Crosswell Seismic Reflection Imaging Of A Shallow Cobble-Andsand Aquifer: An Example From The Boise Hydrogeophysical Research Site

Crosswell seismic data contain first-arrival information for velocity inversion and reflections<br>for seismic stratigraphic analysis. Seismic velocity information is useful for directly comparing<br>to, and inverting for, physical properties such as porosity. Reflections within the data are<br>often under utilized, but can help map the subsurface structural architecture that often define<br>hydrostratigraphic bounding surfaces between sedimentary units. We have acquired numerous<br>crosswell data sets from the Boise Hydrogeophysical Research Site (BHRS), a shallow (less than<br>20 m depth) cobble-and-sand unconfined aquifer. Preliminary crosswell seismic reflection results<br>show meter-scale structure that can help constrain our velocity model and define seismic boundaries<br>that first arrival tomograms cannot provide. Both crosswell reflection and velocity information<br>can help constrain hydrostratigraphic parameters that may be used to model groundwater<br>flow.