Abstract. Double differences (DD) seismic data are widely used to define elasticity distribution in the Earth's interior, and its variation in time. DD data are often pre-processed from earthquakes recordings through expert-opinion, where couples of earthquakes are selected based on some user-defined criteria, and DD data are computed from the selected couples. We develop a novel methodology for preparing DD seismic data based on a trans-dimensional algorithm, without imposing pre-defined criteria on the selection of couples of events. We apply it to a seismic database recorded on the flank of Katla volcano (Iceland), where elasticity variations in time has been indicated. Our approach quantitatively defines the presence of changepoints that separate the seismic events in time-windows. Within each time-window, the DD data are consistent with the hypothesis of time-invariant elasticity in the subsurface, and DD data can be safely used in subsequent analysis. Due to the parsimonious behavior of the trans-dimensional algorithm, only changepoints supported by the data are retrieved. Our results indicate that: (a) retrieved changepoints are consistent with first-order variations in the data (i.e. most striking changes in the DD data are correctly reproduced in the changepoint distribution in time); (b) changepoint locations in time do correlate neither with changes in seismicity rate, nor with changes in waveforms similarity (measured through the cross-correlation coefficients); and (c) noteworthy, the changepoint distribution in time seems to be insensitive to variations in the seismic network geometry during the experiment. Our results proofs that trans-dimensional algorithms can be positively applied to pre-processing of geophysical data before the application of standard routines (i.e. before using them to solve standard geophysical inverse problems) in the so called exploration of the data space.

中文翻译：

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跨维采样数据空间探索：以地震双差数据为例

摘要。双差 (DD) 地震数据被广泛用于定义地球内部的弹性分布及其随时间的变化。DD 数据通常通过专家意见从地震记录中进行预处理，其中根据一些用户定义的标准选择地震对，然后从选定的地震对中计算出 DD 数据。我们开发了一种基于跨维算法准备 DD 地震数据的新方法，而无需对事件对的选择强加预定义的标准。我们将其应用到记录在卡特拉火山（冰岛）侧面的地震数据库中，其中显示了弹性随时间的变化。我们的方法定量地定义了在时间窗口中分隔地震事件的变化点的存在。在每个时间窗口内，DD数据与地下弹性时不变假设一致，DD数据可安全用于后续分析。由于跨维算法的简约行为，仅检索数据支持的变化点。我们的结果表明： (a) 检索到的变化点与数据的一阶变化一致（即 DD 数据中最显着的变化在变化点分布中及时正确再现）；(b) 时间上的变化点位置既不与地震活动率的变化相关，也不与波形相似性的变化（通过互相关系数测量）相关；(c) 值得注意的是，时间上的变化点分布似乎对实验期间地震网络几何形状的变化不敏感。