The Baumgarten explosion occurred on 12 December 2017 at a gas storage site about 30 km east of Vienna, Austria. Acoustic arrivals from this accidental surface explosion were detected at dozens of stations of the AlpArray seismic network to distances up to 150 km, mainly in easterly directions. Thus it was expected that the Hungarian infrasound array PSZI located about 230 km to the east-southeast of Baumgarten would detect this acoustic wave as well. Standard progressive multichannel correlation processing and frequency-wavenumber analysis identified a signal emerging at 7:57:55 UTC from an azimuth of 296°–300° and with trace-velocity > 400 m/s. The extraordinarily high trace-velocity and excessive backazimuth residual, relative to the explosion site direction of 282°, however cast strong doubts on the arrival’s connection to the Baumgarten event. Accounting for the effect of non-planar geometry of the infrasound array results in a reduction of the azimuth residual by half. Additionally, 2D and 3D raytracing methods are used including the European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric model to further explain the remaining azimuth residual as well as to elucidate the large trace velocity estimates. The prevailing stratospheric winds in excess of 150 m/s are identified as the underlying cause. Including both factors the initial azimuth residual of up to 18° decreases to ~ 4°, allowing to associate the infrasound signal at PSZI with the Baumgarten event. Finally, the data from a seismic station at 30 km range is re-investigated for magnitude estimation. The local magnitude of ML < 1.0 explains well the scarcity of seismic observations within 50 km range, where three or four stations show signals, mainly consisting of Rg-type surface waves, but no body waves.

中文翻译：

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2017 年 12 月 12 日 Baumgarten 天然气中心爆炸：关于了解大量次声方位残差和缺乏地震观测发生的案例研究

Baumgarten 爆炸于 2017 年 12 月 12 日发生在奥地利维也纳以东约 30 公里的一个储气库。在 AlpArray 地震网络的数十个台站检测到来自这次意外地表爆炸的声波到达，距离最远可达 150 公里，主要是在向东方向。因此，预计位于鲍姆加滕东南偏东约 230 公里处的匈牙利次声阵列 PSZI 也能探测到这种声波。标准的渐进式多通道相关处理和频率-波数分析确定了一个在 UTC 时间 7:57:55 从 296°–300° 方位角出现且轨迹速度 > 400 m/s 的信号。相对于 282° 的爆炸现场方向，极高的轨迹速度和过多的后方位残差，然而，对抵达与鲍姆加滕事件的联系表示强烈怀疑。考虑到次声阵列的非平面几何结构的影响，方位角残差减少了一半。此外，还使用了 2D 和 3D 射线追踪方法，包括欧洲中期天气预报中心 (ECMWF) 大气模型，以进一步解释剩余的方位角残差以及阐明大轨迹速度估计。超过 150 m/s 的盛行平流层风被确定为根本原因。包括这两个因素，高达 18° 的初始方位角残差降低到 ~ 4°，允许将 PSZI 的次声信号与 Baumgarten 事件相关联。最后，重新调查 30 公里范围内地震台站的数据以进行震级估计。ML < 1 的局部震级。