.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "api/gallery/volcanology/plot_17_newhall_self_volcanic_explosivity_index.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_api_gallery_volcanology_plot_17_newhall_self_volcanic_explosivity_index.py>`
        to download the full example code or to run this example in your browser via JupyterLite.

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_api_gallery_volcanology_plot_17_newhall_self_volcanic_explosivity_index.py:


Newhall and Self's Volcanic Explosivity Index (1982)
====================================================

Chris Newhall and Stephen Self combined erupted volume, column height and
eyewitness descriptions into one index from 0 to 8, so that eruptions in the
historical record could be compared. Above VEI 2 each step is a factor of ten
in tephra volume. Approximate volumes of a few well-known eruptions place them
on the scale.

.. GENERATED FROM PYTHON SOURCE LINES 11-38



.. image-sg:: /api/gallery/volcanology/images/sphx_glr_plot_17_newhall_self_volcanic_explosivity_index_001.png
   :alt: One step per factor of ten
   :srcset: /api/gallery/volcanology/images/sphx_glr_plot_17_newhall_self_volcanic_explosivity_index_001.png
   :class: sphx-glr-single-img





.. code-block:: Python


    import matplotlib.pyplot as plt
    import numpy as np

    from earthsciencekit.volcanology import volcanic_explosivity_index

    eruptions = {
        "Kilauea, lava lake": 1e3,
        "Stromboli, typical": 1e5,
        "Mount St Helens 1980": 1.0e9,
        "Pinatubo 1991": 1.0e10,
        "Tambora 1815": 1.5e11,
        "Toba, 74 ka": 2.8e12,
    }
    volume = np.array(list(eruptions.values()))
    index = volcanic_explosivity_index(volume)
    np.testing.assert_array_equal(index, [0, 1, 5, 6, 7, 8])

    grid = np.logspace(2, 13, 600)
    fig, ax = plt.subplots()
    ax.semilogx(grid, volcanic_explosivity_index(grid), drawstyle="steps-post")
    for (name, v), i in zip(eruptions.items(), index):
        ax.plot(v, i, "ko")
        ax.annotate(name, (v, i), textcoords="offset points", xytext=(-6, 6), ha="right", fontsize=8)
    ax.set(xlabel="bulk tephra volume [m^3]", ylabel="VEI", title="One step per factor of ten", yticks=range(9))

    plt.show()


.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 0.112 seconds)


.. _sphx_glr_download_api_gallery_volcanology_plot_17_newhall_self_volcanic_explosivity_index.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: lite-badge

      .. image:: images/jupyterlite_badge_logo.svg
        :target: ../../../lite/lab/index.html?path=api/gallery/volcanology/plot_17_newhall_self_volcanic_explosivity_index.ipynb
        :alt: Launch JupyterLite
        :width: 150 px

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: plot_17_newhall_self_volcanic_explosivity_index.ipynb <plot_17_newhall_self_volcanic_explosivity_index.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: plot_17_newhall_self_volcanic_explosivity_index.py <plot_17_newhall_self_volcanic_explosivity_index.py>`

    .. container:: sphx-glr-download sphx-glr-download-zip

      :download:`Download zipped: plot_17_newhall_self_volcanic_explosivity_index.zip <plot_17_newhall_self_volcanic_explosivity_index.zip>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_