Over the last ten years large earthquakes and tsunamis have been observed with a diverse suite of geophysical sensors. Land-based seismometers, off-shore pressure sensors and space geodetic systems have provided an incredibly rich view of these phenomena. In this talk we will discuss the methods for combining these diverse observations into a coherent modeling framework as well as the physical insights they provide about the source processes of these large events. Finally, because large earthquakes and tsunamis impact human lives and infrastructure, we will discuss holistic approaches to warning systems that leverage all these observations to provide alerts in advance of strong shaking and tsunami arrival to the near-source shores.