EARS (ears.iris.washington.edu) is a fully automated data product* that monitors both the IRIS station database and the USGS/NEIC weekly PDE (WHDF) catalog to calculate bulk crustal properties of stations as new candidate data arrive. Through its processing sequence, EARS calculates the receiver functions and transforms them from the amplitude-time domain to amplitude as a function of crustal thickness, H, and the Vp/Vs ratio, K, using the predicted travel times of the Ps, PpPs and PsPs/PpPs phases over a suite of single-layer models. The calculated H and K values are then weighted based on the instantaneous phase of the receiver functions and an HK stack is formed for the station to allow estimation of its crustal thickness and Vp/Vs values (see figure).

Due to its dynamic nature, EARS coverage of the continental US is extending to the east as the Transportable Array (TA) component of the USArray is rolling eastward (see the current map) and new station data become available at the IRIS DMC. Maps below show the latest EARS crustal thickness and Vp/Vs coverage of the continental US.

The EARS user interface (http://ears.iris.washington.edu) provides access to EARS receiver functions, the corresponding processed seismograms and the calculated bulk crustal properties. For more information on EARS see The Electronic Seismologist column of Seismological Research Letters, Nov/Dec 2005 by H. Philip Crotwell and Thomas J. Owens. Additional details of the processing model used within EARS can be found in chapter 4 of Philip Crotwell's dissertation.

Data Access

1. Direct access using the EARS web interface

Use the EARS web interface (ears.iris.washington.edu) to download the event-based or station-based receiver functions.

2. Bulk access using Python scripts

To download receiver functions for multiple stations and/or events, use the helper Python scripts (the usage instructions are included).

3. EARS results in FuncLab

The downloaded EARS receiver functions, after a format conversion, could be further processed by FuncLab, a MATLAB interactive receiver function toolbox developed by Kevin C. Eagar and Matthew J. Fouch of Arizona State University. For a shell script to convert EARS data to FuncLab format and to download FuncLab, visit geophysics.asu.edu/funclab.

Credits:

* EARS was developed as an EarthScope/USArray data product by H. Philip Crotwell and Thomas J. Owens of University of South Carolina with an initial goal of estimating the crustal thickness and Vp/Vs ratio across the continental United States, using the IRIS DMC waveform archive. After its initial successful implementation at the University of South Carolina and because of its high level of automation, its scope was expanded to cover all stations in the extensive waveform archive of the IRIS DMC. The EARS database now contains over 250,000 receiver functions and H-K values for over 2500 stations from 133 networks around the world.

In April 2010, EARS was moved to IRIS DMC and became an IRIS DMC data product and continues to monitor the weekly PDE (WHDF) catalog and station database for candidate data that can contribute to calculation of the bulk crustal properties of stations.

EARS development was supported by the EarthScope Program through NSF grants #EAR-0346113 and EAR-0642890 to the University of South Carolina. Continuing operation of EARS at the IRIS DMS is supported by the NSF grants #EAR-0552316 and EAR-0733069.

If you use EARS data in publications please cite:

Crotwell, H. P., and T. J. Owens (2005), Automated receiver function processing, Seism. Res. Lett., 76, 702-708.

Trabant, C., A. R. Hutko, M. Bahavar, R. Karstens, T. Ahern and R. Aster (2012), Data products at the IRIS DMC: stepping-stones for research and other application, Seismologi cal Research Letters, 83(6), 846:854. doi: 10.1785/0220120032