Laser scanning shows rates and patterns of surface deformation from the South Napa earthquake, California, USA

These spatially extensive measurement techniques provide new understanding of how earthquakes and other phenomena deform the shape of Earth's surface, reinforce the notion that not all surface deformation occurs during an earthquake itself, and provide insight into what can be expected following future earthquakes. When earthquakes strike, damage is expected to occur along the fault trace over a few seconds or perhaps minutes as Earth's tectonic plates shift, shake, and tear the ground.

However, in some cases, the damage to Earth's crust and what sits on top of it can unfold slowly over hours, days, weeks, and even years following an earthquake. This is often termed "afterslip." and it has been observed following many moderate earthquakes. Surface deformation following the South Napa quake occurred variously as discrete fault slip, rotation of a block of earth adjacent to the fault, and by vertical elevation changes. Comparison of the new 2014 terrestrial laser scanner data with 2003 airborne laser scanner data also indicate that the earthquake caused vertical warping across the fault zone rather than forming a distinct vertical scarp, challenging notions of how topography is created in moderate earthquakes.