International Joint Workshop on Slow-to-Fast Earthquakes 2023
Novia Anggraini
Institute of Seismology and Volcanology, Hokkaido University

In commemoration of the 100th anniversary of the Great Kanto Earthquake in 1923,
the International Joint Workshop on Slow-to-Fast Earthquakes this year was held at theUniversity of Tokyo, and the field trip was to observe the uplifting of the events in 1923 and1703 around Boso Peninsula. This meeting was very impressive, where people from different
backgrounds talked about the same topic, slow earthquakes.
This is my first time participating in this meeting. It is always thrilling to attend
academic meetings for the first time. However, this meeting had a family feel, which made me
comfortable being a part of it. I had a presentation on the first day. I could see that all thecommittees had prepared everything well so that I could present my topic smoothly. I learned
many things from other presentations, found new terms, new approaches, the development of
the science of slow earthquakes, and so on. One of my favorite sessions was group discussion.
I joined a group that I think is relevant to me: "International Joint Research with Developing
Countries." In this group, we shared the problems that we thought had become obstacles toconducting international joint research with developing countries and addressed some solutions.
This session is beneficial in broadening our point of view on the research world in general andslow earthquakes, to be precise. On Friday, I had the opportunity to visit the Earthquakes
Research Institute (ERI) and obtain an explanation of the construction of this earthquakeresilient building, the OBS, and a seismograph museum in the basement of the building.
After the three main days, the next day, we went on a field trip to the southern area ofthe Boso Peninsula in Chiba. The purpose is to observe the terraces uplifted in large events inthis area. We had three stops: Kenbutsu Coast, Shirahama Coast, and Chikura Coast. On theKenbutsu coast, we could see the terraces from the 1923 and 1703 events. Meanwhile, inShirahama, there is only the uplifting from the latest event. From these locations, we could findcoral fossils attached to the rocks, which show quite different characteristics. These fossils help
scientists estimate the time when the event happened by calculating radiocarbon decay. InKenbutsu, we found oyster fossils, and in Shirahama, we found blue-coral worm fossils.
Different from the two stops, in the last stop, we could also find traces of prehistoric events
that were located quite far from the coast.

To sum up, this meeting provided very useful and practical knowledge. I hope thescience of slow-to-fast earthquakes and this meeting continue to make innovations for scienceand the community.

Figure 1. The venue of International Joint Workshop on Slow-to-Fast Earthquakes 2023 in Ito InternationalResearch CenterFigure 2. Omori Long Period Seismograph exhibited in Seismograph Museum of ERI

Terrace from 1703
earthquake
Terrace from 1923
earthquake

Figure 3. Terraces from 1923 and 1703 events in Kenbutsu Coast

Figure 4. Terrace from 1923 Great Kanto Earthquake in Shirahama CoastFigure 5. The location where trace of large event in 2,000 yBP, found ~300m from the coast.

Figure 6. The location where trace of large event in 3,200 yBP, found ~700 m from the coast.