Immediate and updated forecasting of aftershock hazard

Ogata, Yosihiko; Katsura, Koichi

doi:10.1029/2006gl025888

Cited by 70 publications

(58 citation statements)

References 12 publications

(11 reference statements)

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“…However, unlike seismicity increases, it is difficult to distinguish whether a decrease in seismicity is actual or artificial because the detection capability of small events may be lowered just after a great earthquake (e.g., Ogata and Katsura, 2006). The magnitude threshold in the PDE catalog is temporally higher, presumably because the determination of the hypocenters was delayed due to occurrences of a large number of earthquakes after March 11.…”

Section: Resultsmentioning

confidence: 99%

Change in seismicity beneath the Tokyo metropolitan area due to the 2011 off the Pacific coast of Tohoku Earthquake

et al. 2011

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Section: Resultsmentioning

confidence: 99%

Change in seismicity beneath the Tokyo metropolitan area due to the 2011 off the Pacific coast of Tohoku Earthquake

et al. 2011

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“…The distinct magnitude‐time pattern in the early part of an aftershock sequence can be seen conveniently if one plots the aftershock magnitude versus the logarithm of the time log 10 ( t ) after the mainshock [ Kagan , 2004; Ogata and Katsura , 2006]. It is obvious in Figures 2a, 2b, 2c, and 2d that the larger aftershocks begin early in the sequence, whereas the occurrence is progressively delayed for weaker events.…”

Section: Data and Definition Of Aftershocks: Preliminary Analysis Of mentioning

confidence: 99%

Decay of aftershock activity for Japanese earthquakes

et al. 2007

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[1] Aftershock decay is often correlated with the modified Omori's law: dN/dt = t À1 (1 + t/c) Àp , where dN/dt is the occurrence rate of aftershocks with magnitudes greater than a lower cutoff m, t is time since a mainshock, t and c are characteristic times, and p is an exponent. Extending this approach, we derive two possibilities: (1) c is a constant independent of m and t scales with m and (2) c scales with m and t is a constant independent of m. These two are tested by using aftershock sequences of four relatively recent and large earthquakes in Japan. We first determine for each sequence the threshold magnitude above which all aftershocks are completely recorded and use only events above this magnitude. Then, visual inspection of the decay curves and statistical analysis shows that the second possibility is the better approximation for our sequences. This means that the power law decay of smaller aftershocks starts after larger times from the mainshock. We find a close association of our second result with a solution obtained for a damage mechanics model of aftershock decay. The time delays associated with aftershocks, according to the second possibility, can be understood as the times needed to nucleate microcracks (aftershocks). Our result supports the idea that the c value is a real consequence of aftershock dynamics associated with damage evolution.

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“…Next, given the estimate of the b -value and detection rate function, we can estimate the parameters K , c , and p of the Omori–Utsu formula for the underlying aftershocks27. The occurrence rate ν ( t,M ) of detected aftershocks is given by the product of the rate λ ( t,M ) of the underlying aftershocks in equation (1), and the estimated detection rate function Φ ( M|μ,σ ) in (3) as follows: .…”

Section: Resultsmentioning

confidence: 99%

“…The estimated b -values and other parameters are listed in Table 2. In a previous study27, μ ( t ) was assumed to be a parametric model of a monotonically decreasing function of time. However, the estimated μ ( t ) includes some oscillations that are scarcely realized by such a simple parametric model.…”

Section: Resultsmentioning

confidence: 99%

Forecasting large aftershocks within one day after the main shock

Omi

Ogata

Hirata

et al. 2013

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Forecasting the aftershock probability has been performed by the authorities to mitigate hazards in the disaster area after a main shock. However, despite the fact that most of large aftershocks occur within a day from the main shock, the operational forecasting has been very difficult during this time-period due to incomplete recording of early aftershocks. Here we propose a real-time method for efficiently forecasting the occurrence rates of potential aftershocks using systematically incomplete observations that are available in a few hours after the main shocks. We demonstrate the method's utility by retrospective early forecasting of the aftershock activity of the 2011 Tohoku-Oki Earthquake of M9.0 in Japan. Furthermore, we compare the results by the real-time data with the compiled preliminary data to examine robustness of the present method for the aftershocks of a recent inland earthquake in Japan.

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Immediate and updated forecasting of aftershock hazard

Cited by 70 publications

References 12 publications

Change in seismicity beneath the Tokyo metropolitan area due to the 2011 off the Pacific coast of Tohoku Earthquake

Change in seismicity beneath the Tokyo metropolitan area due to the 2011 off the Pacific coast of Tohoku Earthquake

Decay of aftershock activity for Japanese earthquakes

Forecasting large aftershocks within one day after the main shock

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