Seismic moment tensors and estimated uncertainties in southern Alaska. Issue 4 (27th April 2016)

• Record Type: Journal Article
• Authors: Silwal, Vipul; Tape, Carl
• Is Part Of: Journal of geophysical research. Volume 121:Issue 4(2016:Apr.)
• Page Start: 2772
• Page End: 2797
• Publication Date: 2016-04-27
• Subjects: moment tensors -- uncertainty; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1002/2015JB012588
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: We present a moment tensor catalog of 106 earthquakes in southern Alaska, and we perform a conceptually based uncertainty analysis for 21 of them. For each earthquake, we use both body waves and surface waves to do a grid search over double couple moment tensors and source depths in order to find the minimum of the misfit function. Our uncertainty parameter or, rather, our confidence parameter is the average value of the curve 𝒫 ( V ), where 𝒫 ( V ) is the posterior probability as a function of the fractional volume V of moment tensor space surrounding the minimum misfit moment tensor. As a supplemental means for characterizing and visualizing uncertainties, we generate moment tensor samples of the posterior probability. We perform a series of inversion tests to quantify the impact of certain decisions made within moment tensor inversions and to make comparisons with existing catalogs. For example, using an L1 norm in the misfit function provides more reliable solutions than an L2 norm, especially in cases when all available waveforms are used. Using body waves in addition to surface waves, as well as using more stations, leads to the most accurate moment tensor solutions. Key Points: Catalog of 106 moment tensors using body waves and surface waves Moment tensor uncertainty estimates provided for 21 earthquakes Choices in the waveform misfit function influence the moment tensor solution