Nearest - WP2 30 months Progress Report Nearest 30 Months Meeting Brest, April 2-3, 2009 Task 2.2 Wide-Angle Seismic cruise

Nearest - WP2 Nearest - WP2 30 months Progress Report30 months Progress Report

Nearest 30 Months MeetingBrest, April 2-3, 2009Task 2.2 Wide-Angle Seismic cruise

Characterisation of the potential tsunami source areas Definition of the geometry and velocity structure of the continental margin offshore SW Iberia Definition of the main plate limits and geological domains Relate earthquake and tectonic structures, specially the deep décollement surfaces.

Overall objective of WP2

Integration of existing MCS data (SWIM, Rifano, IAM, Sismar, etc) with newly acquired Wide-Angle Seismic data (Nearest-Seis survey).

Nearest 30 Months MeetingBrest, April 2-3, 2009Objectives

State of knowledge concerning the main active, potentially tsunamigenic structures > tectonic map as D1 Legacy data of MCS profiles re-processed up to PSDM > compilation as D4 (Task 2.1 -finished-) Preparation of the Nearest-Seis survey, including assembly of instrumentation (OBS and guns), definition of scientific and technical teams, lines, vessel schedule, acquisition geometry, etc.

Starting point (activities done in 2008)

Nearest-Seis survey took place between Oct 27th and Nov 11th on board R/V Hespérides

Nearest 30 Months MeetingBrest, April 2-3, 2009Starting point

Provide information on the physical properties of the crust as well as the crust-mantle boundary geometry Identify the nature of the crust (eg. oceanic vs. continental) and the limits of the different crustal domains Obtain information to construct a 3-D P-wave velocity model to be used to improve earthquake locations (WP3)

Specific objectives of Nearest-Seis

Nearest 30 Months MeetingBrest, April 2-3, 2009Specific objectives

Meeting presentations

Bartolomé, R., Gràcia, E., Martínez-Loriente, S. and EVENT and NEAREST Teams (2009). Estructuras activas en el Golfo de Cádiz, 1ª Reunión del Proyecto de Excelencia de la Junta de Andalucía RNM 3713, 12 March 2009, Granada, Spain.

Martínez-Loriente, S. (2009). Stratigraphy and structure of external Gulf of Cadiz from pre-stack depth migrated seismic profiles (SWIM-2006) implications for earthquake and tsunami hazard in SW Iberia, IPGP Doctoral Student Congress; 16-20 March 2009; Paris, France.

Publications

Martínez-Loriente, S. (2009) "Estratigrafia i estructura de la part externa del Golf de Cadis basades en dades de sísmica de reflexió multicanal migrades en profunditat pre-stack". DEA report presented at the University of Barcelona.

Martínez-Loriente, S., Gràcia, E., Bartolomé, R., Sallarès, V., Dañobeitia, J.J., and Swim-06 Cruise Party (2008). Pre-stack depth migration seismic imaging of the Coral Patch Ridge and adjacent Horseshoe and Seine Abyssal Plains (Gulf of Cadiz): Tectonic implications. Trabajos de Geología, ISSN: 0474-9588.

Falivene, O., Arbués, J., Ledo, J., Benjumea, B., Muñoz, J.A., Fernandez, O., Martínez-Loriente, S. (2008). Synthetic seismic from outcrop-derived reservoir-scale facies models, the Ainsa turbidite system (NE Spain). Submitted to AAPG Bulletin.

Nearest 30 Months MeetingBrest, April 2-3, 2009


Task 2.2 Wide-Angle Seismic cruise

Took place between Oct 27th (Cartagena) and Nov 11th (Cadiz) on board BIO Hespérides:Length: 82,5 mArm: 14,30 mMilitary crew : 52Sci/tech crew: 29Widely used for Antarctic operationsMain Spanish seismic ship to date


Devoted to the acquisition of WAS data, together with complementary swath bathymetry, sediment profiler, gravity data


Scientific/technical teams

A total of 27 persons:12 Scientific (9 institututions)12 Technical (5 OBS, 4 gunners, 2 shooting, 1 acoustics) 3 journalists (ZDF)



Instrumentation

19 MicrOBS OBS from Ifremer/UBO 17 LC2000 OBS from UTM-CSIC 7 Hathor LEAS landstations (1 Hz) 7 Bolt 1500LL guns (250-1000 c.i.) Simrad EM120 multibeam (12 kHz) Topas sediment profiler (3.5 kHz) BGM-3 gravimeter


OBS

Short period (4.5 Hz), 3 components seismometer Hydrophone Differ in size, weight, functioning and authonomy


Gun array

4520 c.i. maximum (2 new guns were constructed), but only 3520 c.i. in most P1 12 m depth (notch at 80 Hz), 90 s shooting interval Useful bandwith between 10-50 Hz (peak at 25 Hz)



WAS profiles P1 is 350 km long, with 29 OBS separated 5 nm in average P2 is 260 km long, with 15 OBS (7 nm) and 7 landstations


WAS profiles P1 is ~coincident with PSDM MCS lines SW13 and IAM4 P2 is coincident with PSDM MCS line SW01


WAS data along P1


WAS data along P1


WAS data along P1


WAS data along P2


WAS data along P2


WAS data along P2


WAS data along P2


Earthquakes recorded by OBS

Waveforms from OBSs 8 ( top), 13 (mid), 14 (bottom), P1 profile (right).


Task 2.3 Processing and modelling of WAS data

Task 2.3 Processing and modelling

All data have been pre-processed (record sections constructed, clock correction done, OBS relocated, bandpass filtering done) P2 has been modeled (preliminary model by A. Gailler) P1 will be modeled by S. Martínez (starting next week)


Gantt Table

Task 2.3 Processing and modelling

Task\Month 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36

WP2 Provisional

WP2 Actual

Task 2.1 Provisional

Task 2.1 Actual x x x x x x x x x


Task 2.2 Actual x x x x


Task 2.3 Actual x x

Documents

Nearest - WP2 30 months Progress Report Nearest 30 Months Meeting Brest, April 2-3, 2009 Task 2.2 Wide-Angle Seismic cruise