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A threshold-based earthquake early warning using dense accelerometer networks

Zollo, Aldo and Amoroso, Ortensia and Lancieri, Maria and Wu, Yih-Min and Kanamori, Hiroo (2010) A threshold-based earthquake early warning using dense accelerometer networks. Geophysical Journal International, 183 (2). pp. 963-974. ISSN 0956-540X.

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Most earthquake early warning systems (EEWS) developed so far are conceived as either ‘regional’ (network-based) or ‘on-site’ (stand-alone) systems. The recent implementation of nationwide, high dynamic range, dense accelerometer arrays makes now available, potentially in real time, unsaturated waveforms of moderate-to-large magnitude earthquakes recorded at very short epicentral distances (<10–20 km). This would allow for a drastic increase of the early warning lead-time, for example, the time between the alert notification and the arrival time of potentially destructive waves at a given target site. By analysing strong motion data from modern accelerograph networks in Japan, Taiwan and Italy, we propose an integrated regional/on-site early warning method, which can be used in the very first seconds after a moderate-to-large earthquake to map the most probable damaged zones. The method is based on the real-time measurement of the period (τ_c) and peak displacement (Pd) parameters at stations located at increasing distances from the earthquake epicentre. The recorded values of early warning parameters are compared to threshold values, which are set for a minimum magnitude 6 and instrumental intensity VII, according to the empirical regression analyses of strong motion data. At each recording site the alert level is assigned based on a decisional table with four alert levels defined upon critical values of the parameters Pd and τ_c, which are set according to the error bounds estimated on the derived prediction equations. Given a real time, evolutionary estimation of earthquake location from first P arrivals, the method furnishes an estimation of the extent of potential damage zone as inferred from continuously updated averages of the period parameter and from mapping of the alert levels determined at the near-source accelerometer stations. The off-line application of the method to strong motion records of the M_w 6.3, 2009 Central Italy earthquake shows a very consistent match between the rapidly predicted (within a few seconds from the first recorded P wave) and observed damage zone, the latter being mapped from detailed macroseismic surveys a few days after the event. The proposed approach is suitable for Italy, where, during the last two decades, a dense network of wide dynamic-range accelerometer arrays has been deployed by the Department of Civil Protection (DPC), the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and other regional research agencies.

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Additional Information:© 2010 The Authors. © 2010 RAS. Accepted 2010 August 4. Received 2010 July 24; in original form 2010 April 30. Article first published online: 28 Sep. 2010. We are grateful to the editor and reviewers Maren Böse and Holly Brown for their constructive and very helpful comments and remarks. Our work greatly benefited from discussions with Gaetano Festa, Giovanni Iannaccone and Claudio Satriano. This work has been partially funded by project INGV-DPC-S5 (2007–2009).
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Subject Keywords:Earthquake ground motions; Earthquake source observations; Early warning
Record Number:CaltechAUTHORS:20101123-152358613
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Official Citation:Zollo, A., Amoroso, O., Lancieri, M., Wu, Y.-M. and Kanamori, H. (2010), A threshold-based earthquake early warning using dense accelerometer networks. Geophysical Journal International, 183: 963–974. doi: 10.1111/j.1365-246X.2010.04765.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:21007
Deposited By: Benjamin Perez
Deposited On:24 Nov 2010 16:06
Last Modified:11 Apr 2015 00:28

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