Strong aftershocks continued to strike even months after the main quake. Rolleston was close to many of the aftershocks following the September quake. The epicenter of the 6.9 quake was in Pichilemu, O'Higgins Region. As such, it is considered to be an aftershock of 25 April quake. Geologists have also determined the Pacific Northwest is not prepared for such a colossal quake. However, there are still thousands of smaller buildings that remain vulnerable to quake damage. Barns and industrial structures were destroyed by the quake. Two people suffered minor injuries as a result of the quake. The mountains quake with the tumult and the sky turns black. There was no historic record of such a strong quake in Mexico. Several notable buildings were relatively untouched by the quake. There were two official expansion packs released for "Quake". This problem was also present in the "Doom 3", "Quake", and "Quake II" engines. "Unreal"s method of creating maps differs in major ways from that of "Quake". It is the first game in the "Quake" series.