Abstract

This paper describes the behavior of several seismic precursors prior to the 2016–2019 activation in an area of a complex geodynamic setting at the boundary of the Pacific, North American, and Eurasian plates. We used an integrated approach to combine identified precursors with a view to getting more accurate locations of possible rupture zones of future large earthquakes. The precursors include quiescence based on the RTL parameter and the “Z-function”, variations in the slope of the earthquake recurrence graph (γ-value), and the areas of seismic ruptures dS. For the first time in Kamchatka, we analyze anomalies in the parameter dS interpreted as seismic activations to show the presence of a precursory component before the onset of the foreshock activation. Examples include increases in the values of that parameter before events that were the largest for the areas where they occurred: the Near-Islands Aleutian earthquake of July 17, 2017, M_w = 7.8 and the Uglovoe Podnyatie earthquake of December 20, 2018, M_w = 7.3. The overall extent of the anomalous area, which still exists and includes consecutive quiescence and foreshock phases, is ~900 km, which creates conditions for possible occurrence of a new great earthquake in the junction zone of the three plates with a magnitude that can exceed whatever has been recorded in the region so far.

中文翻译：

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千岛堪察加半岛与阿留申岛弧交界处大地震（M≥6.0）的地震前兆

摘要

本文描述了 2016 年至 2019 年地震活动之前，在太平洋、北美和欧亚板块边界的复杂地球动力学环境区域中的几个地震前兆的行为。我们采用综合方法将已识别的前兆结合起来，以期获得未来大地震可能破裂带的更准确位置。前兆包括基于RTL参数和“ Z函数”的静止、地震复发图斜率的变化（γ 值）以及地震破裂面积dS。我们首次在堪察加半岛分析了被解释为地震活动的参数dS异常，以显示前震活动开始之前存在前兆成分。例如，在事件发生之前该参数值的增加是发生地区最大的：2017 年 7 月 17 日的阿留申群岛近岛地震，M _w = 7.8 和 2018 年 12 月 20 日的 Uglovoe Podnyatie 地震，M _w = 7.3。异常区域仍然存在，包括连续的静止期和前震期，其总范围约为900公里，这为三个板块的交界处可能发生新的震级超过任何级别的大地震创造了条件。迄今为止，该地区已有记录。