Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/nhess-2018-75
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
26 Mar 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Natural Hazards and Earth System Sciences (NHESS).
Growth of a sinkhole in a seismic zone of the Northern Apennines (Italy)
Alessandro La Rosa1,2, Carolina Pagli2, Giancarlo Molli2, Francesco Casu3, Claudio De Luca3, and Amerino Pieroni4 1Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Via G. La Pira, 4, 50121 Firenze, Italy
2Dipartimento di Scienze della Terra, Università di Pisa, Via S. Maria, 53, 56126 Pisa, Italy
3CNR, Consiglio Nazionale delle Ricerche, Istituto per il Rilevamento Elettromagnetico dell'Ambiente (IREA-CNR), Via Diocleziano, 328, 80124 Napoli, Italy
4Pro.Geo. s.r.l. Via Valmaira, 14, 55032, Castelnuovo di Garfagnana, Italy
Abstract. Sinkhole collapse is a major hazard causing substantial social and economic losses. However, the surface deformations and sinkhole evolution are rarely recorded, as these sites are known mainly after a collapse, making the assessment of sinkholes-related hazard challenging. Furthermore, 40 % of the sinkholes of Italy are in seismically hazardous zones; it remains unclear whether seismicity may trigger sinkhole collapse. Here we use a multidisciplinary dataset of InSAR, surface mapping and historical records of sinkhole activity to show that the Prà di Lama lake is a long-lived sinkhole that was formed over a century ago and grew through several events of unrest characterized by episodic subsidence and lake-level changes. Moreover, InSAR shows that continuous aseismic subsidence at rates of up to 7.1 mm yr−1 occurred during 2001–2008, between events of unrest. Earthquakes on the major faults near the sinkhole are not a trigger to sinkhole activity but small-magnitude earthquakes at 4–12  km depth occurred during sinkhole unrest in 1996 and 2016. We interpret our observations as evidence of seismic creep in an active fault zone at depth causing fracturing and ultimately leading to the formation and growth of the Prà di Lama sinkhole.
Citation: La Rosa, A., Pagli, C., Molli, G., Casu, F., De Luca, C., and Pieroni, A.: Growth of a sinkhole in a seismic zone of the Northern Apennines (Italy), Nat. Hazards Earth Syst. Sci. Discuss., https://doi.org/10.5194/nhess-2018-75, in review, 2018.
Alessandro La Rosa et al.
Alessandro La Rosa et al.
Alessandro La Rosa et al.

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Short summary
In the last years, the shallow deformation phenomena occured at Prà di Lama have drawn the attention of scientific communities due to the risk of collapses that could involve the urban area of Pieve Fosciana and to possible connections with seismicity. This paper aims at answering these open questions by showing the long term evolution of the sinkhole-related deformations. We hypotize fault creep as the controlling mechanism while no connections with great earthquakes have been found.
In the last years, the shallow deformation phenomena occured at Prà di Lama have drawn the...
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