Importance of small earthquakes for stress transfers and earthquake triggering

By Agnes Helmstetter, Y. Kagan, D. Jackson. 2004

292 citations recorded by the source corpus.

[1] We estimate the relative importance of small and large earthquakes for static stress changes and for earthquake triggering, assuming that earthquakes are triggered by static stress changes and that earthquakes are located on a fractal network of dimension D. This model predicts that both the number of events triggered by an earthquake of magnitude m and the stress change induced by this earthquake at the location of other earthquakes increase with m as similar to 10(Dm/2). The stronger the spatial clustering, the larger the influence of small earthquakes on stress changes at the location of a future event as well as earthquake triggering. If earthquake magnitudes follow the Gutenberg-Richter law with b > D/2, small earthquakes collectively dominate stress transfer and earthquake triggering because their greater frequency overcomes their smaller individual triggering potential. Using a southern California catalog, we observe that the rate of seismicity triggered by an earthquake of magnitude m increases with m as 10(alpha m), where alpha = 1.05 +/- 0.05. We also find that the magnitude distribution of triggered earthquakes is independent of the triggering earthquake's magnitude m. When alpha approximate to b, small earthquakes are roughly as important to earthquake triggering as larger ones. We evaluate the fractal correlation dimension D of hypocenters using two relocated catalogs for southern California. The value of D measured for distances 0.1 < r < 5 km is D = 1.54 for the Shearer et al. catalog and D = 1.73 for the Hauksson et al. catalog. The value of D reflects both the structure of the fault network and the nature of earthquake interactions. By considering only those earthquake pairs with interevent times larger than 1000 days, we can largely remove the effects of short-term clustering. Then D approximate to 2, close to the value D = 2 alpha = 2.1 predicted by assuming that earthquake triggering is due to static stress. The value D approximate to 2b implies that small earthquakes are as important as larger ones for stress transfers between earthquakes and that considering stress changes induced by small earthquakes should improve models of earthquake interactions.

Subfields: Artificial Intelligence, Geophysics

View Paper: https://www.semanticscholar.org/paper/07f4e3c4114bd75b66ce20f621a1531948a78a20

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Artificial Intelligence

In Geophysics

Citations in the corpus

Connecting near-field and far-field earthquake triggering to dynamic strain (2010, methodology): “Previous work using earthquake counting and carefully declustered seismicity catalogs has shown that the number of local aftershocks following a main shock of magnitude M goes as 10aM, with a ≈ 1 [Felzer et al., 2004; Helmstetter et al., 2005].”
Prediction (2010, unknown): “2 Importance of small events for triggering other event s of any size [46, 47] In the context of earthquakes for which the productivity exp onenta is estimated smaller than, but close to, the Gutenberg-Richter exponent β, small events have been found to provide a dominating contribution to the overa”
Afterslip and aftershocks in the rate‐and‐state friction law (2007, result): “Comparison with aftershock data Aftershock studies [Helmstetter et al., 2005; Peng et al., 2007] have shown that seismicity rate decreases with time according to R ∼ R0/(1 + t/c) , with a characteristic time c that is no larger than 10 sec, and an exponent p that can be either smaller or larger than”
Estimation of Space–Time Branching Process Models in Seismology Using an EM–Type Algorithm (2006, background): “The model parameter â = 1.034, for instance, is commonly thought to be closer to log(10) ≈ 2.3 (Felzer, Abercrombie, and Ekström 2004; Helmstetter, Kagan, and Jackson 2005, 2006).”
Data‐driven spatial b value estimation with applications to California seismicity: To b or not to b (2015, methodology): “Because the Southern Californian network underwent a substantial upgrade in 1984, we use all m≥ 2.2 (chosen as the highest observed value during this time period) events in the period of 1 January 1984 to 1 January 2014 (125,760 events with m ≥ 2.2).”