Orientation Estimates of AACSE OBS Using Ambient Noise and Teleseismic Rayleigh Wave Methods

This dataset provides horizontal component orientation estimates for 53 ocean bottom seismometers (OBSs) deployed during the Alaska Amphibious Community Seismic Experiment (AACSE; network code XO, available at https://www.fdsn.org/networks/detail/XO_2018/). The orientations were determined in late 2020 using seismic data accessed via the EarthScope Data Management Center (https://ds.iris.edu/ds/nodes/dmc/). All AACSE OBSs use a left-handed coordinate system for their three-component channels: positive Z points upward; the two horizontal components are H1 and H2, where H2 is 90 degrees clockwise from H1. The orientation estimates reported here represent the clockwise angle from North to H1, ranging from 0 to 360°. Two independent methods were applied: (1) The ambient noise technique described by Zha et al. (2013), and (2) The teleseismic Rayleigh wave method of Stachnik et al. (2012). For most stations, the two methods yield consistent results within estimated uncertainties, although notable discrepancies exist for a subset. In general, I consider the teleseismic Rayleigh wave results more reliable, as earthquake back-azimuthal coverage typically provides better constraints than station array geometry in this region. Each orientation estimate was manually reviewed and assigned a quality flag: "Good" - reliable; "Bad" - unreliable; "?" - uncertain. I recommend using the "Good" estimates with confidence. The "?" flagged results may benefit from additional verification. In early 2021, independent orientations were calculated by OBSIC (https://obsic-metrics.whoi.edu/XO) using software by Doran and Laske (2017). These OBSIC results closely agree with my teleseismic Rayleigh wave estimates, particularly for stations with "Good" quality, though OBSIC excludes several stations due to multiple-frequency data selection and strict quality control requirements. The OBSIC-derived orientations are available at: http://ds.iris.edu/data/reports/XO_2018_2019/AACSE_orientations_DLOPy.csv