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Keynote speech by Sylvain Barbot during the Oceanology International Conference

16 Sep 2013

Assistant Professor Sylvain Barbot delivered a keynote speech, “On the fringe of science and exploration: A call to investigate natural hazards with ocean laboratories”, during the opening plenary session of the Oceanology International China Conference on September 3, 2013.

Oceanology International is a platform that brings together industrialists, researchers and stakeholders to exchange views on marine technology and oceanology, with the purpose of better exploiting and protecting the world’s oceans.

The Oceanology International China Conference was held in Shanghai from September 3rd to September 5th, 2013.

llustration of a potential geodetic network involving GPS, Wave Gliders (i.e. autonomous marine robots) and geophones installed on the seafloor to monitor with an exquisite precision the tectonic plates motion.


On the fringe of science and exploration: A call to investigate natural hazards with ocean laboratories

Sylvain Barbot, Emma Hill, Paul Tapponnier

In the past decade, humans have endured particularly severe seismic hazards originating offshore. In Asia, we have seen the devastating effects of giant earthquakes and tsunamis. And with rapidly expanding human populations in coastal areas, we are poised to endure more trials of our resilience.

The March 2011 Mw 9.0 Tohoku-Oki earthquake that took place on the Japan Trench brought tremendous devastation to the Japanese shores and shook old assumptions about seismic hazards in Japan and prevailing theories about subduction-earthquake mechanics. The seismic rupture raced towards the trench, cutting through soft and water-saturated sediments, and generated large uplifts of the seabed that created a tsunami of an exceptional size. In another example, after a series of great and giant earthquakes along the Sunda Megathrust, a tsunami earthquake ruptured offshore the Mentawai Islands in 2010. The Mw 7.8 quake seems to have ruptured only near-trench faults and it generated a tsunami larger than anticipated for its magnitude. The fundamental underlying mechanism of this type of rupture is still debated and largely unknown. Was the Tohoku earthquake a sort of extreme event, or are our preconceptions about subduction earthquakes and tsunamis hindered by a severe lack of data offshore? In many cases around the world, imaging near trench processes is challenging, with the nearest land-based instruments located several hundreds of kilometers away.

More generalized monitoring of the Earth’s deformation offshore will be key to understanding the tectonic processes at the origin of seismic and tsunami hazards along our coasts. But as access to the ocean and the ocean floor remains difficult, dangerous, and costly, new systems must emerge to facilitate long-term and continuous offshore data acquisition. Persistent ocean laboratories may revolutionize our understanding of subduction-zone seismic processes and may simultaneously deliver instruments of risk mitigation, such as the infrastructure for earthquake and tsunami early warning systems. And as we push the horizon of human sight far into our deepest oceans, scientific exploration may also lead us to unforeseen discoveries.