A study of some earthquakes (M > 5.3) affecting Southeastern Sicily was performed to define their seismic sources and to estimate seismic hazard in the region. An analysis of historical reports allowed us to reassess intensities of the 1542, 1693, 1818, 1848 and 1990 earthquakes by using the new European Macroseismic Scale 98. The new intensity data were used to define parameters and the orientation of seismic sources. The sources obtained were compared with the ones computed using the MCS intensities retrieved from the Catalogue of Strong Italian Earthquakes. The adopted procedure gives results that are statistically significant, but both the epicentre location and source azimuth, in some cases, are strongly affected by the azimuthal gap in the intensity distribution. This is evident mainly for the 1693 January earthquakes. For these earthquakes the macroseismic data uncertainty gives significantly different solutions, and does not allow the events to be associated with known active faults. By handling the new estimated intensity data and using the site seismic histories, the seismic hazard for some localities was calculated. The highest probability of occurrence, for destructive events (I = 10), was obtained in the area between Catania, Lentini and Augusta, suggesting that the seismogenic sources are located near the Ionian coast.
{"title":"Earthquake sources and seismic hazard in Southeastern Sicily","authors":"M. S. Barbano, R. Rigano","doi":"10.4401/AG-3570","DOIUrl":"https://doi.org/10.4401/AG-3570","url":null,"abstract":"A study of some earthquakes (M > 5.3) affecting Southeastern Sicily was performed to define their seismic sources and to estimate seismic hazard in the region. An analysis of historical reports allowed us to reassess intensities of the 1542, 1693, 1818, 1848 and 1990 earthquakes by using the new European Macroseismic Scale 98. The new intensity data were used to define parameters and the orientation of seismic sources. The sources obtained were compared with the ones computed using the MCS intensities retrieved from the Catalogue of Strong Italian Earthquakes. The adopted procedure gives results that are statistically significant, but both the epicentre location and source azimuth, in some cases, are strongly affected by the azimuthal gap in the intensity distribution. This is evident mainly for the 1693 January earthquakes. For these earthquakes the macroseismic data uncertainty gives significantly different solutions, and does not allow the events to be associated with known active faults. By handling the new estimated intensity data and using the site seismic histories, the seismic hazard for some localities was calculated. The highest probability of occurrence, for destructive events (I = 10), was obtained in the area between Catania, Lentini and Augusta, suggesting that the seismogenic sources are located near the Ionian coast.","PeriodicalId":350899,"journal":{"name":"Annali Di Geofisica","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126686964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Southeastern Sicily is one of the Italian regions with high seismic risk and is characterised by the occurrence in the past of large destructive events (Ms = 6.4-7.3) over a territory which is densely urbanised today. The main earthquakes were analysed and some minor damaging shocks reviewed to investigate the main seismogenic features of the region. The comparison between the pattern of seismicity and evidence of Quaternary tectonics allowed us to propose a first tentative, tectonic interpretation of the earthquakes. On the whole, the seismicity of SE Sicily seems distributed along regional fault systems which have had a role in the recent geodynamic evolution of the area. The Malta escarpment, the only structure whose late Quaternary-recent activity is currently known, appears the most probable source for earthquakes with about 7 magnitude. Although no evidence of tectonics subsequent to the middle Pleistocene is available for them, the Scicli line and the NE-SW fault system delimiting the northern sector of the Hyblean plateau seem seismically active with events with maximum magnitude of 5.2 and 6.4, respectively.
{"title":"Analysis of the seismicity of Southeastern Sicily: a proposed tectonic interpretation","authors":"R. Azzaro, M. S. Barbano","doi":"10.4401/AG-3628","DOIUrl":"https://doi.org/10.4401/AG-3628","url":null,"abstract":"Southeastern Sicily is one of the Italian regions with high seismic risk and is characterised by the occurrence in the past of large destructive events (Ms = 6.4-7.3) over a territory which is densely urbanised today. The main earthquakes were analysed and some minor damaging shocks reviewed to investigate the main seismogenic features of the region. The comparison between the pattern of seismicity and evidence of Quaternary tectonics allowed us to propose a first tentative, tectonic interpretation of the earthquakes. On the whole, the seismicity of SE Sicily seems distributed along regional fault systems which have had a role in the recent geodynamic evolution of the area. The Malta escarpment, the only structure whose late Quaternary-recent activity is currently known, appears the most probable source for earthquakes with about 7 magnitude. Although no evidence of tectonics subsequent to the middle Pleistocene is available for them, the Scicli line and the NE-SW fault system delimiting the northern sector of the Hyblean plateau seem seismically active with events with maximum magnitude of 5.2 and 6.4, respectively.","PeriodicalId":350899,"journal":{"name":"Annali Di Geofisica","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115395299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The current Italian seismic catalogues are generally considered «complete» as regards the destructive seismic events which occurred from the 17th century onwards. In fact, research performed using target methodologies still reveal earthquakes of high intensity, not yet known to the seismological tradition. This is the case of an earthquake which occurred on 14 September 1780, which caused serious damage and victims in some towns of the Tyrrhenian coast of North-eastern Sicily (Io = VIII MCS). The information reported in an anonymous printed account was verified in the administrative records; this allowed a reconstruction of a macroseismic outline of great interest, which may make more precise the seismic hazard assessment in an area at high environmental risk due to the presence in Milazzo of an important chemico-industrial complex.
目前的意大利地震目录通常被认为是“完整的”，关于17世纪以来发生的破坏性地震事件。事实上，使用目标方法进行的研究仍然揭示了地震传统尚未知道的高强度地震。这是1780年9月14日发生的一次地震的情况，在西西里岛东北部第勒尼安海岸的一些城镇造成了严重的破坏和人员伤亡(Io = VIII MCS)。在一个匿名的打印帐户中报告的信息在行政记录中得到核实;这使得重建大地震的轮廓非常有趣，这可能使更精确的地震危害评估在一个地区的高环境风险，因为在米拉佐存在一个重要的化学工业综合体。
{"title":"An unknown destructive earthquake in 18th century Sicily","authors":"D. Mariotti","doi":"10.4401/AG-4060","DOIUrl":"https://doi.org/10.4401/AG-4060","url":null,"abstract":"The current Italian seismic catalogues are generally considered «complete» as regards the destructive seismic events which occurred from the 17th century onwards. In fact, research performed using target methodologies still reveal earthquakes of high intensity, not yet known to the seismological tradition. This is the case of an earthquake which occurred on 14 September 1780, which caused serious damage and victims in some towns of the Tyrrhenian coast of North-eastern Sicily (Io = VIII MCS). The information reported in an anonymous printed account was verified in the administrative records; this allowed a reconstruction of a macroseismic outline of great interest, which may make more precise the seismic hazard assessment in an area at high environmental risk due to the presence in Milazzo of an important chemico-industrial complex.","PeriodicalId":350899,"journal":{"name":"Annali Di Geofisica","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121071108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Several attempts have been made recently to infer the dynamic rupture processes of moderate-size earthquakes from kinematic waveform inversion and dynamic crack inversion. These studies have revealed a quite heterogeneous distribution of dynamic stress drop and relative fault strength over the fault for most earthquakes. In two strike-slip California earthquakes, negative stress drop has been identified in a shallow section of the fault, suggesting the possible existence of a zone of velocity-strengthening frictions. The dynamic models yielded quite short rise times comparable to those inferred from kinematic modelling of observed waveforms. The short slip durations for these earthquakes may probably be attributed to shorter length scale of fault segmentation due to the heterogeneities of shear stress and fault strength.
{"title":"Dynamic fault rupture processes of moderate-size earthquakes inferred from the results of kinematic waveform inversion","authors":"T. Mikumo","doi":"10.4401/AG-4140","DOIUrl":"https://doi.org/10.4401/AG-4140","url":null,"abstract":"Several attempts have been made recently to infer the dynamic rupture processes of moderate-size earthquakes from kinematic waveform inversion and dynamic crack inversion. These studies have revealed a quite heterogeneous distribution of dynamic stress drop and relative fault strength over the fault for most earthquakes. In two strike-slip California earthquakes, negative stress drop has been identified in a shallow section of the fault, suggesting the possible existence of a zone of velocity-strengthening frictions. The dynamic models yielded quite short rise times comparable to those inferred from kinematic modelling of observed waveforms. The short slip durations for these earthquakes may probably be attributed to shorter length scale of fault segmentation due to the heterogeneities of shear stress and fault strength.","PeriodicalId":350899,"journal":{"name":"Annali Di Geofisica","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125934307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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