SEAFLOOR OBSERVATORY SCIENCE Paolo Favali (1) , Roland Person (2) , Chris R. Barnes (3) , Yoshiyuki Kaneda (4) , John R. Delaney (5) , Shu-Kun Hsu (6) (1) Istituto Nazionale di Geofisica e Vulcanologia (INGV), Via di Vigna Murata, 605, Roma (Italy), Email: emsopp@ingv.it (2) IFREMER (French Institute for Exploitation of the Sea/Institut Français de Recherche pour l'Exploitation de la Mer) BP 70, 29280 Plouzané, France, Email: esonet-coordinator@ifremer.fr (3) University of Victoria, PO Box 1700 STN CSC, Victoria BC V8W 2Y2 Canada, Email: crbarnes@uvic.ca (4) Japan Agency for Marine-earth Science and Technology, 2-15 Natsushima, Yokosuka, Kanagawa, 237-0061, Japan, Email: kaneday@jamstec.go.jp (5) University of Washington, 7600 Sand Point Way NE, Seattle, WA 98115, USA, Email: jdelaney@u.washington.edu (6) Institute of Geophysics, National Central University, No.300, Jhongda Rd., Jhongli City, Taoyuan County 32001, Taiwan (R.O.C.), Email: hsu@ncu.edu.tw ABSTRACT This paper deals with a new emerging science the “Seafloor Observatory Science”. It is evolved rapidly over the last two decades by means of new projects and programmes towards the establishment of permanent underwater networks. The main on-going initiatives at global scale are presented for Canada (NEPTUNE - North East Pacific Time-series Underwater Networked Experiments), USA (OOI - Ocean Observatories Initiative), Japan (DONET - Dense Oceanfloor Network system for Earthquakes and Tsunamis), Taiwan (MACHO - Marine Cable Hosted Observatory) and Europe (through ESONET-NoE - European Seas Observatory NETwork-Network of Excellence and recently with the infrastructure project EMSO - European Multidisciplinary Seafloor Observatory). Moreover, the scientific motivations for seafloor observatories and their main architecture are discussed. Finally, the applications and opportunities of cabled observatories beyond those in ocean science research, technology and data services are outlined. It is important to recognise that the advent of cabled ocean observatories heralds in a new era of ocean exploration and interpretation, which will make profound contributions to socio-economic benefits, public policy formulation, and public education and engagement. 1. INTRODUCTION The ocean exerts a pervasive influence on Earth’s environment. It is therefore important that we learn how this system operates. Understanding the ocean, and the complex physical, biological, chemical, and geological systems operating within it, is a challenge for the opening decades of the 21 st century. The establishment of a global network of seafloor observatories will help to provide the means to accomplish this goal. A fully comprehensive definition of the term “seafloor observatories” was given for the first time by the NRC (National Research Council) report “Illuminating the Hidden Planet. The future of Seafloor Observatory Science”, where we can read: “…an unmanned system, at a fixed site, of instruments, sensors, and command modules connected to land either acoustically or via a seafloor junction box to a surface buoy or a fibre-optic cable…” [1] The establishment of a global network of seafloor observatories will provide powerful means to understand the ocean and the complex physical, biological, chemical, and geological processes. Many large-scale projects have been planning to establish permanent seafloor networks at International level. Canada, USA, Japan, Taiwan and Europe are the major actors. In Canada the major component of this effort is NEPTUNE (North East Pacific Time-series Underwater Networked Experiments) [2] and VENUS (Victoria Experimental Network Under the Sea) [3]. In the United States, the OOI (Ocean Observatories Initiative) a NSF (National Science Foundation) Division of Ocean Sciences program [4] has launched the RSN (Regional- Scale Nodes) [5]. Japan started in 1978 to manage cabled seafloor observatories for scientific use, and particularly for real-time monitoring for seismic and tsunami warning. One of the most recent Japanese projects is DONET (Dense Oceanfloor Network system for Earthquakes and Tsunamis) [6]. In Taiwan the project MACHO (Marine Cable Hosted Observatory) recently started and is a submarine cabled observatory offshore of eastern part of the island with the main purpose to establish offshore seismic stations, to provide early warning of earthquakes and tsunamis, and to monitor submarine volcanic activity [7]. In Europe the effort to build a seafloor observation infrastructure have been supported by the EC (European Commission) first through ESONET-NoE (European Seas Observatory NETwork-Network of Excellence), aimed at gathering together the community interested in multidisciplinary ocean observatories [8], and more recently with the EMSO-PP project (European Multidisciplinary Seafloor Observatory-Preparatory Phase), aimed at establishing the legal entity charged of the construction and management of the EMSO infrastructure. The European-scale network of seafloor observatories widely distributed for long-term monitoring of