Use of Low and High Noise Models for Land Surface-seismic Data

In land surface-seismic acquisition ambient noise levels can vary significantly both during a survey and from one survey to another. We show that, for a relatively quiet survey, the addition of increasingly strong realistic noise levels progressively damages the data, especially in the high frequencies. To mitigate such damage, the planned survey effort must offer robustness in the prevailing variable noise conditions. The robustness also renders the data impervious to sensor/system noise in state-of-the-art acquisition systems. In global seismology, Low and High Noise Models are used to describe the range of noise levels encountered on Earth. Models specific to land surface-seismic are not openly available. This may be partly due to the historical use of geophone arrays. High-channel count acquisition systems using broadband digital point-receivers, which have been in operational use in many different areas for more than ten years, provide a new and reliable source of data on acquisition noise levels. From broadband point-receiver ambient noise recordings around the world, we compiled models of the median and extreme values of the noise spectral density. More analysis will be required, but once established, the land surface-seismic noise models can serve as reference for survey and system design.