Aber Dinlle Fault is a SW-NE trending fault in North Wales . It forms part of the Menai Strait Fault System , with the Berw and Dinorwic Faults . It lies close to the epicentre of the 1984 Llŷn Peninsula earthquake , although it is not thought to have been responsible for that event . The fault was active during deposition of Ordovician rocks in the Welsh Basin . It was reactivated as a normal fault in the Carboniferous with a downthrow to the northwest and again reactivated as a reverse fault during Late Carboniferous inversion associated with the Variscan Orogeny
1984 Llŷn Peninsula earthquake
1984 Llŷn Peninsula earthquake
Aber Dinlle Fault