Cruise inventory

FS Sonne SO198-2

Cruise summary report

Cruise Info. 
Ship name (ship code)FS Sonne (06BE)
Cruise identifierSO198-2
Cruise period2008-06-18 — 2008-07-31
StatusCompleted
Port of departureCigading, Indonesia
Port of returnCigading, Indonesia
PurposeResearch
ObjectivesAll 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 scientistTimothy J Henstock (National Oceanography Centre, Southampton)
ProjectUK Sumatra Consortium
Coordinating bodyNOCS
Cruise reportFS Sonne SO198-2 cruise report sonne198-2.pdf — access key 'C' (11.21 MB) 
Ocean/sea areas 
GeneralIndian Ocean
SpecificIndian Ocean, west of Sumatra
Track chartsFS Sonne SO198-2 cruise track — sonne198trk.pdf (00 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
BathythermographQuantity: number of profiles = 21
Description: Underway XBTs
Meteorology 
Other meteorological measurementsQuantity: activity duration in days = 24
Description: Underway
Other meteorological measurementsQuantity: activity duration in days = 7
Description: Underway
Geology and geophysics 
Multi-beam echosoundingQuantity: activity duration in days = 7
Description: Simrad EM120 run continuously in survey box
Multi-beam echosoundingQuantity: activity duration in days = 24
Description: Simrad EM120 run continuously in survey box
Single channel seismic reflectionQuantity: activity duration in days = 24
Description: Parasound (high-resolution profiler) run continuously in survey box
Single channel seismic reflectionQuantity: activity duration in days = 7
Description: Parasound (high-resolution profiler) run continuously in survey box
Multichannel seismic reflectionQuantity: track kilometres = 1500
Description: 5420 cu in source, 2.4km 12.5 group interval digital streamer
Multichannel seismic reflectionQuantity: track kilometres = 3350
Description: 5420 cu in source, 2.4km 12.5 group interval digital streamer
Gravity measurementsQuantity: activity duration in days = 7
Description: Lacoste and Romberg Seasys S40 run continuously in survey box
Gravity measurementsQuantity: activity duration in days = 24
Description: Lacoste and Romberg Seasys S40 run continuously in survey box
Magnetic measurementsQuantity: activity duration in days = 24
Description: Seaspy proton precession magnetometer
Magnetic measurementsQuantity: activity duration in days = 7
Description: Seaspy proton precession magnetometer