FS Sonne SO198-2
Cruise summary report
| Cruise Info. | |
| Ship name (ship code) | FS Sonne (06BE) |
| Cruise identifier | SO198-2 |
| Cruise period | 2008-06-18 — 2008-07-31 |
| Status | Completed |
| Port of departure | Cigading, Indonesia |
| Port of return | Cigading, Indonesia |
| Purpose | Research |
| Objectives | All plate boundaries are divided into segments - pieces of fault that are distinct from one another, either separated by gaps or with different orientations. The maximum size of an earthquake on a fault system is controlled by the degree to which the propagating rupture can cross the boundaries between such segments. A large earthquake may rupture a whole segment of plate boundary, but a great earthquake usually ruptures more than one segment at once.
The December 26th 2004 MW 9.3 earthquake and the March 28th 2005 MW 8.7 earthquake ruptured, respectively, 1200-1300 km and 300-400 km of the subduction boundary between the Indian-Australian plate and the Burman and Sumatra blocks. Rupture in the 2004 event started at the southern end of the fault segment, and propagated northwards. The observation that the slip did not propagate significantly southwards in December 2004, even though the magnitude of slip was high at the southern end of the rupture strongly suggests a barrier at that place. Maximum slip in the March 2005 earthquake occurred within ~100 km of the barrier between the 2004 and 2005 ruptures, confirming both the physical importance of the barrier, and the loading of the March 2005 rupture zone by the December 2004 earthquake. Cruise SO198-2, from Merak to Merak between 18th June and 30th July 2008 is the second of three cruises, funded by the Natural Environment Research Council (NERC), which will form a coherent set of geophysical observations in the source regions of the 2004 and 2005 great Sumatra earthquakes. This cruise collected seismic reflection (MCS) profiles at SB1 and SB2 with the following objectives: 1.To image the geometry and nature of the downgoing slab from the trench to 30-40 km depth within the forearc 2.To image faults within the over-riding plate responsible for the development of the accretionary wedge 3.To provide a set of shots that will calibrate the array of ocean-bottom seismome |
| Chief scientist | Timothy J Henstock (University of Southampton School of Ocean and Earth Science) |
| Project | UK Sumatra Consortium |
| Coordinating body | NOCS |
| Cruise report |  (11.21 MB) |
| Ocean/sea areas | |
| General | Indian Ocean |
| Specific | Indian Ocean, west of Sumatra |
| Track charts | (0.70 MB) |
| Measurements | |
| Physical oceanography | |
| Surface measurements underway (T,S) | Quantity: activity duration in days = 7 Description: Underway |
| Surface measurements underway (T,S) | Quantity: activity duration in days = 24 Description: Underway |
| Bathythermograph | Quantity: number of profiles = 21 Description: Underway XBTs |
| Meteorology | |
| Other meteorological measurements | Quantity: activity duration in days = 24 Description: Underway |
| Other meteorological measurements | Quantity: activity duration in days = 7 Description: Underway |
| Geology and geophysics | |
| Multi-beam echosounding | Quantity: activity duration in days = 7 Description: Simrad EM120 run continuously in survey box |
| Multi-beam echosounding | Quantity: activity duration in days = 24 Description: Simrad EM120 run continuously in survey box |
| Single channel seismic reflection | Quantity: activity duration in days = 7 Description: Parasound (high-resolution profiler) run continuously in survey box |
| Single channel seismic reflection | Quantity: activity duration in days = 24 Description: Parasound (high-resolution profiler) run continuously in survey box |
| Multichannel seismic reflection | Quantity: track kilometres = 1500 Description: 5420 cu in source, 2.4km 12.5 group interval digital streamer |
| Multichannel seismic reflection | Quantity: track kilometres = 3350 Description: 5420 cu in source, 2.4km 12.5 group interval digital streamer |
| Gravity measurements | Quantity: activity duration in days = 7 Description: Lacoste and Romberg Seasys S40 run continuously in survey box |
| Gravity measurements | Quantity: activity duration in days = 24 Description: Lacoste and Romberg Seasys S40 run continuously in survey box |
| Magnetic measurements | Quantity: activity duration in days = 24 Description: Seaspy proton precession magnetometer |
| Magnetic measurements | Quantity: activity duration in days = 7 Description: Seaspy proton precession magnetometer |
