COSEISMIC LANDSLIDES IN SUBDUCTION EVENTS: INSIGHTS FROM THE 2011 M9 TOHOKU, JAPAN INVENTORY (Invited Presentation)

Coseismic landslides from the 2011 Mw9.0 Tohoku, Japan earthquake produced, mobilized, and transported large amounts of debris, which damaged buildings, obstructed transportation networks, modified fluvial networks, denuded slopes, and caused fatalities. The Tohoku coseismic landslide inventory, which was initially developed shortly after the earthquake and was recently revised, is among the largest (~28,000 km2), high-quality catalogs of seismically induced ground failures. Analysis of the inventory reveals that most landslides occurred in younger rock units and Quaternary sediments. The most common type of landslide was disrupted slides in sedimentary rocks; however, when considered in the context of landslide debris mobilization, lateral spreading within Quaternary sediments largely dominate the inventory. Records from Japan’s dense seismograph network provide a unique opportunity to examine the relationship between coseismic landslides and strong ground motion. Interestingly, our comparisons found no significant correlation between overall landslide intensity and common ground shaking parameters such as peak ground acceleration (PGA). However, relationships between landslide intensity and ground motion begin to emerge when the data is disaggregated according to landslide mode.