An improved space‐time ETAS model for inverting the rupture geometry from seismicity triggering

Guo, Yicun; Zhuang, Jiancang; Zhou, Shuhua

doi:10.1002/2015jb011979

Cited by 47 publications

(29 citation statements)

References 48 publications

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“…Here we briefly introduce the formulation of the FS ETAS model; more details can be found in Guo et al (2015). In the space-time ETAS model (Ogata, 1998;Ogata & Zhuang, 2006), the conditional intensity can be written as…”

Section: Fs Etas Model and Stochastic Declustering Methodsmentioning

confidence: 99%

“…Here we briefly introduce the formulation of the FS ETAS model; more details can be found in Guo et al (). In the space‐time ETAS model (Ogata, ; Ogata & Zhuang, ), the conditional intensity can be written as

λ ((),,, t, x, y) = μ ((),, x, y) + \sum_{\{i : t_{i} < t\}} κ ((), m_{i}) g ((), t - t_{i}) f ((),;, x - x_{i}, y - y_{i}, m_{i})

where μ ( x , y ) means the background seismicity rate, and

κ ((), m) = {Ae}^{α ((), m - m_{c})}, m \geq m_{c}

is the productivity, which means expected number of aftershocks induced by an event of magnitude;

g ((), t) = \frac{p - 1}{c} {(1 + \frac{t}{c})}^{- p}

is the time probability density function, and

f ((),;, x, y, m) = \frac{q - 1}{π {De}^{γ ((), m - m_{c})}} {[1 + \frac{x^{2} + y^{2}}{{De}^{((), m - m_{c})}}]}^{- q}

is the spatial probability density function.…”

Section: Detection Of Seismicity Rate Changes By Using the Fs Etas Modelmentioning

confidence: 99%

“…It is worth mentioning that in the FS ETAS model, the functions τ ( u , v ) and μ ( x , y ) do not have a parametric form. They are expressed as a numerical solution to the iterative algorithm in section 2 of Guo et al ().…”

Section: Detection Of Seismicity Rate Changes By Using the Fs Etas Modelmentioning

confidence: 99%

“…In equation (4), earthquakes are taken as point sources when triggering aftershocks, which could cause biases when fitting the model to aftershock sequences of large mainshocks (Guo et al, 2015;Hainzl et al, 2008;Marsan & Lengliné, 2010). In this study, we use the FS ETAS model (Guo et al, 2015) in which the rupture extensions of large main shocks are incorporated when triggering aftershocks.…”

Section: Journal Of Geophysical Research: Solid Earthmentioning

confidence: 99%

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Did the 2008 Mw 7.9 Wenchuan Earthquake Trigger the Occurrence of the 2017 Mw 6.5 Jiuzhaigou Earthquake in Sichuan, China?

et al. 2018

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The 2017 Mw 6.5 Jiuzhaigou earthquake occurred at the southeastern boundary of the Bayankala block in Tibetan Plateau. Here we investigate the spatial and temporal seismicity rate changes in the Jiuzhaigou region using the finite‐source epidemic‐type aftershock sequence model and stochastic declustering method. The background probabilities of all events are obtained, and the cumulative background seismicity is extracted and fitted by a linear function. Following from this, we argue that there was a decrease of background seismicity in Jiuzhaigou region immediately after the occurrence of the 2008 Mw 7.9 Wenchuan earthquake. On the other hand, we also calculate the static and viscoelastic stress changes in the area around the hypocenter of the Jiuzhaigou earthquake induced by the Wenchuan earthquake. Although opposite results are resolved by previous studies, we infer a negative Coulomb failure stress change under reasonable assumptions of parameters for this case. Combining these two observed empirical relationships, we conclude that the 2017 Jiuzhaigou earthquake is delayed by the Wenchuan earthquake and the former event possibly results from the southeastward movement of the Bayankala block, which in turn arises from the collision of Indian‐Australian Plate and the Eurasian Plate. These findings indicate that Bayankala block and its adjacent tectonic faults are still in the highly active seismic period that started in the 1990s.

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Section: Fs Etas Model and Stochastic Declustering Methodsmentioning

confidence: 99%

λ ((),,, t, x, y) = μ ((),, x, y) + \sum_{\{i : t_{i} < t\}} κ ((), m_{i}) g ((), t - t_{i}) f ((),;, x - x_{i}, y - y_{i}, m_{i})

where μ ( x , y ) means the background seismicity rate, and

κ ((), m) = {Ae}^{α ((), m - m_{c})}, m \geq m_{c}

is the productivity, which means expected number of aftershocks induced by an event of magnitude;

g ((), t) = \frac{p - 1}{c} {(1 + \frac{t}{c})}^{- p}

is the time probability density function, and

f ((),;, x, y, m) = \frac{q - 1}{π {De}^{γ ((), m - m_{c})}} {[1 + \frac{x^{2} + y^{2}}{{De}^{((), m - m_{c})}}]}^{- q}

is the spatial probability density function.…”

Section: Detection Of Seismicity Rate Changes By Using the Fs Etas Modelmentioning

confidence: 99%

Section: Detection Of Seismicity Rate Changes By Using the Fs Etas Modelmentioning

confidence: 99%

Section: Journal Of Geophysical Research: Solid Earthmentioning

confidence: 99%

See 2 more Smart Citations

Did the 2008 Mw 7.9 Wenchuan Earthquake Trigger the Occurrence of the 2017 Mw 6.5 Jiuzhaigou Earthquake in Sichuan, China?

et al. 2018

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“…Recent articles by Guo, Zhuang, and Zhou (2015) and Guo, Zhuang, Hirata, and Zhou (2017) investigated how fault geometry estimated using previous seismicity for large (M ≥ 7.5) earthquakes in China and Japan impacted parameter estimates of ETAS models (Ogata, 1998). However, these studies did not quantify the extent to which including fault geometry in the models improved earthquake forecasts.…”

Section: Introductionmentioning

confidence: 99%

Assessing the predictive accuracy of earthquake strike angle estimates using nonparametric Hawkes processes

2018

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Earthquake focal mechanism estimates have been posited to have predictive value for forecasting future seismicity. In particular, for strike‐slip earthquakes, aftershocks should occur roughly along the estimated mainshock strike. However, the errors in such estimated strike angles are considerable. We compare the degree to which estimated strike angles forecast the direction of future seismicity around a given earthquake with that of uniformly distributed angles and with strike angles estimated based on previous seismicity. The fit of nonparametrically estimated Hawkes models using the estimated strike angle that best fits the post‐mainshock set of events for each mainshock is compared with that of corresponding models that exclude these estimates. Strike angle estimates are shown to have marginal predictive value for forecasting the direction of future seismicity but no more than the better fitting of a uniformly distributed angle and its complement.

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Heterogeneity of direct aftershock productivity of the main shock rupture

et al. 2017

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The epidemic type aftershock sequence (ETAS) model is widely used to describe and analyze the clustering behavior of seismicity. Instead of regarding large earthquakes as point sources, the finite‐source ETAS model treats them as ruptures that extend in space. Each earthquake rupture consists of many patches, and each patch triggers its own aftershocks isotropically. We design an iterative algorithm to invert the unobserved fault geometry based on the stochastic reconstruction method. This model is applied to analyze the Japan Meteorological Agency (JMA) catalog during 1964–2014. We take six great earthquakes with magnitudes >7.5 after 1980 as finite sources and reconstruct the aftershock productivity patterns on each rupture surface. Comparing results from the point‐source ETAS model, we find the following: (1) the finite‐source model improves the data fitting; (2) direct aftershock productivity is heterogeneous on the rupture plane; (3) the triggering abilities of M5.4+ events are enhanced; (4) the background rate is higher in the off‐fault region and lower in the on‐fault region for the Tohoku earthquake, while high probabilities of direct aftershocks distribute all over the source region in the modified model; (5) the triggering abilities of five main shocks become 2–6 times higher after taking the rupture geometries into consideration; and (6) the trends of the cumulative background rate are similar in both models, indicating the same levels of detection ability for seismicity anomalies. Moreover, correlations between aftershock productivity and slip distributions imply that aftershocks within rupture faults are adjustments to coseismic stress changes due to slip heterogeneity.

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An improved space‐time ETAS model for inverting the rupture geometry from seismicity triggering

Cited by 47 publications

References 48 publications

Did the 2008 Mw 7.9 Wenchuan Earthquake Trigger the Occurrence of the 2017 Mw 6.5 Jiuzhaigou Earthquake in Sichuan, China?

Did the 2008 Mw 7.9 Wenchuan Earthquake Trigger the Occurrence of the 2017 Mw 6.5 Jiuzhaigou Earthquake in Sichuan, China?

Assessing the predictive accuracy of earthquake strike angle estimates using nonparametric Hawkes processes

Heterogeneity of direct aftershock productivity of the main shock rupture

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