[Perspective] “Weather bomb” induced seismic signals
The atmosphere-ocean system interacts with the solid Earth to produce seismic signals called microseisms, which are observed globally. This interaction results from large-scale, slowly moving extratropical storms but also from smaller, intense weather systems such as tropical cyclones (called hurricanes in the Atlantic and eastern Pacific, and typhoons in the western Pacific). These are smaller storms, often travel much faster, and have steeper atmospheric pressure gradients that produce very strong winds. All storm systems generate various types of microseisms, which have been studied extensively. A special case of fast-developing, small, extratropical storms in which the central pressure intensifies rapidly, dropping by more than 1 mbar/hour for 24 hours, is called a “weather bomb” (1). On page 919 of this issue, Nishida and Takagi (2) report on the detection of previously unobserved S wave microseisms generated under a weather bomb between Greenland and Iceland. Authors: Peter Gerstoft, Peter D. Bromirski