged targets. The seafloor morphology and subsurface structures are quite unique and we look forward to exciting days of data processing and interpretation once back at home at GEOMAR. The final piece of our expedition is the acoustic data recovery of five geodetic stations deployed at the underwater flanks of the Etna volcano. Here, scientists of GEIOMAR conduct a long-term study of seafloor deformation linked to volcano activity and fault movements. With the help of a transducer (Figure 1), we did recover over ~3 hours all seafloor geodetic data from those five stations recorded since 21.08.2016.   Today, on Thursday, July 13, we are in Catania. Packing, unloading and preparing the trucks for transport of our gear back to Kiel.     This is the official end of the expedition of project CALVADOS. All crew and scientists can look back with pride to the accomplished tasks and this very successful cruise. We are now looking forward to a day in Catania and a safe trip home.  At this point, I am left with saying Thanks to all that contributed to this expedition, especially Captain Matthias Günther and his never-tiring excellent crew onboard the FS POSEIDON. Of course, my thanks also go to all scientists onboard, who enthusiastically endured many days of routine 3D data acquisition and long hours of shift work in the laboratories. And finally, I would like to thank the entire GEOMAR team back home in Kiel for all financial and logistical support, and our collaborating scientists from the University in Bremen and OGS Trieste.   Figure  1.  Preparing for data acquisition at the Mnt. Etna marine geodetic stations (from left to right: Nikolas-Ulrich Stange, Magnus Keller, Anne Krabbenhöft).   Michael Riedel, July 13, 2017 and the CALVADOS team   

4. Wochenbericht POS515 CALVADOS

http://dspace.mit.edu/bitstream/1721.1/94857/1/85ja029_full.pdf

Electric probes in plasmas

Abstract

Similar works

Full text

Available Versions

OceanRep

DSpace@MIT

OceanRep

OceanRep

OceanRep