In the project we would like to use all 2100 Texans with vertical geophones to do a dense deployment across about 1/4 of the Shale Hills Critical Zone Observatory, which is located a few miles from Penn State University. Stations will be spaced 2 to 5 m apart. Hammer and shotgun sources will be used and spaced a few meters apart over the entire survey area. Shot timing will be provided by Verif-I gps synchronizers (Galen tells me that he has several). Shooting will be done in one day, with data being recorded continuously. The data will be used for a 3D P-wave tomography of the shallow subsurface. After collecting the active source data, the Texans will be redeployed to record ambient noise for a couple of days. Some of the Texans will also be used with 3-component (L-28s) sensors to collect a few dense 2D profiles for S-wave tomography after the 3D survey has been completed.