A subset of mobile devices is selected from a set of mobile devices located in a local area. From a mobile device in the subset, a magnetic measurement value obtained by performing a magnetic measurement is received. The magnetic measurement value comprises a change in a magnetic property of an immediate surrounding ambient environment of the mobile device. When the magnetic measurement corresponds to a deviation in a network condition in a portion of a network, the portion being located in the local area, a conclusion is output that the deviation is caused by an electromagnetic disturbance (EMD), where an effect of the EMD causes the magnetic measurement value. A notification including an indication of the EMD and an identification of the local area is generated.