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Poster #183, Seismology

Quantifying the Sensitivity of Microearthquake Slip Inversions to Station Distribution Using the LASSO Nodal Array in Oklahoma

Colin N. Pennington, Hilary Chang, Justin L. Rubinstein, Rachel E. Abercrombie, Nori Nakata, Takahiko Uchide, & Elizabeth S. Cochran
Poster Image: 

Poster Presentation

2021 SCEC Annual Meeting, Poster #183, SCEC Contribution #11163 VIEW PDF
To investigate the sensitivity of slip inversions to station distribution we examine three microearthquakes (M1.7, M2.1, and M2.7) that occurred within the high density LArge-n Seismic Survey in Oklahoma (LASSO) nodal array. The LASSO array’s dense distribution of 1825 geophones provides an exceptional level of spatial and azimuthal coverage, which allows us to resolve slip at the scale of tens of meters. This density allows for more accurate calculation of slip inversions than are possible with typical station distributions and, in turn, it allows for the exploration of the sensitivity of slip inversions to station distribution and parameter choices. The effects of these choices were exami...ned using three well-recorded strike-slip microearthquakes using an Empirical Green’s Function method. From this analysis and the systematic testing of varied subsets of the network, we find that station distributions that have uniform coverage of azimuth and distance can retrieve the overall pattern of slip, but the estimated amplitude of slip can vary by 30% for high slip regions. The distance range most important to resolving the overall pattern of slip is 0.5-2 times the maximum fault dimension. Concerning azimuthal coverage, a network with > 270° coverage performs similar to having complete coverage. The choice of EGF, depending on its similarity to the target earthquake, can shift the location of resolved areas of slip and their amplitude.