Magnitude Scaling of Early-Warning Parameters for the Mw 7.8 Tocopilla, Chile, Earthquake and Its Aftershocks

Lancieri, M.; Fuenzalida, A.; Ruiz, Sergio; Madariaga, Raúl

doi:10.1785/0120100045

Cited by 27 publications

(23 citation statements)

References 46 publications

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“…The motivation behind this specific study comes from our recent observation (Lancieri et al 2011) that the the integral of the squared velocity measured during a few seconds of P and S phases scales with the event size. The motivation behind this specific study comes from our recent observation (Lancieri et al 2011) that the the integral of the squared velocity measured during a few seconds of P and S phases scales with the event size.…”

Section: O N C L U S I O N Smentioning

confidence: 99%

Spectral scaling of the aftershocks of the Tocopilla 2007 earthquake in northern Chile

Lancieri

Madariaga

Bonilla

2012

Geophysical Journal International

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SUMMARY We study the scaling of spectral properties of a set of 68 aftershocks of the 2007 November 14 Tocopilla (M 7.8) earthquake in northern Chile. These are all subduction events with similar reverse faulting focal mechanism that were recorded by a homogenous network of continuously recording strong motion instruments. The seismic moment and the corner frequency are obtained assuming that the aftershocks satisfy an inverse omega‐square spectral decay; radiated energy is computed integrating the square velocity spectrum corrected for attenuation at high frequencies and for the finite bandwidth effect. Using a graphical approach, we test the scaling of seismic spectrum, and the scale invariance of the apparent stress drop with the earthquake size. To test whether the Tocopilla aftershocks scale with a single parameter, we introduce a non‐dimensional number, , that should be constant if earthquakes are self‐similar. For the Tocopilla aftershocks, Cr varies by a factor of 2. More interestingly, Cr for the aftershocks is close to 2, the value that is expected for events that are approximately modelled by a circular crack. Thus, in spite of obvious differences in waveforms, the aftershocks of the Tocopilla earthquake are self‐similar. The main shock is different because its records contain large near‐field waves. Finally, we investigate the scaling of energy release rate, Gc, with the slip. We estimated Gc from our previous estimates of the source parameters, assuming a simple circular crack model. We find that Gc values scale with the slip, and are in good agreement with those found by Abercrombie and Rice for the Northridge aftershocks.

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Section: O N C L U S I O N Smentioning

confidence: 99%

Spectral scaling of the aftershocks of the Tocopilla 2007 earthquake in northern Chile

Lancieri

Madariaga

Bonilla

2012

Geophysical Journal International

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“…This effect was proposed as a seismic event trigger, because the noise was shown to display a Gaussian behavior very different from the first digit phenomenon. The practical consequences of this property are far reaching, because seismic localization algorithms and early warning methods depend on the ability to detect with precision the arrival time of seismic signals (Allen and Kanamori, 2003;Lancieri et al, 2011;Lomax et al, 2012). Our insight is that this property of the earthquake arrival is directly related to the seismic source and related processes.…”

Section: The Tohoku Earthquake From the Point Of View Of The First Digitmentioning

confidence: 94%

Earthquake source parameters that display the first digit phenomenon

Toledo¹,

Riquelme²,

Campos³

2015

Nonlin. Processes Geophys.

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Abstract. We study the main parameters of earthquakes from the perspective of the first digit phenomenon: the nonuniform probability of the lower first digit different from 0 compared to the higher ones. We found that source parameters like coseismic slip distributions at the fault and coseismic inland displacements show first digit anomaly. We also found the tsunami runups measured after the earthquake to display the phenomenon. Other parameters found to obey first digit anomaly are related to the aftershocks: we show that seismic moment liberation and seismic waiting times also display an anomaly. We explain this finding by invoking a selforganized criticality framework. We demonstrate that critically organized automata show the first digit signature and we interpret this as a possible explanation of the behavior of the studied parameters of the Tohoku earthquake.

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“…Similarly, Lancieri et al . [] investigated the behavior of IV2 estimated from P and S wave time windows on the aftershock sequence of the Tocopilla event of November 2007 ( M w 7.8) in northern Chile. Both Festa et al .…”

Section: The Analyzed Parametersmentioning

confidence: 99%

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

et al. 2015

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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.

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Magnitude Scaling of Early-Warning Parameters for the Mw 7.8 Tocopilla, Chile, Earthquake and Its Aftershocks

Cited by 27 publications

References 46 publications

Spectral scaling of the aftershocks of the Tocopilla 2007 earthquake in northern Chile

Spectral scaling of the aftershocks of the Tocopilla 2007 earthquake in northern Chile

Earthquake source parameters that display the first digit phenomenon

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

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