Predicting the macroseismic intensity from early radiated P wave energy for on‐site earthquake early warning in Italy

Abstract

Earthquake Early Warning Systems (EEWS) are potentially effective tools for risk mitigation in active seismic regions. The present study explores the possibility of predicting the macroseismic intensity within EEW timeframes using the squared velocity integral (IV2) measured on the early P wave signals, a proxy for the P wave radiated energy of earthquakes. This study shows that IV2 correlates better than the peak displacement measured on P waves with both the peak ground velocity and the Housner Intensity, with the latter being recognized by engineers as a reliable proxy for damage assessment. Therefore, using the strong motion recordings of the Italian Accelerometric Archive, a novel relationship between the parameter IV2 and the macroseismic intensity (IM) has been derived. The validity of this relationship has been assessed using the strong motion recordings of the Istituto Nazionale di Geofisica e Vulcanologia Strong Motion Data and Osservatorio Sismico delle Strutture databases, as well as, in the case of the MW 6, 29 May 2012 Emilia earthquake (Italy), comparing the predicted intensities with the ones observed after a macroseismic survey. Our results indicate that P wave IV2 can become a key parameter for the design of on‐site EEWS, capable of proving real‐time predictions of the IM at target sites.

A rapid response magnitude scale for timely assessment of the high frequency seismic radiation

“…The rapid assessment of E r and M 0 is based on extracting, from the time histories, proxies for these two source parameters, and correcting them for attenuation along the path. In particular, the radiated seismic energy is estimated from the squared velocity integrated over the S-wave time window 33 (IV2 S ), whereas the seismic moment is derived from the S-wave peak-displacement 34 (PD S ). The parameters IV2 S and PD S are linked to E r and M 0 through empirical attenuation models derived using data set D1, as detailed in the section Method (eqs 8 and 9 ).…”

On-site earthquake early warning: a partially non-ergodic perspective from the site effects point of view

“…Only recordings with SNR greater than 6 for at least 75 per cent of the frequencies within the frequency range were considered in the analysis. For each processed recording, we computed the integral of the squared velocity (IV2) (Kanamori et al 1993;Brondi et al 2015) and the peak ground displacement (PD) over the vertical P-wave window (i.e. considering a time window starting from the P-wave onset and ending at the S-wave arrival).…”

“…in terms of peak ground velocity, PGV). Different studies proposed empirical relationships for on-site EEW (Kanamori 2005;Wu & Kanamori 2008;Böse et al 2009;Zollo et al 2010;Picozzi 2012;Brondi et al 2015;Colombelli et al 2015;Caruso et al 2017). The data sets used for the calibration generally include recordings from multiple stations in a given region, such as (Caruso et al 2017) for Italy; (Wu & Kanamori 2005) for Taiwan; (Wu et al 2006) for California, or include data from different regions (Wu et al 2006;Zollo et al 2010).…”

An on‐site alert level early warning system for Italy

“…This approach is particularly useful for sites located within the blind zone of a regional EEW system, allowing for a still usable warning before the arrival of strong shaking waves. The P wave‐based, on‐site approaches use previously determined empirical relations to estimate the maximum ground‐shaking amplitude, through the measurement of P wave amplitude, frequency, integral of squared velocity, and other related quantities [ Kanamori , ; Wu and Kanamori , ; Böse et al ., ; Zollo et al ., ; Picozzi , ; Colombelli et al ., ; Brondi et al ., ].…”