## 3 The WebGIS System
### The Post-Event Management  
As previously stated, many of the calamitous events that have occurred in recent years have been characterized by the involvement of a large number of private citizens (without formal qualifications) in the production of geographic information. This function, usually reserved for professional operators, is accomplished by untrained volunteers and the results in many cases could be inaccurate. Nevertheless, from a cooperative point of view, VGI represents a strong innovation in GIS approaches, with important consequences in the relationship between citizens and emergency managers. Some authors [5,35,36] also use the term \"crowdsourcing\" to describe this typology of data acquisition by large and diverse groups of people, using web technology and specific data sources. To this end, there are two fundamental technologies used for VGI: geo-referencing, either using GPS or mobile devices positioning (e.g., phone or tablet), and the web 2.0.  
In the course of the research activities described in the present paper, a collaborative way to acquire geospatial data during the earthquake post-event phase has been implemented. The main goal was to collect information about buildings, by reporting their structural condition after the main shock. These surveys can be carried out by groups of volunteers, who--after a rapid training--are able to collect a defined list of information about structures and infrastructures struck by the earthquake (typology, damages, suitability, security measures to be adopted, _etc._). These data are georeferenced using a  
Figure 6: WebGIS visualization of expected damage map (Earthquake simulation: epicenter in Lapio, LM 7.0).  
handheld device (equipped with GPS receiver) and then recorded into the WebGIS system by mobile Internet access.  
Building damages following an earthquake event, processed by the proposed EWS and stored in its Geodatabase module, can be updated and used to generate more reliable vulnerability maps. Consequently, updated expected damage maps will be used not only to efficiently support the management of the post event phase but also to take into account the possible effects of other damages due to the aftershocks.  
Moreover, the volunteers involved in these activities can access the WebGIS to look through existing maps, digital orthophotos and scenarios and also to provide refinements (e.g., updated information) for existing georeferenced maps and data. Figure 7 shows an example of data about buildings collected according to the above described procedure (such as: location, information about building, age of construction, typology, structural conditions, level of damage, actions to be taken, _etc._) and displayed in the implemented WebGIS interface.  
Considering that the aftershock sequence can cause the collapse of seriously jeopardized structures, it is very important to gather information about the real conditions of buildings after the initial main shock. The proposed approach allows collecting these data in a rapid and timely way, jointly exploiting  
Figure 7: Post-event phase: visualization in the WebGIS of building information collected by means of handheld devices.  
the potential of VGI and web 2.0. Finally, this methodology offers the advantage to easily provide information about the damages, which is very useful to support stakeholders and emergency managers to: (a) outline the real crisis scenario after the disastrous event; (b) efficiently address and manage the emergency tasks.