Source mechanisms of micro-earthquakes induced in a fluid injection experiment at the HDR site Soultz-sous-Forêts (Alsace) in 2003 and their temporal and spatial variations
Source mechanisms of micro-earthquakes induced in a fluid injection experiment at the HDR site Soultz-sous-Forêts (Alsace) in 2003 and their temporal and spatial variations
复制标题
2003年HDR站点Soultz-sous-Forêts（阿尔萨斯）注液实验诱发微震的震源机制及其时空变化
DOI：
10.1111/j.1365-246x.2010.04506.x
复制
发表时间：
2010
影响因子：
2.8
通讯作者：
J. Šílený
中科院分区：
文献类型：
--
作者：
J. Horalek;Z. Jechumtálová;L. Dorbath;J. Šílený
我们反演了45个震级微震的直达P波峰值振幅
M = 1.4 和 2.9 之间，发生在 2003 年 Soultz-sous-Forˆets 热干岩设施的 GPK3 钻孔中大量流体注入期间和之后。这些事件
由斯特拉斯堡大学拉泰尔科学观测学院运营的由 15 个台站组成的地面地震网络记录了这些数据。应用该机制的无约束力矩张量 (MT) 表达式，允许将偶极子的一般系统（即双电偶 (DC) 和非 DC 源）描述为拉伸断裂。除一个事件外，所有事件的机制主要是 DC，并带有百分之几的附加成分
最多。我们在引导试验中仔细检查了 MT 检索的可靠性，通过模拟震源的错位并在构建格林函数时应用该区域的简化速度模型，消除了一些数据。在一些试验中
出现了百分之几十的非 DC 成分，但 F 检验将其分类为微不足道。即使是唯一具有极高非 DC 机制的微地震也无法明确分类——F 检验对
纯直流溶液。 DC的巨大优势表明剪切滑移是所研究的微地震的机制。这些机制表现出很大的可变性
属于正倾滑型、斜正走滑型。 T 轴相当稳定，大致集中在东西方向上。相反，P轴在N-S方向上受到不良约束，从近垂直到近水平变化，这
指向 Soultz 注入体积中的异质应力。这与原位测量的应力模式一致：最小应力轴很好地限制在东西向，而最大和中间应力值彼此接近，使得
P轴方向的模糊性。我们发现源机制对震级或深度没有显着依赖性。分析事件的时空分布表明，注入激活了该地区存在的两段自然断层（我们的 I 和 II）
符号）显示不同的源机制模式。倾滑型态是断层 I 的特征，在注入期间和注入后都发生地震活动，而走滑型在断层 II 中占主导地位，仅在注入关闭后才触发地震活动。这表明假设在注入过程中产生的张性裂缝可能比纯剪切微地震发生的规模更小。
调查了。
We have inverted the peak amplitudes of direct P waves of 45 micro-earthquakes with magnitudes
between M = 1.4 and 2.9, which occurred during and after the 2003 massive fluid injection in the GPK3 borehole of the Soultz-sous-Forˆets Hot Dry Rock facility. These events
were recorded by a surface seismic network of 15 stations operated by the Ecole et Observatoire des Sciences de la Terre, University of Strasbourg. The unconstrained moment tensor (MT) expression of the mechanism was applied, allowing the description of a general system of dipoles, that is, both double-couple (DC) and non-DC sources, as tensile fractures. The mechanisms of all but one event are dominantly DCs with a few per cent additional components
at the most. We have checked carefully the reliability of the MT retrieval in bootstrap trials eliminating some data, by simulating the mislocation of the hypocentre and by applying simplified velocity models of the area in constructing Green’s functions. In some of the trials
non-DC components amounting to several tens of per cent appear, but the F-test classifies them as insignificant. Even the only micro-earthquake with an exceptionally high non-DC mechanism cannot be classified unambiguously—the F-test assigns similar significance to the
pure DC solution. The massive dominance of the DC indicates the shear-slip as the mechanism of the micro-earthquakes investigated. The mechanisms display large variability and
are of normal dip-slip, oblique normal to strike-slip types. The T-axes are fairly stable, being concentrated subhorizontally roughly in the E–W direction. On the contrary, the P-axes are ill constrained varying in the N–S direction from nearly vertical to nearly horizontal, which
points to heterogeneous stress in the Soultz injected volume. This is in agreement with the stress pattern from in situ measurements: the minimum stress axis is well constrained to E–W, whereas the maximum and intermediate stress values are close to one another, enabling the
ambiguity of the P-axis direction. We found no significant dependence of source mechanisms either on magnitudes or depths. The time–space distribution of the events analysed suggests that the injection activated two segments of the natural faults existing in the area (I and II in our
notation) showing different source mechanism patterns. The dip-slip regime is characteristic of fault segment I where the seismicity occurred during and also after injection, whereas the strike-slip regime prevails in segment II where the seismicity was triggered only after the injection shut in. This indicates that the tensile fractures, which are assumed to be created during injection, may have occurred on a smaller scale than the pure shear micro-earthquakes
investigated.
日本野岛断层带观测到的注入地震和地震群
DOI：
--
发表时间：
2008
期刊：
影响因子：
--
作者：
Tadokoro;K.
通讯作者：
K.