تحلیل الگوی رفتاری پارامترهای مبنایی پیش‌لرزه‌ها با هدف پیش‌بینی زمین‌لرزه‌های بزرگ در ایران

تحلیل پارامترهای مبنایی پیش‌لرزه‌ها یکی از کاربردی ترین پژوهش‌های صورت‌گرفته در خصوص کاهش خطرات ناشی از زمین‌لرزه است. چراکه شناسایی الگوی رفتاری پیش‌لرزه‌ها می‌تواند، محققان را با شرایط حاکم بر گسل‌های فعال در هر منطقه آشنا کند؛ ضمن این‌که تحلیل پارامترهای مربوطه، مطالعات در خصوص پیش‌بینی زمین‌لرزه را به شکل هدفمندتری به نتیجه مورد نظر نزدیک خواهد کرد. در پژوهش حاضر شناسایی الگوی رفتاری پیش‌لرزه‌ها در پهنه‌های مختلف زمین‌ساختی در ایران، با هدف پیش‌بینی زمین‌لرزه‌های بزرگ‌تر از 5، به‌عنوان هدف اصلی درنظر گرفته شد. بر این اساس با استفاده از تحلیل پارامترهای مبنایی پیش‌لرزه‌ها از جمله رابطه بین بزرگی و عمق آنها به بررسی احتمال رخداد زمین‌لرزه‌های بزرگ‌تر از 5 در ایران برای یک دوره 10 ساله (از 1386 تا 1396) پرداخته شده است. نتایج حاصل از این تحقیق حاکی از شباهت مشخص مدل‌های بزرگی‌ عمق پیش‌لرزه‌ها در یک پهنه زمین‌ساختی خاص و تفاوت این مدل‌ها در پهنه‌های مختلف با یکدیگر است که می تواند به‌عنوان یک پیش‌نشانگر مناسب در پیش‌بینی زمین‌لرزه‌های بزرگ‌تر از 5 در ایران مورد استفاده قرار گیرد.

Analysis of behavioral pattern the basic parameters in foreshocks with target for the prediction of big earthquakes in Iran

The analysis of the basic parameters of the foreshocks is one of the most applied researches for risk reduction of earthquakes. Because identification of behavioral pattern of foreshocks can help researchers in detection of the active fault conditions in different areas. Also accurate analysis of these parameters help to study of earthquake prediction as more effective. In this study, we study about behavioral pattern of foreshocks in different tectonic zons in Iran. This research was conducted for prediction of probability the earthquakes with M>5 in Iran. According to this research, accurate analysis of the basic seismic parameters of foreshocks (including: relationship between depth and magnitude of foreshocks) is studied with target for the prediction of big earthquake in various zons for a tenyear period (from 2007 until 2017). The results of this research suggest that there are certain similarities in the magnitudedepth models for the one zone and also different for various zones. Therefore, this can be used as a precursor in earthquake prediction with Magnitude>5 for different zones in Iran. The important results presented in this article can be presented in the following cases: Investigation of the information of seismicity parameters of foreshocks regarding the relationship between the focal depth of the main earthquake and the frequency of the foreshocks that used in some parts of the world as a precursor of earthquake suggested that main shocks with M>5 and shallow depth have more foreshocks abundances (Fig 2). Due to the relationship between the type of fault with the occurrence and nonoccurrence of aftershocks in different parts of the world, in the case of earthquakes greater than 5 in Iran, in earthquakes with reverse faults have relatively more aftershocks recorded compared to strikeslip faults. The results of the statistical study conducted in this study show that for earthquakes with reverse fault, the frequency of foreshocks increases with magnitude. However, we do not see such conditions for earthquakes with faults of strikeslip. The result of this study shows that more earthquake especially in Zagros zone and near salt domes happened without foreshocks. The reason for this is related to effect of salt dome on movement fault from slide to creep. The creep is a gradual movement and it is not usually accompanied by rapid movement such as slides that lead to large and recordable earthquakes. Based on the present study on earthquakes, for the Zagros (especially in the northern and central part) and Central Iran and SanandajSirjan, can be used more confidently as a precursor of earthquake because in this zones earthquakes happened with more foreshocks. In Zagros and Iran Markazi zone the relationship between variations of the depth and magnitude of foreshocks is fruitful for predicting of the main shocks. For other zones we need to have more complete data bank that has earthquakes with higher frequency of foreshocks. Based on this data bank we can present suitable relations and models for the study of foreshock with the aim of predicting the big earthquakes.