Genuine non-double-couple (non-DC) components of a seismic source, defined here as the non-DC components that are not due to summation of pure double-couple (DC) components, provide important insight into special physical processes in non-earthquake sources such as explosion, volcano eruption and collapse etc. Yet they remain challenging to be resolved. To address the issue and explore the physical mechanism of those special events, we develop a waveform-polarity-based moment tensor (WPMT) inversion method and employ it to study physical process in the 2014–2015 Bárðarbunga volcano event sequence. The WPMT method incorporates P-wave polarity data and seismic waveforms in the source inversion, designs a source simplicity test to check possible complex rupture in the seismic source, and employs a simulated annealing algorithm to search the best source solution. The simplicity test checks consistency of the source processes in the initiation stage of the event and the major energy release process of the event, thus ensuring that the inferred non-DC components are genuine to the seismic source. Real event and synthetic tests indicate that the WPMT method can identify and resolve genuine non-DC components in a seismic source. The WPMT inversions of the Bárðarbunga sequence yield many genuine non-DC source components and reveal that the eruptions are accompanied by seismic activities in depths of 1–5 km with magma migrations out of chambers, collapses of conduits, failures of normal faults, and a magma recharge at a depth of 9 km accompanied by a failure on a nearby normal fault.

中文翻译：

---

震源非双力偶分量：2014-2015 年冰岛 Bárðarbunga 火山事件序列的方法与应用

震源的真正非双耦合（非 DC）分量，这里定义为不是由纯双耦合（DC）分量的总和产生的非 DC 分量，为非地震中的特殊物理过程提供了重要的见解。 - 爆炸、火山喷发、崩塌等地震源，但解决起来仍然具有挑战性。为了解决这个问题并探索这些特殊事件的物理机制，我们开发了一种基于波形极性的矩张量（WPMT）反演方法，并用它来研究2014-2015年Bárðarbunga火山事件序列的物理过程。 WPMT方法在震源反演中结合纵波极性数据和地震波形，设计震源简单性测试来检查震源中可能存在的复杂破裂，并采用模拟退火算法来搜索最佳震源解。简单性测试检查事件起始阶段的震源过程和事件主要能量释放过程的一致性，从而确保推断的非直流分量对于震源来说是真实的。真实事件和综合测试表明，WPMT方法可以识别和解析震源中真正的非直流分量。 Bárðarbunga 序列的 WPMT 反演产生了许多真正的非 DC 源成分，并揭示了喷发伴随着 1-5 km 深度的地震活动，其中包括岩浆迁移出房间、管道塌陷、正断层破坏和岩浆在 9 公里深处补给，并伴随着附近正断层的破裂。