ERC Advance Grant Trans-Atlan3c Imaging of Lithosphere-Asthenosphere boundary a Story. Sa#sh Singh IPG Paris NTU Singapore

Transcription

1 ERC Advance Grant Trans-Atlan3c Imaging of Lithosphere-Asthenosphere boundary a Story Sa#sh Singh IPG Paris NTU Singapore

2 TransAtlan3cILAB: Summary ERC Advance Grant SubmiFed in 2012 Awarded in 2013, 3.5 m Started in November 2014 Led to a second ERC Start Grant, in 2015 Five marine experiments Image the oceanic Lithosphere-Asthenosphere Boundary (LAB) Also funding from UK NERC, German DFG, US NSF and Schlumberger

3 CV mafers: Sa3sh Singh -1 Grew up in India PhD at the University of Toronto, Canada, with a year of stay at the University of Cambridge Post-doc at IPG Paris, two years Joined the University Cambridge in 1990 Led the crea3on of LITHOS group Moved to Paris in 1999 (keeping the posi3on in Cambridge) Led the crea3on of Marine Geosciences Department at the IPG Paris

4 CV mafers: Sa3sh Singh-2 By 2012 Published 125 papers in peer reviewed journals, 10 in Science and Nature Supervised 27 PhD students and was supervising 10 Supervised 25 post-docs 2009 Dis3nguished Lecturer for the European Associa3on of Geoscien3sts and Engineers 2009 Laureate of the French Ministry of Research in Scien3fic Innova3on and Crea3on Elected Fellow of the American Geophysical Union in 2010 Awarded Grand Prix of the French Academy of Sciences in 2011

5 Idea mafers In 2011 I had two ideas Idea 1 Apply the idea I had develop to study the Sumatra subduc3on zone and apply to Java subduc3on zone, which can produce a devasta3ng earthquake and tsunami offshore Java

6 Idea mafers Idea 1 I had done five marine experiments, including two funded by industry (Schlumberger and CGG) using the state of the art technology. Had over 30,000 km of seismic reflec3on data from two other companies (PGS and TGS) Had published over 20 papers in peer reviewed journals, including two in Nature Geoscience Supervised 4 PhD students and five master students

7 Idea mafers There was a crying need from Indonesia to start this project Important scien3fic problem, well proven, but not that original Idea 1 Got funded in 2017 (3.5 m $)

8 Idea mafers Idea 2 There was (s3ll is) a debate about the nature of the lithosphere-asthenosphere boundary (LAB), at the base of the tectonic plate Is it a sharp boundary (500 m) or thick ( km) transi3on zone? Does this boundary deepens with the age of the lithosphere (from 3-5 km at ocean spreading centre to 100 km at 100 Ma) Exis3ng methods do not have the resolu3on to solve this problem

9 Idea mafers Idea 2 I thought of using my experience from Sumatra, where I had imaged 500 m thick layer at 60 km below the seafloor using industry technology Can I use this technology to image the LAB? Industry had come out with a befer technology than before, which can allow me to image 500 m thick layer at 100 km depth, but the cost would be horrendous I talk to industry and see if they would be willing to help on this project, they said they would if a vessel happens to be in the area

10 Idea mafers Idea 2 I had never worked on such a problem nor knew much about the debate High-risk High- reward, so I opted for the second idea.

11 Take your 3me Pressure from the IPG Paris was to write the proposal in 2011 I said no, I want the idea to mature, and write a good proposal, and I decided wait and to go for 2012 Compe33on was very high, globally and within the IPG Paris (11 candidates) I spent most of my 2012 summer at Scripps Ins3tute of Oceanography learning about the problem, and drahing the proposal

12 Think carefully My project was very ambi3ous: use all possible geophysical methods at the same loca3on to address the scien3fic ques3ons: (1) seismic reflec3on, (2) seismic refrac3on, (3) broadband seismology, and (4) magnetotelluric method I am only expert at seismic reflec3on (most expensive) and refrac3on. I asked colleagues from Southampton if they would be interested in broadband seismology and Scripps colleague for magetotelluric

13 Think carefully The total cost of the experiment would be about 15 m, but we can only ask for a maximum of 3.5 m So I decided to focus on the seismic reflec3on (6 m ) and refrac3on (3 m ) part and proposed that the other two experiments could be considered as a piggyback, subject to funding from other sources. Loca3on of experiment was crucial: Equatorial Atlan3c because of seismic vessels transi3ng this area from South Africa/America to Europe

14 Ultra-deep seismic reflec3on experiment using ISOMETRIX system Ultra-long offset refrac3on experiment (70 OBS) to get velocity Tele-seismic using 30 BBOS (receiver func3on and surface wave) 40 Magnetotelluric deployment (resis3vity) From zero age to 100 Ma old oceanic lithosphere Equatorial Atlan3c Ocean for 2D study Profile crossing the fracture zones Presented at ERC in 2013 Trans-Atlan3c ILAB: Dream

15 Dream come true I got my ERC Advance grant in 2013 UK Na3onal Environment Council funded ship 3me for the deployment of broadband seismometers Kate Rychert (Southampton) wrote an ERC Star3ng Grant for broadband seismometer part of the project in 2014 and got it. German Science Founda3on funded part of the refrac3on experiment United States Na3onal Science Founda3on funded the deployment of magnetotelluric instruments We got all the funds we needed

16 Reality Hits Contract nego3a3on: One year Gelng the vessels and instruments to do the experiment, most importantly industry vessel for seismic reflec3on, specifically as the cost of petrol went down from 120 $/barrel to 50 $/ barrel Fortunately, we had a seismic vessel passing through our study area in March Following all the procedure of tendering etc., we went Ghana to board the vessel. We found that Ghana has claimed 350 miles EEZ, instead on 200 miles before, and our profile was within the new Ghana s EEZ limit.

17 Reality Hits We changed the profile hoping to go straight, but later we learned that this new line will go through the disputed area of the Bri3sh territory, Ascension Island, and hence has to change again.

18 Reality Hits But we end up having excellent data We have two PhD students working on these data and a paper in Nature Geoscience has been accepted for publica3on, a fundamental discovery.

19 As of today Seismic reflec3on experiment completed in 2015 on board the Schlumberger seismic vessel, Western Trident Broadband seismometer and magnetotelluric instruments were deployed in April 2016 and recovered in April 2017 The first refrac3on experiment is taking place now on the German R/V Maria S Merian The second refrac3on experiment is planned in September-October 2018 on board French R/V L Atlante

20 Acknowledgements ERC Advanced Grant to Singh (IPGP) ERC Start Grant to Rychert (NOC) UK NERC for ship 3me for Teleseismic and MT study (Harmon, NOC) German Science Founda3on for ship 3me and refrac3on study (Grevemeyer) US NSF for funding MT deployment (Constable, Scripps) Schlumberger (WesternGeco) for providing Western Trident for ultra-deep seismic study

21

22 Survey details Streamer: 12 km long Pressure (3.125 m), Az, and Ay (0.76 m) components Tow at 30 m water depth Number of streamers: 1 Source: cubic inch Shot interval: 50 m, 62.5 m and 75 m Record length: 20, 25, and 30 s 2200 km 2D data (0-75 My) (A-G) 600 km Across Fracture zones (G-H) Change of lines due to 350 miles EEZ requirements Four 3me zones Crossing of the equator April 2015 Western Trident

23 BBOBS and MT Experiment UK NERC ship 3me ERC Start Grant US NSF for MT February 2016 to April 2017 Rychert + Harmon (Southampton) Constable (Scripps)

24 2. LITHOS 70 OBS 0-50 Ma African plate 2017 on German vessel Refrac3on study: LITHOS

25 1. SPARC: OBS 0-25 Ma Great Fracture zones L Atlante Refrac3on study

26 Acknowledgements The project is funded by ERC, UK NERC, German Science Founda3on, and US NSF Schlumberger provided IsoMatrix vessel, Western Trident