Carbon dioxide eruptions triggered by the 2015 earthquake in Nepal
An international team has highlighted disturbances in the flow of gases and fluids in the Earth's crust following the Gorkha earthquake in 2015. These observations are leading to a better understanding of the role of hydrothermal systems in the deformation associated with this earthquake.
Publication date: 26/07/2018
Press, Research
Related teams :
Physics of natural sites
Related themes : Natural Hazards
Current knowledge does not allow us to predict major earthquakes, even though a growing population in northern India, for example, is exposed to this type of risk. However, a number of scientific avenues are currently being explored to gain a better understanding of the mechanisms that trigger an earthquake, as well as the effects that the earthquake has around it. The effects of fluids in the earth’s crust (circulation of underground water, emission of carbon dioxide (CO2)) following an earthquake suggest a strong interaction between these fluids and the mechanisms linked to earthquakes.
The deadly Gorkha earthquake in Nepal in April 2015, followed by numerous aftershocks that considerably complicated the work of the rescue services, is still remembered as a major disaster at the start of this century. It was also the first earthquake in the Himalayas for which instrumentation of the area enabled a comparison of measurements taken before and after the quake. These circumstances enabled scientists to make some spectacular observations.
In a study published in Nature Communications on July 27th, an international team led by researchers from the Institut de Physique du Globe de Paris (IPGP) has shown that this seismic crisis was accompanied by massive CO2 gas emissions in the vicinity of hot springs in the high Himalayan range. These emissions occurred at several sites more than 10 kilometres apart, and continue to this day. What’s more, one of these hot springs, an important pilgrimage site, completely stopped 6 months after the earthquake.
These observations show for the first time that the upwelling of this CO2 produced in the Earth’s crust, which can be identified by its isotopic composition, is closely linked to earthquakes. In addition, intermittent puffs of CO2 were observed before the Gorkha earthquake, once again opening up the possibility of the existence of earthquake precursor signals. These pre-seismic observations have yet to be confirmed, but new studies are already underway to analyse this prospect more precisely.
Ref: Girault, F., Adhikari, L.B., France-Lanord, C., Agrinier, P., Koirala, B.P., Bhattarai, M., Mahat, S.S., Groppo, C., Rolfo, F., Bollinger, L., Perrier, F. (2018). Persistent CO2 emissions and hydrothermal unrest following the 2015 earthquake in Nepal. Nature Communications, doi:10.1038/s41467-018-05138-z
