gtcrustГеодинамика и тектонофизикаGeodynamics & Tectonophysics2078-502XInstitute of the Earth's crust of the Russian Academy of Sciences, Siberian Branch10.5800/GT-2025-16-1-0804yrhyslgtcrust-1989Research ArticleСОВРЕМЕННАЯ ГЕОДИНАМИКАRECENT GEODYNAMICSРОЙ ЗЕМЛЕТРЯСЕНИЙ 2020–2021 гг. В ЮЖНОЙ ЧАСТИ АЛЬБОРАНСКОЙ ВПАДИНЫ И ЕГО ВОЗМОЖНАЯ СВЯЗЬ С ЮЖНЫМ ПРОДОЛЖЕНИЕМ СИСТЕМЫ РАЗЛОМОВ АЛЬ-ИДРИССИTHE SOUTH ALBORAN BASIN SEISMIC SWARM IN 2020-2021 AND ITS POSSIBLE RELATION TO THE SOUTHERN DEVELOPMENT OF THE AL-IDRISSI FAULT SYSTEMБухалиК.BouhaliK.

50000, Мекнес, Марокко

Meknès 50000, Morocco

РуаиМ.RouaiM.

50000, Мекнес, Марокко

Meknès 50000, Morocco

ДекайирA.DekayirA.

50000, Мекнес, Марокко

 

Meknès 50000, Morocco

ЭссайедА.EssaiedA.

50000, Мекнес, Марокко

 

Meknès 50000, Morocco

Университет Мулая ИсмаилаМароккоMoulay Ismail UniversityMorocco202519022025161804804Copyright © Бухали К., Руаи М., Декайир A., Эссайед А., 20252025Бухали К., Руаи М., Декайир A., Эссайед А.Bouhali K., Rouai M., Dekayir A., Essaied A.Данная работа распространяется под лицензией Creative Commons Attribution 4.0.This work is licensed under a Creative Commons Attribution 4.0 License.https://www.gt-crust.ru/jour/article/view/1989

Целью данного исследования является количественное определение и картирование недавней роеобразной последовательности сейсмических событий 2020–2021 гг. с акцентом на юг Альборанской впадины. Выявление сейсмических кластеров может быть проведено с помощью критерия сейсмичности, учитывающего распределение двух параметров: плотности ядер землетрясений и плотности сейсмических моментов. Первый параметр определяет местоположение двух сейсмических кластеров: к северу от Эль-Хосейма, в пределах южного сегмента системы разломов Аль-Идрисси (AIFS), и в Гранадской впадине. Второй параметр указывает на то, что оба кластера высвободили значительное количество энергии, в особенности в южной части AIFS, где оно достигает 1.6·1014 Дж·км–2·год–1. Сейсмическое 3D моделирование выявляет кластеризацию сейсмических проявлений на севере Марокко, ориентированную в восточном направлении с точки зрения глубины. Данное наблюдение наводит на мысль о существующих по соседству геологических формациях, которые могут быть связаны с AIFS. Анализ в соответствии с законом Гутенберга – Рихтера указывает на то, что роеобразная сейсмическая последовательность в южной части Альборанской впадины принимает значение b, близкое к 1, свидетельствующее о формировании режима скольжения. Временной анализ вариации значения b указывает на существование двух режимов напряжения: уменьшение, при котором значение b становится близким к единице, и последующее резкое увеличение, свидетельтсвующее о режиме растяжения как о возможном следствии раскрытия трещин. Механизмы очагов указывают на чередование сдвигов и сдвигов со сбросовой компонентой смещений, являющееся признаком режима транстенсии. Такой тип разломообразования предполагает наличие как латерального смещения, так и некоторой силы растяжения, что согласуется с определенным ростом значения b, поскольку и то, и другое может соответствовать высвобождению напряжений, связанных с раскрытием трещин или сегментов разлома, несмотря на отсутствие точного соответствия между временем и колебаниями значений b. Взятые в совокупности, эти результаты указывают на сложную тектоническую обстановку, отмеченную силами сдвига и растяжения, свидетельствующими о южном продолжении AIFS.

The aim of this study is to quantify and map a recent seismic swarm sequence that occurred in the Alboran Sea between 2020 and 2021, focusing specifically on the South Alboran Basin. To identify the seismic clusters, a criterion based on seismicity is employed, considering the distribution of two parameters: the kernel density of earthquakes and the kernel density of seismic moments. The first parameter reveals the presence of two seismic clusters: one located north of Al Hoceima, specifically within the southern segment of the Al-Idrissi Fault System (AIFS), and another in the Granada Basin. The second parameter indicates that both clusters released significant amounts of energy, particularly in the southern part of the AIFS, with values reaching up to 1.6·1014 J·km–2·year–1. The 3D seismic modeling indicates a clustering of seismic occurrences in northern Morocco, displaying an eastward pattern in terms of depth. This observation leads to speculation about the existence of nearby geological formations, possibly associated with the AIFS system. Analysis according to the Gutenberg-Richter law shows that the seismic swarm sequence in the southern Alboran Basin exhibits a b-value close to 1, indicating a slip regime. Temporal analysis of the b-value variation reveals two stress regimes: an initial decreasing regime with a b-value close to one, succeeded by a sharp increase indicative of an extensional regime, possibly due to fracture opening. The focal mechanisms show an alternation between strikeslip and strike-slip with normal components, indicative of a transtensional regime. This type of faulting suggests both lateral motion and some degree of extensional force, which aligns with certain rises in the b-value, as these could correspond to stress release events associated with opening fractures or fault segments, although the timing does not perfectly match b-value fluctuations. Together, these findings highlight a complex tectonic environment marked by strike-slip and transtensional forces, supporting the ongoing southern development of the AIFS.

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The authors declare that there are no conflicts of interest present.