Takahiro Hirose

Disclaimer

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

The transcripts of the research project Oral Histories of Scientific Ocean Drilling are polished representations of oral conversations, and are intended solely for the purpose of preserving and documenting personal accounts and memories. They are not a literary product, and are not intended to exhibit literary qualities.

The primary goal of this transcript is to capture the spoken words and memories of the interviewee as accurately as possible. Minor editing and polishing works have been performed to enhance clarity and readability while maintaining the authenticity of spoken discourse, including non-standard grammar, inconsistencies, repetitions, and pauses.

The reader must be aware that memories of an event can vary between individuals and may evolve over time due to various factors, such as subsequent experiences, interactions with others, and personal emotions.

Use and citation

This transcript is the property of JAMSTEC and is subject to its regulations. Quoting, reproducing, or distributing this transcript for non-commercial purposes is allowed with due attribution.

Please cite the interview as:

Interview of Takahiro Hirose by Beatriz Martinez-Rius on 2025 April 2, Kochi Institute for Core Sample Research, Kochi (Japan). [link]

Beatriz Martinez-Rius (BMR): Today is April 2nd of 2025. I am Beatriz Martinez-Rius, historian of science at JAMSTEC, and I am at the Institute for Core Sample Research at Kochi with director Takehiro Hirose. Thank you very, very much. Can you please say your name, your position and your affiliation?

Takahiro Hirose (TH): My name is Takahiro Hirose. I’m a scientist and also the Director of the Kochi Institute for Core Sample Research, JAMSTEC.

BMR: How does it change being the director or a scientist?

TH: I’m still a scientist, but my major role at the moment is as director. So, I shifted to management, but I’m still a scientist (laughs). I enjoy science.

BMR: Are you able to divide your time between administration and science?

TH: Not strictly, but when scientists ask me something about the science, I become a scientist. I enjoy talking to them.

BMR: As a director of the Kochi Institute, do you have some views on where do you want to bring the center?

TH: That’s difficult… That’s a really tough point, actually. But if I had to say, the most important thing, to me, is to enjoy the science. Whatever the science field, that’s what drives us: not drilling science, but also kinds of science. I believe it’s quite important to bring different disciplines together and make connections. That’s where new ideas come from, and I want to make that happen at the institute. So, “enjoy science”. That’s my message I’d like to share as director.

BMR: How many scientists are now in here?

TH: Sixteen scientists, plus four or five engineers, plus staff, curators… In total, more than 50 staff in this building.

BMR: How often do overseas researchers come to visit the center?

TH: Now that we are recovering from Covid-19, the number has increased. I’m not sure, but at the moment, ten to twenty scientists from overseas per year.

BMR: It’s a nice place to do research, for sure. So, let’s start chronologically, before talking about the science. Where did you grow up, and what is your background?

TH: I grew up in Osaka, the second biggest city in Japan. In my childhood, I loved nature so much. I enjoyed hiking, catching insects, and fishing in the mountains… But, you know, Osaka is full of concrete buildings, and there is not  much nature. So, I decided to leave Osaka when I got into university.

BMR: Where did you go, to university?

TH: Hiroshima University for the undergrad and master course, and then I moved to Kyoto University.

BMR: Were your parents related to science, technology, engineering…? Or someone in your close family?

TH: Oh, no. Actually, my father was a businessman, but when I graduated from Hiroshima University, he quit his job and started running tomato farm in Nara, near Osaka. He enjoyed the farming and keep it going for more than 20 years. I sometimes helped out (laughs). My mother supported him at home. So, nothing particularly special, I guess.

Well, tomato farming is quite special, coming from Osaka (both laugh).

TH: Yeah, that’s true.

BMR: Was it like commercial farming?

TH: Oh, yeah, yeah. Basically, we sold tomatoes to major markets like Tsukiji, and Ohta in Tokyo, you know that?

BMR: Yeah. Were they supportive of you doing natural sciences at the University?

TH: Yes. My father and mother also love nature, so I got a lot of support from my parents.

BMR: Was there someone during these university years that kind of influenced you in your research?

TH: Oh, yes. My mentors during the undergraduate and master course had a strong influence on me. He really loves geology, and you could tell he genuinely enjoyed it. He looked like having so much fun with everything in nature. So, I really loved his behavior. He is definitely the most influential person in my life.

BMR: May I ask his name?

TH: Yasutaka Hayasaka-sensei. Hayasaka-sensei.

BMR: I’ve never heard about him before. Is he in Kyoto?

TH: No, in Hiroshima. Three or four years ago he retired, and he is now in Kumamoto. Actually, he is the director of a kind of museum. Last year, I visited his museum and we enjoyed drinking (laughs).

BMR: Nice. So, how did you get into fault zone research?

TH: Oh, that’s an important thing. I learned geology at Hiroshima University and then moved to Kyoto University for the PhD. The reason I became interested in faulting and earthquakes was that I saw the Kobe earthquake in 1995. That happened during the third year of my undergraduate. I was looking for a research topic in the future- and then I saw the devastation in  Kobe. Not through the TV but with my  eyea. At that time, I was very shocked and I couldn’t believe what had happened. That moment became  the starting point for me..

In Hiroshima, I was focused on regional onland geology, not sesimology. Then, I moved to Kyoto University to study the more faulting or mechanics of earthquake. That is where I could start  doing experimental work. That’s really the reason I moved to Kyoto University. Again, the Kobe earthquake was kind of my starting point.

BMR: The earthquake also affected Osaka, right?

TH: Oh yes, sure. My parent’s house was also a little bit damaged. We often visited Kobe city, so I knew the city well, and it was totally devastated.

BMR: When was your first international collaboration?

TH: During my master course, I visited the US  and Micronesia for fieldwork, and there were foreign researchers involved. But in terms of really working closely with international colleagues,  that started during my PhD at Kyoto University. Basically, we mainly collaborated with European researchers who were around the same generation as me. We contact each other even now, and I sometimes invite them here, and other times I go them.

BMR: Did you travel to Europe, at that time?

TH: Oh, yes. Part of my doctoral research involved fieldwork in Scotland, in the Outer Hebrides islands. I went there to do fieldwork  as part of my PhD research. At the time, I also collaborated with European researchers.

BMR: Was there any sort of cultural shock, or cultural difference that you noticed?

TH: Uhm… To me, not so much. I could accept everything pretty easilly, because I was surrounded by so much nature. I really enjoyed both the fieldwork and the culture in Europe.

BMR: I’m glad to hear that as a European (both laugh).

TH: You know, I was in Switzerland as a postdoc for more than three or four years. I got to know the culture in Europe.

BMR: Switzerland, still, I think it’s the most similar country in terms of social interaction, and society… to Japan.

TH: Yes.

BMR: If you go to Spain or other countries… That’s different (both laugh).

TH: Exactly. So first, I stayed at Switzerland for three or four years and everything was punctual, pretty similar to Japan. I really… You know, there’s basically no problem at all. After that, I moved to Italy as a postdoc for just half a year… but there were  so many troubles (laughs).  Still I liked the Italian personality. They are energetic, have a  good sense of humor… and I really enjoyed that too.

BMR: Things in Mediterranean countries are more relaxed. Paperwork takes time, lunchtime takes time… (both laugh). So, how did you know about scientific ocean drilling for the first time?

TH: My first cruise was in 2004. It was at the mid-Atlantic Ocean ridge. At that time, I was in Switzerland, studying the serpentinite: It’s a type of mantle rock. One of  my colleagues recommended that I join the cruise because the cruise’s purpose was drilling at mantle rocks. So, I just joined. To be honest, I had no background in the drilling science, but I got onboard the JR and spent two months at sea. That’s my kick off cruise of IODP, just because my colleague recommended it to me. That’s how it all started.

BMR: Is there something remarkable that you remember? The fun, the stressful, the…?

TH: (laughs) Yeah, actually, yes. The most impressive thing was the scientists with different backgrounds gathered in a very small ship, and co-worked for two months. I first felt that it’s kind of training camp of a high-school club (laughs). My first impression was that. And honestly, some of my best memories are – just drinking, before and after the cruise. Of course I had a responsibility to publish paper, but I don’t really care about that (laughs). So, sharing special time onboard, that’s the memory that stand out for me.

BMR: When I went aboard Chikyu, I also had the feeling that it looked like a summer camp (laughs). So, that was your first expedition in 2004, and that was also the beginning of the first IODP. Chikyu was being built, at that time. Did you know something about the Japanese drilling program?

TH: Yes. I remember JAMSTEC researchers gave a presentation that I saw  at university. But honestly, I was not so much interested at that time. But once I joined the JR, I realized – this is a completely different world. Immediately I started to get more interested. It expanded my research in new directions. So, after the first cruise, I started to get into it..

BMR: How did your research develop after that first cruise?

TH: At that time, just after  or maybe during the postdoc, I had two main ways: one was seismology, and the other one was rock mechanics, more basic science. I was also searching for my next position. Then, I had the opportunity to get a position here. When I arrived, the NanTroSEIZE drilling had just started, so that I got involved in NanTroSEIZE and conducted the research on both seismology and rocks mechanics, here in Kochi. That’s  the path I’ve taken.

BMR: What attracted you about JAMSTEC, about coming to Kochi?

TH: The facility. I was hired by JAMSTEC, and JAMSTEC told me, “You can buildyour own lab” (laughs) and JAMSTEC prepare a budget”. That was the most attractive thing, because my research, at that time, was very difficult to conduct outside Japan because of the technology, the engineers… So, to continue the research at that time, I had to come back to Japan. It was really nice to me to get back to Japan.

BMR: How was the Kochi Core Center when you arrived here? What did you find here?

TH: Many researchers from different disciplines: there were microbiologists, geochemists… For example, at university, I’ve never talked with microbiologists. It felt like there was a real barrier between fields. But here, in Kochi, there’s no barrier. They are sitting right  at the next desk (laughs), so we can chat. To me, that was a very  greatenvironment—it really helped expanding my research.

BMR: Looking now back in time, and comparing, how has the center changed or evolved?

TH: The number of scientists has grown a little bit, and the facilities have improvedas well. We got some large, expensive analytical machines, here in Kochi, so,  the center has developed a lot. To me, it’s kind of a fantastic institute, compared to the universities or other institutes in Japan. I’m quite happy to be here.

BMR: We can talk more about how Kochi has changed in a minute. Now I’d like to go back to the moment you arrived to Kochi and you were introduced into the NanTroSEIZE project. So, tell me about your involvement in that 13-year long project.

TH: JAMSTEC hired me right around the time the NanTroSEIZE was starting. So, to me, it felt like  part of  my job to contribute to the NanTroSEIZE project, as I was based here. Of course, I was quite happy to join such a big international program. It was my big pleasure for me.

BMR: What were your positions in the project?

TH: For the first two or three NanTroSEIZE cruises I just did on land research, as a sample requester. But I participated in the same meetings as the science party during the first three or four years of the NanTroSEIZE project.

BMR: How did your participation of NanTroSEIZE changed your perspective on science or collaborations, or even the limits of science?

TH: That’s not easy! So, the NanTroSEIZE project was the only scientific drilling project to access the seismogenic zone. That was a rare opportunity to see the rocks in the seismogenic zone. So, I kept the motivation to use the data, cores in the seismogenic zone…at the end, we could not achieve it. However, I planned to utilize whatever came out to further expand my research. I kept this mind in myself for all sciences for more than ten years.

BMR: I see. I know that, at some point, you were co-chief of a NanTroSEIZE expedition.

TH: Yeah.

BMR: How did it happen, that you became co-chief?

TH: Can you imagine? For my first NanTroSEIZE expedition, I joined as a co-chief (laughs). I’d never joined as a member of the shipboard science party before. But it was a nice experience indeed.

BMR: The difficult question that I always ask – what is the part you enjoyed the most of being co-chief, and the part that was tough or more challenging?

TH: Of course, it’s a big responsibility. So, it’s quite a tough task. But I think I actually enjoy that tough part. Co-chiefs  had to search the scientists, select them, and build a team —then, conduct the exciting science together. I could contribute some of that process and enjoy it. Of course, there are also many… troubles,  thatI had to make  significant decisions. I’m not sure but looking back it was all valuable experience. The first time I served as co-chief was in 2014 and the second time was in 2019.  That 2019 expedition was actually the last NanTroSEIZE cruise. At that time the name had changed and it was not co-chief, science leader… I forgot (laughs). For the second time, I might be able to fulfil my role as co-chief better than the first time.

Photos from IODP Expedition 348, onboard Chikyu (2013). For this expedition, part of the NanTroSEIZE project, Hirose served as co-chief scientist together with Harold Tobin (right photo). In left, Sean Toczko (Expedition Project Manager), Takahiro Hirose, Demian Saffer, Harold Tobin, and Yuzuru Yamamoto discussing over the samples. In the right picture, Harold Tobin and Takahiro Hirose celebrating a new depth drilling record. JAMSTEC/IODP.

BMR: One of these expeditions that had multiple co-chiefs, right? I have interviewed several other people involved in NanTroSEIZE. I know what happened overall, so I’d always like to ask, if you could now take a decision regarding NanTroSEIZE to do it differently, what would that be?

TH: Of course, we learned a lot from what it happened. It wasn’t something we expected beforehand. So, maybe we will select a different site. We can definitely do it much, much better now.

BMR: What is the biggest achievement or contribution, from your perspective, of the entire NanTroSEIZE program? What did you learn?

TH: For the scientific part, we know the stress state at the seismogenic zone in the Nankai area. That’s one of the biggest contributions. You know, people don’t know how the stress, how the forces, act on the wedge. It’s a quite important parameter for seismologists. We could reveal this stress state. That’s the most interesting thing to me.

BMR: And now that you’ve mentioned that this is something that’s not very well-known despite being a big contribution, I was thinking, how the people outside the scientific community – like policymakers or the public in Japan – how do you think they value this science?

TH: I see. We are still doing basic science. It’s not directly aimed at mitigating the earthquake damage, but we are developing knowledge  that contributes to the seismology. That is one important aspect. Also, when I talk to the NanTroSEIZE science community, basically they enjoy working with  the  latest science, current technology, and they do not think about what society wants from them. Politicians or the director of JAMSTEC complain a lot, of course (laughs). But when I talk to the engineers in universities or in industries, they always very supportive. They say things like  “it’s a big project, something totally new that’s never been done before. So, even if something goes wrong, that’s acceptable. That is part of the challenge.” When I heard those comments, I felt very reassured and… I think that we should keep doing these kinds of  things in the future.

BMR: Like, continuing with the…?

TH: Challenge.

BMR: Always at the limit (both laugh). Now that we are talking about policy making and politicians. How is the support to the Kochi Core Center? Is it different to the support for scientific ocean drilling? Do they understand the importance of having a core repository?

TH: The center itself?

BMR: I guess you have to apply for money to run the center…

TH: Oh yes, sure. But I feel like that we are currently not taking about  big money, here. For example, we have two parts: a scientific part and the core repository part. For the science part, of course, we need a lot of funding. But for the core repository, my feeling is that even though it’s an international facility, I feel like the amount of money required isn’t that big.  So, we really hope JAMSTEC or society will support the core curation continuously, as a part of its mission.

But for the scientific part, we do need significant funding. And for that, we have to apply for grants or find external sources. When we ask JAMSTEC,  they don’t provide  so much. But, somehow, we can manage to get funding from outside. That’s how I see it.  Regarding the money issue, I don’t worry too much. I just want to do good science, interesting science. That’s the most key point. 

BMR: It’s good that money doesn’t worry you so much (both laugh).

TH: Of course, scientists complain a lot, “we need much more money,” but as compared to other institutes or universities, we have enough budget.

BMR: I want to touch upon something you mentioned. This is an international facility, in the sense that it is part of the IODP repositories systems. How does the relationship between the Kochi Core Center and the other repositories work?

TH: Basically, the IODP curator makes a connection and they talk to each other and coordinate things. The IODP framework is well established, so far, so we just follow or modify a bit the previous framework. I really appreciate the people who make such a framework in the last 40 or 50 years. So, at the moment, I don’t feel like  a big issue. Everything works pretty smoothly.

BMR: Changing a bit of topic, I know that you’ve participated in some Chikyu expeditions for science, but also for industry or government. How different or similar are the expeditions for science and for other purposes?

TH: I joined this gas hydrate cruise as a kind of scientist. So, to me, there’s no difference between IODP or this commercial cruise. I conducted science and published a paper. I really enjoyed being onboard. I learned new things about gas hydrates. I really enjoyed. Maybe because I was not a co-chief, so no responsibility, basically (laughs). That’s the reason why I enjoyed. And one great thing is, at that cruise, there were scientists, engineers, technicians… gathered from all departments of JAMSTEC.  There wear many people I hadn’t worked with before , and we  got to know each other and strengthened our bonds. That was a really good opportunity. So, I like that kind of cruises. If there’s  another one in the future, I definitely like to join again.

BMR: What is the interaction of the Kochi Core Center with Chikyu?

TH: We receive all the cores, all the materials from Chikyu.  Everything comes here. And actually, it’s kind of the big event to install the new cores… a kind of festival (laughs). I really hope Chikyu will take more cores in the near future.

BMR: What are your future science plans, with scientific ocean drilling?

TH: I never really think about that (laughs). At the moment it’s kind of in the background, maybe because I’m getting older (laughs). I am definitely over 50 now (both laugh). We have a young generation here in Kochi, and I feel that if I join a cruise, I might be taking away opportunities from younger scientists. That’s my feeling. For example,  for the  recent JTRACK cruise, I just stayed here and support the outreach team instead. Of course, my background or experience is sometimes useful for the cruise, so I still talk with scientists and work with them on the science.

BMR: But also, you can see onboard that there’s senior, middle-career, and young-career scientists. And there’s like this mentorship relation going on between them, that’s kind of valuable onboard.

TH: Yeah, sure. If there’s opportunity to join as a mentor, I’m happy to join. Not as a co-chief (laughs),  too much responsibility —I couldn’t sleep (laughs). But if I can support young researchers as a menter, I’d love to join, of course.

BMR: What is the most valuable part, for your career, of your involvement in scientific ocean drilling?

TH: That’s quite important. In the scientific sense… in case of NanTroSEIZE, we made many holes, and collected  a lot of valuable data and cores or cutting materials. Also, there’s seismic data obtained by seismometers, the DONET. These kinds of datasets have been quite useful to expand my research. I think that is been a  key part for my career – having  access to this unique opportunity. It’s very difficult to to get this datasets otherwise. And… I really shared this situation with other scientists from all over the world.

BMR: And what have you learned about management, that’s been useful as Kochi Institute’s director?

TH: For example, the management of the onboard team is kind of a rare situation. All the scientists are from different disciplines, different countries, and different cultures. In the last cruise, there were more than 50 scientists. But somehow, we managed to work together and build a strong team. That made me confident. Here, in Kochi, (there are) more than fifty… fifty to sixty staff, similar numbers (laughs), scientist from different age and different disciplines, as well. Here, almost 90% of the staff are Japanese, so I know the culture and it’s actually easier to manage. That’s a good point for me (laughs).

BMR: You said that over these fifty staff people, there are about sixteen scientists. How do you decide who might be a good fit for the Kochi Center? I’m wondering about how to recruit – if I can ask this (laughs)

TH: I always think about that. There are many talented scientists around the world, but evaluating if they fit with this institute is… it’s not easy. We have many functions here– IODP science, and also JAMSTEC science  beyond drilling sciences. Our team includes people with very different skills, but sometimes we have to fill out some skills that we do not have. So we actively  look for researchers with those specific skills.

At the same time, the candidate has to fit into the environment of this institute. This institute is located  in the country side. Some of the European postdoc doesn’t like this place, because they like much more… like Tokyo area, or something like that. Sometimes it’s very hard to hire people for such a local instate. That’s a difficulty. But, somehow, we are looking for some talented scientists to fit here. Not easy (laughs).

BMR: Now that you mention the location of Kochi, why the Kochi Core Center is here? Which is paradoxical, because it’s probably one of the most high-risk areas (for tsunami hazard) in all Japan.

TH: That’s true. A lot of people have asked me this, actually. But this is behind politics. In 2002 or 2003, we got the budget to build such a repository, but JAMSTEC could not directly receive this type of budget because it’s a national institute. This budget can be accepted by a university. So, I’ve heard that JAMSTEC people were looking for a university to build to core repository using that budget, and Kochi University raised its hand. That’s the starting point of this institute.

BMR: They said, we have some empty land.

TH: Yes, yes. They could prepare the land, basically. That’s the key.

BMR: A core repository requires a lot of space… You might not be able to find it in Tokyo or Kanagawa prefecture.

TH: Yeah, that’s difficult.

BMR: After your seventeen years here, in Kochi, what do you think it’s the biggest achievement of the institute? And what is some part that still needs to be done?

TH: That’s very hard to say. There are many, many achievements. (laughs)

BMR: Well, you can say more than one (both laugh)

TH: With time, for example after the JFAST cruise, we published a Nature paper with the stress state. This contributed to the IODP science. Also, we have many bio-cruises. These cruises are led by our scientists here, and published many high-impact papers. The last few years, we have a Hayabusa 2 project led by JAXA but the recovered material from the Asteroid Ryugu came to here, and we analyzed them and contributed a lot. Uhm… So many, I couldn’t select. (laughs)

BMR: Essentially, a big list of scientific achievements that have had an impact worldwide. They’ve been a real contribution to science.

TH: Yeah, world science, basically.

BMR: Which is very interesting because, as you said, this is a relatively small center, in a quite remote place in Japan. Not in Tokyo or other well-known areas.

TH: Yeah.

BMR: So, what needs to be done?

TH: That’s difficult… Basically, I don’t care  too much about which journals something is published in or how the science is viewed from the outside. If the scientists here are really interested in, that’s the key. Whatever the paper is, whatever the science is, it’s okay. If they feel strongly and passionately about it , then they will show their passion to the outside world. That’s the key. My hope is that we can keep doing that kind of sscience in the future, as well.

BMR: We are about to finish but I just wanted to point out something. I realized that, although you are the director, you have a very close relationship with the staff here.

TH: Yeah, yeah, sure. It’s small, right?

BMR: Yeah, but I don’t think this is that common, that the director of a research center is so close to the scientists and other staff.

TH: One of the reasons is here is a branch of JAMSTEC. My feeling is that we have more freedom. In the main JAMSTEC, there are many other duties unrelated to science. In addition, the size of the building is just right for communication.

BMR: Are you also flexible to the workers?

TH: Yeah, sure. The city is also small. So, when I go to the city on Sunday, I meet someone who is related to here (laughs). It’s a very small world.

BMR: I see, it’s a small community, so it’s easier to communicate, or know what everyone is doing…

TH: I know their family, as well (both laugh), same school, same teachers…

BMR: That’s quite nice, actually!

TH: I’m not sure. There’re people who don’t like such a situation, but people here, they enjoy this situation.

BMR: Do you miss something from Osaka?

TH: Basically, no. I like people in Osaka, and I enjoy chatting with Osaka people, but nature is important for me. Clear air, nice landscape, sunlight, smells from the soil…

BMR: I can really understand. Is there something that you’d like to talk about that I haven’t ask you?

TH: No, so many questions (laughs)

BMR: Yes, (laughs) we’ve covered your entire life and career. Well, thank you very, very much. It was a pleasure.

TH: You’re welcome.

Pingpong match aboard Chikyu, during IODP Expedition 348. JAMSTEC/IODP