Electronic Supplement to
Strong-Motion Observations of the M 7.8 Gorkha, Nepal, Earthquake Sequence and Development of the N-SHAKE Strong-Motion Network

by Amod Mani Dixit, Adam T. Ringler, Danielle F. Sumy, Elizabeth S. Cochran, Susan E. Hough, Stacey S. Martin, Steven Gibbons, James H. Luetgert, John Galetzka, Surya Narayan Shrestha, Sudhir Rajaure, and Daniel E. McNamara

This electronic supplement presents figures of Pg arrivals, earthquake locations, epicenter change vectors, and travel-time misfit vector residuals, and tables of QCN and NetQuake stations and relocated hypocenter timing, location, and magnitude.

Earthquake Relocations

With the earthquake relocation procedures described in the main article, we examine the use of local waveforms recorded by the Quake-Catcher Network (QCN) and the U.S. Geological Survey NetQuakes permanent sensor KATNP and show how they affect the epicentral location of the earthquakes.

Figures

Figure S1. (a) 25 April 2011 M 7.8 Pg arrivals recorded at stations roughly 70 km away in Kathmandu (NQ.KATNP, QC.31523). (b) Map of the M 7.8 mainshock epicentral region. The red dots are earthquake locations scaled by magnitude. Also shown are epicenter change vectors and 95th percentile confidence uncertainty ellipses determined in the hypocentroidal decomposition relocation analysis.

Figure S2. Additional constraints on event hypocenter location using P- and S-wave arrival time picks on a QCN station at near-regional distances. The event is a magnitude 5 aftershock with an approximate origin time of 06:53:42.7 UTC on 25 April 2011. (a), (b), and (c) The L1 travel-time misfit vector residual, shown in three different sections through a volume of trial hypocenters (1° × 1° × 25 km in depth), for which the only constraints are with teleseismic P-wave arrivals. The azimuthal distribution of stations is good, but there is no resolution in depth. Clear P-wave and S-wave arrivals were observed on station QCN 45298 (location indicated by the red triangle), and this significantly reduces the location uncertainty, shown in (d), (e), and (f). A depth of close to 10 km appears to be most probable.

Tables

Table S1. QCN and NetQuake parameters (station name and type, sample rates, location, and installation and/or online date).

Table S2. Relocated earthquake hypocenter timing, location, and magnitude (W-phase moment magnitude Mww, short-period body-wave magnitude mb, surface-wave magnitude Ms, regional-phase moment magnitude Mwr, and body-wave moment magnitude Mwb)

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