As the EaaS (Everything as a Service) paradigm is taking power in the computational environment, other fields of science have started to apply virtualization as a solution to the infrastructure problems. Additionally, the large capacity of new machines allows researchers to develop new models of reality simulation that control a huge amount of variables converted into data. The main goal of this project is to provide a Modeling and Simulation as a Service tool flexible, scalable, and with a trustworthy engine for the simulation of specific events or the construction of probabilistic hazard maps for volcanic ash fallout. The development process of a Modelling and Simulation as a Services (MSaaS) tool for volcanic ash fallout has been built upon microservices and Dockers architecture and over the HAZMAP simulation tool for Linux. The four main phases of a Simulation process (problem characterization, tool design, service development, and evaluation of the model) are detailed and documented in the present project.