Curved Fault Slip Captured by CCTV Video During the 2025 Mw 7.7 Myanmar Earthquake

Earthquake caught on cameraCCTV映像の解析で明らかになったミャンマー地震の断層すべり挙動 --湾曲したすべりとパルス的破壊の動態に関する新知見-- . 京都大学プレスリリース. 2025-07-24.On-fault geological observations from surface-breaking earthquakes typically contain curved slickenlines, suggesting fault slip is curved. However, slickenlines commonly record only a fraction of coseismic slip, making it difficult to reconstruct the full slip trajectory. Near-fault seismic records, though capable of capturing ground motions associated with rupture, are limited in their ability to constrain on-fault slip direction because they record motion on only one side of the fault. Here, we overcome these challenges by directly observing fault slip using video footage of the 2025 Mw 7.7 Myanmar, strike-slip earthquake. We use pixel cross correlation to track features in successive frames of the video, revealing a pulse of fault slip with a magnitude of 2.5 ± 0.5 m, a duration of 1.3 ± 0.2 s, and a peak velocity of 3.2 ± 1.0 m/s. The observed trajectory is notably curved and includes a transient (0.3 m) dip-slip component on a steeply dipping strike-slip fault. These observations are consistent with geological records of curved slickenlines, supporting mechanical models that link rupture propagation direction to near-surface slip curvature. Our results provide the first direct visual evidence of curved coseismic fault slip, bridging a critical gap among seismological observations, geological data, and theoretical models

Impact of land tenure security on technical efficiency for maize production: the case of Central province in Zambia

The impact of land tenure security on smallholder crop productivity in Sub-Sahara Africa (SSA) is inconclusive. In Zambia, maize production which serves to satisfy national food security requirements and the generation of foreign exchange from maize exports to regional markets is a big challenge, whereby the majority maize producers are smallholders under an insecure customary land tenure system. We employed an endogeneity-robust stochastic production frontier (SPF) framework to examine the effect of land tenure security on technical efficiency (TE) for smallholder maize producers in Zambia's Central province. Synthetic Minority Oversampling Technique (SMOTE) was used to treat sample class imbalance between Title Deed Certificate (TDC) holders and non-holders. Our main findings show that use of land on TDCs, including that on customary land tenure types, such as chief-authorized and inherited land had significant impacts on mean TE expansion for smallholder maize production. The production function showed that only chemical fertilizer had a significant positive marginal effect on maize output under drought conditions. Use of oxen helped to expand average maize output. A 90.15% average TE implied that only a small maize output improvement was still possible, using same inputs and technology, under same climatic conditions. We associated the 3–4 ha TE dip with productive capacity transition from subsistence to market-oriented farming. For policy improvements, we recommended the legal recognition of some customary land tenure types, alongside TDC issuances. Lastly, we recommended the expansion of smallholder fertilizer support, and scale efficiency improvement, including minimum land use rate legislation, for eventual maize output expansion in Zambia

複雑性による量子力学と古典力学のカオス性の研究

京都大学新制・課程博士博士(理学)甲第25812号理博第5123号京都大学大学院理学研究科物理学・宇宙物理学専攻(主査)教授 橋本 幸士, 教授 杉本 茂樹, 教授 齊藤 圭司学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDFA

Validation Data for optimal design of 3D-steel frames as assembly of 2D-frames

鋼構造立体骨組の最適設計のための強化学習エージェントを訓練するためのプログラムと論文に使用した検証デー

Do Zambian farmers manage climate risks?

This study investigates production responses to climate risk among farmers in Zambia by combining historical rainfall with nationally representative household data. After identifying the importance of January and February rainfall in maize production, we define these months' historical rainfall variations as the climate risk index. We then relate this index to agricultural decisions. Results indicate little crop or plot diversifications in response to weather risks. Conversely, farmers in high-climate-risk regions apply less fertilizer and consequently achieve lower maize yields than their counterparts in low-risk regions. Overall, Zambian farmers manage climate risk by underinvesting risky inputs at the expense of returns

Trajectory tracking control of slidable-wheel omnidirectional mobile robot based on linear model predictive control

Omnidirectional mobile robots with conventional wheels avoid the drawbacks (e.g., shock, slippage, and low load capacity) of omnidirectional mobile robots with wheels that have special structures. We previously proposed such a robot, called the slidable-wheel omnidirectional mobile robot (SWOM), as well as its controller for point-to-point movement. However, for practical applications, such as transporting goods in factories and warehouses, SWOM needs to be able to follow a predefined trajectory. In this paper, we present the design of a trajectory tracking controller for SWOM. Given that SWOM is a nonlinear system with constraints on both inputs and outputs, model predictive control (MPC) is adopted. Due to the high computational demands and time consumption associated with nonlinear MPC, linear MPC is used to achieve trajectory tracking. By expanding the previous research, an original method for generating a reference path that includes not only state variables but also inputs is proposed in this paper for the trajectory tracking task. The linearized kinematic model of SWOM is obtained using a first-order Taylor expansion around reference points on the reference path. Simulations considering slippage are conducted and the results show that SWOM can well track the reference path. Experiments conducted on a prototype also validate the effectiveness of the proposed control method

Fast enumeration of all cost-bounded solutions for combinatorial problems using ZDDs

We propose a fast method for exactly enumerating a large number of all cost-bounded solutions for combinatorial problems using Zero-suppressed Binary Decision Diagrams (ZDDs). Enumerating cost-bounded solutions is an important task to know the exact ranking of any given solution, and it enables statistical p-value evaluation and quality-controlled random sampling. Our method is based on a backtracking search for a given ZDD representing the set of all feasible solutions. The key idea is to integrate “BDD operation cache” technique and “interval-memoizing” technique with a depth-first manner of backtracking procedure. The computation time of the algorithm is empirically bounded by the input and output sizes of ZDDs. It can be significantly faster than existing enumeration systems, especially when the input and output ZDDs are well-compressed and the range of the cost constraint is large. As application examples, we applied our method to a set of difficult instances of the Hamiltonian cycle/path problems. Although it is NP-hard to find any one feasible solution without cost constraints, we tried more difficult problems to enumerate all cost-bounded solutions, and succeeded in implicitly enumerating all cost-bounded solutions for many nontrivial instances which contain billions of solutions. As cost constraints often appear in many real-life situations, our method will be useful in various fields, including data mining, statistical testing, hardware/software design, and many other operations research problems