Focusing patterns of seismicity with relocation and collapsing
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Seismicity is generally concentrated on faults or in fault zones of varying, sometimes complex geometry. An earthquake catalog, compiled over time, contains useful information about this geometry, which can help understanding the tectonics of a region. Interpreting the geometrical distribution of events in a catalog is often complicated by the diffuseness of the earthquake locations. Here, we explore a number of strategies to reduce this diffuseness and hence simplify the seismicity pattern of an earthquake catalog. These strategies utilize information about event locations contained in their overall catalog distribution. They apply this distribution as an a priori constraint on relocations of the events, or as an attractor for each individual event in a collapsing scheme, and thereby focus the locations. The latter strategy is not a relocation strategy in a strict sense, although event foci are moved, because the movements are not driven by data misfit. Both strategies simplify the seismicity pattern of the catalog and may help to interpret it. A synthetic example and a real-data example from an aftershock sequence in south west Iceland are presented to demonstrate application of the strategies. Entropy is used to quantify their effect.
KeywordsProbability distributions Clustering Seismicity Image processing
We would like to thank an anonymous reviewer for his constructive comments.
- Brandsdóttir B, Parsons M, White RS, Gudmundsson O, Drew J, Thorbjarnadóttir B (2010) The May 29 2008 earthquake aftershock sequence within the South Iceland Seismic Zone: fault locations and source parameters of aftershocks. Jökull 60:23–46Google Scholar
- Einarsson P (2010) Mapping of Holocene surface ruptures in the South Iceland Seismic Zone. Jökull 60:117–134Google Scholar
- Greenwood PE, Nikulin MS (1996) A Guide to Chi-Squared Testing. Wiley-InterscienceGoogle Scholar
- Khodayar M, Björnsson S (2014) Fault ruptures and geothermal effects of the second earthquake, 29 May 2008, South Iceland Seismic Zone. Geothermics 50:44–65. doi: 10.1016/j.geothermics.2013.07.002.. http://www.sciencedirect.com/science/article/pii/S0375650513000503 CrossRefGoogle Scholar
- Lomax A, Michelini A, Curtis A (2009) Earthquake Location, Direct, Global-Search Methods. In: Meyers RA (ed) Encyclopedia of Complexity and Systems Science. Springer, New York, pp 2449–2473. doi: 10.1007/978-0-387-30440-3_150
- Martinsson J (2013) Robust Bayesian hypocentre and uncertainty region estimation: the effect of heavy-tailed distributions and prior information in cases with poor, inconsistent and insufficient arrival times. Geophys J Int 192(3):1156–1178. 10.1093/gji/ggs067. http://gji.oxfordjournals.org/content/192/3/1156 CrossRefGoogle Scholar
- Papoulis A, Pillai SU (2002) Probability,random variables and stochastic processes, 4th edn. McGraw-HillGoogle Scholar
- Skilling J (1989) Classic maximum entropy. In: Skilling J (ed) Maximum entropy and bayesian methods. Springer, Netherlands, Dordrecht, pp 45–52, doi: 10.1007/978-94-015-7860-8, (to appear in print)
- Spence W (1980) Relative epicenter determination using P-wave arrival-time differences. Bull Seismol Soc Am 70(1):171–183Google Scholar