Concert area, 5:00 pm: visualization of the alarm spreading in the target area for one simulation with the enabling radius equal to 100 m. The enabling area is colored in blue. Red circles represent nodes within 1 km of the alarm center, orange circles represents nodes within 2 km of the alarm center and green ones represent infected nodes. The radius of each circle is 50 m. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)