The recent availability of high-resolution light detection and ranging (LiDAR) data in Connecticut has led to the discovery of a 125-km-long, northeast-trending geomorphic lineament, herein named the Eastford lineament, in eastern Connecticut and south-central Massachusetts. It appears to represent a surface expression of the 50-km-long Eastford fault that continues to the northeast and southwest. The proposed fault zone appears to be post-Triassic in age, since the Eastford fault and other shorter mapped faults along the lineament offset the ~201-m.y.-old Higganum dike system and Paleozoic lithotectonic terranes and structures. An integration of borehole data from the Moodus Deep Well, the 1987 cluster of seismicity north of Moodus, and faults identified from recently acquired seismic surveys suggest that displacements on the proposed continuation of the Eastford fault north of Moodus are the source of the Moodus earthquakes.

In south-central Connecticut, the Eastford lineament is truncated by a 14-km-long, northwest-trending fault zone, herein named the Bunker Hill fault zone, which is associated with an en echelon zone of LiDAR lineaments. Like the Eastford lineament, the Bunker Hill fault zone appears to dextrally offset the Higganum dike system and Paleozoic formations on the western flank of the Killingworth Dome. An abrupt change in strike of the Higganum dike system and LiDAR lineaments across the Bunker Hill fault zone suggests, however, that this offset may be, at least in part, from dip-slip motion on the Bunker Hill fault zone. To the northwest, the Bunker Hill fault zone continues across the Eastern Border fault and part of the Jurassic Portland Formation of the Hartford Basin, which suggests that it postdates the latest phase of rifting in the basin. It also coincides with a linear, northwest-trending aeromagnetic low that sinistrally offsets a linear, northeast-trending positive aeromagnetic anomaly by ~1.4 km.