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Basal nucleation and the prevalence of ascending swarms in Long Valley caldera

Li, Bing Q. and Smith, Jonathan D. and Ross, Zachary E. (2021) Basal nucleation and the prevalence of ascending swarms in Long Valley caldera. Science Advances, 7 (35). Art. No. eabi8368. ISSN 2375-2548. PMCID PMC8397262. doi:10.1126/sciadv.abi8368.

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Earthquake swarms are ubiquitous in volcanic systems, being manifestations of underlying nontectonic processes such as magma intrusions or volatile fluid transport. The Long Valley caldera, California, is one such setting where episodic earthquake swarms and persistent uplift suggest the presence of active magmatism. We quantify the long-term spatial and temporal characteristics of seismicity in the region using cluster analysis on a 25-year high-resolution earthquake catalog derived using leading-edge deep-learning algorithms. Our results show that earthquake swarms beneath the caldera exhibit enlarged families with statistically significant tendency for upward migration patterns. The ascending swarms tend to nucleate at the base of the seismogenic zone with a spatial footprint that is laterally constrained by the southern rim of the caldera. We suggest that these swarms are driven by the transport of volatile-rich fluids released from deep volcanic processes. The observations highlight the potential for extreme spatial segmentation of earthquake triggering processes in magmatic systems.

Item Type:Article
Related URLs:
URLURL TypeDescription Materials CentralArticle
Li, Bing Q.0000-0002-4158-4941
Smith, Jonathan D.0000-0002-1684-1344
Ross, Zachary E.0000-0002-6343-8400
Additional Information:© 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution License 4.0 (CC BY). Submitted 2 April 2021; Accepted 8 July 2021; Published 27 August 2021. We thank A. Flinders for providing the detailed velocity model and A. Hotovec-Ellis and D. Shelly for the insightful reviews. B.Q.L. was partially supported by NSF/IUCRC Geomechanics and Mitigation of Geohazards (NSF award 1822214). This study was partially supported by NSF award EAR-2034167. Author contributions: B.Q.L. constructed the earthquake catalog and conducted the cluster analysis. All authors contributed to the conceptualization, interpretation, and editing of the manuscript. The authors declare that they have no competing interests. Data and materials availability: All raw waveforms are available through the NCEDC (, SCEDC (, and IRIS ( All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials.
Group:Seismological Laboratory
Funding AgencyGrant Number
Issue or Number:35
PubMed Central ID:PMC8397262
Record Number:CaltechAUTHORS:20210830-140310619
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Official Citation:B. Q. Li, J. D. Smith, Z. E. Ross, Basal nucleation and the prevalence of ascending swarms in Long Valley caldera. Sci. Adv. 7, eabi8368 (2021); DOI: 10.1126/sciadv.abi8368
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:110601
Deposited By: Tony Diaz
Deposited On:30 Aug 2021 16:35
Last Modified:26 Oct 2022 18:25

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