ASMI Archivio Storico Macrosismico ItalianoItalian Archive of Historical Earthquake Data

On November 24, 2004 an earthquake (Mw= 5.0) struck the west side of Lake Garda (northern Italy), producing moderate but widespread damage. It provided the opportunity of reviewing the seismicity of all the area over the past two centuries, whose former most significant event is the October 30, 1901 earthquake (Mw= 5.5), while other minor but damaging events are the January 5, 1892 (Mw=5.0) and November 16, 1898 (Mw=4.6) earthquakes. On the reviewing we found common similarities in ground shaking distribution as recurrent damaged spots, amplification zones due to local site condition or energy radiation. We believe that these findings are suitable to provide information for provisional purposes in low hazard level area hampered by the lack of knowledge about the seismic sources. New data are provided both in MCS scale and EMS. The sensitivity of a source parameters estimation technique was evaluated for the major event.

L'Istituto Nazionale di Geofisica e Vulcanologia (INGV), gestisce una rete di corrispondenti per il rilevamento degli effetti dei terremoti sulle persone, le cose e l'ambiente. I corrispondenti, mediante appositi questionari basati sulla scala Mercalli-Cancani-Sieberg (MCS), forniscono una serie d'informazioni relative alla propria zona d'indagine. La rete dei corrispondenti è costituita dalle Stazioni dell'Arma dei Carabinieri, con 3864 punti rilevamento (fig. 1), dai Comuni e relative frazioni, per un totale di 8205 punti (fig. 2) e dalle Stazioni del Corpo Forestale dello Stato, con punti 1141 (fig. 3). Queste strutture sono state scelte come campione, in quanto costituiscono una garanzia di corretta ed esauriente informazione tecnica, poiché coinvolte direttamente e territorialmente nell'emergenza sismica. In totale abbiamo 13210 punti di rilevamento con una densità media territoriale di circa 23 kmq e una densità effettiva di circa 37 kmq. In caso di eventi particolarmente significativi, sono previsti sopralluoghi di personale qualificato dell'Ente stesso.

On November 24, 2004, Northern Italy was struck by a Ml ~ 5.2 earthquake located near the Garda Lake. A few smaller events followed the main shock. The fell area was very large, ranging from Venice to Milan, and from Ljubljana (Slovenia) to Pisa. Significant damage occurred in the epicentral area, which is approximately the same of the October 30, 1901 earthquake. The day after the quake, reconnaissance teams performed a macroseismic survey of the affected area in order to define the damage scenario. Damage was mostly concentrated in the area west of Lake Garda, between the town of Said and the Valsabbia valley. Damage to old masonry buildings consisted in partial collapses, falling of chimneys and roof tiles and large cracks in walls. Some churches and towers were also damaged. There was almost no damage to reinforced concrete (RC) structures.