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Anomalous Surge in the Mobility Scaling Exponent Reveals Unique Collective Behavior during the 2024 Noto Peninsula Earthquake

  • Atushi Ishikawa 1,*,†,   
  • Shouji Fujimoto 1,†,   
  • Takayuki Mizuno 2,†

Received: 29 Sep 2025 | Revised: 12 Dec 2025 | Accepted: 13 Jan 2026 | Published: 27 Jan 2026

Abstract

A scaling law, SLα, governs the relationship between the area S enclosed by a human mobility loop and its trajectory length L. Previous studies have established that for short-range movements (L < 5 km), the scaling exponent is typically α ∼ 2.0, indicative of two-dimensional efficient exploratory behavior that efficiently covers the surrounding area. For long-range movements (L ≥ 5 km), it is typically α ∼ 1.5–1.6, corresponding to one-dimensional destination-oriented behavior characterized by a nearly straight-line trajectory toward the destination. In this study, we analyze highresolution (1-min interval) GPS data from Agoop, comprising approximately 20,000 daily records, to examine human mobility traces in Ishikawa Prefecture before and after the Noto Peninsula Earthquake on 1 January 2024. We focus on the changes in the scaling exponent α. This major earthquake provides a valuable “natural experiment” to investigate collective human behavior under established social norms. Our analysis revealed a highly anomalous phenomenon immediately following the earthquake. Contrary to normal conditions, the long-range scaling exponent, αLong, surged to α ∼ 1.8 across the entire prefecture, a value comparable to the short-range exponent, αShort. This phenomenon was observed even in areas with relatively minor physical damage and returned to its baseline value by the next day. This anomalous change in the scaling exponent strongly suggests that the shift in mobility patterns was not a direct result of the earthquake’s physical damage. Rather, it indicates that individuals who were outdoors temporarily altered their movement from one-dimensional, destination-oriented travel to two-dimensional, exploratory behavior while evacuating to safer locations, such as higher ground, in response to tsunami alerts. This study is the first to demonstrate that the mobility scaling exponent can function as a real-time quantitative indicator for characterizing collective psychological states, such as widespread precautionary evacuation, even in the absence of direct physical damage.

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Ishikawa, A.; Fujimoto, S.; Mizuno, T. Anomalous Surge in the Mobility Scaling Exponent Reveals Unique Collective Behavior during the 2024 Noto Peninsula Earthquake. Journal of Social Physics 2026, 1 (1), 3.
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