The 1997 Umbria and Marche earthquake occurred in the regions of Umbria and Marche, centralItaly on the morning of 26 September. It was preceded by a foreshock almost as strong as the main quake. The foreshock occurred at 02:33 CEST (00:33 UTC), rated Mw5.7, and the second – the main shock – occurred at 11:40 CEST (09:40 UTC), rated Mw 6.0. Their epicentre was in Annifo. The mainshock was assigned X (Extreme) and foreshock VIII (Severe) on the Mercalli intensity scale.[2]
There were several thousands of foreshocks and aftershocks from May 1997 to April 1998, more than thirty of which had a magnitude more than 3.5. Eleven people are known to have died following the shocks.
List of foreshocks and aftershocks
Only shocks (both foreshocks and aftershocks) with magnitude 5.0 or higher are listed.[3]
^"M 6.0 – 3 km SSE of Nocera Umbra, Italy". earthquake.usgs.gov. USGS. Retrieved 3 July 2021.
^"M 5.7 – 6 km WSW of Serravalle di Chienti, Italy". earthquake.usgs.gov. USGS. Retrieved 3 July 2021.
^"NEIC: Earthquake Search Results". earthquakes.usgs.gov. 2009-10-01. Archived from the original on 2012-05-25. Retrieved 2009-10-01.
Further reading
Amato, A.; Azzara, R.; Chiarabba, C.; Cimini, G. B.; Cocco, M.; Di Bona, M.; Margheriti, L.; Mazza, S.; Mele, F.; Selvaggi, G.; Basili, A.; Boschi, E.; Courboulex, F.; Deschamps, A.; Gaffet, S.; Bittarelli, G.; Chiaraluce, L.; Piccinini, D.; Ripepe, M. (1998), "The 1997 Umbria-Marche, Italy, Earthquake Sequence: A first look at the main shocks and aftershocks" (PDF), Geophysical Research Letters, 25 (15): 2861–2864, Bibcode:1998GeoRL..25.2861A, doi:10.1029/98GL51842, S2CID 140166678
Cattaneo, M.; Augliera, P.; De Luca, G.; Gorini, A.; Govoni, A.; Marcucci, S.; Michelini, A.; Monachesi, G.; Spallarossa, D.; Trojani, L.; Xgums (2000), "The 1997 Umbria-Marche (Italy) earthquake sequence: Analysis of the data recorded by the local and temporary networks", Journal of Seismology, 4 (4): 401–414, Bibcode:2000JSeis...4..401C, doi:10.1023/A:1026511209166, S2CID 129453544
Cinti, F. R. (2009), "The 1997-1998 Umbria-Marche post-earthquakes investigation: Perspective from a decade of analyses and debates on the surface fractures", Annals of Geophysics, 51 (2–3), CiteSeerX10.1.1.611.4395, doi:10.4401/ag-4450
Dolce, M.; Masi, A.; Goretti, A. (2018), "Damage to buildings due to 1997 Umbria-Marche earthquake", Seismic Damage to Masonry Buildings, pp. 71–80, doi:10.1201/9780203740040-6, ISBN 9780203740040, S2CID 135235868
Ripepe, M.; Piccinini, D.; Chiaraluce, L. (2000), "Foreshock sequence of September 26th, 1997 Umbria-Marche earthquakes", Journal of Seismology, 4 (4): 387–399, Bibcode:2000JSeis...4..387R, doi:10.1023/A:1026508425230, S2CID 126729602
Spence, Robin; d'Ayala, Dina (1999), "Damage Assessment and Analysis of the 1997 Umbria-Marche Earthquakes", Structural Engineering International, 9 (3): 229–233, doi:10.2749/101686699780482014
Earthquake Assisi, Italy – Terremoto Assisi, Italia 1997 – The only existing video footage of the quake, showing the moment it destroyed the Basilica of Saint Francis of Assisi.
The International Seismological Centre has a bibliography and/or authoritative data for this event.