In summer 2018, a total of 43 passive seismic surveys were conducted in the Des Moines River floodplain. The horizontal-to-vertical spectral ratio (HVSR) method is a passive seismic technique that uses a three-component seismometer to measure the vertical and horizontal components of ambient seismic noise. A resonance frequency (f0) is induced in the unconsolidated deposits when there is a substantial contrast (greater than 2:1) in shear-wave acoustic impedance between the overburden and the bedrock. The f0 is determined from the analysis of the spectral ratio of the horizontal and vertical components of the seismic data. The thickness of the overburden can be related to the f0. In general, lower f0 relates to thicker sediments, and higher f0 relates to relatively thinner overburden. This data release contains a text file (Readme_HVSR.txt) that explains data files and processing references, 6 .zip folders 5 related to survey line(s) on a given date and one for individual measurements not related to survey lines with each zip folder containing measurement site folders and original data files and resultant measurement report (.trc, .saf or .dat, and .doc) , a notes file for archiving surface-geophysical data (HVSR_Archive_Notes_DesMoinesIA.csv), and another comma-separated values file (HVSR_Index_DesMoinesIA.csv) that can be used to help navigate the data files. Field notes taken at the time of data collection are not included in this data release but are available upon request.