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2 Refining analogue searches
Use the optional flags -Ts, -G, -M, -Sz, -St to customise the weights that PyVOLCANS assigns to each of the volcanological criteria: tectonic setting, rock geochemistry, volcano morphology, eruption size (Volcanic Explosivity Index, VEI, Newhall and Self, 1982), and eruption style, respectively (abbreviations are as in Tierz et al., 2019, Equation 1).
For example, call PyVOLCANS using an equal-weight scheme between eruption size and eruption style, setting the other volcanological criteria to 0 (Scheme B in Tierz et al., 2019):
$ pyvolcans Hekla -Sz 0.5 -St 0.5
Top 10 analogue volcanoes for Hekla, Iceland (372070):
name country smithsonian_id total_analogy
Taupo New Zealand 241070 0.947620
Kikhpinych Russia 300180 0.940538
Chichinautzin Mexico 341080 0.934044
Carrán-Los Venados Chile 357140 0.933013
Newberry United States 322110 0.930016
Khodutka Russia 300053 0.927797
Tangkoko-Duasudara Indonesia 266130 0.922440
Dukono Indonesia 268010 0.921541
Okmok United States 311290 0.921246
Agua de Pau Portugal 382090 0.921154
NB. You can also use fractions to define the weighting scheme. For instance, the last command above is equivalent to: $ pyvolcans Hekla -Sz 1/2 -St 1/2
Use the optional flag --count to change the number of top analogue volcanoes:
$ pyvolcans Hekla --count 5
Top 5 analogue volcanoes for Hekla, Iceland (372070):
name country smithsonian_id total_analogy
Torfajokull Iceland 372050 0.941676
Bardarbunga Iceland 373030 0.921407
Prestahnukur Iceland 371070 0.919877
Langjokull Iceland 371080 0.915929
Hengill Iceland 371050 0.911855
Use the optional flag --verbose to print the weighting scheme on-screen, and also to obtain the single-criterion analogy values, in addition to the total-analogy values that PyVOLCANS outputs by default. From PyVOLCANS v1.3.0, the verbose mode also provides the ID profile (i.e. summary of volcanological data available for VOLCANS calculations) for the specific volcano of interest, as nested dictionaries that follow a json file format (please see Tierz et al., 2019 for further details on the meaning and use of each of the variables shown in the ID profile):
$ pyvolcans Hekla --verbose
PyVOLCANS: Supplied weights: {'tectonic_setting': 0.2, 'geochemistry': 0.2, 'morphology': 0.2, 'eruption_size': 0.2, 'eruption_style': 0.2}
Top 10 analogue volcanoes for Hekla, Iceland (372070):
name country smithsonian_id total_analogy ATs AG AM ASz ASt
Torfajokull Iceland 372050 0.941676 0.2 0.188235 0.187584 0.180280 0.185577
Bardarbunga Iceland 373030 0.921407 0.2 0.188235 0.187584 0.172727 0.172861
Prestahnukur Iceland 371070 0.919877 0.2 0.188235 0.189474 0.169091 0.173077
Langjokull Iceland 371080 0.915929 0.2 0.188235 0.177193 0.169091 0.181410
Hengill Iceland 371050 0.911855 0.2 0.192157 0.173684 0.169091 0.176923
Brennisteinsfjoll Iceland 371040 0.907751 0.2 0.164706 0.184211 0.169091 0.189744
Kverkfjoll Iceland 373050 0.906833 0.2 0.188235 0.187584 0.169091 0.161923
Fremrinamar Iceland 373070 0.905074 0.2 0.188235 0.168421 0.169091 0.179327
Ecuador Ecuador 353011 0.901611 0.2 0.164706 0.194737 0.169091 0.173077
Marion Island South Africa 234070 0.892960 0.2 0.141176 0.200000 0.169091 0.182692
ID profile for Hekla, Iceland (372070):
{
"name": "Hekla",
"country": "Iceland",
"smithsonian_id": 372070,
"tectonic_setting": {
"0.0": "Rift Oceanic Crust"
},
"geochemistry": {
"Foidite": 0.0,
"Phonolite": 0.0,
"Trachyte": 0.0,
"Trachyandesite/Basaltic trachyandesite": 0.0,
"Phono-tephrite/Tephri-phonolite": 0.0,
"Tephrite/Basanite/Trachybasalt": 0.0,
"Basalt": 0.25,
"Andesite": 0.25,
"Dacite": 0.25,
"Rhyolite": 0.25
},
"morphology": 0.39473684210526316,
"eruption_size": {
"VEI leq 2": 0.26666666666666666,
"VEI 3": 0.35,
"VEI 4": 0.2833333333333333,
"VEI 5": 0.1,
"VEI 6": 0.0,
"VEI 7": 0.0,
"VEI 8": 0.0
},
"eruption_style": {
"Lava flow and/or fountaining": 0.8769230769230769,
"Ballistics and tephra": 0.6923076923076923,
"Phreatic and phreatomagmatic activity": 0.0,
"Water-sediment flows": 0.15384615384615385,
"Tsunamis": 0.015384615384615385,
"Pyroclastic density currents": 0.09230769230769231,
"Edifice collapse/destruction": 0.0,
"Caldera formation": 0.0
}
}
From PyVOLCANS v1.3.0, the program can provide the ID profile for either the target volcano selected by the user and/or for each of the top analogue volcanoes identified (whose number is set by the --count flag; default=10). As explained above, selecting the flag --verbose prints the ID profile for the target volcano into the standard output. In order to save this ID profile into a json-formatted file, users should use the option --output_volcano_data (or -ovd), as in the following example:
$ pyvolcans Hekla -v -ovd
which saves a file named Hekla_IDprofile.json into the current working directory. If users want to save the ID profiles for the top analogue volcanoes as well, they can do so by choosing the option --output_analogues_data (or -oad):
$ pyvolcans Hekla -v -oad
which saves a file named Hekla_top10analogues_Ts0200G0200M0200Sz0200St0200_IDprofiles.json into the current working directory as well. Please note that the set of top analogue volcanoes is dependent on the weighting scheme selected by the user. Therefore, modifying that weighting scheme (e.g. $ pyvolcans Hekla -G 0.7 -M 0.3 -v -oad) can lead to a different set of top analogue volcanoes, whose ID profiles would then be saved into the corresponding json-formatted file when the -oad flag is chosen. This is the reason why the names of these files contain specifications as to what weighting scheme was used to generate the set of top analogue volcanoes (please see the Home Wiki page and/or Tierz et al., 2019 for more details on the generation of analogue volcanoes via VOLCANS/PyVOLCANS).
You can save your PyVOLCANS results into a comma-separated-value (csv) file that you might use for your records and/or to perform further analyses on the data.
For example, typing:
$ pyvolcans Hekla --write_csv
generates the same standard PyVOLCANS output as $ pyvolcans Hekla, but, in addition, it saves a file named:
Hekla_top10analogues_Ts0200G0200M0200Sz0200St0200.csv
into the current working directory.
The filename is a unique identifier of the three main parameters that are used by PyVOLCANS, each separated by the underscore sign:
(1) target volcano (Hekla);
(2) weighting scheme (Ts0200G0200M0200Sz0200St0200)
(3) number of top analogue volcanoes (top10analogues)
The weight selected for each volcanological criterion is indicated by the abbreviation of the criterion (see above and in Equation 1 of Tierz et al., 2019), followed by a four-digits number, where the first number indicates the units value (either 0 or 1), and the following three numbers indicate the decimals of the weight value. Thus, the following examples apply:
0200 denotes 0.200, 0850 denotes 0.850, 0125 denotes 0.125, 1000 denotes 1.000, etc.
The content of the csv file is the same as the standard PyVOLCANS output:
$ cat Hekla_top10analogues_Ts0200G0200M0200Sz0200St0200.csv
name,country,smithsonian_id,total_analogy
Torfajokull,Iceland,372050,0.94168
Bardarbunga,Iceland,373030,0.92141
Prestahnukur,Iceland,371070,0.91988
Langjokull,Iceland,371080,0.91593
Hengill,Iceland,371050,0.91186
Brennisteinsfjoll,Iceland,371040,0.90775
Kverkfjoll,Iceland,373050,0.90683
Fremrinamar,Iceland,373070,0.90507
Ecuador,Ecuador,353011,0.90161
Marion Island,South Africa,234070,0.89296