Source-linked AI summary
Quantifying Human Mobility Perturbation and Resilience in Natural Disasters
Qi Wang, John E. Taylor
TL;DR
Human movements during natural disasters are poorly characterized because empirical data are limited and available measurements may lack precision. The study analyzes high-resolution Twitter movement data from New York City during and after Hurricane Sandy, finding significant but brief mobility perturbation and strong resilience. It also reports correlations between steady-state and perturbed mobility measures, suggesting steady-state data may help predict perturbation states.
Problem
Human movements during disasters are comparatively little understood because available evidence is limited and mobile-phone data may lack the precision needed to capture disaster-related mobility changes.
Method
The study examines high-resolution Twitter movement data collected in New York City during and for several days after Hurricane Sandy.
Results
Hurricane Sandy perturbed New York City mobility, but the perturbation lasted less than 24 hours before aggregate mobility returned to a steady state.
Takeaways & Limitations
Steady-state human mobility measures may help predict perturbation states, while mobility patterns can remain resilient during a hurricane.
Takeaways & Limitations
The study’s disaster-mobility evidence is constrained by the precision and coverage limitations of available mobile-phone data, including tower-based coverage areas.
Abstract
from arXiv · showhide
Human mobility is influenced by environmental change and natural disasters. Researchers have used trip distance distribution, radius of gyration of movements, and individuals' visited locations to understand and capture human mobility patterns and trajectories. However, our knowledge of human movements during natural disasters is limited owing to both a lack of empirical data and the low precision of available data. Here, we studied human mobility using high-resolution movement data from individuals in New York City during and for several days after Hurricane Sandy in 2012. We found the human movements followed truncated power-law distributions during and after Hurricane Sandy, although the β value was noticeably larger during the first 24 hours after the storm struck. Also, we examined two parameters: the center of mass and the radius of gyration of each individual's movements. We found that their values during perturbation states and steady states are highly correlated, suggesting human mobility data obtained in steady states can possibly predict the perturbation state. Our results demonstrate that human movement trajectories experienced significant perturbations during hurricanes, but also exhibited high resilience. We expect the study will stimulate future research on the perturbation and inherent resilience of human mobility under the influence of natural disasters. For example, mobility patterns in coastal urban areas could be examined as tropical cyclones approach, gain or dissipate in strength, and as the path of the storm changes. Understanding nuances of human mobility under the influence of disasters will enable more effective evacuation, emergency response planning and development of strategies and policies to reduce fatality, injury, and economic loss.
Disasters
Using high-resolution Twitter movement data from New York City during and after Hurricane Sandy, the study finds that mobility was significantly perturbed but rapidly resilient. Displacement patterns changed during the first 24 hours, while steady-state mobility measures correlated with perturbation measures.
- Motivation: Human mobility during natural disasters remains comparatively understudied because available data are limited and often lack the precision needed to capture rapid changes.The study addresses this gap using high-resolution movement data from New York City during and after Hurricane Sandy.
- Mobility perturbation: Short-distance trips under 1 km increased during the first 24-hour period, while longer-distance travel significantly decreased.These changes provided evidence that Hurricane Sandy perturbed human mobility.
- Resilience: The perturbation’s significance lasted less than 24 hours, with aggregate mobility returning to a steady state on October 30, 2012.Post-disaster trajectories generally showed similar patterns, except during the first 24-hour period.
- Individual responses: Individuals primarily perturbed mobility by shifting their movements to different places and changing their travel distances.The study interprets this resilience as maintaining mobility, albeit over shorter distances, including movement toward safer places during a hurricane.
- Resilience: The center-of-mass shift ΔdCM and radius of gyration rg^N were strongly correlated, supporting use of steady-state mobility to predict perturbation states.The study reports a correlation coefficient of 0.23 with p<0.001 and describes ΔdCM as following a stretched exponential distribution.