# 5.1.19. MT / ZTEM data: MTZ3D GIF file¶

This file is the structure for MT and/or ZTEM data associated with the inversion program MTZ3D. The type of data is set by a data flag. Data that should be ignored are denoted by an i. The general format is:

Parameter definitions:

• DT: The data type flag. The flag DATATYPE preceeds this input. The options for the data flag are:
• MTZ: MT data; impedance data with both imaginary and real parts.

• MTR: MT data; apparent resitivities and phases

• MTT: ZTEM data; real and imaginary tipper functions is absolute ratio. Hx and Hy are constant at the reference (base) station location. This is the most typical flag for ZTEM data.

• MTB: Both MT and ZTEM data; ZTEM data is denoted by providing a reference (base) station after the frequency declaration.

• flg: Any value that does not contain actual data. By default, GIFtools will export NaN as the ignore value. The flag IGNORE preceeds this input.

• FREQ: The frequency for the data type.

• nRec: Number of receivers associated with the given frequency.

• [$$BaseX_{[j,k]} ...$$]: This line is only present for ZTEM data. The line consists of the (X,Y,Z) for the base station followed by “i” (usually 8 columns) for the number of data columns given on the next line.

• [$$X_{[j,k]} ...$$]: Easting (m) of the $$k^{th}$$ receiver for the $$j^{th}$$ data type.

• [$$Y_{[j,k]} ...$$]: Northing (m) of the $$k^{th}$$ receiver for the $$j^{th}$$ data type.

• [$$Z_{[j,k]} ...$$]: Elevation (m) of the $$k^{th}$$ receiver for the $$j^{th}$$ data type.

• data: Columns of data / uncertainty pairs depending upon the data type:

• Impedence MT data: The 16 data columns are in MT coordinates (X+ north, Y+ East, Z+ down) and consist of the following in order:

• $$ZXX^r$$: Real part of the ZXX component

• $$ZXX^r_{stn}$$: Standard deviation of the real part of the ZXX component

• $$ZXX^i$$: Imaginary part of the ZXX component

• $$ZXX^i_{stn}$$: Standard deviation of the imaginary part of the ZXX component

• $$ZXY^r$$: Real part of the ZXY component

• $$ZXY^r_{stn}$$: Standard deviation of the real part of the ZXY component

• $$ZXY^i$$: Imaginary part of the ZXY component

• $$ZXY^i_{stn}$$: Standard deviation of the imaginary part of the ZXY component

• $$ZYX^r$$: Real part of the ZYX component

• $$ZYX^r_{stn}$$: Standard deviation of the real part of the ZYX component

• $$ZYX^i$$: Imaginary part of the ZYX component

• $$ZYX^i_{stn}$$: Standard deviation of the imaginary part of the ZYX component

• $$ZYY^r$$: Real part of the ZYY component

• $$ZYY^r_{stn}$$: Standard deviation of the real part of the ZYY component

• $$ZYY^i$$: Imaginary part of the ZYY component

• $$ZYY^i_{stn}$$: Standard deviation of the imaginary part of the ZYY component

• Apparent resistivity / phase MT data: The 16 data columns consist of the following in order (phase in degrees and apparent resistivity in Ohm-m):

• $$ZXX^r$$: ZXX component of apparent resistivity

• $$ZXX^r_{stn}$$: Standard deviation of the ZXX component of apparent resistivity

• $$ZXX^p$$: ZXX component of phase

• $$ZXX^p_{stn}$$: Standard deviation of the ZXX component of phase

• $$ZXY^r$$: ZXY component of apparent resistivity

• $$ZXY^r_{stn}$$: Standard deviation of the ZXY component of apparent resistivity

• $$ZXY^p$$: ZXY component of phase

• $$ZXY^p_{stn}$$: Standard deviation of the ZXY component of phase

• $$ZYX^r$$: ZYX component of apparent resistivity

• $$ZYX^r_{stn}$$: Standard deviation of the ZYX component of apparent resistivity

• $$ZYX^p$$: ZYX component of phase

• $$ZYX^p_{stn}$$: Standard deviation of the ZYX component of phase

• $$ZYY^r$$: ZYY component of apparent resistivity

• $$ZYY^r_{stn}$$: Standard deviation of the ZYY component of apparent resistivity

• $$ZYY^p$$: ZYY component of phase

• $$ZYY^p_{stn}$$: Standard deviation of the ZYY component of phase

• ZTEM data: The 8 data columns are in MT coordinates (X+ north, Y+ East, Z+ down) and consist of the following in order:

• $$ZXY^r$$: Real part of the ZXY component

• $$ZXY^r_{stn}$$: Standard deviation of the real part of the ZXY component

• $$ZXY^i$$: Imaginary part of the ZXY component

• $$ZXY^i_{stn}$$: Standard deviation of the imaginary part of the ZXY component

• $$ZYX^r$$: Real part of the ZYX component

• $$ZYX^r_{stn}$$: Standard deviation of the real part of the ZYX component

• $$ZYX^i$$: Imaginary part of the ZYX component

• $$ZYX^i_{stn}$$: Standard deviation of the imaginary part of the ZYX component

NOTE: When using the MTB flag for both data, the locations will include both MT and then ZTEM data and must be in impedances. Therefore, MT data would follow with 8 columns of the ignore flag and ZTEM data would have 16 columns of ignore flag prior to data (see example 3 below).

## 5.1.19.1. Examples¶

The following are two examples of data files.

Example 1: Off-diagonal (ZXY and ZYX) impedance MT data at 3 frequencies (100, 10, and 1 Hz) with 2 observations each for brevity:

Example 2: ZTEM data at 2 frequencies (30 and 45 Hz) with 3 observations each with a single base station:

Example 3: MT and ZTEM data (combining example 1 and example 2). Note that the MT data comes first and then the ZTEM data: