This book develops the theory of electromagnetic (EM) precursors to seaquakes (i.e. underwater earthquakes) and tsunamis, including the sequential stages of the transformation of a weak seismic mechanical excitation of the sea bottom into EM signals in the atmosphere. It further examines the relationship between geophysics and biophysics, using appropriate mathematical support, and a new model of the magnetic location of the epicenter of a possible land earthquake is described, as well as a block-scheme of the multidisciplinary multilevel seaquake monitoring complex. Also discussed are measured changes of brain bioelectric activity and heart functioning under the influence of moderate geomagnetic storms. Written for researchers and specialists (e.g. upper level undergraduates, postgraduates, scientists) in mathematical, computational, geophysical, biophysical, geodynamical, seismological and prognostic disciplines, this book provides multidisciplinary data and analytical tools supporting the theory and practice of seismic prognosis, promoting further understanding of novel marine and land monitoring systems.