Conference paperOpen access
Groundwater anomalies associated with seismic activity in the North Fergana fault zone: Insights from the Chartak No. 2 well
https://doi.org/10.1051/e3sconf/202674501006
Highlights
- Monitoring period: 2002–2025, Chartak No. 2 well, North Fergana deep fault zone.
- Earthquakes selected with M ≥ 4.5 and M/lgR ≥ 2.5; 7-day and 91-day median filters.
- Most informative parameters: He, H₂, CO₂, pH and Eh.
- Correlations in 2024–2026: O₂–N₂ −0.97, O₂–CH₄ −0.86, He–CH₄ +0.81, He–O₂ −0.80; N₂–CO₂ from −0.59 (2003–2005) to −0.84 (2012–2014).
Keywords
- hydrogeoseismology
- groundwater
- gas geochemistry
- Fergana depression
- Chartak
- fault zone
Summary
The authors, from the Institute of Seismology of the Academy of Sciences of Uzbekistan, analysed monitoring data for 2002–2025 from the Chartak No. 2 observation well, which taps confined groundwater in fractured and porous reservoirs in the North Fergana deep fault zone. They looked at dissolved gases (helium, hydrogen, oxygen, nitrogen, carbon dioxide and methane), water chemistry (pH, Eh, bicarbonate) and water temperature.
Earthquakes were selected by magnitude (M ≥ 4.5) and an energy criterion (M/lgR ≥ 2.5), and the volumetric strain at the well was calculated with the Dobrovolsky model. Median filters of 7 and 91 days removed seasonal and short-term variation.
Gas parameters were the most sensitive to deformation before earthquakes; helium, hydrogen, carbon dioxide, pH and Eh were the most informative. Short-term anomalies appear as sharp spikes and trend reversals, long-term ones as a gradual restructuring of the water chemistry. The authors attribute them to changes in permeability caused by deformation, stronger rise of deep fluids and a disturbed balance between water, rock and gas. Water temperature was the most stable parameter and showed only a weak link to earthquake preparation. The paper gives no values for water temperature, well depth or mineralization.
How to cite
Gulhayo Hasanova and Alisher Rasulov (2026). Groundwater anomalies associated with seismic activity in the North Fergana fault zone: Insights from the Chartak No. 2 well. E3S Web of Conferences, vol. 745 (School of Young Seismologists, YSS 2026), 01006. https://doi.org/10.1051/e3sconf/202674501006