The Niigata Ken Chuetsu earthquake triggered a vast number of lanslides in the epicentral region. Landslide concentrations were among the highest ever measured after an earthquake, and most of the triggered landslides were relatively shallow failures parallel to the steep slope faces. The dense concentration of landslides can be attributed to steep local topography in relatively weak geologic units, adverse hydrologic conditions caused by significant antecedent rainfall, and very strong shaking. Many of the landslides could be discerned from high-resolution satellite imagery acquired immediately after the earthquake. ?? 2006, Earthquake Engineering Research Institute.