Abstract: Systems and methods include reception, for each of a first plurality of consecutive time periods, of an acceleration value associated with a first location of a structure, determination of a first value of a first indicator based on absolute values of the acceleration values, determination of a second value of a second indicator based on absolute values of differences of consecutive one of the acceleration values, determination of a first value of an index based on the first value and the second value, determination of a physical characteristic of the structure based on the first value of the first indicator and the first value of the index, and transmission of an alert based on the physical characteristic.