科研之友
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摘要
The 2017 Guptkashi earthquake occurred in a segment of the Himalayan arc with high potential for a strong earthquake in the near future. In this context, a careful analysis of the earthquake is important as it may shed light on source and ground motion characteristics during future earthquakes. Using the earthquake recording on a single broadband strong-motion seismograph installed at the epicenter, we estimate the earthquake's location (30.546A degrees A N, 79.063A degrees A E), depth (H = 19 km), the seismic moment (M (0) = 1.12x10(17) Nm, M (w) 5.3), the focal mechanism (phi = 280A degrees, delta = 14A degrees, lambda = 84A degrees), the source radius (a = 1.3 km), and the static stress drop (Delta sigma (s) similar to 22 MPa). The event occurred just above the Main Himalayan Thrust. S-wave spectra of the earthquake at hard sites in the arc are well approximated (assuming omega (-2) source model) by attenuation parameters Q(f) = 500f (0.9), kappa = 0.04 s, and f (max) = infinite, and a stress drop of Delta sigma = 70 MPa. Observed and computed peak ground motions, using stochastic method along with parameters inferred from spectral analysis, agree well with each other. These attenuation parameters are also reasonable for the observed spectra and/or peak ground motion parameters in the arc at distances ae 200 km during five other earthquakes in the region (4.6 ae M (w) ae > 6.9). The estimated stress drop of the six events ranges from 20 to 120 MPa. Our analysis suggests that attenuation parameters given above may be used for ground motion estimation at hard sites in the Himalayan arc via the stochastic method.
- 出版日期2018-5
