Refraction Seismic Survl3Y Of Some Thick Till In Southeast Alaska

A geotechnical investigation was conducted in a small, steep, tidewater glaciated valley<br>in southeastern Alaska. The geotechnical drilling program encountered unanticipated<br>overburden thicknesses in excess of 100 feet on one side of the valley. A refraction seismic<br>survey was conducted to augment the geotechnical program. Interesting aspects of the<br>geophysical survey included the remote location; logistics to and at the tent camp; limited<br>helicopter use; the steep and rugged forested terrain; the availability of drill hole information;<br>the combination of doing shallow and deep looking surveys; the deep depth of investigation<br>which required long lines, long off-end shots, and large explosive charges; and the snow cover<br>and the short amount of daylight during the early winter survey.