Hydrogeoseismological Research in Kamchatka: 1977–2017

Abstract

This paper is concerned with the main stages in the setting-up and technical development of a system specializing in physical and chemical parameters of groundwater at a network of wells and springs in the Petropavlovsk Geodynamic Test Area, Kamchatka. The focus is on a description of hydrogeochemical and hydrogeodynamic precursors to Kamchatka earthquakes (М w = 6.6-7.8) that occur a few weeks to a few months before a seismic event, manifesting themselves in anomalous changes in chemical composition and groundwater level. The precursors are discussed in application to their use at specialized councils on earthquake prediction. It is shown that the system of automated observation of groundwater parameters at wells as developed at the Kamchatka Branch of the Geophysical Survey of the Russian Academy of Sciences (KB GS RAS) is capable of identifying hydrogeodynamic precursors of water level in near real time and of providing, in some particular cases, quantitative estimates of pre-seismic and coseismic of deformation in water-saturated rocks. This can be useful in geophysical monitoring and intermediate-term prediction of strong earthquakes for the Kamchatka region.

Anomalies in groundwater composition caused by earthquakes: examples and modeling issues

“…; bscheme of mixing two contrasting waters in an area of increased transmissibility (for example, source 1): heffective thickness of the fracture zone and bcharacteristic radius of the mixing area (zone of increased transmissibility) [5]. B -The M-1 well: athe structure of the wells and aquifer: the dotted lines show the portions of wellbore perforations, horizontal arrows -inflow the mixed water into the wellbore, Сthe concentration of macrocomponent in mixed water flowing from the well; bwater-saturated medium with double porosity; С1 -the concentration of macrocomponent in the water from the «fracture», С2 -the concentration of macrocomponent in the water from the «blocks» [4]. determined by the choice with the minimum discrepancy between the model and the observed data at all major macrocomponents of water composition.…”

“…For example, an increase of mineralization to 25% and a change the hydrogeochemical type of water as a result of the relative increase of sulphate ion concentration and decreasing the concentration of hydrocarbonate ion was observed in the M-1 well before the March 2, 1992 earthquake (Table 1) (Fig. 3) [4]. It demonstrates not only changing the conditions of mixing of waters contrasting on a mineralization, but also indicates changes of conditions of water-rock interaction in water-bearing system of the well.…”

“…In addition, the study of hydrogeochemical anomalies in water of observational wells and sources on the basis of fundamental laws on the formation of groundwater composition in the «water -rock» systems allows their meaningful explanation not only for purpose of seismic forecast, and also for an assessment of seismic impact on the formation of chemical composition of groundwater in seismically active regions. Some issues of modeling such recorded anomalies were previously discussed in [1,4,5,6]. Table 2.…”

“…5) and in the M-1 well (Fig. 3) [4,5]. Using the model of aquifer system as a medium with double porosity for the M-1 well (Fig.…”

“…3). It was discovered that during the preparation of earthquakes there was an increase of water flow with raised concentrations of sulfate ion, calcium, and sodium from low permeable blocks to the fractures system [4]. In the second model of hydrogeochemical anomalies registered in the changes composition of groundwater from the M-1 well during the preparation and implementation of the earthquake March 2, 1992, M = 6.8, were used methods of equilibrium thermodynamics and analysis of elementary chemical reactions taking place in the «waterrock» system [7].…”