Now it is possible to remotely detect large landslides within minutes of occurrence and to quickly determine whether they are close to open water and present a tsunami hazard. Researchers at the University of Alaska Fairbanks have devised a way to determine a landslide’s location, volume and potential impact. This might support the National Oceanic and Atmospheric Administration’s goal of issuing a tsunami warning within five minutes of a landslide. A prototype system capable of real-time detection has been in place since August in the area of the Barry Arm of Prince William Sound, Alaska. It uses data from seismic stations already in the Alaska network. The method involves quickly identifying a landslide’s long-period waves amid a seismic record busy with short-period waves created not only by a landslide but also by nearby earthquakes and glaciers and by human-caused activity. A landslide’s initial onset generally registers as short-period waves; it isn’t until the slide accelerates that the identifiable long-period waves materialize. Landslides produce disproportionately more long-period energy compared with other sources. Most earthquake ruptures last only seconds, while landslides routinely last a minute or more
