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TitleEarthquake and tsunami forecasts: Relation of slow slip events to subsequent earthquake rupture
AuthorDixon, T H; Jiang, YORCID logo; Malservisi, R; McCaffrey, R; Voss, N; Protti, M; Gonzalez, V
SourceProceedings of the National Academy of Sciences of the United States of America vol. 111, 48, 2014 p. 17039-17044, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20182282
PublisherProceedings of the National Academy of Sciences
Mediapaper; on-line; digital
File formatpdf
ProgramPublic Safety Geoscience Assessing Earthquake Geohazards
Released2014 11 17
AbstractThe 5 September 2012 Mw 7.6 earthquake on the Costa Rica subduction plate boundary followed a 62-y interseismic period. Highprecision GPS recorded numerous slow slip events (SSEs) in the decade leading up to the earthquake, both up-dip and down-dip of seismic rupture. Deeper SSEs were larger than shallower ones, if characteristic of the interseismic period, release most locking down-dip of the earthquake, limiting down-dip rupture and earthquake magnitude. Shallower SSEs were smaller, accounting for some but not all interseismic locking. One SSE occurred several months before the earthquake, but changes in Mohr-Coulomb failure stress were probably too small to trigger the earthquake. Because many SSEs have occurred without subsequent rupture, their individual predictive value is limited, but taken together they released a significant amount of accumulated interseismic strain before the earthquake, effectively defining the area of subsequent seismic rupture (rupture did not occur where slow slip was common). Because earthquake magnitude depends on rupture area, this has important implications for earthquake hazard assessment. Specifically, if this behavior is representative of future earthquake cycles and other subduction zones, it implies that monitoring SSEs, including shallow up-dip events that lie offshore, could lead to accurate forecasts of earthquake magnitude and tsunami potential.

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