A newly published study shows that landslides triggered by seismic vibrations will be a major hazard of large earthquakes. The study offers better ways to model and forecast these landslides, offering foresight to the people who plan emergency quake response.
Earthquakes cause several distinct varieties of damage. Some of these are fairly well understood in theory, and experts can make useful scenarios for them. These include the "big four" of shaking damage to buildings, tsunamis, ground liquefaction, and fault motion. We can counter their respective threats by computer-tested structure designs, tsunami modeling and warnings, liquefaction hazard maps, and regulations keeping structures away from active faults.
Landslides are kind of a wild card, though. The typical urban landslide occurs when gravity overrules the strength of a hillslope, because heavy rainfall lubricates it or human activities disturb it (usually both at once). Common landslides can be fairly well assessed by geotechnical professionals, and geological agencies have been preparing maps of this general hazard for many years.
Earthquake landsliding is a different animal that typical methods can't predict, and they can have devastating effects. For instance, the 2008 Wenchuan earthquake in China caused an estimated 60,000 landslides, which were responsible for tens of thousands of deaths. Few studies have made systematic surveys of landslides after earthquakes, so we don't have good databases to work from—and those are only trustworthy for the specific geologic setting of their locations.