Latter, J.H. 1979 Volcanological observations at Tongariro National Park, 2: types and classification of volcanic earthquakes, 1976-1978. [s.l.]: [s.n.]. Report / Geophysics Division 150 60 p.
Abstract: Volcano-seismic research at Ruapehu and Ngauruhoe, since installation of seismometers near each volcano, has highlighted some shortcomings in existing schemes of classification of seismic events associated with volcanoes. A new classification is proposed, separating earthquakes near the volcanoes into `volcanic', `volcano-tectonic', and `tectonic' classes. It is suggested that earthquakes in the `volcanic' class are generated by an extended source mechanism, quite different to the instantaneous fracturing of competent rock, which is considered responsible for `volcano-tectonic' and `tectonic' earthquakes. Types of earthquakes near the volcanoes are described, and some consideration is given to an interpretation of their occurrence in five kinds of phreato-magmatic and phreatic eruptions at Ruapehu
