The Japan Landslide Society

Online Web lecture by overseas researchers in fiscal year 2025

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　International Affairs Department,
　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　Japan Landslide Society (JLS)

　International Affairs Department of JLS will hold the online Web lecture on the date below. The speaker is Dr. Gordon G.D. Zhou, Key Laboratory of Mountain Hazards and Earth Surface Process / Institute of Mountain Hazards and Environment, Chinese Academy of Sciences. JLS members can join this online Website to register. The lecture and the following Q&A will be held in English.

1. Date: 9 January 2026, 17:00 – 19:00 in JST (16:00 – 18:00 in CST)
2. Online: Zoom
3. Organizer: Japan Landslide Society (JLS)
4. Capacity: 200 participants
5. Admission: fee for JLS members, 1,650 JPY (including tax) for non-member of JLS
6. Title: Segregation Dynamics in Landslides Across Varying Material and Fluid Conditions
7. Abstract:
　Particle size segregation plays a fundamental role in determining the dynamics, runout and deposit structure of landslides. In dry granular flows, segregation arises from shear-induced mechanisms such as kinetic sieving and squeeze expulsion, which produce coarse-rich surface layers and fine-rich basal zones that influence bulk friction, pore pressure evolution, and overall mobility. However, natural landslides often contain variable amounts of interstitial fluid and materials with diverse physical properties, introducing complexities that classical dry granular theories cannot capture. Our research focuses on how fluid content, density contrast, and surface friction differences affect segregation processes and how the resulting patterns feed back into flow behavior.
　Using numerical simulations, we find that viscous interstitial fluids primarily slow segregation by (i) buoyant forces that weaken contact stresses and (ii) viscous damping that suppresses granular temperature. Viscous effects become significant only above threshold viscosities, consistent with rheological transitions from viscous to inertial regimes. In the low-viscosity limit, where grain inertia dominate, segregation depends on flow conditions and material properties in a manner similar to dry granular flows. Building on these results, we develop a semi-empirical continuum model that captures the rate and magnitude of segregation in granular–fluid mixtures.
　To explore segregation in cold, mixed-material systems, discrete element simulations are applied to rock–ice landslides, which represent flows in glacierized or high-altitude regions. The size, density, concentration, and surface friction contrasts between rock and ice particles produce distinctive segregation patterns which induce sharp velocity gradients across the flowing layer. Regions enriched in low-friction ice tend to deform more rapidly, inducing creeping motion within underlying rock-rich zones dominated by higher frictional resistance. From these findings, we propose an effective mixture friction framework that accounts for the various material differences, extending a nonlocal granular fluidity model to describe the coupled segregation–flow feedbacks in rock–ice avalanches. This framework links micro-scale frictional heterogeneity to bulk mobility and stratification in multiphase landslides.
　Overall, understanding segregation behavior across a continuum from dry to fluid-rich and mixed-material conditions provides a unified basis for predicting the internal structure, entrainment and mobility of complex mass movements in natural terrains. These insights advance the development of physically grounded models for hazard assessment in diverse geomorphic settings.

8. Application
　8.1 Application Period: December 1, 2025 – January 5, 2026
　　　Advance application and payment are required. On-site applications are not accepted.
　8.2 (Note!) Registration is free for members.
　　　 Please apply via the application link below and follow the steps below.
　　　 This system’s screen display and email is in Japanese only.
　　(1) Enter your membership category, name, membership ID, etc., and
　　　　select Event 2 (2025 Japan Landslide Society Lecture by Overseas Researchers).
　　(2) Confirm that the participation fee is 0 yen and apply.
　　(3) A message will appear stating, “Please transfer the participation fee by the application deadline.”
　　　　Ignore this and close the window.
　　(4) Your application is complete when you receive an email stating,
　　　　”The following order has been completed. Total amount: 0 yen.”
　■Application Link: Click Here

　8.3 (For Non-members) Payment of the Participation Fee
　　- You can pay the participation fee by bank transfer or credit card.
　　- No refunds will be made if the application is cancelled after the application deadline.
　■ (For bank transfers) The bank account to transfer your payment to is as follows.
　　Please make the transfer so that the secretariat can confirm the payment by January 5, 2026.
　　Bank transfer details: Mizuho Bank, Shinbashi Chuo Branch
　　Regular account: 1901650
　　Account name: Japan Landslide Society, Public Interest Incorporated Association
　　　　　　　　　　SHA) NIHON JISBERIGATSUKAI
　■ (For credit card payments) VISA, MasterCard, JCB, and American Express are accepted.
　　Please pay according to the instructions on the screen.
　■ If you pay by credit card, you can print a receipt. If you pay by bank transfer, you can print an invoice.

　8.4 Forestry CPD members must also apply and pay through the society’s website.
　　　Forestry CPD members must register with both the Japan Landslide Society and JAFEE.
9. Lecture Materials
　Instructions on how to download the materials will be sent via email a few days before the presentation.
10. How to Connect to the Conference
　Participants will receive instructions on how to connect to the conference via email closer to the event date.
11. CPD: This is a JAFEE (affiliated with the Construction CPD Council)-accredited program (2.0 credits).
12. Contact: contact3=landslide-soc.org (Please replace “,” with “@” when sending)