This is an SGER award which will take advantage of dynamite explosions during a previously funded CD project (the High Lava Plains Experiment). The PIs will collect high-resolution (100 m spacing, 1 ms temporal sampling) P ? and S ? wave profiles at multiple azimuths in south-eastern Oregon. The data will be analyzed for anisotropy and S ? wave velocity, utilizing the high spatial resolution. Although some preliminary observations of crustal anisotropy have been made in the USA, it has not normally been possible to localize their depth extent, because passive observations are typically made at far lower frequencies (coarser resolution) than active-source measurements. Hence the need to make 3 component (3C) active-source measurements to complement the now standard 3C passive-source receiver-function methods. If the PIs are successful, their results, in conjunction with the existing CD funded explosive-source refraction velocity model and receiver function images, will help estimate the relative roles of magmatic intrusions and crustal flow in maintaining crustal thickness in SE Oregon.
In addition to collecting data of scientific interest to the CD-funded High Lava Plains Experiment, the PIs will demonstrate the technical feasibility of using three one-component (1C) recorders in parallel at a single site to record 3C data. Success in the latter aim will open a path to fuller utilization of the PASSCAL and EarthScope Texan recording facility, more complete recording of the waveforms generated by NSF-funded controlled-source experiments, and extraction of additional scientific results from future experiments. IRIS is arranging fabrication of 300 ?harnesses? to connect 900 existing 1C recorders (Texans) in groups of 3 to 300 existing 3C 4.5 Hz geophones, at no charge to this project.
