Abstract
Quick and rapid estimation of earthquake magnitude within the first few seconds after P-wave arrival and before arriving of damaging strong ground motions is considered to be the main challenge in earthquake early warning systems (EEWSs). In recent years, three frequency-based approaches, so called predominant period, , characteristic period, , and log-average period, , have been applied by EEWSs or studied by scientists in order to estimate earthquake size. , and parameters suffer from biasing towards high frequencies which yield erroneous results. For magnitude prediction in EEWSs, we propose a new wavelet-based scale obtained from P-wave time windows of borehole accelerograms of earthquakes in Japan with magnitude of 3-8 and epicentral distance less than 100 km. For events with 5.5 the new empirical formula obtained from regression of provides more accurate and reliable magnitude estimation than other , and proxies. The magnitude estimation error -one of the main causes of the false and missed alarms in EEWSs- can be reduced by using parameter.