Recent catastrophic earthquakes have highlighted the importance of advancing seismic hazard models over a wide range of time frames, for example to support more reliable building codes and to track the short-term evolution of seismic sequences. Over the past years, the exponential growth of ground-motion data, short- and long-term forecasting models, hazard model test results, new engineering needs, and progress in research on earthquake predictability and ground-motion processes are creating a strong motivation for the exploration and incorporation of new concepts and methods into the next generation of probabilistic forecasts, both for long-term probabilistic seismic hazard assessment (PSHA), and operational earthquake forecasting. Owing to the important societal impact, any forecasting model has to be scientifically reliable. Prospective modeling is the best way of testing alternate hypotheses and models, and hence advancing our scientific understanding of the processes involved. Pragmatically, prospective testing provides an essential scientific contribution to improving the capacity to manage seismic hazard and risk in a wide range of forecasting time windows, for a broad range of stakeholders, including vulnerable societies. The development of such new and innovative long- and short-term forecasting/hazard models is a necessary but insufficient step: major advances in forecasting and hazard assessment require a solid testing phase that allows for model evaluation and quantifies any increase in forecasting skill over a benchmark model. 

We solicit contributions related to new developments in all aspects of long- and short-term seismic hazard and earthquake forecasting models:
   • Definition of earthquake sources and determination of activity rates and their uncertainty, including assessment of earthquake datasets, calibration of magnitude scales, representation of seismogenic sources and their geological constraints, and the emerging roles of strain and simulation-based earthquake-rupture forecasts.
   • Development of innovative earthquake forecasting models with forecast horizons of days to decades.
   • Estimation of strong ground motions and their uncertainty, development of new ground-motion models, assessment of site effects, the consideration of new parameters to characterize the intensity of shaking, and potential insights and uses of physics-based simulations of ground shaking. 
   • Testing and evaluation of hazard and earthquake forecasting models including statistical tests of 
activity rates, earthquake occurrence, calibration of ground-motion models, hazard-model parameterization and implementation, sensitivity analyses of key parameters and results, as well as the development of innovative testing procedures.
   • Case studies of PSHA from Europe and around the globe. 
   • Model building processes and related uncertainties, formal elicitation of expert opinion and its consequences for the levels of knowledge or belief, and comprehensive treatment of aleatory and epistemic uncertainties.
   • Contributions related to the ongoing update of the Harmonized European Seismic Hazard model and the emerging EPOS infrastructure on hazard and risk.
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