Report on the effects of the Aquilano earthquake
of 6 April 2009

[RPT02 – 9.04.2009]

Survey coordinated by P. Galli and R. Camassi

R. Camassi, F. Bernardini, G. Vannucci, S. Salimbeni, E. Ercolani,
V. Castelli, A. Cavaliere, D. Tripone (INGV, BO);
M. Vecchi, A. Rossi, A. Maramai, L. Arcoraci, M. Berardi, C. Castellano, I. Leschiutta, S. Del Mese (INGV, RM);
R. Azzaro, S. D'Amico, R. Platania, L. Zuccarello (INGV, CT);
A. Marturano, S. Carlino (INGV, NA);
P. Galli, S. Castenetto, G. Naso, A. Lucantoni (DPC, RM);
M. Mucciarelli (UniBas, PZ);
R. Gallipoli (CNR-IMAA, PZ).

Foreword

In consequence of the damaging earthquake occurred in the Aquilano on 6 April 2009, at 3:32 a.m. local time, the QUEST team (QUick Earthquake Survey Team) has immediately started the macroseismic survey of the effects. On this occasion the team was formed by surveyors of the INGV departments of Bologna, Napoli and Catania, the National Department of Civil Protection (DPC) with the support by ENEA technicians, and of colleagues of the University of Calabria (UniBas, PZ) and CNR (CNR-IMAA, PZ). Some teams reached the epicentral area as early as 5 a.m., so that the damage scenario of the most affected places was outlined by noon and for more than 30 settlements by the evening of the same day.
The reconnaissance had the exclusive goal to define as best as possible the limits of the area affected by moderate-to-serious damage; this report does not include the information of the not damaged area that were not directly collected by the surveyor teams. The next releases of the report will supplement the information obtained by means of macroseismic questionnaires and telephonic interviews.
Once the reconnaissance is completed, an analytic survey of the effects will be carried out, making use of the European Macroseismic Scale 98, which appears to be a more suitable tool to describe the characteristics of the damage in the affected area.
By 9 April late afternoon (6 p.m.), 130 places had been surveyed, in some cases more than once, and for each of them the related forms had been filled in. This report mainly describes the scenario immediately before the strong aftershock of 7 April at 19:47, which together with the many aftershocks caused some further damage. According to a sample check on some places, carried out on 9 April, the changes in the damage scenario do not seem to modify the already assigned intensity values.

Building typologies and state of repair

In the Aquilano as well as in L’Aquila itself there are very different building typologies and maintenance conditions. They range from the historical building asset in stone, usually not squared, of irregular size and with sporadic insertions of brickwork (the latter played a major role as they were responsible of really heavy damage), to spots where the reinforced concrete dominates, of recent and not-so-recent buildings. In the old towns of many settlements, among the stonework buildings many spots (sometimes large ones) are abandoned since decades. Close to the deserted houses, can be found brickwork houses, inhabited and in a good state of repair, reinforced concrete buildings of some decades ago or newly built apartment buildings.
In some cases brickwork buildings show recently made modifications, with the superimposition of a string-course and a reinforced concrete top. As observed during the survey following the Umbria-Marche 1997 earthquake, these modifications, when not made in coincidence with a strengthening of the vertical structures, have induced negative effects on the masonry buildings.

Damage assessment

The reconnaissance evidenced an irregular behaviour of the building asset. The most damaging effects are distributed along a NW-SE direction, with an increase in the propagation towards SE.
The maximum damage (Is ≥ 9 MCS) can be seen in some small settlements scattered in an area of lesser damage (Is ≤ 8 MCS).
In general, a relevant component of seismic vulnerability is apparent, in some cases in association with site effects, as for some settlements in the medium Aterno valley, both on soft alluvial soil (Onna) and on high grounds made of white mid-Pleistocene silts.
At this stage, it is very difficult to estimate the macroseismic effects for the urban agglomeration of L’Aquila, not yet open to the surveyors. The assignment still varies between 8 and 9 MCS degree, and mostly refers to the old town. Such an estimate should be reconsidered, and hopefully might differentiate among the different parts of the town.
The survey will be further improved in the next days, especially to check on controversial situations, to extend the analysis to places for which a direct request was received, and finally to systematically collect data related to the use of the European Macroseismic Scale EMS98.

The intensity values, still under examination, will be made available [in public format also], together with the photographic documentation and an improved assessment.