MTpy Example 01 - Open-source Python packages for Magnetotellurics

Transfer Function Collection¶

Goal: demonstrate how to build a standardized collection of tranfer functions from various file types (“EDI”, “EMTFXML”).

Test Data: Yellowstone, WY, USA

Broadband data provided by University of Washington and Oregon State University processed by Paul Bedrosian (USGS)
Earthscope long period data archived at IRIS
Long period data from DeGroot-Hedlin archived at IRIS

We will build an MTCollection using MTpy v2.0. Under the hood MTCollection is storing the transfer functions in an MTH5 file and using mt_metadata to read the transfer functions into a standardize transfer function. We will also have a look at how to adjust some metadata so that your transfer functions can be nicely organized. Each of these data sets were collected as different surveys and we will store them as such. We will go survey by survey loading in the transfer functions.

from copy import deepcopy
from pathlib import Path

from mtpy import MT, MTCollection

Create Transfer Function Collection¶

The first thing to do is to open a new MTCollection object. You can call it what you want, for now we will call it yellowstone_mt_collection.

Add Earthscope Data¶

The data is provided locally, but the data are publicly available on the IRIS EMTF SPUD. Just draw a box around the area of interest and click download spud bundle. This will give you a zip file that contains an EDI, EMTFXML, ZRR file and an image of what the response should look like. We have copied the EMTFXML files into a single folder for convenience.

Broadband Data¶

First we will load in broadband transfer functions which are in EDI format. These files have no survey.id type information, therefore we are going to add it. These files are stored locally on your machine, so just adjust the file path. We will loop over each file and add in the appropriate metadata

data_path = Path().cwd().parent.parent.parent.joinpath("shared","shortcourses", "mt", "data", "transfer_functions")

%%time

with MTCollection() as mc:
    mc.open_collection(
        filename=Path().cwd().joinpath("yellowstone_mt_collection.h5")
    )
    # broadband data
    bb_edi_path = data_path.joinpath("broadband")
    mc.add_tf(
        mc.make_file_list(bb_edi_path, file_types=["edi"]),
        new_survey="YSBB",
    )

    ## long period data from the MTArray
    earthscope_path = data_path.joinpath("earthscope")
    mc.add_tf(mc.make_file_list(earthscope_path, file_types=["xml"]))

    tf_df = mc.dataframe

Fetching long content....

Make sure everything loaded in properly¶

We want to make sure everything loaded in properly. MTCollection has a convenient property called dataframe this will list all transfer functions found in the MTH5 file.

Note: This is a property that when called returns a summary of all transfer functions contained in the MTH5 at the point that it is called. Therefore, if you update the file by adding a transfer function and then calle dataframe you will get an updated summary. There is more we can do with dataframe which we will look at in a later lesson.

tf_df

tf_df.survey.unique()

array(['Transportable_Array', 'YSBB', 'Yellowstone-Snake_River_Plain'],
      dtype=object)

Next Example¶

In the next we will have a look at the various plotting functions MTCollection has and how to use them.