Intermediate-term precursors of large (M ≥ 6.6) Kamchatka earthquakes for the period from 1987 to 2004: A retrospective assessment of their information content for prediction

Abstract

Abstract-Data from the literature were used to systematize intermediate term (with advance times of 1 month to ~2.5 years) precursors to the M ≥ 6.6 Kamchatka earthquakes of 1987−2004. The precursors were observed as changes in seismological, geodetic, geophysical, water level, and hydrochemical parameters. Retrospective assessment of the information content in these intermediate term precursors for earthquake prediction is in progress. The focus was on estimating the occurrence times of various precursors as functions of earthquake parameters (magnitude M, hypocentral distance R, and epicenter location). In the conditions of the Kamchatka observing network, precursors can be identified by a combination of methods, mostly before M ~ 7 earthquakes or greater south of the Kronotskii Peninsula, for which It is shown that the relative proportion of earthquakes for which precursors have been identified in the observations con sidered here is 0.43-0.86.

Hydrogeological Earthquake Precursors: A Case Study From the Kamchatka Peninsula

“…At the same time, the relatively low statistical estimates of the correlation between the PS1 and the subsequent earthquakes make the PS1 applicable for seismic forecasting only if combined with the other observation data and other precursors. The correlations between the other precursors and the subsequent earthquakes in Kamchatka are also low and not exceeding the values obtained for the PS1 (Serafimova and Kopylova, 2010;Chebrov et al, 2011;Chebrov et al, 2013). This highlights the need for developing new methods for analyzing of the prognostic data for increase the accuracy and reliability of earthquake forecasting.…”

Synchronization signals in the variations of groundwater chemical composition in Kamchatka in relation to the strong (M W ≥ 6.6) earthquakes

“…The key elements of the expert anal ysis are the regular reports on the separate types of observations based on the current data on the particu lar types of precursors and their comparison with the retrospective experience in observing these effects in relation to the earthquakes. According to the data of (Kopylova and Serafimova, 2009;Serafimova and Kopylova, 2010;Chebrov et al, 2011), in the Kam chatka region, the precursors in the individual types of observations and in their complex appear within a few weeks and months before the earthquakes with magni tudes of at least 6-7 at a distance of a few hundred km.…”

“…Additional support for this assumption is provided by the precursory anomalies recorded before these earthquakes not only in the changes of individual time series of the hydro geochemical data but also in the water level variations and a number of seismological and deformational parameters. Particularly striking anomalies in a wide set of parameters preceded earthquakes 1, 2, and 7 (Kopylova and Serafimova, 2009;Serafimova and Kopylova, 2010). (Fig.…”

“…In 1992-1999, Kamchatka experienced an increased seismic activity and was hit by eight earth quakes with M w = 6.9-7.8, including the strongest Kronotskoe earthquake on December 5, 1997 (М w = 7.8), which was preceded by intermediate term pre cursors in the variations of seismological, deforma tional, and hydrogeological parameters (Kopylova and Serafimova, 2009;Serafimova and Kopylova, 2010). Therefore, retrospective estimation of the synchroni zation signals in the variations of multidimensional hydrogeochemical data during a long period that included a few strong seismic events is of interest for designing the methods for processing and interpreta tion of the hydrogeochemical observations, which are focused on the detection of precursors of strong earth quakes in Kamchatka.…”