| abstract |
An apparatus includes a conductive plate operable to generate a reference signal and a shield configured to surround at least a portion of the conductive plate and to attenuate at least a portion of a horizontal electromagnetic signal. The apparatus also includes an electrode configured to be electrically coupled to the shield and to a ground, where the electrode is responsive to a vertical electromagnetic signal, and the vertical electromagnetic signal generated by a subsurface earth formation in response to an electroseismic or seismoelectric conversion of a passive electromagnetic source signal. The apparatus also includes an amplifier comprising a first input and a second input, where the first input is configured to electrically couple to the conductive plate and the second input is configured to electrically couple to the electrode. |