and the resulting shock waves were detected and used to help pinpoint a more accurate crustal velocity value of 5.3 to 5.4 km/s. The epicenters of the recorded aftershocks formed a relatively narrow band. On the east end the events were shallow while on the western side, where the majority of the larger aftershocks were concentrated, the hypocenters were up to deep. The shocks at the southeastern segment indicated right-lateral strike-slip movement along a nearly vertical fault and may have been related to the Alavar fault. Moving westward closer to the central segments though, a transition of the fault type was becoming apparent, where an almost equal distribution of reverse fault mechanisms was observed as the strike-slip type. The east-central segment coincided with the surface breaks between Spitak and Gekhasar, while the west-central portion's break was concealed under an anticline and was not visible at the surface. Along the western segments, the fault split into two branches with one to the southwest and the other to the northwest. Liquefaction Buildings and other structures were extensively damaged during the earthquake, but roadways and railways also experienced disturbances. Many case histories pertaining to liquefaction in sandy soil exist, but few exist with respect to gravel and gravelly sands. In certain situations, gravelly sands may liquefy in a similar fashion as saturated sands. The first well-documented case of liquefaction in gravelly sands was in regard to the 1983 Borah Peak earthquake in the United States. Several investigations of that event took place in the 1980s and early 1990s and the primary conclusions were that a critical condition for liquefaction to occur in that type of soil was the presence of a low permeable crust that did not allow pore water pressures to subside and that the assessment method and associated standard penetration test values used with sandy soils also applied to gravelly soils. Three locations between Spitak and Nalband (to the west) that were within several kilometers of the fault were examined for ground disturbances and each site was scrutinized for the effects of liquefaction. The first site was on the highway that linked the three most damaged cities and was adjacent to a tributary of the Pambak river where the water table was close to the surface. The highway's embankment failed, and though the site was repaired immediately, the resulting damage to the highway caused considerable delay in getting people and supplies