Nature, wavefield properties and source mechanism of volcanic tremor: A review.

摘要: Abstract Volcanic tremor has attracted considerable attention by seismologists because of its potential value as a tool for forecasting eruptions and better understanding the physical processes that occur inside active volcanoes. However, unlike tectonic earthquakes where dominant source process is brittle failure rock, driving mechanism seems to involve complex interactions magmatic fluids with surrounding bedrock. These are responsible following distinct characteristics found in volcanic recorded at many volcanoes worldwide: (a) onset may be emergent or impulsive, amplitude showing cases direct relationship activity; (b) frequency domain spectra consist series sharp peaks band 0.1–7 Hz, representing either fundamental harmonics, random distribution, while quite often they exhibit temporal variations their content; (c) depth can vary considerably from one volcano another range few hundred metres 40 km; (d) prior and/or after duration ranges several minutes days months. The methods used study include spectral analysis using both Fast Fourier Transform Maximum Entropy Method, polarisation wavefield make use array data deduce backazimuth type seismic waves well location source. Visual acoustic observations ongoing activity have assisted further constrain proposed mechanisms generation tremor. models suggested possible sources grouped follows: fluid-flow-induced oscillations conduits transporting fluids; excitation resonance fluid-filled cracks; bubble growth collapse due hydrothermal boiling groundwater; variety involving magma bodies different geometries. It been authors not unique differ another, fact adds more difficulty modelling efforts. As quality, computer power speed improving, it near future decipher accurately model environments.