15:30 〜 16:30
[S06-P-04] Similarities and differences of a hydrogeological response to underground nuclear explosions and earthquakes
We analyzed hydrogeodynamic state change due to large-scale underground nuclear explosions that had took place on the Semipalatinsk testing area (USSR, present Kazakhstan) in 1983-1989. We performed to mark out several key stages of hydrogeodynamic state change:
1. Excess reservoir pressure at the moment of the explosion
2. Drop-like or gradual level decrease to the initial value or even below depending to entire volume of induced fracturing and existence of hydraulic link to zones that were weakened by explosion and connected to explosion epicenter.
3. Establishment of quasi-stationary underground water flow and subsequent level recovery to the initial static state.
Marked stages' duration depends on explosion characteristics, geological-structural and hydrogeological conditions of testing area. We discovered that both co-seismic and post-seismic hydrogeological effects due to explosions are often similar to those associated with the passage of the waves of large-scale earthquakes in the case of solid massif but can differ in the affected zones of faults of different range. We considered vertical velocity of ground motion as the parameter of comparison.
We found out differences in the nearest zone of explosions and earthquakes in case of peak ground velocity exceeding 40 cm/s. Maximum water level decrease lasted more than three months after the burst in the wellbore on the Semipalatinsk testing area whereas post-seismic level changes after earthquakes usually end in hours or days. Certain exceptions tend to fault zones where water level alterations sometime come up to tens of meters. Following research will show does this difference relates either to local geological-structural peculiarities of different fault zones or inherent physics of impact.
This work was supported by the Russian Science Foundation (Project No. 16-17-00095) and Russian Academy of Science (Project No 0146-2015-0012).
1. Excess reservoir pressure at the moment of the explosion
2. Drop-like or gradual level decrease to the initial value or even below depending to entire volume of induced fracturing and existence of hydraulic link to zones that were weakened by explosion and connected to explosion epicenter.
3. Establishment of quasi-stationary underground water flow and subsequent level recovery to the initial static state.
Marked stages' duration depends on explosion characteristics, geological-structural and hydrogeological conditions of testing area. We discovered that both co-seismic and post-seismic hydrogeological effects due to explosions are often similar to those associated with the passage of the waves of large-scale earthquakes in the case of solid massif but can differ in the affected zones of faults of different range. We considered vertical velocity of ground motion as the parameter of comparison.
We found out differences in the nearest zone of explosions and earthquakes in case of peak ground velocity exceeding 40 cm/s. Maximum water level decrease lasted more than three months after the burst in the wellbore on the Semipalatinsk testing area whereas post-seismic level changes after earthquakes usually end in hours or days. Certain exceptions tend to fault zones where water level alterations sometime come up to tens of meters. Following research will show does this difference relates either to local geological-structural peculiarities of different fault zones or inherent physics of impact.
This work was supported by the Russian Science Foundation (Project No. 16-17-00095) and Russian Academy of Science (Project No 0146-2015-0012).