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Sunday
Apr262015

Nepal, 25 April, 2015 - Mw 7.9

The large earthquake and its aftershocks that struck beneath the Katmandu region of Nepal produced widespsread damage. The USGS page has the scientific information, and you can visit earthquake-report.com for updates. Here's a map of Mainshock and aftershock locations. The aftershock locations relative to that of the mainshock suggest that the rupture propagated about 140 km from NW to SE and extended beneath Katmandu.

There are not many openly available seismic stations in or near the source region. The two closest include LSA, Lhasa, Tibet, China (about 600 km away) and Shillong, Meghalaya, India (about 700 km away). The latency of data at both stations may be significant.

IC; LSA; 00; BHZ; Lhasa, Tibet, China (Vertical)
IC; LSA; 00; BH2; Lhasa, Tibet, China (East-West)
IC; LSA; 00; BH1; Lhasa, Tibet, China (North-South
IN; SHL; --; HHZ;  Shillong, Meghalaya, India (Vertical)
IN; SHL; --; HHE;  Shillong, Meghalaya, India (East-West)
IN; SHL; --; HHN;  Shillong, Meghalaya, India (North-South

Here is the mainshock at LSA on two different instruments at LSA. The top three channels show the strong-motion instrument and the lower three show the broad-band instrument. The strong-motion sensor has a better short-period response and does not go off scale, as did the broadband sensor. The broadband sensor would be better for detecting smaller aftershocks.

 

Right now the latency at SHL is low. Here's a recent aftershock plot (these observations are from several hundred km from the epicentral region). 

For reference, here's a map of the station locations: