## 2 Data and Methods Used
### Historical and Recent Seismicity  
Durres and the surrounding region were hit by strong earthquakes (M \(>\) 6.0), in the past [40]. The ancient city of Durres (Dyrrachium) has been nearly destroyed by several strong historical earthquakes in 58 BC, 334 AD, 346 AD, 506 AD, 521, 1273 and 1870 (see Table 1). The historical abandonment of Durres was a consequence of a number of devastating earthquakes with epicentral intensity I\({}_{\text{MAX}}\) = VIII-IX degree (MSK-64), in 334, 346 and 506 AD (Figure 3), [40]; in 1273, with a magnitude M6.7 ([41,42]) and in 1926, with a magnitude M6.3, [40, 41, 42, 43]. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Date** & **Latitude** & **Longitude** & **Depth** & **Mag.** & **Location** \\ \hline yyyyy/mm/dd & N-S & E-W & km & M & \\
58 BC & 41.2 & 19.3 & 33 & 6.5 * & Durres \\
334 & 41.3 & 19.5 & 33 & 6.2 * & Durres \\
346 & 41.3 & 19.3 & 33 & 6.5 * & Durres \\
506 & 41.3 & 19.5 & 33 & 6.2 * & Durres \\
521 & 41.3 & 19.5 & 33 & 6.0 * & Durres \\
1273 & 41.2 & 19.3 & 33 & 6.7 * & Durres \\
1617 & 19.700 & 41.500 & 15 & 6.2 * & Kruja \\
1852 & 19.500 & 41.600 & 15 & 6.2 * & Rodoni Cape \\
1860 & 19.70 & 41.300 & 15 & 6.2 * & Ndroqi \\
1870 & 19.446 & 41.314 & 15 & 6.5 * & Durres \\
1926 & 19.50 & 41.300 & 11 & 6.3 & Durres \\
1934 & 19.60 & 41.250 & 12 & 5.7 & Ndroqi \\
1970 & 19.60 & 41.15 & 55 & 5.6 & Vrapi \\
1975 & 19.30 & 41.50 & 15 & 5.4 & Rodoni Cape \\
1979 & 42.16 & 18.87 & 16 & 6.9 & Montenegro \\
1988 & 41.22 & 19.81 & 5 & 5.7 & Tirana \\
2019, Sept. 21 & 19.503 & 41.476 & 23.4 & 5.6 & Durres \\
2019, Nov. 26 & 19.469 & 41.421 & 20.5 & 6.4 & Durres \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Historical and instrumental era earthquakes (M \(>\) 6.0), 58 BC-2019, in the Durres region (M implying moment magnitude and with * being the equivalent moment magnitude [44]. Figure 2: Seismic sequence of September 2019–June 2020, corresponding focal mechanism solutions (FM) of the larges shocks and the active faults influencing Durres region. The most significant seismic events in the region (Table 1 and Figure 3), that have also impacted Durres, are the 1617 Kruja earthquake (M6.2), with an epicentral Intensity I\({}_{\rm MAX}\) = VIII (MSK-64); the 26 August 1852 Rodoni Cape earthquake (M6.2), with an epicentral Intensity I\({}_{\rm MAX}\) = VIII (MSK-64); the May 16, 1860 Ndrooi (Beshiri Bridge) earthquake (M6.2), with epicentral Intensity I\({}_{\rm MAX}\) = VIII (MSK-64); the 4 February 1934 Ndroqi earthquake (M5.7); the 19 August 1970 Vrapi earthquake (M5.6), with an epicentral Intensity I\({}_{\rm MAX}\) = VII degree (MSK-64); the 16 September 1975 Rodoni Cape earthquake (M5.4); the 15 April 1979 (M6.9) Montenegro coastal area earthquake; and the 9 January 1988 Tirana earthquake (M5.9), with an epicenter Intensity I\({}_{\rm MAX}\) = VII-VIII degree (MSK-64). The most recent strong earthquakes, having a significant socio-economic impact for Durres and its surrounding regions, are the 21 September 2019 (M5.6), with an epicentral Intensity I\({}_{\rm MAX}\) = VII-VIII degree (MSK-64) and the earthquake of 26 November 2019 (M6.4), with epicenter Intensity I\({}_{\rm MAX}\) = VIII-IX degree (MSK-64), ([40-42,45]). (Figure 3 and Table 1). The 16 November 2019 (M6.4) mainshock was located 16 km north of Durres city, with its epicenter on the Adriatic coast of Albania (Figure 2), about 33 km northwest of Tirana, the capital of Albania ([32,37-39]) It was subsequently followed by intense aftershock activity. On 21 September 2019, the same area was hit by an earthquake of moderate magnitude (M5.6), 12 km north of Durres. _A posteriori_ it is believed to be the main foreschock of the November 26, 2019, earthquake. An absence of seismic activity until 25 November was observed. Immediate foreshock activity started on 25 November 2019, at 03:22 am (UTC), including eight earthquakes with magnitudes between 2.0-4.6 (M\({}_{\rm L}\)).