Studio di faglie attive in relazione ai processi di innesco della sismicità naturale e antropogenica nell'area di Aswan (Egitto)

Responsabili di progetto

Tonyalfredo Stabile, Raafat El-shafei Fat-helbary

Accordo

EGITTO - ASRT - Academy of Scientific Research and Technology

Bando

CNR/ASRT biennio 2018-2019 2018-2019

Dipartimento

Scienze del sistema terra e tecnologie per l'ambiente

Area tematica

Scienze del sistema Terra e tecnologie per l'ambiente

Stato del progetto

Nuovo

Proposta di ricerca

Recently, the scientific community has shown a growing interest in earthquakes that could be potentially triggered by anthropogenic activities. One of the most common source of triggered earthquakes is water reservoirs. Reservoir-triggered seismicity is mostly observed after the initial impoundment of the reservoir or after the water level increased above the previous maximum; then, generally, seismicity around the reservoir returns to the status before the impoundment. However, some reservoirs, like Lake Mead (Carder, 1945), Koyna-Warna (Durá-Gómez and Talwani, 2010), Nurek Dam (Simpson and Negmatullaev, 1981), Pertusillo (Stabile et al., 2014; 2015) still exhibit reservoir-triggered seismicity occurring almost continuously through time. This type of reservoir-triggered seismicity has been classified as protracted (Talwani, 1997) or continued (Gupta, 2002), and it is being also observed nearby the Aswan reservoir (Egypt) for more than three decades. Aswan hosts the largest dam in Egypt, 111 m high, with a crest 3830 m long and a volume of 44.3 million cubic meters. Such dam is the most important water reservoir for Egypt and thus has a strategic role from social, agricultural and energy production points of view, being a unique case in the world where one single dam controls almost whole nation in its downstream.
The Aswan area is known to be seismically active since the occurrence of the 1981, Ms 5.3 Aswan earthquake. Geological and geophysical surveys in the area confirm the existence of a network of strike-slip E-W dextral (e.g., Kalabsha and Seyal faults) and N-S sinistral (e.g., Khor El-Ramla and Kurkur faults) active faults to the southwest of the Aswan High Dam, and the observed seismicity is concentrated along N-S and E-W fault intersections. The pore pressure appears to be the main factor for the occurrence of such reservoir-triggered events, including the November 14, 1981, Ms 5.3 earthquake (Gahalaut et al., 2017). A recent statistical study on the seismicity of the Aswan area carried out jointly by the Italian and Egyptian teams (Telesca et al., 2017) identified two depth classes of events with a threshold at about 12 km, both likely generated by the same mechanism: the water loading/unloading operation of the Aswan reservoir.
The presence of the dam, the complex interconnected seismic fault system, and the seismic risk that it could raise, suggest that a deep dynamical characterization of the seismic process governing Aswan area is challenging and, at same time, crucial to best understand the mechanisms related to the generation of earthquakes for each of the active faults present in the region.
The activity to be developed in this project is addressed to the application of seismological and statistical methodologies for studying the active faults involved in the tectonic and reservoir-related processes that cause seismicity in the Aswan area. From a seismological point of view, our project is aimed to make a significant progress in the knowledge of the triggering processes of seismic events by better clarifying interactions among rock, faults, and fluids in the study area. A 3D tomographic Vp, Vs, and Vp/Vs models of the area will be developed and then accurate absolute relocation of the seismicity by using the obtained 3D velocity models will be performed. Relative differential earthquake location technique in 3D models (De Landro et al., 2015) will be applied of selected clusters of seismicity located along each of the known active faults with the aim to have a high-resolution image of the faults and to eventually observe earthquake migration in the Aswan area, which should provide compelling insights on the role of fluids in the triggering processes of earthquakes. From a statistical point of view, particular attention will be paid to better understand the links between the water level fluctuations of the reservoir and the earthquake occurrence along each active fault and to apply several independent statistical methods to obtain the most detailed picture of the dynamical properties of the seismic process in the area, in order to clarify the role of each fault in the reservoir-triggering mechanism. The proposal is also aimed at providing the scientific community with more accurate seismic hazard assessment and risk mitigation of the Aswan area, which will have also great societal impact since the results could be used for civil protection actions to be directed towards risk reduction interventions. Furthermore, the results will have also a great scientific impact on better understanding of seismo-tectonic characteristics of Aswan area, clarifying the links among different physical, mechanical and geological parameters of the triggering processes with size and location of earthquakes. The results will be disseminated through reports, international conferences and ISI papers, and on appropriate website to be shared with the scientific community
Added value and larger broader impact from the cooperation: This project entails a joint research effort among experts from the two teams: the Egyptian team has a great experience in seismology and geology of the investigated area as well as in seismic hazard and risk assessment, while the Italian team complements with an outstanding experience in reservoir-triggered seismicity and knowledge of advanced nonlinear seismic time series tools, necessary to perform the planned activities. The outcomes of the project (papers, knowledge transfer, staff mobility, exchange of methods and human resources) will reinforce the Egyptian-Italian cooperation that has been developed in the last years in the context of seismic analysis and that will exploited for future continuation of joint research/education activities in the frame of European projects, where the cooperation with Mediterranean non-member countries, like Egypt, often represents an added value for their success.

Obiettivi della ricerca

The general aim of the project is to better understand processes associated with triggering and migration of natural and anthropogenic earthquakes in the Aswan area. A comprehensive study that integrates seismological, statistical, geological and geodynamical information helps the evaluation of the system response before the occurrence of critical events, allowing a risk mitigation strategy. The specific objectives are: 1) geological setting of the Aswan area and evaluation of the local stress field; 2) development of 3D tomographic Vp, Vs, and Vp/Vs models of the study area, eventually also in time-lapse mode; 3) accurate absolute and relative earthquake location in 3D models and estimation of seismic source parameters; 4) integration of physical-based and statistical-based analyses of earthquakes to investigate and understand the processes involved in the reservoir-triggered seismicity; 5) study the space-time evolution of the seismicity at Aswan area, estimation of the hydraulic diffusivity of the area, and track the variability of faulting style, stress and strength of active faults even at small-scale dimension; 6) analyse the space-time relationship of the triggered seismicity with the water level of the reservoir and the geological settings; 7) assessment of the seismic hazard of the area; 8) dissemination of the preliminary and final results of the project in international conferences, publications, and in a project-oriented internet website.

Ultimo aggiornamento: 01/07/2025