1. Defining and optimizing submarine landslide monitoring sites P Henry, CEREGE, CNRS-UPCAM, Aix-en-Provence Map from Urgeles, Fantoni and Camerlenghi, 2008, IGC Oslo and EUROMED 2

2. LIMO IODP project Installation of (Cabled) Borehole Observatories on the Ligurian Margin Pierre Henry, Roland Person, Charles K. Paull, Nicole Béthoux, Anne Deschamps, Achim Kopf, Sébastien Migeon, Barbara Romanowicz, Etienne Ruellan, Françoise Sage, Bruno Savoye, Ralph Stephen, Nabil Sultan.

3. LIMO - Science added value Approach gravity driven processes at different scales –Alpine collapse, margin failure and subduction initiation –Failure of sedimented slope Coupling between stress, pore-pressure and strain –external forcing (sea level, fluid migration, sedimentation and compaction, jetty) vs. internal processes (dilatancy, compaction) –Influence of coastal aquifers on offshore slope stability (1979 Landslide) Geodynamics Local geohazards

4. Submarine slope monitoring - Cap Ferrat Slope Nested instabilites –Large instabilities at base of slope –Retrogressive failures on decollement surfaces –Seafloor erosion Testable hypothesis –Creep occurs on decollement surfaces and may lead to catastrophic failure limo-3B

5. Salinity 20 g/l Piezometer (Guglielmi and Prieur, 1997)

6. Nice slope: hydraulic regime (N. Sultan) Precipitations – Nice area

7. Who and what Ifremer Brest (N Sultan, A Cattaneo) –1979 Site surveys: geophysics and geotechnics Prisme 2007 Atalante cruise with Penfeld penetrometer. –Long term instrumentation: Piezometer acoustically connected through ASSEM node Instrumental developments Sediment transfer in Var canyon… Geosciences Azur (S Migeon, F Sage, E Ruellan, P Charvis, A Deschamps) –Slope surveys: AUV, HR seismics, side scan sonar, coring Malisar Suroît cruises, Thetis cruises. –Building infrastructure CPER PRIMA, DeepSeaNet RCOM Bremen (A Kopf) –1979 site survey and fluid geochemistry Meteor 2007 cruise CEREGE (P Henry) –IODP liaison SOACSY (P Plantevin) –THR (>400 Hz) rough seafloor, shallow water chirp (Pôles Mer et Risques) Geosciences Montpellier (P Pezard) –Instrumental developments with Ifremer (ANR-OFMOGH) Université de Provence Aix-Marseille I (Y Guglielmi) –Hydrogeology

8. Demonstration Objectives –Long term: definition of monitoring strategy on unstable (creeping) slopes combining seafloor and in situ instruments –Short term: Piezometer refit Complementary site surveys Seismic data processing and interpretation Synthesis of site survey data (3D modeling) -> IODP alternate platform proposal Operations –Poseidon cruise June 20- July 6, 2009. Lead by C. Waldmann (ESONET WP2) Antares Ligurian margin work (assumes ESONET WP4 support) –Diver intervention (25-30 m) Piezometer / ASSEM refit Fluid sampling and analysis (Thomas Pichler, Roy Price, RCOM), Ra isotope analysis (O Radakovitch, C Claude, CEREGE) –Haliotis microbathymetry in 1979 scar (October 21 deadline) –SOAC-CHIRP trial at 1979 Site –Scientist exchange: RCOM/Ifremer/Geosciences Azur/CEREGE Prospective –Hydrophone array for detecting landslides and gas emissions –Extension of geophysical investigations West of Antares –Instrument testing –Connection method

9. 3.5 kH profiles offshore Nice airport, 1979 landslide site Gas flare Fault Strata outcroping in headwall