Emergency communications after earthquake reveal social network backbone of important ties

Jayson S. JIA*, Yiwei LI, Sheng LIU, Nicholas A. CHRISTAKIS, Jianmin JIA

*Corresponding author for this work

Research output: Journal PublicationsJournal Article (refereed)peer-review


Social networks provide a basis for collective resilience to disasters. Combining the quasi-experimental context of a major earthquake in Ya'an, China, with anonymized mobile telecommunications records regarding 91,839 Ya'an residents, we use initial bursts of postdisaster communications (e.g. choice of alter, order of calls, and latency) to reveal the "important ties"that form the social network backbone. We find that only 26.8% of important ties activated during the earthquake were the strongest ties during normal times. Many important ties were hitherto latent and weak, only to become persistent and strong after the earthquake. We show that which ties activated during a sudden disaster are best predicted by the interaction of embeddedness and tie strength. Moreover, a backbone of important ties alone (without the inclusion of weak ties ordinarily seen as important to bridge communities) is sufficient to generate a hierarchical structure of social networks that connect a disaster zone's disparate communities.

Original languageEnglish
Article numberpgad358
JournalPNAS Nexus
Issue number11
Early online date2 Nov 2023
Publication statusPublished - Nov 2023

Bibliographical note

© The Author(s) 2023. Published by Oxford University Press on behalf of National Academy of Sciences.


  • earthquake disaster
  • quasi-experiment
  • social network activation
  • structural embeddedness
  • tie strength


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