Off-fault deformation and shallow slip deficit in the 2016 Norcia, Italy earthquake captured by differential terrestrial laser scanning and structure-from-motion

Earthquakes typically create a rapid displacement at the earth’s surface, called a surface rupture. This rupture occurs during the earthquake, and the size and length of the rupture at the surface relates to what happened on the fault line at depth in the earth's brittle crust. We do not fully understand exactly how the surface rupture relates to slip at depth, and how it is preserved in the geological record. The fault may also experience some slower motion in the days, weeks, and months following the earthquake. This ‘post-seismic’ motion can tell us something about the friction acting on the fault surface, which is in turn important for understanding how and why earthquakes occur. We targeted a magnitude 6.6 earthquake that occurred in central Italy in 2016, which was part of a sequence of events that killed nearly 300 people and left many thousands homeless. We used a laser to make a very detailed map at centimeter resolution of the surface rupture and its surroundings, finding that the displacement in the earthquake is sometimes distributed over 100’s of meters. We will discuss how the displacement evolves over time, and what this may imply for the frictional properties of this fault.