Macroseismic Survey of the 2002 Molise, Italy, Earthquake and Historical Seismicity of San Giuliano di Puglia

Galli, Paolo; Molin, Diego

doi:10.1193/1.1766034

Cited by 19 publications

(18 citation statements)

References 8 publications

(6 reference statements)

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“…Every strong earthquake occurred in Italy in the past 20 years, geologists from the Italian Dipartimento della Protezione Civile and from the Istituto Nazionale di Geofisica e Vulcanologia start the macroseismic survey within a few hours after the main shock (Bernardini et al, ; Camassi et al, ; Galli et al, , , ; Galli & Molin, ). The main purpose of this emergency survey is to provide the Civil Protection with (1) a univocal snapshot of the heavy damage distribution within a couple of days and (2) a reliable distribution of damage in the far field within 20–30 days.…”

Section: The 30 October Earthquake Macroseismic Surveymentioning

confidence: 99%

The Macroseismic Intensity Distribution of the 30 October 2016 Earthquake in Central Italy (M_w 6.6): Seismotectonic Implications

2017

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The central Italy Apennines were rocket in 2016 by the strongest earthquakes of the past 35 years. Two main shocks (Mw 6.2 and Mw 6.6) between the end of August and October caused the death of almost 300 people, and the destruction of 50 villages and small towns scattered along 40 km in the hanging wall of the N165° striking Mount Vettore fault system, that is, the structure responsible for the earthquakes. The 24 August southern earthquake, besides causing all the casualties, razed to the ground the small medieval town of Amatrice and dozens of hamlets around it. The 30 October main shock crushed definitely all the villages of the whole epicentral area (up to 11 intensity degree), extending northward the level of destruction and inducing heavy damage even to the 30 km far Camerino town. The survey of the macroseismic effects started the same day of the first main shock and continued during the whole seismic sequence, even during and after the strong earthquakes at the end of October, allowing the definition of a detailed picture of the damage distribution, day by day. Here we present the results of the final survey in terms of Mercalli‐Cancani‐Sieberg intensity, which account for the cumulative effects of the whole 2016 sequence (465 intensity data points, besides 435 related to the 24 August and 54 to the 26 October events, respectively). The distribution of the highest intensity data points evidenced the lack of any possible overlap between the 2016 earthquakes and the strongest earthquakes of the region, making this sequence a unique case in the seismic history of Italy. In turn, the cross matching with published paleoseismic data provided some interesting insights concerning the seismogenic behavior of the Mount Vettore fault in comparison with other active normal faults of the region.

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Section: The 30 October Earthquake Macroseismic Surveymentioning

confidence: 99%

The Macroseismic Intensity Distribution of the 30 October 2016 Earthquake in Central Italy (M_w 6.6): Seismotectonic Implications

2017

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“…Table 1 -Earthquakes considered in this study. Pondrelli et al (2004); the VI and VII MCS intensity isoseismals are redrawn from Galli and Molin (2004). (Rovelli et al, 1988).…”

Section: Table Captionmentioning

confidence: 99%

“…On 31 October 2002, a M w 5.7 earthquake occurred in Apulian foreland of Italy (Figure 1), at the border between the Molise and Puglia administrative regions (Maffei and Bazzurro, 2004, and papers therein;Chiarabba et al, 2005). Its macroseismic effects reached MCS intensity VII in the epicentral area and were moderate to low all around it (Galli and Molin, 2004). A distinctive exception was the town of San Giuliano di Puglia, where an instrumentally well documented local site effect (Cara et al, 2005) caused an intensity anomaly.…”

Section: Introductionmentioning

confidence: 98%

Do Strike-Slip Faults of Molise, Central-Southern Italy, Really Release a High Stress?

Calderoni

Rovelli

Milana

et al. 2010

Bulletin of the Seismological Society of America

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The 31 October and 1 November 2002, Molise earthquakes (both Mw 5.7) were caused by right-lateral slip between 12 and 20 km depth. These earthquakes are the result of large-scale reactivation of pre-existing, left-lateral, regionally extended E-W structures of Mesozoic age. Although recorded ground motions were generally smaller than expected for typical Italian earthquakes, a recent paper attributes a stress drop as high as 180 bars to the Molise earthquakes. We remark that a high stress drop is in contrast both with the relatively long source duration inferred in previous investigations and with geodetic evidence for a significantly smaller fault slip compared with other Apennines earthquakes having similarly large rupture area (e.g. 1997 Umbria-Marche earthquakes). We analyzed both ground acceleration spectra of the mainshocks and single-station spectral ratios of broad-band seismograms in an extended magnitude range (2.7 ≤ Mw ≤ 5.7). Our results show that neither the spectral amplitudes of recorded ground motions nor the spectral ratios can be fit by a high stress drop source. Instead we find that the observations are consistent with a low stress drop, our best estimates ranging between 6 and 25 bars, in agreement with the relatively long source duration and small coseismic slip. We interpret the low stress of the 2002 Molise earthquakes in terms of lower energy release mechanisms due to the reutilization of faults reactivated opposite to their original sense of slip.

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“…The 2016-2017 sequence has been the most destructive in Italy since EMS intensities have come into use, because the maximum intensity in the 2012 Emilia seismic sequence has been VIII (Tertulliani et al 2012), and in the 2009 L'Aquila Earthquake has been IX (Azzaro et al 2011). As for Mercalli-Cancani-Sieberg (MCS, Sieberg 1930) intensities, the 2004 Molise Earthquake induced a IX-X (Galli and Molin 2004), the 1997-1998 Umbria-Marche sequence caused a maximum intensity of VIII-IX (Camassi et al 2008), the 1980 Irpinia Earthquake several X and the 1976 Friuli sequence several IX-X (Rovida et al 2016). According to Margottini et al (1987), IEMS = X roughly corresponds to IMCS = XI.…”

Section: Introductionmentioning

confidence: 99%

Seismic behaviour of ordinary masonry buildings during the 2016 central Italy earthquakes

Sorrentino

Cattari

Porto

et al. 2018

Bull Earthquake Eng

199

103

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Between August 2016 and January 2017 nine shallow earthquakes ranging from 5.0 and 6.5 of moment magnitude affected Central Italy, involving several municipalities wherein unreinforced masonry buildings are more than three quarters of all constructions. Damage state has been very severe, with sixteen settlements belonging to the municipalities of Amatrice, Arquata del Tronto, Accumoli. Castelsantangelo sul Nera and Norcia experiencing a cumulative European macroseismic scale intensity larger than IX. Ground motion demand in terms of peak ground velocity was approximately two or three times what expected for a 475 years return period while the pseudoacceleration response spectra showed values between once and twice gravity acceleration for the period range typical of two and three storeys unreinforced masonry buildings. Moreover, since October 2016, such large seismic demand acted on structures damaged from previous shocks testifying the effects of damage accumulation, too. The significant shaking alone cannot explain the extremely severe damage of some settlements, with large portions of whole blocks completely collapsed, highlighting the need for investigating the specific vulnerability factors and construction features of unreinforced masonry buildings in the affected area. In fact, although some deficiencies already highlighted in previous Italian earthquakes (e.g. inadequate structural connections) have been surveyed also during this sequence, a marked vulnerability of masonry and its mortar has been noticed, in particular in the area between Amatrice and Arquata del Tronto. On the contrary, the historical constructions in Norcia performed much better, as a result of the 1860 seismic code and of the retrofitting interventions implemented after the different earthquakes occurred in the last two centuries. Finally, a number of demolished and rebuilt constructions performed very well, and this was also the case also of modern hollow clay blockwork buildings that protected not only human life, but also cost of construction and continuity of use.

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Macroseismic Survey of the 2002 Molise, Italy, Earthquake and Historical Seismicity of San Giuliano di Puglia

Cited by 19 publications

References 8 publications

The Macroseismic Intensity Distribution of the 30 October 2016 Earthquake in Central Italy (M_w 6.6): Seismotectonic Implications

The Macroseismic Intensity Distribution of the 30 October 2016 Earthquake in Central Italy (M_w 6.6): Seismotectonic Implications

Do Strike-Slip Faults of Molise, Central-Southern Italy, Really Release a High Stress?

Seismic behaviour of ordinary masonry buildings during the 2016 central Italy earthquakes

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Macroseismic Survey of the 2002 Molise, Italy, Earthquake and Historical Seismicity of San Giuliano di Puglia

Cited by 19 publications

References 8 publications

The Macroseismic Intensity Distribution of the 30 October 2016 Earthquake in Central Italy (Mw 6.6): Seismotectonic Implications

The Macroseismic Intensity Distribution of the 30 October 2016 Earthquake in Central Italy (Mw 6.6): Seismotectonic Implications

Do Strike-Slip Faults of Molise, Central-Southern Italy, Really Release a High Stress?

Seismic behaviour of ordinary masonry buildings during the 2016 central Italy earthquakes

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The Macroseismic Intensity Distribution of the 30 October 2016 Earthquake in Central Italy (M_w 6.6): Seismotectonic Implications

The Macroseismic Intensity Distribution of the 30 October 2016 Earthquake in Central Italy (M_w 6.6): Seismotectonic Implications