In Northeast Algeria, a sequence of 143 small earthquakes (Md ≤ 4.7) occurred near the Mcid Aïcha-Debbagh (MAD) Fault between 4 and 16 March, 2017. During this sequence, 74% of the seismic activity occurred in the first two days. Although the earthquakes were not large, they yielded important new information and have improved our understanding of seismic activity in three distinct regions along the fault. In the Sidi Dris region (western MAD Fault), 106 events (1 ≤ Md ≤ 3.2) were located in an aftershock cluster trending NNE-SSW, highlighting a transverse fault with ∼6 km of strike-slip displacement that locally cuts the MAD Fault. In the El Kantour region (central MAD Fault), 31 events were recorded along a 3 km long fault segment, including the Mw 4.7 mainshock. The mainshock had a focal mechanism consistent with predominantly strike-slip motion on a N110°E-striking fault plane, in agreement with the WNW-ESE orientation of the central MAD Fault segment. Finally, six diffuse events occurred in the Hammam Debbagh region (eastern MAD Fault). A significant event (Md 3.0) in this region had a focal mechanism consistent with strike-slip movement and a normal component trending NW-SE. This is consistent with the fault plane orientations of key events in the time period 2003–2014, likely related to the NW-SE-striking Hammam Debbagh Fault. The present-day stress tensor is characterized by a strike-slip tectonic regime and a σ1 orientation (N342°E) that closely matches the maximum regional compressive stress orientation (NNW-SSE). [ABSTRACT FROM AUTHOR]