Magnitude determination using cumulative absolute absement for earthquake early warning

The cumulative absolute absement (CAA) of the 3 s window after P-wave arrival can be used to estimate the magnitude ( M_CAA ) of an earthquake. This method can achieve good results even when only the six stations nearest to the epicenter are used. The standard deviation between the estimated CAA magnitude ( M_CAA ) and the moment magnitude ( M_w ) is found to be 0.3 when using either 6 or 20 stations. This means that M_CAA can be reliably predicted using the closest 6 stations. On the other hand, the magnitude ( M_Pd ) derived from P_d using the closest 20 stations has a standard deviation of 0.4 between the estimated M_Pd and M_w . This suggests that CAA is a better magnitude determination parameter for the EEW system than P_d .