Dynamics of the 2015 M7.8 Nepal earthquake

TitleDynamics of the 2015 M7.8 Nepal earthquake
Publication TypeJournal Article
Year of Publication2015
AuthorsDenolle M.A, Fan W.Y, Shearer PM
JournalGeophysical Research Letters
Date Published2015/09
Type of ArticleArticle
ISBN Number0094-8276
Accession NumberWOS:000363412400030
Keywordsdepth; earthquake; energy; fault; gorkha; great earthquakes; kathmandu basin; main himalayan thrust; Nepal Earthquake; radiated energy; rupture; shallow earthquake; source spectra; stress drop

The 2015 M7.8 Nepal earthquake ruptured part of the Main Himalayan Thrust beneath Kathmandu. To study the dynamics of this event, we compute P wave spectra of the main shock and of two large aftershocks to estimate stress drop and radiated energy. We find that surface reflections (depth phases) of these shallow earthquakes produce interference that severely biases spectral measurements unless corrections are applied. Measures of earthquake dynamics for the main shock are within the range of estimates from global and regional earthquakes. We explore the azimuthal and temporal variations of radiated energy and highlight unique aspects of the M7.8 rupture. The beginning of the earthquake likely experienced a dynamic weakening mechanism immediately followed by an abrupt change in fault geometry. Correlation of backprojection results with frequency-dependent variations in the radiated energy rate and with the suggested geometry of the Main Himalayan Thrust yields new constraints on dynamic ruptures through geometrical barriers.

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