**2. The southern Apennines**

The Apennines are a Neogene and Quaternary thrust and fold belt located in the hangingwall of the west-plunging Adria plate (Cinque et al., 1991; Doglioni et al., 1996). The Southern Apennines are a complex curved structure elongated from the Abruzzi-Molise to the Calabria-Basilicata border.

Several kilometers of vertical displacement occurred on the Tyrrhenian margin mainly along southwest-dipping normal and oblique slip faults. The extensional movements, due to their progressive shift toward the eastern sectors of the still uplifting Apennines, created deep tectonic basins elongated north-west.


Table 1. Major earthquakes in studied area. I0 epicentral intensity; M macroseismic magnitude according to CPTI04 (2004), (\*) surface wave magnitude.

Fig. 1. (a) Sketch map of the Southern Apennines.

dislocation phenomena in complex systems of faults with different mechanisms and orientations. According to this model the coseismic dislocation during strong earthquakes produces a notable deformation of the superficial crust (surface layers) which influence directly the surface aquifers. Therefore, the hydrological regime and the spatial variation of anomalies are correlated to the spatial variation of the volumetric deformation produced by

Here we resume the hydrological changes associated with some of the big earthquakes that occurred in the XX century in the Southern Apennines (Italy): 1930, 1980 and 1984. For the 23 July 1930 (MS=6.7) in Eastern Irpinia, 23 November 1980 (MS=6.9) in Irpinia-Lucania and 7 May 1984 (MS=5.8) in Southern Abruzzo earthquakes (figures 1a,b and 2a,b,c). We collected an abundance of well founded hydrological information, that cannot be ascribed to environmental or anthropical causes. We analysed also hydrometric and pluviometric data monitored from the hydrological network of Italian Hydrographic Survey (IHS), looking for significant changes in wells, springs and mountain streams. Hydrological data relative to wells, rivers and springs indicate that many changes can be correlated with the earthquakes. For these earthquakes, the pre- and co-seismic stresses and the tectonic deformations have been studied in order to find a possible model of interaction between

In this chapter a description of Southern Apennines, the three earthquakes and the types of

The Apennines are a Neogene and Quaternary thrust and fold belt located in the hangingwall of the west-plunging Adria plate (Cinque et al., 1991; Doglioni et al., 1996). The Southern Apennines are a complex curved structure elongated from the Abruzzi-Molise to

Several kilometers of vertical displacement occurred on the Tyrrhenian margin mainly along southwest-dipping normal and oblique slip faults. The extensional movements, due to their progressive shift toward the eastern sectors of the still uplifting Apennines, created deep

Year Month Day Hour-Min Epicentral Area I0 M 1688 6 5 15.3 Sannio XI 6.7 1694 9 8 11.4 Irpinia-Basilicata X-XI 6.9 1702 3 14 5 Sannio-Irpinia IX-X 6.3 1732 11 29 7.4 Irpinia X-XI 6.6 1805 7 26 21 Molise X 6.6 1930 7 23 0.08 Irpinia X (\*) 6.7 1962 8 21 18.19 Irpinia IX (\*) 6.2 1980 11 23 18.34 Irpinia X (\*) 6.9 1984 5 7 17.49 Southern Abruzzo VIII (\*) 5.8

Table 1. Major earthquakes in studied area. I0 epicentral intensity; M macroseismic

magnitude according to CPTI04 (2004), (\*) surface wave magnitude.

the phenomena of the coseismic dislocation in a wide area.

stress state and hydrological anomalies.

**2. The southern Apennines** 

the Calabria-Basilicata border.

tectonic basins elongated north-west.

hydrological effects for each earthquake are reported.

Fig. 1. (b) Hydrographic sketch map of the Southern Apennines with the epicenters of the three earthquakes

Fig. 2. (a) Isoseismal map for the 1930 earthquake

Fig. 2. (b) Isoseismal map for the 1980 earthquake

Fig. 2. (a) Isoseismal map for the 1930 earthquake

Fig. 2. (b) Isoseismal map for the 1980 earthquake

Fig. 2. (c) Isoseismal map for the 1984 earthquake

Studies of active tectonics and paleoseismicity confirm that extensional tectonics is still active in the southern Apennines, with slip-rates of several tens of millimetres per year, mostly for active faults from late Holocene until now (Westaway, 1992, 1993; Pantosti et al., 1993). The present-day tectonic setting of the mountain belt is governed by a system of Quaternary faults responsible for frequent moderate to strong crustal earthquakes, with typical hypocentral depths of 7-20 km. Table 1 lists the major earthquakes in the last centuries in studied area.
