Phased Reconnaissance Approach to Documenting Landslides following the 2016 Central Italy Earthquakes

Abstract

The 2016 Central Italy earthquake sequence caused numerous landslides over a large area in the Central Apennines. As a result, the Geotechnical Extreme Events Reconnaissance Association (GEER) organized post-earthquake reconnaissance missions to collect perishable data. Given the challenging conditions following the earthquakes, the GEER team implemented a phased reconnaissance approach. This paper illustrates this approach and how it was used to document the largest and most impactful seismically induced landslides. This phased approach relied upon satellite-based interferometric damage proxy maps, preliminary published reports of observed landslides, digital imaging from small unmanned aerial vehicles (UAVs), traditional manual observations, and terrestrial laser scanning. Data collected from the reconnoitered sites were used to develop orthophotos and meshed three-dimensional digital surface models. These products can provide valuable information such as accurate measurements of landslide ground movements in complex topographic geometries or boulder runout distances from rock falls. The paper describes three significant landslide case histories developed and documented with the phased approach: Nera Valley, Village of Pescara del Tronto, and near the villages of Crognaleto and Cervaro.

Sequential Earthquake Damage Assessment Incorporating Optimized sUAV Remote Sensing at Pescara del Tronto

“…The eBee is a small fixed-wing sUAV manufactured by SenseFly at about 0.6 kg of platform weight, and can collect up to 8 km 2 of surface area and 40 min of flight time depending on payload for the reconnaissance mission. The equipped payload included a digital camera Canon Power Shot S100, 1/1.7" Canon CMOS sensor, focal length of 5.2 mm, and 12 MP images [6]. While the platform can be navigated manually by a ground pilot, a piece of mission-planning software called eMotion [19] pre-programmed the system with GPS aerial waypoints.…”

“…Images showing the layout of the GCP markers and layout in Pescara del Tronto are shown below (see Figures 3 and 4 from the GEER report) [1]. After the images and ground control points were obtained during the 2016 reconnaissance projects, 3D models developed and recorded current conditions and detected deformations that took place between the two events [6] (see Figures 5 and 6 for the models). The models were made through Bentley TM ContextCapture modeling software which determines 3D point locations within a scene using GPS and camera metadata.…”

“…A sequence of large earthquakes caused considerable damage to multiple cities surrounding the faults in the Central Italian Apennine Mountain Range [1][2][3][4][5][6][7]. Analysis of high-magnitude earthquake sites assists post-disaster recovery and preventative efforts; an example in Iran is shown by Karimzadeh et al [8].…”

“…The August 2016 earthquake caused significant damage in the following villages: Arquata del Tronto, Accumoli, Amatrice, and Pescara del Tronto [4,5]. The October events caused significant damage primarily in the villages of Visso, Ussita, and Norcia [2,6], and exacerbated the damage in Pescara del Tronto. Other analyses of the 2016 earthquake sequence include geohazard forensics of Norcia in Barone and Di Maggio [9] as well as numerical modeling of ground deformation in Valerio et al [10], the mechanisms of the earthquakes in Zhong et al [11], and Amatrice building damage assessment using synthetic aperture radar (SAR) in Karimzadeh and Matsuoka [12].…”

“…The peak ground acceleration (PGA) in city for the M6.2 24 August, M6.1 26 October, and M6. 6 30 October events were 0.48 g, 0.10 g, and 0.34 g, respectively [4,5]. The closest ground motion station to the events' epicenters was located at 42.962 • N 13.050 • E at a distance of 29.6 km from Pescara del Tronto, as recorded on the USGS web site for each event (https://earthquake.usgs.gov/earthquakes/).…”