eprintid: 1419 rev_number: 17 eprint_status: archive userid: 2 dir: disk0/00/00/14/19 datestamp: 2015-02-23 14:47:00 lastmod: 2017-02-08 12:21:35 status_changed: 2015-04-27 12:10:52 type: article metadata_visibility: show creators_name: Helmstetter, Agnes creators_name: Kagan, Yan Y. creators_name: Jackson, David D. creators_id: agnes@ldeo.columbia.edu creators_id: ykagan@ucla.edu creators_id: djackson@ucla.edu corp_creators: Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California, USA corp_creators: Department of Earth and Space Sciences, University of California, Los Angeles, California, USA corp_creators: Department of Earth and Space Sciences, University of California, Los Angeles, California, USA title: Importance of small earthquakes for stress transfers and earthquake triggering ispublished: pub subjects: MP5 divisions: EPOS-P full_text_status: none abstract: 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 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 am, where a = 1.05 ± 0.05. We also find that the magnitude distribution of triggered earthquakes is independent of the triggering earthquake’s magnitude m. When a=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 =2, close to the value D = 2a = 2.1 predicted by assuming that earthquake triggering is due to static stress. The value D= 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. date: 2005-03-15 date_type: published publication: Journal of Geophysical Research volume: 110 number: B5 publisher: American Geophysical Union pagerange: 1-13 id_number: doi:10.1029/2004JB003286 refereed: TRUE issn: 0148-0227 official_url: http://dx.doi.org/10.1029/2004JB003286 access_IS-EPOS: limited owner: Publisher citation: Helmstetter, Agnes and Kagan, Yan Y. and Jackson, David D. (2005) Importance of small earthquakes for stress transfers and earthquake triggering. Journal of Geophysical Research, 110 (B5). pp. 1-13. DOI: https://doi.org/10.1029/2004JB003286