MTpy Example 10 - Open-source Python packages for Magnetotellurics

Phase Tensor Pseudosections¶

A pseudosection plot distance on the x-axis and period on the y-axis. Phase tensor ellipses are plotted for each station at each period measured. This provides a plot that is an proxy for structures at depth. The ellipses and induction vectors are plotted in map view, so up is North and to the right is East.

from pathlib import Path
from mtpy import MTCollection
%matplotlib inline

2022-10-15 11:48:02,175 [line 135] error.get_mtpy_logger - INFO: Logging file can be found C:\Users\jpeacock\OneDrive - DOI\Documents\GitHub\mtpy\logs\mtpy_error.log
2022-10-15 11:48:02,178 [line 135] matplotlib.get_mtpy_logger - INFO: Logging file can be found C:\Users\jpeacock\OneDrive - DOI\Documents\GitHub\mtpy\logs\matplotlib_warn.log
2022-10-15 11:48:09,267 [line 135] mth5.setup_logger - INFO: Logging file can be found C:\Users\jpeacock\OneDrive - DOI\Documents\GitHub\mth5\logs\mth5_debug.log

Open MTCollection¶

In the previous example we created a MTH5 file from existing Yellowstone data. Let’s open that file here for plotting.

mc = MTCollection()
mc.open_collection(Path().cwd().parent.parent.joinpath("data", "transfer_functions", "yellowstone_mt_collection.h5"))

Plot Phase Tensor Pseudosection for the Snake River Plane stations¶

Since the DeGroot-Hedlin Snake River Plane line was collected with 2D modeling in mind, lets use that for an example.

%%time
mc.working_dataframe = mc.master_dataframe[mc.master_dataframe.station.str.startswith("SR2")]
dgh_mt_data = mc.to_mt_data()

Wall time: 27.1 s

plot_pt_pseudosection = dgh_mt_data.plot_phase_tensor_pseudosection( 
    plot_tipper="yri", 
    fig_num=2, 
    profile_reverse=True,
    y_limits=(10**5, 1),
)

Adjust Plot Parameters¶

Adjust some plot parameters to make it look nice.

# the stretch in the y direction
plot_pt_pseudosection.y_stretch = 3000

# ellipse properties
plot_pt_pseudosection.ellipse_size = 400

# arrow properties
plot_pt_pseudosection.arrow_lw = .5
plot_pt_pseudosection.arrow_size = 1500
plot_pt_pseudosection.arrow_head_width = 50 

# station name index
plot_pt_pseudosection.station_id = [3, None]

# y limits for the period range
plot_pt_pseudosection.y_limits=(30000, 5)

# need a new figure number from the main, otherwise it updates that plot
plot_pt_pseudosection.fig_num = 3
plot_pt_pseudosection.redraw_plot()

Shallow Observations¶

Shallow here is between 1 - 50 seconds

Looks like the Snake River Plane is filled with resistive material.
A possible fault between stations SR240 and SR244 as indicated by the induction vectors.
Similarly, a possible fault between SR264 and SR265, both of these are near the edge of the range front.
A possible basin or conductive body to the north of the southern part of the line as indicated by the induction vectors.

plot_stations = dgh_mt_data.plot_phase_tensor_map(
    plot_tipper="yri", 
    plot_period=30, 
    fig_num=6,
    ellipse_size=.15,
    arrow_size=.30,
    arrow_head_width=.02,
    arrow_head_length=.01,
    arrow_lw=.005,
)

Middle Observations¶

Shallow here is between 50 - 1000 seconds

The middle to lower crust is becomeing more conductive, with the more conductive bits being down the middle of the Snake River Plane as indicated by the induction vectors.

plot_stations.plot_period = 300
plot_stations.fig_num = 7
plot_stations.redraw_plot()

Lower Observations¶

Shallow here is between 1000 - 30000 seconds

There appears to be a strong northeast trending conductive zone in the lower crust to upper mantle, as highlighted by the induction vectors.

plot_stations.plot_period = 3000
plot_stations.fig_num = 8
plot_stations.redraw_plot()

Close MTCollection¶

mc.close_collection()

2022-10-15 11:52:18,695 [line 753] mth5.mth5.MTH5.close_mth5 - INFO: Flushing and closing C:\Users\jpeacock\OneDrive - DOI\Documents\GitHub\mt_examples\data\transfer_functions\yellowstone_mt_collection.h5