Multi-temporal Maps of the Montaguto Earth Flow in Southern Italy from 1954 to 2010

Figures & data

Figure 1. The Montaguto earth flow on 27 April 2006. Photo taken from a helicopter looking south toward the earth-flow toe.

Table 1. Data used for base maps.

Date	Data source	Product used for base map	Pixel size (single-sided dimension)
19 October 1954	Aerial photos (stereo pair)	Rectified aerial photo	1 m
23 June 1976	Aerial photos (stereo pair)	Rectified aerial photo	1 m
16 June 1991	Aerial photos (stereo pair)	Rectified aerial photo	1 m
8 June 2003	Aerial photos (stereo pair)	Rectified aerial photo	1 m
June 2005	Color orthophoto	Gray-scale orthophoto	0.2 m
May 2006	LiDAR data	Shaded-relief DEM	1 m
2 October 2007	Eros B data	Orthorectified photo	0.7 m
July 2009	LiDAR data	Shaded-relief DEM	1 m
March 2010	LiDAR and Eros B data	Shaded-relief DEM	1 m

Figure 2. Back-tilted surface on the body of the earth flow with a small pond (about 7-m wide) located in the depression formed by back-tilting. Arrow shows the direction of back-tilting. Movement of the earth flow is from left to right.

Figure 3. Thrust fault in the earth-flow source area. Linework shows the position of the mapped thrust fault. Thrust fault is about 100-m long at this location.

Figure 4. Flank ridge in the middle part of the source area of the earth flow. Linework shows the topographic crest of the ridge. Distance across the photo from left to right is about 150 m.

Figure 5. Normal faults at the head of the earth flow. Linework connects points along the top of the scarp. Height of the prominent scarp at the upper right is about 2 m.

Figure 6. Strike-slip fault along the body of the earth flow. Slickensides and arrow show movement direction. Distance from left to right across the photo is about 4 m.

Table 2. Earth flow movement and mitigation activities that occurred between mapping dates. Sources of information are given in column 2.

Time period	Documented movement and modification of the earth flow
19 October 1954 to 23 June 1976	The following quote was from an interview with the owner of the farm land that includes and surrounds the earth flow. The owner has lived on the land his entire life (he was 92 years old in 2011). ‘In 1954-55, the lama (the term in the local dialect for landslide) ate my land, and my sheep drank water from ponds on the lama. From December to May there were many ponds. In 1958 my old house was ‘eaten’ by the lama and I and my parents had to move to where I live today. Between 1954 and 1961, I have not cultivated some of my land due to the lama.' From these quotes, it appears that the earth flow was moving in 1954–55 and 1958.
23 June 1976 to 16 June 1991	The land owner told the authors that during this period, his family was able to grow crops on the earth flow because the earth flow was relatively stable, and that the earth flow only moved during periods when there were ponds in the source area.
16 June 1991 to 8 June 2003	The land owner indicated that the lower part of the earth flow was active during this period. From our mapping, the earth-flow toe appears to have expanded, and been modified by human activity, during this period.
8 June 2003 to June 2005	The land owner and other local residents indicated that the earth flow moved in the spring, and possibly summer of 2004.
June 2005 to May 2006	The land owner told the authors that during this period the entire length of the earth flow was active. In December 2005, the mayor of Montaguto, Giuseppe Andreano, recognized that movement of the earth flow was a potential problem for the community and National Road SS90. On 26 April 2006 a large remobilization of earth flow covered and closed SS90 and damaged some buildings near the toe. The remobilization lengthened the earth flow by about 700 m and filled a v-shaped drainage downslope from the previous toe with about 1 million m^3 of earth-flow material.
May 2006 to October 2007	From official closures of the National Road, interviews with road maintenance officials, and field observations of the authors, it is clear that the earth flow was very active during this period. From 3 to 13 May 2006, the community of Montaguto was without water because the earth flow cut a water supply line. Excavation related to earth-flow mitigation and rebuilding of SS90 modified the surface of the earth flow. Removal of material from SS90 induced additional movement in the toe area. On 30 August 2006, SS90 was reopened. From December, 2006 to August, 2007, SS90 was closed and reopened four times.
October 2007 to July 2009	Observations of the authors indicate that earth-flow activity during this period was concentrated in the source area and near the toe. Between March and November, 2008, earth-flow movement was minimal. Between January and July, 2009, SS90 was closed and reopened three times. During the night between 5 and 6 June, 2009 part of the earth-flow toe moved about 50 m in about 12 h. The surface of the earth flow continued to be modified by mitigation activities.
July 2009 to March, 2010	Field observations of the authors indicated that the entire earth flow was moving from August 2009 to March 2010. The source area was particularly active in early 2009 when the headscarp progressed upslope. On 10 March 2010, another large remobilization of the earth flow occurred. This reactivation covered and closed the national road and the Benevento-Foggia railway.