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Historical and Instrumental Seismicity of the Sansepolcro Basin, Northern Apennines, Italy
Author(s)
Type
Poster session
Language
English
Obiettivo Specifico
3.10. Sismologia storica e archeosismologia
Status
Published
Issued date
September 7, 2008
Conference Location
Hersonissos, Crete, Greece
Abstract
In this work we analyse the most important earthquakes of the 20th century occurred in the Altotiberina Valley in 1917, 1918, 1919 and 1948; in particular instrumental relocation and Ms magnitude estimation are re-evaluated. The area investigated, the Sansepolcro basin, is characterized by the presence of important earthquakes in the past with estimated intensity even larger than IX MCS (the 1352 Monterchi earthquake, the 1389 Boccaserriola, the 1458 Citta' di Castello, the 1781 Cagliese and the 1917 Monterchi-Citerna earthquakes, CPTI
Working Group, 2004) and by a surprisingly scarce instrumental seismicity compared to the adjacent areas struck by high seismicity (Castello et al., 2005; Ciaccio et al., 2006). In particular, the area north of Sansepolcro has been struck in recent years by four minor sequences, occurred between 1987 and 2001 with magnitude ranging from Ml3.0 to Mw4.7. The relocation of these earthquakes is particularly critical and in an important issue. An instrumental and precise location is critical for the complexity of the problems associated with the study of seismograms prior to the rst half of the twentieth century and is relevant because in the surrounding regions higher seismicity is observed. Regarding this peculiarity of the area, it’s very important to detect the localization of the historical earthquakes: in particular, the 1917 event is often associated to the possibility that the regional low angle Altotiberina Fault (Barchi et al., 1998) is able or not to nucleate large- or moderate-magnitude events, being historically located close to its surface (Boncio and Lavecchia, 2000).
Working Group, 2004) and by a surprisingly scarce instrumental seismicity compared to the adjacent areas struck by high seismicity (Castello et al., 2005; Ciaccio et al., 2006). In particular, the area north of Sansepolcro has been struck in recent years by four minor sequences, occurred between 1987 and 2001 with magnitude ranging from Ml3.0 to Mw4.7. The relocation of these earthquakes is particularly critical and in an important issue. An instrumental and precise location is critical for the complexity of the problems associated with the study of seismograms prior to the rst half of the twentieth century and is relevant because in the surrounding regions higher seismicity is observed. Regarding this peculiarity of the area, it’s very important to detect the localization of the historical earthquakes: in particular, the 1917 event is often associated to the possibility that the regional low angle Altotiberina Fault (Barchi et al., 1998) is able or not to nucleate large- or moderate-magnitude events, being historically located close to its surface (Boncio and Lavecchia, 2000).
References
* BAAS, British association for the advancement of science. Seismological committee - Bulletin for March, April 1917, Prof. H. H. Turner,
University Observatory Oxford.
* Barchi, M.R., A. De Feyter, M.B. Magnani, G. Minelli, G. Pialli and B.M. Sotera (1998) Extensional tectonics in the Northern
Apennines (Italy): Evidence from the CROP03 deep seismic reflection line, Mem. Soc. Geol. It., 52, 527-538
* Boncio, P. and G. Lavecchia (2000) A structurl model for active extension in Central Italy, J. of Geodynamics, 29, 233-244.
* Brune J.N. (1970, 1971), Tectonic stress and spectra of seismic shear waves from earthquakes, Journal of Geophisical research, 76, p.
5002, 1971.
* Caciagli M., Palombo B., Batllo’ J. 2006, The Alta Val Tiberina (Italy) Earthquake of 26th April 1917: reassessment of the main
seismological, Geneva, 3-8 September 2006.
* Castello, B., G., Selvaggi, C., Chiarabba, and A., Amato (2005), CSI Catalogo della sismicità italiana 1981-2002, versione 1.0.
INGV-CNT, Roma http://www.ingv.it/CSI/
* Ciaccio M.G., Pondrelli S., Frepoli A. (2006) Earthquake fault-plane solutions and patterns of seismicity within the Umbria Region,
Italy, ANNALS OF GEOPHYSICS, VOL. 49, N. 4/5, August/October 2006.
* CPTI Working Group (2004) Catalogo Parametrico dei Terremoti Italiani versione 2004 (CPTI04). INGV, Bologna.
http://emidius.mi.ingv.it/CPTI/
* Guidoboni E., Ferrari G., D.Mariotti, A.Comastri, G.Tarabusi and G.Valensise 2007 - CFTI4Med, Catalogue of Strong Earthquakes in Italy (461
B.C.-1997) and Mediterranean Area (760 B.C.-1500). INGV-SGA. http://storing.ingv.it/cfti4med/
* Lomax A., (2005), A reanalysis of the hipocentral location and related observations for the great 1906 California earthquake, Bull.Seismol. Soc. Am., 95, 861-877
* Pintore S. et al. (2005), Teseo: A vectoriser of historical seismograms, Computers & Geosciences, 31, , Pages 1277-1285
* Snoke 2002, FOCMEC:FOcal MEChanism determinations, International Handbook of Earthquake and Engineering Seismology, Part B, edited by W.H.K.Lee et al., chap 85.12, pp 1629-1630, Academic Press, San Diego
University Observatory Oxford.
* Barchi, M.R., A. De Feyter, M.B. Magnani, G. Minelli, G. Pialli and B.M. Sotera (1998) Extensional tectonics in the Northern
Apennines (Italy): Evidence from the CROP03 deep seismic reflection line, Mem. Soc. Geol. It., 52, 527-538
* Boncio, P. and G. Lavecchia (2000) A structurl model for active extension in Central Italy, J. of Geodynamics, 29, 233-244.
* Brune J.N. (1970, 1971), Tectonic stress and spectra of seismic shear waves from earthquakes, Journal of Geophisical research, 76, p.
5002, 1971.
* Caciagli M., Palombo B., Batllo’ J. 2006, The Alta Val Tiberina (Italy) Earthquake of 26th April 1917: reassessment of the main
seismological, Geneva, 3-8 September 2006.
* Castello, B., G., Selvaggi, C., Chiarabba, and A., Amato (2005), CSI Catalogo della sismicità italiana 1981-2002, versione 1.0.
INGV-CNT, Roma http://www.ingv.it/CSI/
* Ciaccio M.G., Pondrelli S., Frepoli A. (2006) Earthquake fault-plane solutions and patterns of seismicity within the Umbria Region,
Italy, ANNALS OF GEOPHYSICS, VOL. 49, N. 4/5, August/October 2006.
* CPTI Working Group (2004) Catalogo Parametrico dei Terremoti Italiani versione 2004 (CPTI04). INGV, Bologna.
http://emidius.mi.ingv.it/CPTI/
* Guidoboni E., Ferrari G., D.Mariotti, A.Comastri, G.Tarabusi and G.Valensise 2007 - CFTI4Med, Catalogue of Strong Earthquakes in Italy (461
B.C.-1997) and Mediterranean Area (760 B.C.-1500). INGV-SGA. http://storing.ingv.it/cfti4med/
* Lomax A., (2005), A reanalysis of the hipocentral location and related observations for the great 1906 California earthquake, Bull.Seismol. Soc. Am., 95, 861-877
* Pintore S. et al. (2005), Teseo: A vectoriser of historical seismograms, Computers & Geosciences, 31, , Pages 1277-1285
* Snoke 2002, FOCMEC:FOcal MEChanism determinations, International Handbook of Earthquake and Engineering Seismology, Part B, edited by W.H.K.Lee et al., chap 85.12, pp 1629-1630, Academic Press, San Diego
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