ABSTRACT:

The 10 year long surface controls, integrated with inclinometer monitoring reveal that after the main failure the 1989 Caramanico landslide has remained substantially inactive (dormant). The periurban areas, including the mainscarp and the crown zone, have not shown any clear signs of renewed instability. Recurrent seasonal activity has been observed, however, in the two areas of the slide in the last few years; this included shallow retrogressive slump-earthflow movements. Of particular concern is the instability of the down-valley part of the toe and of the right flank. These local movements have been slow, but, if left uncontrolled, they could enlarge uplslope and thus undermine the stability of the nearby Caramanico cemetery. Although the effects on the tunnel to be located uphill of the 1989 slide are difficult to foresee, its designers and contractors will be faced with very complex subsurface conditions inherited from the past large-scale landsliding and neotectonics.

INTRODUCTION

In the fall of 1989, after a prolonged period of heavy precipitation a large (over 33 ha), tens of meters deep complex landslide was remobilised in the southern periphery of Caramanico Terme (southcentral Italy). The movement damaged several houses and destroyed over 600 m of the state highway 487. To date (1999), no stabilisation works have been realised on the 1989 landslide and the 487 route has not been repaired. Recently, the National Highway Administration (ANAS), has decided to construct a tunnel over one km long that by-passes the 1989 landslide area about 200–300 m further up-slope (Figure 1). Then, on the basis of inclinometer monitoring data integrated with surface observations, we will present the overview of the 10 year post-failure activity of the 1989 landslide and attempt to offer some insight into the present and future slope stability conditions.

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