Using H/V Spectral Ratio in Gravelly Soil Near Grand Teton National Park

Session: Near-Surface Effects: Advances in Site Response Estimation and Its Applications [Poster]
Type: Poster
Date: 4/28/2020
Time: 08:00 AM
Room: Ballroom
Description: 

Accurate determination of depth to bedrock may be determined using many methods. This includes conventional borings and soundings, surface wave testing, horizontal to vertical (H/V) ratio, refraction and others. The determination of this depth is an important design consideration for some foundation types, seismic site response analyses and source‑path‑site models. This study presents the data collection, analyses and interpretation of the bedrock depths inferred from the H/V testing along two cross sections one in Grand Teton National Park and one approximately 10 miles south of Grand Teton National Park. In general, H/V testing is known to produce satisfactory estimates of bedrock depths at soft soil sites with significant velocity contrasts. However, in this study the soil is likely a mix of stiff gravels and cobbles that may or may not include a significant velocity contrast at depth. A previous project in the region resulted in poor H/V data, which prompted this study. In order to infer bedrock depths in these difficult soil types data was analyzed and interpreted in an aggregate manner. Each of the cross sections begin near the Teton fault where it is assumed bedrock depths are shallower and progresses towards the middle of the Teton Valley near the Snake River. This paper presents the collection, analyses and interpretation of the inferred bedrock depth using H/V testing. Although the H/V data produced reliable H/V peaks at many locations, the high frequency H/V data did not produce realistic depths of bedrock at either cross section.

Presenting Author: Shawn Griffiths

Authors