Variety and sustainability of volcanic lakes: Response to subaqueous thermal activity predicted by a numerical model
Variety and sustainability of volcanic lakes: Response to subaqueous thermal activity predicted by a numerical model
复制标题
火山湖的多样性和可持续性：数值模型预测的水下热活动的响应
DOI：
10.1002/2017jb014387
复制
发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Hashimoto Takeshi
中科院分区：
文献类型：
--
作者：
Terada Akihiko;Hashimoto Takeshi
我们使用一个数值模型来研究控制热火山口湖在活火山的存在或不存在的因素。我们发现，给定一对合适的参数（例如，水下火山口的焓和湖底输入流体的质量通量与湖面面积的比率），热火山口湖可以维持相对较长的时间尺度。无论是高降水率还是湖底的不透水层都不是长期可持续发展所必需的。这两个控制参数会影响火山口湖的各种水文特性，包括温度、化学浓度和水位的时间变化。在低温火山口湖的情况下，通量和焓的增加，这是潜水或潜水岩浆喷发的常见前兆，导致温度和水位的增加。相反，在高温湖泊中，水位下降伴随着温度上升。此外，我们的模型表明，陨石坑的几何形状是控制水温的关键。对于具有圆锥形地形的湖泊，由于微不足道的非火山活动（如低水平的降水）而引起的水位扰动可能导致水温和化学浓度持续升高，以及水位下降，即使水下火山活动没有改变。这种不是由火山活动引起的火山口湖的变化类似于火山爆发前的火山动荡。
We use a numerical model to investigate the factors that control the presence or absence of a hot crater lake at an active volcano. We find that given a suitable pair of parameters (e.g., the enthalpy of subaqueous fumaroles and the ratio of mass flux of the fluid input at the lake bottom to lake surface area), hot crater lakes can be sustained on relatively long timescales. Neither a high rate of precipitation nor an impermeable layer beneath the lake bottom are always necessary for long‐term sustainability. The two controlling parameters affect various hydrological properties of crater lakes, including temperature, chemical concentrations, and temporal variations in water levels. In the case of low‐temperature crater lakes, increases in flux and enthalpy, which are a common precursor to phreatic or phreatomagmatic eruptions, result in an increase in both temperature and water level. In contrast, a decrease in water level accompanied by a rise in temperature occurs at high‐temperature lakes. Furthermore, our model suggests that crater geometry is a key control on water temperature. For lakes with a conical topography, a perturbation in the water level due to trivial nonvolcanic activity, such as low levels of precipitation, can cause persistent increases in water temperature and chemical concentrations, and a decrease in the water level, even though subaqueous fumarolic activity does not change. Such changes in hot crater lakes which are not caused by changes in volcanic activity resemble the volcanic unrest that precedes eruptions.