The contribution of the ambient vibration prospecting in sismic microzoning: an example from the area damaged by the 26th April 2009 L'Aquila (Italy) earthquake

Ambient vibration prospecting represented an important tool for the seismic characterization of shallow geological structures in the areas damaged by the April 6, 2009 L'Aquila (Italy) earthquake. Just after the mainshock, in the first exploratory phases, single-station ambient vibration monitoring (HVSR approach) was widely applied by several research groups operating in the area to detect sites where possible resonance phenomena could had been responsible for damage enhancement. Afterwards, ambient vibration measurements both in the single-station and multi-station (seismic array) configurations were extensively applied to support seismic microzoning studies and in particular, to constrain geological reference models and local V-S profiles. The procedures adopted in these field activities are described in detail, along with both first-glance interpretations and refined inversion procedures applied in exploratory surveys and seismic microzoning activities. The parallel application of other prospecting techniques (geological surveys, resistivity prospecting, drilling, etc.) allowed us to validate the experimental procedures adopted and to define protocols useful for future applications.