Volcanic tremor at Ruapehu: Characteristics and implications for the resonant source

摘要: Abstract Many volcanoes produce volcanic tremor with consistent sharp peaks, which suggests that one or more resonators have been excited by a process. Such “harmonic” can be classified as single‐resonator multiple‐resonator. Multiple‐resonator has number of not harmonically related, and the relative energy in peaks varies rapidly time. Single‐resonator tremor, observed on Ruapehu, few spectrum, signal shows some coherence. The main Ruapehu dominant frequency c. 1.8–2.3 Hz, very little second harmonic energy. Recordings within 1 km Crater Lake sometimes show strong third harmonic, but this is attenuated at greater distances. “Gliding” changes are rarely seen. Tremor 3 Hz also occurs, appears to come from another source, intensity independent source. “2 Hz” recorded near source complex par...