Archive for April, 2015

Nepal, April 2015: Magnitude 7.8 Main Shock and Magnitude 6.7 Aftershock

April 28, 2015

We actually do still record the old-style “paper on a rotating drum” seismograms at Weston Observatory.

Note, however, how much higher-quality the modern digital recordings are (see below). This makes it possible to learn much, much more about the earthquakes than we used to be able to.




USGS Tectonic Summary
2015-04-26 07:09:10 (UTC)
19km (12mi) SSE of Kodari, Nepal
Magnitude 6.7
depth=17.3 km (10.7 mi)


Magnitude 7.8 – 34km ESE of Lamjung, Nepal – April 25, 2015

April 25, 2015

NepalUSGS: “Seismicity in the Himalaya dominantly results from the continental collision of the India and Eurasia plates, which are converging at a relative rate of 40-50 mm/yr. Northward underthrusting of India beneath Eurasia generates numerous earthquakes and consequently makes this area one of the most seismically hazardous regions on Earth.”

USGS Tectonic Summary
2015-04-25 06:11:26 (UTC)
Magnitude 7.8
34km (21mi) ESE of Lamjung, Nepal
28.147°N 84.708°E depth=15.0 km (9.3 mi)

Magnitude 6.2 – 182km WSW of Bella Bella, Canada – April 24, 2015

April 24, 2015

MLMA NEMAUSGS Tectonic Summary
2015-04-24 13:56:16 (UTC)
182km (113mi) WSW of Bella Bella, Canada
51.769°N   -130.695°W
depth=10 km (6.2 mi)