Hydrogeological Earthquake Precursors: A Case Study From the Kamchatka Peninsula

Abstract

The relevance of hydrogeological precursors (HGPs) study is justified by the need to obtain reliable information about the spatio-temporal manifestations and the relationships of HGPs with the parameters of subsequent earthquakes for seismic forecasting. In the review the data on repeated manifestations of HGPs before strong earthquakes obtained from long-term observations in five deep wells on the Kamchatka Peninsula (Far East of Russia) are presented. The analysis of the correlation of HGPs occurring in several wells is carried out in comparison with earthquake parameters characterizing both earthquake sources (magnitude, linear size of the source) and the impact of earthquakes in the area of wells (specific energy density in wave, intensity of shaking). It is shown that the manifestation of HGPs in several wells is observed before earthquakes with Mw = 6.6–7.8 at epicentral distances up to the first hundreds of km to observation wells in the near and intermediate zones of the sources with the ratio of the epicentral distances and the source sizes no more than 1–5. A feature of our study was the use of certain types of HGPs in water-level changes for predictive assessments of the strong earthquakes in the Kamchatka Peninsula. The review presents precursors in water-level changes detected in real time and the corresponding earthquake forecasts, which were recognized as successful according to the conclusions of the expert council on earthquake prediction.

Preseismic Groundwater Ion Content Variations: Observational Data in Flowing Wells of the Kamchatka Peninsula and Conceptual Model

“…Data on strong local earthquakes preceded by hydrogeochemical precursors in at least two observation wells (Figure 1a, Table 2) were previously presented in [2]. Anomalous effects in ionic and gas composition of groundwater preceding earthquakes (Figure 1a, Table 2) clearly manifested themselves in time series of observations (Figure 3) and were statistically confirmed [14,15,[24][25][26].…”

“…Perhaps this is due to high rate of water exchange in wellbore due to high water flow rate (q = 1.5 dm 3 /s) compared to wells GK-1 and G-1 (q = 0.1 and <0.001 dm 3 /s). Figure 5 from paper [2] demonstrates the relationship between preseismic hydrogeochemical anomalies and magnitude and epicentral distance to wells of subsequent earthquakes. Distribution of specific density of seismic energy e [9,11,22,23] depending on earthquake parameters also shows in Figure 5.…”

“…Observations of ion-salt groundwater composition in wells to search for hydrogeochemical earthquake precursors (HGCP) have been carried out for more fifty years in seismically active regions of the Earth, including Russia [1,2], Uzbekistan [3], China [4], India [5], Japan [6], Italy [7], Iceland [8] and other countries [9]. Such studies are carried out to obtain data on spatiotemporal manifestations of HGCP, depending on parameters of earthquakes and to assess the prospects for using HGCP for earthquake prediction.…”

“…Brief information about hydrogeochemical observations on the Kamchatka Peninsula was given earlier in [11,14,15]. The review [2] provides the most complete data on hydrogeochemical precursors in wells of the Kamchatka Peninsula. At the same time, the main attention was paid to issues of the relationship between hydrogeological precursors and parameters of earthquakes as well as prospects of such observations for predicting earthquakes.…”

“…[20]. (ii) -e values were estimated by the formula logd e = 0.48M w − 0.33loge − 1.4 [2,[21][22][23]. (iii) -Medvedev-Sponheuer-Karnik scale, also known as 12-points MSK-64, is a macroseismic intensity scale used for evaluating shaking of Earth's surface based on observed effects in the earthquake area; the values of points are given for Petropavlovsk-Kamchatsky city.…”