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December 9, 2022

International Ocean Discovery Program (IODP) Expedition 398
Hellenic Arc Volcanic Field

As part of the International Ocean Discovery Program (IODP, *1), JOIDES Resolution (*2) research cruise IODP Expedition 398 is set to begin on 11 December 2022 (see addendum). The research target of this cruise is to increase our understanding of island arc volcanism and its associated hazards through study of the processes that drive such volcanism and how the volcanoes interact with their marine surroundings. The purpose of this cruise is to reconstruct the history of volcanic activity of the arc, including eruptions of Santorini caldera, and to elucidate the origin of the magmas and the factors that determine eruption styles and hazards. Therefore, this cruise will drill and collect several hundred meters-thick sediments, including volcanic deposits, that comprise the seafloor.

Twenty-eight researchers from Australia, China, Germany, France, India, Japan, United Kingdom, and the United States are scheduled to join the research cruise, including three Japan-based onboard research participants.

*1 International Ocean Discovery Program (IODP)
This international scientific research cooperative project started in October 2013. By drilling deep below the ocean floors using drilling vessels provided by Japan (JAMSTEC DV Chikyu), the United States (JOIDES Resolution), and Europe (Mission-Specific Platforms), IODP promotes research aimed at elucidating the internal structure and the biosphere within and below the Earth’s crust.

JOIDES Resolution ©IODP

*2 JOIDES Resolution
The JOIDES Resolution Science Operator (JRSO) manages and operates the riserless drillship, JOIDES Resolution, for the International Ocean Discovery Program (IODP). The JRSO is based in the College of Geosciences of Texas A&M University.


Hellenic Arc Volcanic Field

1. Schedule (local time)
  IODP Expedition 398

11 December, 2022
Research cruise begins (Port of departure: Tarragona, Spain)
10 February, 2023
Research cruise finishes (Port of return: Heraklion, Greece)

※ The schedule may change depending upon the condition/inflences of COVID-19, the progress in sailing preparations, weather conditions, and/or research activities.

2. Onboard scientists scheduled to participate from Japan

Name Affiliation / position Specialized field
Shun Chiyonobu Faculty of International Resource Sciences, Akita University / Professor Micropaleontologist (nannofossils)
Iona McIntosh Japan Agency for Marine-Earth Science and Technology / Researcher Physical Properties Specialist/Downhole Measurements
Yuzuru Yamamoto Graduate School of Science, Kobe University / Professor Structural Geologist

3. Research Purposes and Objectives

The Hellenic Arc Volcanic Field in the Aegean Sea is an active volcanic arc. It includes the famous Santorini caldera, whose last catastrophic caldera-forming eruption ca. 3,800 years ago severely impacted Late Bronze Age civilizations in the Mediterranean, and also the submarine Kolumbo volcano, which most recently erupted in 1650 AD, and is today the location of a spectacular hydrothermal field where diverse microbial communities thrive in extreme temperature and pH conditions. In addition to reconstructing the history of volcanic activity in the arc, its association with crustal deformation and elucidating the origin of the erupted magmas, this cruise will also examine the interrelation between volcanic activity, the marine environment, and life itself. This Expedition will sample hundreds of meters of volcanic sediments at four sites in the Rift Basin and two sites inside the Santorini caldera.

Caldera-type volcanoes are found around the world, including several in Japan. In their caldera-forming eruptions they can spout >100 km3 of volcaniclastics (boulders, pumice, ash) in a matter of days and create huge pyroclastic flows and extremely thick accumulations of volcanic ash that surely threaten our human lives and societies. However, there are no clear differences between catastrophic caldera-forming eruptions and smaller non-caldera eruptions in terms of chemical composition and formation of magma. Therefore, the scientific understanding of how caldera-forming eruptions occur – which is the first step towards predicting future events – is still controversial. By unlocking the detailed volcanic archives preserved in the seafloor sediments, IODP Expedition 398 is expected to illuminate these kinds of remaining mysteries about how our planet works.

Druitt, T., Kutterolf, S., and Höfig, T.W., 2022. Expedition 398 Scientific Prospectus: Hellenic Arc Volcanic Field. International Ocean Discovery Program. https://doi.org/10.14379/iodp.sp.398.2022


Figure  Locations of drilling sites.
The orange circles represent the primary target sites and the yellow circles represent alternate sites.
The ‘*’ indicates that some of the proposed drilling points overlap at this scale.

Table  List of primary drilling sites in the projected target

Site / borehole name Water depth (m) Target drilling depth (m) No. of scheduled working days
CSK-01A 489 765 13
CSK-03A 397 566 10
CSK-05C 384 234 4
CSK-07B 292 360 6
CSK-09A 694 595 11
CSK-13A 489 857 13

Note: Drilling sites may change depending upon sailing preparations, weather conditions, and/or research progress.

*Figure is cited from the IODP website with partial modification.
IODP JRSO・Expeditions・Hellenic Arc Volcanic Field

【Reference】IODP Copyright Statement


(For IODP and this scientific expedition)
Saneatsu Saito, Deputy Director, Operations Department, Institute for Marine-Earth Exploration and Engineering
(For press release)
Press Office, Marine Science and Technology Strategy Department
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