A new model for volcanic earthquake at Unzen Volcano: Melt rupture model
A new model for volcanic earthquake at Unzen Volcano: Melt rupture model
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DOI：
10.1029/1999gl900569
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发表时间：
1999-08-15
影响因子：
5.2
通讯作者：
Goto, A
中科院分区：
文献类型：
--
作者：
Goto, A
在1991-1995年云仙火山活动期间，流动的岩浆内部发生了小地震。这一矛盾现象可以解释为，当岩浆的粘度与应变率的乘积超过某一阈值时，即使是流动的岩浆也会发生脆性破坏。通过对管道中岩浆应变速率的估算，得出当粘度大于10（11.5）Pa·s时，岩石将发生脆性破坏的结论。对样品的实验室测量表明，在干燥条件下，温度在850 ℃以下，在800 ℃下，0.6wt.%水考虑到Fe-Ti氧化物地热温度计的温度（780-880 ℃）和气体温度（800 ℃），管道内部可以满足脆性破坏条件。剪切流动引起的熔体破裂可能是山顶地区地震的震源。
Small earthquakes occurred inside the flowing magma during the 1991-1995 activities of Unzen Volcano. This paradoxical phenomenon can be explained when we consider that even a flowing magma fails brittly under the condition that the product of viscosity and strain rate of magma exceeds a certain threshold value. The estimated strain rate of magma in the conduit leads us to the conclusion the brittle failure is expected when the viscosity is over 10(11.5) Pa s. Laboratory measurements of samples show that this viscosity range can be attained when the temperature is under 850 degrees C in dry condition, and 800 degrees C with 0.6 wt.% water. Considering the temperature from Fe-Ti oxide geothermometer (780-880 degrees C) and the gas temperature (800 degrees C), the brittle failure condition could be satisfied inside the conduit. The melt failure by shear flow could be the source of the earthquakes occurred at the summit area.