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System Erde; 8, Geodesy aims to determine the geometric figure and the gravitational field of the Earth, as well as its orientation in space. Steadily increasing accuracies, with which these tasks are being solved, are based on corresponding improvements in geodetic measuring data, both, on the quantitative as well as the qualitative level. Similar developments in the acquisition, processing and analysis of observation data, which have always been at the limit of the technically and scientifically feasible, are witnessed in the fields of seismology and geomagnetism as well. Recently however, innovative developments, building on Big Data approaches, are emerging with the combination of diverse data streams into integrated processing environments. Geodetic, seismological and geomagnetic observation data are fundamental for a better understanding of Earth system processes. The combination of these geoscience data collected by ground- and space-based sensors, their consistent processing, validation and assimilation into complex Earth system models contribute in an essential way to the future implementation of GGOS, the Global Geodetic Observing System.

System Erde; 7, Along with cell phones and the internet, satellite navigation is an integral part of everyday life. However, satellite navigation signals provide much more than precise information on user locations. Even before the GPS was declared fully operational in 1995, the potential for these globally and continuously available navigation signals for Earth observation and geoscientific applications was recognized. Such applications include the precise monitoring of continental plate movements with sub-mm/year accuracy (now used in real-time as part of early earthquake warning systems), regional and global atmospheric and ionospheric sounding to improve weather forecasts and climate change predictions, and for monitoring of water, ice, and land surfaces. The Earth observation prospects and related spectrum of applications are continuously growing, mainly stimulated by the transition from a single constellation (GPS) to Multi-GNSS (Global Navigation Satellite System) with the Russian GLONASS, Chinese BeiDou and European Galileo satellites and by the increasing number of GNSS receivers available both on the ground and aboard Low Earth Orbiting satellites.

Modern near-field tsunami early warning systems must provide a tsunami alarm as early as 5 to 10 minutes after an earthquake. Working within this time limit, traditional seismic methods tend to underestimate the total moment magnitude in case of giant (Sumatra 2004, Tōhoku 2011) as well as slow, ‘tsunami’ (Java 2006, Mentawai 2010) earthquakes. Moreover, representation of a tsunami source as a point-source, i.e. location plus magnitude, is usually insufficient for a reliable near-field early warning. Using numerical simulation of earthquake rupture and associated crustal deformation and tsunami wave’s propagation, we demonstrate that recent high-precision real-time Global Navigation Satellite System (GNSS) arrays may serve as a key component of near-field tsunami early warning system. The main advantage of the GNSS-arrays, placed close to an epicenter, is that they directly measure surface displacements necessary for tsunami source inversion already during the earthquake. Taking the Great March 2011 Tōhoku-oki earthquake as an example, we demonstrate the ability of real-time GNSS to provide qualified tsunami early warning in only three minutes after beginning of the earthquake. To do so, we combine real-time Precise Point Positioning (PPP) processing with fast slip inversion and on-the-fly tsunami simulation. This allows the observation of the earthquake growth in almost real-time (plus about one minute processing overhead) by simultaneously computing tsunami warning levels. Already three minutes after the earthquake begins, GNSS-derived moment magnitude estimation reaches its final value of Mw = 9.0 and tsunami forecasting stabilizes as well.