===== Network centric simulation (EUCENTRE) and Early warning (EUCENTRE) =====



An earthquake early warning system is based on the different nature of seismic waves, characterised by a varying propagation direction and speed in the ground. The great majority of damages to buildings is due to S waves, since they produce an alternating transversal movement with respect to the propagation direction. Luckily, they are slower with respect to P waves, which are longitudinal and less dangerous. As a matter of fact, there is a small amount of time to broadcast a warning message, carried by an electro-magnetic wave travelling at the speed of light, in order to preserve some relevant and strategic structures. The useful interval can be estimated in tens of seconds or few minutes, on the basis of the distance between the origin of the earthquake and the sensors. It is not enough even to start a complex model evaluating all the parameters involved or to estimate the uncertainty of measurements. However, the computational and storage capabilities of the Grid can be very useful during the post event phase, when it is fundamental a fast damage assessment and a good coordination of rescue teams. From this point of view, risk maps represent an invaluable tool, but the process yielding to their creation is made up of many steps.
The Grid technology can help in speeding up the analysis, starting from the data acquired by instrument elements including at most an entire seismic sensor network. This analysis is the starting point for fast calculation of fragility curves, shake and risk maps. In particular, fragility curves involve a set of operations including time-history analysis, non-linear analysis and Monte Carlo simulations which may be will handled by parallel mechanisms provided by the Grid.
P waves estimation and fragility curves are thus the two basic ingredients of this application and the Grid represents a suitable solution to store the huge amount of data related to this task. High availability, strict access control and a distributed community of users are the key aspects making the Grid one of the best candidates for this application. Moreover, an earthquake early warning system represents a good study case to test the impact of transport protocols, the network design and the quality of service due to tight time constraints.