An automatically generated high-resolution earthquake catalogue for the 2016-2017 Central Italy seismic sequence, including P and S phase arrival times
An automatically generated high-resolution earthquake catalogue for the 2016-2017 Central Italy seismic sequence, including P and S phase arrival times
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自动生成的 2016-2017 年意大利中部地震序列高分辨率地震目录，包括 P 和 S 相到达时间
DOI：
10.1093/gji/ggaa604
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发表时间：
2021
影响因子：
2.8
通讯作者：
Spallarossa D
中科院分区：
文献类型：
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作者：
Spallarossa D
2016-2017年意大利中部地震序列始于8月24日阿马特里斯镇附近的第一次主震（Mw6.0），随后是10月26日Visso附近的两次大地震（Mw5.9）和10月30日Norcia附近的两次大地震（Mw6.5），以及2017年1月18日几个小时内的四次Mw> 5.0的地震。在地震序列开始之前，受影响的地区一直由意大利国家地震网络（RSNC）进行监测，并在地震序列期间由国家地球物理和火山研究所以及英国地质调查局部署的临时台站进行了加强。到9月中旬，有一个由155个台站组成的密集网络，震中区的平均间隔为6-10公里，与该地区最有可能发生地震的深度范围相当。该网络配置保持稳定整整一年，产生了2.5 TB的连续波形记录。在这里，我们描述了如何使用完全自动地震处理器（CASP）程序使用这些数据来开发一个大型和全面的地震目录。该程序在第一次主震后的一年中检测到超过45万个事件，并通过高级拾取器引擎（RSNI-Picker 2）确定它们的相位到达时间，产生一组约700万P波和1000万S波到达时间。然后使用非线性定位（NLL）算法、针对该地区校准的一维速度模型和台站校正来定位事件，然后计算其局部震级（ML）。通过将相位拾取和地震参数的导出数据与手工挑选的参考目录（以下称为“RefCat”）进行比较，验证了该程序。在Intel Core-i7工作站上，自动化程序需要不到12小时的时间来分析主要波形数据，并在序列中地震最活跃的一天检测和定位3000个事件。这证明了CASP算法可以有效地为日常业务地震预报提供实时数据的概念，结果表明，与使用手动相位拾取获得的RefCat相比，在同一时期有显著的改善。检测和定位的事件数较高（从84 401到450 000），完整性的幅度较低（从ML 1.4到0.6），相位拾取的数量也较大，aML= 1.4时平均拾取到达数为72，而RefCat使用手动相位拾取时为30个相位。对于绝大多数事件的增强目录，这些传播到震中位置±0.9 km和深度±1.5 km的正式不确定性。总之，这些技术大大提高了对局部平面结构和集群等精细结构的分辨率，特别是识别以前被认为不活跃的地壳部分发生的浅层事件。较低的完整性震级为地震序列演化分析技术的发展和检验提供了丰富的数据，包括b值的实时业务监测、时间相关的危险性评估和余震预测。
The 2016–2017 central Italy earthquake sequence began with the first main shock near the town of Amatrice on August 24 (Mw6.0), and was followed by two subsequent large events near Visso on October 26 (Mw5.9) and Norcia on October 30 (Mw6.5), plus a cluster of four events withMw> 5.0 within few hours on 18 January 2017. The affected area had been monitored before the sequence started by the permanent Italian National Seismic Network (RSNC), and was enhanced during the sequence by temporary stations deployed by the National Institute of Geophysics and Volcanology and the British Geological Survey. By the middle of September, there was a dense network of 155 stations, with a mean separation in the epicentral area of 6–10 km, comparable to the most likely earthquake depth range in the region. This network configuration was kept stable for an entire year, producing 2.5 TB of continuous waveform recordings.Here we describe how this data was used to develop a large and comprehensive earthquake catalogue using the Complete Automatic Seismic Processor (CASP) procedure. This procedure detected more than 450 000 events in the year following the first main shock, and determined their phase arrival times through an advanced picker engine (RSNI-Picker2), producing a set of about 7 millionP- and 10 millionS-wave arrival times. These were then used to locate the events using a non-linear location (NLL) algorithm, a 1-D velocity model calibrated for the area, and station corrections and then to compute their local magnitudes (ML). The procedure was validated by comparison of the derived data for phase picks and earthquake parameters with a handpicked reference catalogue (hereinafter referred to as ‘RefCat’). The automated procedure takes less than 12 hr on an Intel Core-i7 workstation to analyse the primary waveform data and to detect and locate 3000 events on the most seismically active day of the sequence. This proves the concept that the CASP algorithm can provide effectively real-time data for input into daily operational earthquake forecasts,The results show that there have been significant improvements compared to RefCat obtained in the same period using manual phase picks. The number of detected and located events is higher (from 84 401 to 450 000), the magnitude of completeness is lower (fromML1.4 to 0.6), and also the number of phase picks is greater with an average number of 72 picked arrival for aML= 1.4 compared with 30 phases for RefCat using manual phase picking. These propagate into formal uncertainties of ±0.9 km in epicentral location and ±1.5 km in depth for the enhanced catalogue for the vast majority of the events. Together, these provide a significant improvement in the resolution of fine structures such as local planar structures and clusters, in particular the identification of shallow events occurring in parts of the crust previously thought to be inactive. The lower completeness magnitude provides a rich data set for development and testing of analysis techniques of seismic sequences evolution, including real-time, operational monitoring ofb-value, time-dependent hazard evaluation and aftershock forecasting.