Low-cost accelerograph units as earthquake alert devices for Mexico City: how well would they work?
Recently, low-cost accelerograph units have been proposed as earthquake alert devices for Mexico City. These units would trigger when the acceleration reaches a pre-established level, presumably 4 gal. For significant earthquakes, this would occur during P wave or in the early part of its coda. We test the performance of such a unit on accelerograms recorded in the period 1985 - 2008 at SCT and CDAO, two lake-bed sites in Mexico City. As expected, the alert time (the time of arrival of intense ground motion minus the trigger time), T A, for regional earthquakes is found to increase with the PGA. T A of the recorded accelerograms (with PGA > 4 gal) ranges between about -20 and 45 sec; the largest values of T A correspond to the 1985 Michoacan earthquake. With some exceptions, T A is greater than <img border=0 src="../../../../../img/revistas/geoint/v48n2/a4s3.jpg">15 sec for earthquakes which produced PGA > 20 gal. The device may be useful in mitigating injuries and loss of lives if an alert time of 15 to 45 sec is sufficient to put in to effect pre-established safety measures. This may be practical for one- to three-storey public school buildings. The device would be useful for shutting critical facilities before the arrival of large-amplitude ground motion.
| Main Authors: | , , , , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Universidad Nacional Autónoma de México, Instituto de Geofísica
2009
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| Online Access: | http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0016-71692009000200004 |
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