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首页> 外文期刊>Journal of Volcanology and Geothermal Research >Resistivity variations related to the large March 9,1998 eruption at La Fournaise volcano inferred by continuous MT monitoring
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Resistivity variations related to the large March 9,1998 eruption at La Fournaise volcano inferred by continuous MT monitoring

机译：电阻率的变化与1998年3月9日在拉富尔奈瑟斯火山发生的大喷发有关，该喷发是通过连续MT监测得出

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The 2645 m-high La Fournaise volcano, located in the Southwest of Reunion Island (Indian Ocean), is a shield basaltic volcano where effusive eruptions generally occur along long fissures starting from the summit, alongside major fractures that characterize the eruptions' dynamism and effusivity. Between 1992 and 1998, the volcano underwent a quiet period during which few earthquakes were recorded. Minor seismic activity returned after 1997 and picked up in March 1998 during the 35 h preceding the March 9 eruption. From 1996, two autonomous stations (CSV and BAV) were installed on the volcano. CSV was located inside the Enclos Fouque caldera while BAV was positioned 82 km NW of the volcano summit. Horizontal components of the electric and magnetic fields were sampled every 20 s. Continuous time-series were available from 1996 to 1999 at CSV, and from 1997 to March 1998 at BAV. Data have been processed using both single-station and remote-reference processing. Both results show apparent resistivity variations synchronous to the eruption. Time-lapse impedance estimates are computed on overlapping time windows of about two days at both stations. The only major decrease of the observed impedance coincides with the March 1998 eruption. At CSV, the resistivity started to drop about five days before the eruption, reached several local minima until April, and then slowly increased as the volcanic crisis reduced in activity. After the end of the crisis in September 1998, the apparent resistivity recovered its pre-crisis value.
机译：位于留尼汪岛西南部（印度洋）的海拔2645米的拉富尔奈斯火山是盾形玄武岩火山，喷发性喷发通常发生在从山顶开始的长裂缝中，并伴有代表喷发动力和喷发性的主要裂缝。 。在1992年至1998年之间，火山经历了一段平静的时期，在这段时期内几乎没有地震记录。小地震活动在1997年之后恢复，并在3月9日喷发之前的35小时内于1998年3月恢复。从1996年开始，在火山上安装了两个自治站（CSV和BAV）。 CSV位于Enclos Fouque火山口内，而BAV位于火山山顶西北82公里处。每20秒对电场和磁场的水平分量进行一次采样。连续时间序列可从1996年至1999年在CSV上获得，从1997年至1998年3月在BAV上可获得。数据已使用单站和远程参考处理进行了处理。这两个结果均显示出与喷发同步的明显电阻率变化。在两个站点大约两天的重叠时间窗口上计算延时阻抗估算值。观测到的阻抗的唯一主要下降与1998年3月的喷发相吻合。在CSV处，电阻率在喷发前5天左右开始下降，直到4月才达到局部极小值，然后随着火山危机活动减少而缓慢增加。 1998年9月危机结束后，视电阻率恢复了危机前的价值。

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