This process is considered to have been driven by the pressure caused by the rising magma super-heating water trapped within the edifice of the volcano.
Since this form nests in crater crevices, and all known localities are active volcanoes, colonies are believed to be susceptible to periodic extinction.
Extending east and west from the central edifice are two broad fan-shaped lobes (or shoulders), which give the volcano its elongation in the east-west direction.
