|Title||The Microvibe, a broad band, light-weight and cost effective seismic source for near surface imaging|
|Download||Download (whole publication) |
|Author||Pugin, A J -M; Brewer, K; Cartwright, T; Dietiker, B|
|Source||Regional-scale groundwater geoscience in southern Ontario: an Ontario Geological Survey, Geological Survey of Canada, and Conservation Ontario geoscientists open house; by Russell, H A J; Ford, D; Priebe,
E H; Holysh, S; Geological Survey of Canada, Open File 8363, 2018 p. 35, https://doi.org/10.4095/306569 (Open Access)|
|Publisher||Natural Resources Canada|
|Meeting||Regional-Scale Groundwater Geoscience in Southern Ontario: Open House; Guelph; CA; February 28 - March 1, 2018|
|Related||This publication is contained in Russell, H A J; Ford, D;
Priebe, E H; Holysh, S; (2018). Regional-scale groundwater geoscience in southern Ontario: an Ontario Geological Survey, Geological Survey of Canada, and Conservation Ontario geoscientists open house, Geological Survey of Canada, Open File
|Subjects||geophysics; hydrogeology; environmental geology; engineering geology; surficial geology/geomorphology; structural geology; in-field instrumentation; geophysical surveys; seismic surveys, ground; seismic
reflection surveys; seismic waves; p waves; s waves; soil mechanics; earthquakes; bedrock geology; structural features; faults; Microvibe; neotectonics; buried tunnels|
|Program||Aquifer Assessment & support to mapping, Groundwater Geoscience|
|Released||2018 02 16|
|Abstract||For shallow environmental and engineering surveys in generally unconsolidated sediment to depths of a few meters to several hundred metres high resolution seismic reflection surveys require heavy and
expensive vibration sources such as a Minivib(TM). It weights 9 tons and costs approximately $400K. Best practice for optimized characterization of shallow surficial properties multi-component acquisition is required and this necessitates multiple
passes and recording with the Minivibe - landstreamer system with the source being set in various horizontal and vertical directions. To provide a cheaper and lighter seismic source we have developed the Microvibe (180 kg and ~$30k) uses a suite of
lighter electromagnetic transducers that can provide multicomponent seismic signal in a single pass.|
The Microvibe consists of forty tactile transducers, twenty per direction, on a solid concrete block mounted on a steel skid plate. This vibrator
can provide various types of sweeps from 20 Hz up to 800 Hz with a power up to 2000 watts, for each direction, providing ~25% of the power provided by an IVI Minvib. To compensate for the reduced power level, we increase the time length of the sweep.
The Microvibe provides higher frequency ranges than any known land seismic source available on the market.
The Microvibe is coupled with an in-house built landstreamer array designed for use along paved or gravel roads. The landstreamer is built
with 3 kg metal sleds connected using straps or low stretch ropes. The receiver spacing can vary from 0.75 m to 3 m. Receiver set-up is customized depending on the near-surface velocities and the targeted depths of observation. Each sled is equipped
with a 3-component (3-C) geophone unit constructed in-house with 30 Hz omni-directional geophone elements oriented in three orthogonal directions: one vertical and two horizontal, in-line (parallel to the survey direction) and cross-line
(perpendicular to the acquisition direction). The Microvibe - landstreamer combination allows data acquisition with shaking in vertical and horizontal directions in one pass to capture P-wave and S-wave seismic reflection sections.
In order to
demonstrate the value of this new geophysical tool, examples will be presented from a ground water example in the Vars - Winchester esker of southeastern Ontario. The system is also very efficient for evaluating the soft soil response for earthquakes
and for locating neo-tectonic faults or buried tunnels.