When an earthquake occurs, there are many remote sensors that record data from the event: waveforms recorded by seismic instruments are used to locate the hypocentre and magnitude of the earthquake and to assess the strong ground shaking at the surface of the earth; people and buildings feel the shaking and observe or record the impact that it has on them. All of these data can be used to rapidly estimate, in the minutes, hours or days following an earthquake, the impact that the earthquake has on the surrounding people, buildings and infrastructure. In the first few minutes following an earthquake, a simple qualitative assessment (e.g., no impact, minor impact, major impact) is often sufficient to understand the magnitude of the event, and this is referred to as Rapid Impact Assessment In the following hours, however, it becomes important to understand the impact in terms of quantitative losses (e.g., number of collapsed buildings, number of fatalities or homeless people, direct economic loss) and this estimation is referred to as Rapid Loss Assessment. This fast assessment of the impact of the earthquake provides first order estimates of the losses which can be continually updated as more information and data arrive from the remote sensors.