# Earthquake Magnitude and Frequency Forecasting in Northeastern Algeria using Time Series Analysis
## 2 Seismicity and Earthquake Database  
The study area is situated in the Tell Atlas in Northeastern Algeria (Figure 1a). This important geological formation resulted from a collision caused by the Algero-Provencal Basin opening within the Nubia Plate in the Early Miocene. Furthermore, it is most likely related to the Nubian Plate subduction, which is dipping to the north [44; 45]. Onshore and offshore folds and thrust faults extending from NE-SW and from E-W represent the majority of the current tectonic features (e.g., [46; 47]). The compressional movement between the Nubian and Eurasian Plates causes considerable seismicity, which is mostly represented in a moderately diffused seismic area in Northern Africa in its western domain (Figure 1b). This collision zone includes Northern Algeria, where recent geodetic studies reveal an actual plate convergence rate of about 5 \(\pm\) 1 mm/yr in a N60\({}^{\circ}\)W direction, as illustrated in Figure 1a [2; 3; 48; 49; 50]. Earthquakes with a magnitude above Mw 5.0 frequently occur in the area [7; 51], sometimes causing significant damage and casualties [52; 53]. Most well-studied thrusting earthquakes occur on land, including the largest-recorded Ms 7.3 10 October 1980, El Asnam earthquake [54; 55; 56]. Examples of destructive earthquakes in the past include the 3 January 1365, and 5 May 1716 earthquakes, both felt with intensity X (European Macroseismic Scale, EMS-98) [57]. The earthquake that struck on 2 March 1825, with a felt intensity of X-XI on the Modified Mercalli Intensity Scale (MMI), was another historical occurrence. The Mw 6.9 earthquake that struck the area under consideration on 21 May 2003 was the most recent destructive earthquake [7]. The seismicity of the studied area displayed in Figure 1b has been the subject of various studies, both on historical and instrumental seismicity. For instance, [PERSON] et al. [51] performed a clear and comprehensive analysis of the historical seismicity, proposing the re-appraisal of several historical events located in the region. On the other hand, recent instrumental seismicity recorded by the Algerian seismic network has also been the subject of several works [58; 59; 60; 61; 62]. Figure 1c depicts the shallow depth (h \(\leq\) 30 km) focal mechanism data compiled in the region [44; 45]; the Frohlich diagram [63] is displayed, and the Zoback classification [64] is used. In previous studies [44; 45], a detailed analysis of the inversion of the focal mechanism solutions and the inferred stress pattern was performed. The tectonic framework of the Ibero-Maghrebian region is detailed from these data, and the results are found to be in agreement with more recent studies (e.g., [50]). Similar horizontal maximum principal stress directions can be seen throughout the area, and they almost exactly coincide with the previously identified horizontal P axis in the NW-SE direction, as previously established by [PERSON] et al. [65]. Additional tectonic stress regimes have been identified, including extensional, compressional, transpressional and strike-slip schemes. The earthquake data file considered in this analysis was obtained from a seismic catalog previously compiled [7] for Northern Algeria, which has been updated until December 2019. It is well recognized that having an up-to-date Poissonian earthquake data file is a prerequisite for any seismic hazard assessment [66; 67; 68; 69]. A combination of available published studies, bulletins and original data was used to produce the early earthquake data file. This led to the development of a unified earthquake data file, including information on magnitude, regional extent (between 32\({}^{\circ}\) and 38\({}^{\circ}\) latitudes and between 3\({}^{\circ}\)W and 10\({}^{\circ}\)E longitude), and date range (between AD 856 and June 2008) [7].