IRIS and the Rise of Receiver Functions

The development and popularization of the use of receiver functions to model crustal and upper mantle structure over the last 20 years has been driven in a large part by the availability of digital broadband data collected through IRIS programs. Receiver function analysis has become a standard method in passive-source PASSCAL experiments while the structure beneath most GSN stations has been examined using this method. Over the last 20 years, the method has evolved from the detailed analysis of single station receiver functions along two paths: The use of the method as a routine tool for estimation of bulk structural properties (such as thickness and poisson's ratio) and the application of imaging techniques to dense arrays of passive recorders. This paper extends the first of these paths to take advantage of another feature of the IRIS program: the increasing availability of real-time data and access tools that can easily obtain real-time data without human interaction. These capabilities offer the possibility of automating the use of receiver functions in reconnaissance mode for bulk property estimation. These automatically-generated bulk properties are termed "Receiver Reference Models" or RRM. We outline the RRM method and the IRIS data access tool (SOD, Standing Order for Data) that facilitate this approach. The resulting system will be routinely applied to the telemetered data from the EarthScope USArray stations to produce bulk property estimations that can be made available to geoscientists and educators for a wide spectrum of potential applications.