Significant errors in the calculated azimuth and other parameters of a monitored fracture can be caused by not performing accurate borehole deviation surveys for hydraulic fracture monitoring (HFM) and neglecting the effects of the deviating borehole trajectory. For common HFM geometries, a 2° deviation uncertainty of the positions of monitoring or treatment well surveys can cause more than a 40° uncertainty of the inverted fracture azimuths. Furthermore, if the positions of the injection point and the receiver array are not known accurately and the velocity model is artificially adjusted to locate perforations on assumed positions, several milliseconds discrepancies between measured and modelled SH-P-wave traveltime differences may appear along the receiver array. These traveltime discrepancies may then be misinterpreted as an effect of TI anisotropy, and use of such an anisotropic model may lead to the mislocation of the detected fracture(s). The uncertainty of the relative positions between the monitoring and treatment wells can have a cumulative, nonlinear effect on inverted fracture parameters.