Evidence for seismogenic fracture of silicic magma.
511 - 514.
It has long been assumed that seismogenic faulting is confined to cool, brittle rocks, with a temperature upper limit of similar to 600 degrees C (ref. 1). This thinking underpins our understanding of volcanic earthquakes, which are assumed to occur in cold rocks surrounding moving magma. However, the recent discovery of abundant brittle-ductile fault textures in silicic lavas(2-4) has led to the counter-intuitive hypothesis that seismic events may be triggered by fracture and faulting within the erupting magma itself. This hypothesis is supported by recent observations of growing lava domes, where microearthquake swarms have coincided with the emplacement of gouge-covered lava spines(5,6), leading to models of seismogenic stick-slip along shallow shear zones in the magma(7). But can fracturing or faulting in high-temperature, eruptible magma really generate measurable seismic events? Here we deform high-temperature silica-rich magmas under simulated volcanic conditions in order to test the hypothesis that hightemperature magma fracture is seismogenic. The acoustic emissions recorded during experiments show that seismogenic rupture may occur in both crystal- rich and crystal-free silicic magmas at eruptive temperatures, extending the range of known conditions for seismogenic faulting.
|Title:||Evidence for seismogenic fracture of silicic magma|
|Keywords:||SOUFRIERE HILLS VOLCANO, MOUNT-ST-HELENS, ACOUSTIC-EMISSION, UNZEN VOLCANO, LAVA DOME, EARTHQUAKES, MONTSERRAT, SEISMICITY, ERUPTIONS, ANDESITE|
|UCL classification:||UCL > School of Life and Medical Sciences > Faculty of Life Sciences > Biosciences (Division of) > Cell and Developmental Biology
UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Institute for Risk and Disaster Reduction
Archive Staff Only