Title of article :
A frictional law for volcanic ash gouge
Author/Authors :
Lavallée، نويسنده , , Y. and Hirose، نويسنده , , Grey T. and Kendrick، نويسنده , , J.E. and De Angelis، نويسنده , , S. and Petrakova، نويسنده , , L. and Hornby، نويسنده , , A.J. and Dingwell، نويسنده , , D.B.، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2014
Pages :
7
From page :
177
To page :
183
Abstract :
Volcanic provinces are structurally active regions – undergoing continual deformation along faults. Within such fault structures, volcanic ash gouge, containing both crystalline and glassy material, may act as a potential fault plane lubricant. Here, we investigate the frictional properties of volcanic ash gouges with varying glass fractions using a rotary shear apparatus at a range of slip rates (1.3–1300 mm/s) and axial stresses (0.5–2.5 MPa). We show that the frictional behaviour of volcanic ash is in agreement with Byerleeʹs friction law at low slip velocities, irrespective of glass content. The results reveal a common non-linear reduction of the friction coefficient with slip velocity and yield a frictional law for fault zones containing volcanic ash gouge. Textural analysis reveals that strain localisation and the development of shear bands are more prominent at higher slip velocities (>10 mm/s). The textures observed here are similar to those recorded in ash gouge at the surface of extrusive spines at Mount St. Helens (USA). We use the rate-weakening component of the frictional law to estimate shear-stress-resistance reductions associated with episodic seismogenic slip events that accompany magma ascent pulses. We conclude that the internal structure of volcanic ash gouge may act as a kinematic marker of exogenic dome growth.
Keywords :
stress drop , Earthquake slip , Stick-slip , Strain localisation , cyclic extrusion , dome eruptions
Journal title :
Earth and Planetary Science Letters
Serial Year :
2014
Journal title :
Earth and Planetary Science Letters
Record number :
2332724
Link To Document :
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