Hanaya Okuda

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This transcript is based on a video-recorded interview deposited at MarE3, JAMSTEC (Yokosuka, Japan).

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Interview of Hanaya Okuda by Beatriz Martinez-Rius on 2024 November 12, D/V Chikyu (Japan). [link]

Beatriz Martinez-Rius (BMR): Today is November 12 of 2024. I am Beatriz Martinez-Rius, and I am onboard Chikyu, Expedition 405, with Hanaya. Thank you. So, can you please tell your name, your position and your affiliation?

Hanaya Okuda (HO): I’m Hanaya Okuda. I’m a researcher at JAMSTEC, in Kochi Institute for Core Sample Research.

BMR: What is this researcher position about? Is it a sort of postdoc position?

HO: I’m a now researcher, so it’s a kind of tenure track position.

BMR: Oh, that’s good. Before talking about your tenure track position, let’s go back in time. Where did you grow up, and how happened that you started in Earth Sciences?

HO: I was born in Tokyo and lived there until 2023. I finished my PhD in March 2023, so until then I lived and grew up in Tokyo. When I was a kid, I wanted to be an astronaut. I also like stars, the Earth, Mars, moons… those kinds of things. So, probably I had some interests on Earth sciences or planetary science. After I graduated in high school, I went to the University of Tokyo. I was more interested in Physics or Quantum Physics, but I was playing tennis and I didn’t study much. So, I couldn’t go to the Physics Department, and also, I couldn’t enter the Geophysics Department. So, I went to Geology Department and I found myself that, “okay, maybe I like rocks”. But still I was interested in the more physical part of Earth materials. So, during my undergraduate research, I was working on atomic-scale deformation of crystals, and I continued that work during my Master. But in the meanwhile, I also did some experiments on rock deformation, and that was really nice. I continued the experimental rock deformation during my PhD. I got my PhD and now, still, I continue working on rock deformation in Kochi.

BMR: What kind of things do you like about rock deformation? If you tell to someone who doesn’t know about Earth Sciences, “I’m studying rock deformation” maybe it’s difficult to grasp what can be attractive from that.

HO: So, rock deformation is knowing how the rock deforms. That means, how the rock is broken up, and also how earthquake occur. Behind of earthquake generation, we have to know the rock rupture, or fracture, or rock friction – those are all rock deformations. We want to know the rock’s physical properties. That is, how strong the rock is, or how weak the rock is, or if this rock can sustain a high stress or cannot. So, yeah, rock deformation is one of the physics of material sciences. But still, it’s closely related to geology or geosciences.

BMR: Was there anyone who has influenced you in choosing this research field or pathway?

HO: Not really, buy my PhD supervisor is Asuka (Yamaguchi), who is onboard right now. He is a structural geologist, and he wasn’t doing [these sort of] experiments before. But he gave me a lot of insights on structural geology in the field, and also in the Institute where I was doing my PhD. So, I was doing experiments but my supervisor, Asuka, gave me a lot of experiences on different perspectives from the field. That was really helpful for me, to have a relatively vast field of the experimental rock deformation and how the results from experiments can be expanded to the natural conditions.

BMR: So, essentially, you started from an interest in being an astronaut, then you moved to Physics, I guess in order to get into the space…

HO: Yeah, actually a little bit the smaller scale, like atoms, crystals, electrons, ions… At that scale.

BMR: And then, for a number of reasons related to qualifications, you ended up in Geology and kind of find your way in rock deformation. Which I guess it also deals with micro and macro.

HO: Yeah. That’s I think most interesting point, for me. We can discuss the macroscopic scale deformation or phenomena like earthquakes, landslides, accretionary prisms… The larger scale tectonics can be sometimes explained by smaller scale experimental results, or even in atomic scale. So that’s the point I like a lot.

BMR: Can you remember the first time you learned about scientific ocean drilling?

HO: I think that was the first in our Master course.

BMR: How come that you got interested in this?

HO: So, as I said, I did the first experiments during my Master course. After the first experiment, I find myself that I would like to do this, a lot. At the time, I was doing atomic scale deformation. But I am in the Geology Department, so I wanted to know how the experiments can contribute to understand geological phenomena. So, I wanted to know the real materials that make up the subduction zone, like Japan or other area. I contacted my supervisor and told him that I wanted to know more about real materials. And he suggested me to talk to researchers in Bremen, in Germany. Because at the time, the NanTroSEIZE Project, Expedition 358, was going on. Asuka was a co-chief scientist, and the other co-chief scientist was in Germany, Bremen. So, we already had several samples from the IODP. That was a really good chance for me to use, and also know what the scientific drilling is. And also, that was a very nice opportunity to for me to understand the real materials below seafloor. It was a very nice opportunity for me to do experiments with real materials. So, I think that was the first opportunity to contact with the ocean drilling project.

BMR: Why did you apply to this particular expedition?

HO: One of the reasons is, I’m in JAMSTEC (laughs). Another is, that I was working on the Nankai Trough, basically, but I also wanted to know the phenomena in other locations. Particularly, I am focusing on material differences and how material affects the rock deformation properties. And in the Japan Trench, we have a lot of pelagic sediments. That is quite different from the Nankai Trough. Also, we have different seismic activities between the Japan Trench and the Nankai Trough. So, I want to know how the differences in material can contribute to the differences in seismic activities between the Japan Trench and the Nankai Trough. That’s the reason.

BMR: You are interested in a kind of a comparison between the two main areas that produce big earthquakes in Japan. Why do you think you go to the position?

HO: Maybe the experience in doing friction experiments on the Nankai Trough materials might help? (laughs) for me, to be on board here. I think another reason is that I am an in Kochi (Core Center), right now. So, I have a lot of chances to know about IODP, and also, we have some ideas to run experiments with this material. I think that, from after my PhD, and also during my PhD, I have had a lot of chances to interact with people in the IODP and in JAMSTEC. So, I think I have some knowledge about what the IODP is, and what this cruise is targeting at, what Chikyu can do, and what I can do after this cruise. So, probably these are the reasons, I guess.

BMR: Is this your first time in oceanographic expedition?

HO: Including other cruises…? I joined three cruises before. One is in the southwest part of Japan with the Hakuho Maru. And the other two cruises are, with the Shinkai and Yokosuka cruises. So, yeah, I had several cruises, and I think I can manage it.

BMR: What are the differences? Between this and the other cruises.

HO: The size of the vessel. I generally have seasickness in the other vessels, but so far I already spent two weeks here and I don’t have to take any medicines. That’s pretty cool. That’s the biggest difference, I think. And another thing is, in the scientists’ group, we have a lot of international colleagues and we can collaborate. That’s very cool. And another cool thing is, the scientists onboard are… I think half of the onboard scientists are kind of young generation. That means, we can be… we are not like a boss and human power, but like a real colleague and like friends. That’s very cool. Although it’s very intense, because we have 12-hours shift and we have to work on the on the cores, we have to write the report… That’s very intense. But still, I think so far, I can spend a very nice time with international colleagues.

BMR: Is that the thing that has impressed you the most of being these two weeks ago?

HO: Yes, I think so. The international collaboration.

BMR: And the most difficult part to handle?

HO: The shipboard measurements. I am in the structural geologists group, so I am measuring deep angles of fractures… Those kinds of things. We are collaborating to get those shipboard measurements data. But for the sampling party, we have to talk to each other. If we have some conflicts on the same area, the same sample, that’s sometimes a bit hard. I mean, not easy. Well, of course, English is the common language on Chikyu, and for me, like a non-native speaker, it is not always easy to explain my ideas and my reasonings to take the sample. So that is a kind of difficult point, to be onboard the International Ocean Drilling Project.

BMR: Well, I guess that everyone who is non-native experiences these challenges. It’s something we all need to go through.

HO: Yeah, I think so, too. I personally feel that it’s a kind of a good opportunity to train myself to be a good scientist who is involved in the international community.

BMR: Now, the difficult question. Where do you see yourself in ten years?

HO: Well, the honest answer is “I don’t know” (laughs). Personally, I would like to continue my experimental works and… The biggest target or goal is understanding the subduction zone earthquakes from the viewpoint of material. I think I like ocean drilling science because we can directly know the materials incoming to the trench in Japan. So, I hope, I will be able to know the spatial distribution of materials around Japan in ten years. I don’t know. If I would be able to become… The best person who knows the seafloor sediment distribution, then that will be very nice. I want to know the relationship between the distribution of sediment and seismic activities.

BMR: I wish you succeed in that; it will be really cool! So, is there something that you want to explain that I have not asked you?

HO: It’s good, so far.

BMR: Well, thank you very much, that was great.

HO: Thank you.