Theme 1: The Earth as a complex system

Propagation of seismic signals - click for animation.
Atmospheric transport of radioactive emissions from the Fukushima power plant in March 2011 - click for animation.

Scientific and technical advances in monitoring the globe for nuclear explosions require a deep understanding of the way in which features of the Earth influence the relevant signals as they travel from their point of origin to where they are observed. The signals from monitoring networks constitute a huge database and support advances in the Earth Sciences on global, regional and local scales.

Seismic and acoustic signals propagate through the Earth, its atmosphere and its oceans. The Earth’s atmosphere also transports radioactive materials around the globe in minute concentrations, and its properties are relevant for different kinds of satellite observations.

This Theme focuses on any dynamic or static properties of the Earth that can be observed with seismic, hydroacoustic and infrasound data, with radionuclide tracer observations, with on-site geophysical measurements or with other monitoring data. Studying these Earth properties in turn helps to improve the processing or interpretation of monitoring data.


  • Structures in the geosphere, hydrosphere and atmosphere on all scales
  • Interactions between the geosphere, hydrosphere, and atmosphere
  • Scientific applications of seismoacoustic and radionuclide tracer data, e.g. for climate change research
  • Data and models for predicting regional seismic travel times
  • Data and models for predicting local geological changes
  • Time-dependent atmospheric wavespeed models for infrasound propagation
  • Using high-resolution geophysical techniques to explore underground features
  • Atmospheric and sub-surface models of radionuclide tracer transport
  • Follow-up to the Tohoku earthquake and Fukushima accidents