A web application prototype for the multiscale modelling of seismic input

A web application prototype is described, aimed at the generation of synthetic seismograms for user-defined earthquake models. The web application graphical user interface hides the complexity of the underlying computational engine, which is the outcome of the continuous evolution of sophisticated computer codes, some of which saw the light back in the middle '80s. With the web application, even the non-experts can produce ground shaking scenarios at the local or regional scale in very short times, depending on the complexity of the adopted source and medium models, without the need of a deep knowledge of the physics of the earthquake phenomenon. Actually, it may even allow neophytes to get some basic education in the field of seismology and seismic engineering, due to the simplified intuitive experimental approach to the matter. One of the most powerful features made available to the users is indeed the capability of executing quick parametric tests in near real-time, to explore the relations between each model's parameter and the resulting ground motion scenario. The synthetic seismograms generated through the web application can be used by civil engineers for the design of new seismo-resistant structures, or to analyse the performance of the existing ones under seismic load.Comment: 23 pages, 13 figure

A 2-D model for tilt and strain fields associated to earthquakes in crustal block structures

A 2-D model for slow crustal movements, including tilt and strain anomalies before earthquakes as well as shape and time lag of each preseismic anomaly with respect to the time of origin of the corresponding earthquake, is proposed. The model represents a numerical study to evaluate the behavior of a series of crustal rigid blocks separated by narrow fault zones filled with viscoelastic material. Rheology of the fault material is described by constitutive equations of standard linear solid. Vertical displacement and rotation of the blocks result from the vertical uplift of one (central) block due to a vertical Force. Displacements and tilts of blocks are computed from a system of linear differential equations which are solved numerically. The main characteristic feature of the model is that the viscoelastic parameters of the fault zone, where fracture occurs (at the boundary of the rising block), may change in time? simulating the earthquake preparation. Numerical modelling shows that tilt behavior at successive blocks reveals anomalies which are similar in shape to the observed ones. The anomalies are of opposite signs in adjacent blocks, and show a time lag with distance from the fracturing zone. (C) 1998 Elsevier Science B.V