Radon signature of CO flux constrains the depth of degassing: Furnas volcano (Azores, Portugal) versus Syabru-Bensi (Nepal Himalayas).

Substantial terrestrial gas emissions, such as carbon dioxide (CO), are associated with active volcanoes and hydrothermal systems. However, while fundamental for the prediction of future activity, it remains difficult so far to determine the depth of the gas sources. Here we show how the combined measurement of CO and radon-222 fluxes at the surface constrains the depth of degassing at two hydrothermal systems in geodynamically active contexts: Furnas Lake Fumarolic Field (FLFF, Azores, Portugal) with mantellic and volcano-magmatic CO, and Syabru-Bensi Hydrothermal System (SBHS, Central Nepal) with metamorphic CO.

Author Correction: Widespread ground motion distribution caused by rupture directivity during the 2015 Gorkha, Nepal earthquake.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Persistent CO emissions and hydrothermal unrest following the 2015 earthquake in Nepal.

Fluid-earthquake interplay, as evidenced by aftershock distributions or earthquake-induced effects on near-surface aquifers, has suggested that earthquakes dynamically affect permeability of the Earth's crust. The connection between the mid-crust and the surface was further supported by instances of carbon dioxide (CO) emissions associated with seismic activity, so far only observed in magmatic context. Here we report spectacular non-volcanic CO emissions and hydrothermal disturbances at the front of the Nepal Himalayas following the deadly 25 April 2015 Gorkha earthquake (moment magnitude M = 7.

Widespread ground motion distribution caused by rupture directivity during the 2015 Gorkha, Nepal earthquake.

The ground motion and damage caused by the 2015 Gorkha, Nepal earthquake can be characterized by their widespread distributions to the east. Evidence from strong ground motions, regional acceleration duration, and teleseismic waveforms indicate that rupture directivity contributed significantly to these distributions. This phenomenon has been thought to occur only if a strike-slip or dip-slip rupture propagates to a site in the along-strike or updip direction, respectively.