Abstract
One of the challenges on disasters’ understanding is the assessment of impact from a more global perspective, adding to their scenario of injuries, deaths, homeless and economic losses, those effects that are mostly widespread and could last for a long period of time, driving to a serious disruption of a community or a society. Seismic disasters are not just the results of the energy released by the earthquake or buildings’ vulnerability: social, demographic, cultural parameters may instead play a crucial, yet underestimated, role. We carried out a pilot study to investigate the demographic perspective of the impact of 1968 Belice and 1980 Irpinia-Basilicata earthquakes on local communities. The macroseismic MCS intensities were used as a primary parameter upon which the demographic scenario was derived. Population annual growth rates, the ageing index, the child- woman ratio, and the Gini index from the demographic data census of the period 1951-2011 were analyzed to assess population dynamics, age structure evolution and its level of spatial concentration within the disasters’ areas. Demographic data were then matched to macroseismic intensities to outline a new, original analysis which describes the impact of the two seismic disasters with a broad multi-parameter perspective. The results highlight also the existence of a general marginality of most affected areas with respect to the processes of population growth, ageing and fertility, as well as for distribution of the regional population, occurring already before the disasters stroke. This marginality might have enhanced the impact of disasters by significantly increasing vulnerability.
Highlights
Disasters reveal the negative impact of hazards, overwhelming the capacity of a community to cope [Twigg, 2001]
For the Irpinia-Basilicata earthquake even large metropolitan areas such as Naples and its province were involved, and they are classified with I=7, and despite being relatively distant from the epicenter area, they were strongly affected by the impact of the earthquake
We had to convert intensities for 68% and 39% of municipalities for Belice and Irpinia-Basilicata earthquakes, respectively. These values result from summation of municipalities for which interpolation was applied (60% and 32% for Belice and Irpinia-Basilicata earthquakes, respectively) and those municipalities with only one macroseismic locality in their territory, whose intensity values are intermediate between two whole numbers (e.g. I=8-9, corrected than in I=8)
Summary
Disasters reveal the negative impact of hazards, overwhelming the capacity of a community to cope [Twigg, 2001]. In the last 50 years, Italy was affected by several seismic disasters with I0>8 (Figure 1): the 1968 Belice earthquake (MW=6.41, I0 10), the 1976 Friuli (MW=6.45, I0 9-10), the 1980 Irpinia-Basilicata (MW=6.81, I0 10), the 1997 Umbria-Marche (MW=5.97, I0 8-9), the 2009 L’ Aquila (MW=6.29, I0 9-10), the 2016 Amatrice (August 24th, MW=6.20, I0 10) seismic events [Rovida et al, 2016; Rossi et al, 2019b] They all caused disruption of the functioning of society and had a widespread impact in the long run. For the Irpinia-Basilicata earthquake even large metropolitan areas such as Naples and its province were involved, and they are classified with I=7, and despite being relatively distant from the epicenter area, they were strongly affected by the impact of the earthquake We chose these two earthquakes because of the availability of strong and robust datasets both for macroseismic intensities and for demographic data and indicators, compiled respectively by Istituto Nazionale di Geofisica e Vulcanologia (INGV) and National Institute of Statistics (ISTAT).
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