L'Aquila 2009 seismic sequence: integrated dataset of automatic first motion polarities focal mechanisms and RMT with HypoDD high quality relative earthquake locations

This dataset is related to the L'Aquila 2009 seismic sequence that happened in Central Apennines (Italy). It contains: 2782 quality selected focal mechanisms produced with the standard software FPFIT based on automatically determined first motion polarities of automatically detected and analyzed foreshocks and aftershocks recorded from January 2009 to December 2009 (flag fty in the header is MP) 475 (out of 627) quality selected focal mechanisms produced with the standard software FPFIT also based on automatically determined first motion polarities but for only 3204 ML >= 1.9 earthquakes and by using take-off angles calculated within a local 3d tomographic velocity model (Di Stefano et al., 2011) , published and released in Chiaraluce et al., 2011 (flag fty in the header is JG) 165 (out of 181) Regional Moment Tensors determined for earthquakes ML >= 3.0 based on broadband waveform inversion of ground velocities and published by Hermann et al., 2011 (flag fty in the header is HM) The hypocenters of the total 3422 earthquakes reported in the present focal solutions dataset have been taken from the very high quality double difference locations of the about 64000 aftershocks reported in Valoroso et al., 2013 and published, as part of the full dataset, on Zenodo. The association between the focal solutions and the HypoDD hypocenters has been performed through the direct use of the HypoDD event identifier where possible (the whole MP dataset) and through spatial and temporal earthquakes coordinates matching in all the other case by using the capability of a MySQL database. Two files are uploaded, one in plain text with blank separator, the second in plain text with ";" separator and .csv extension. Here below the header is explained. OT_Date: date of the origin time in the format YYYY-MM-DD OT_Time: time of the origin time in the format HH:mm:ss.dcm lat: hypocenter latitude expressed in degrees lon: hypocenter longitude east of Greenwich, expressed in degrees dep: hypocenter depth expressed in km ML: local magnitude (pure number) from Valoroso et al., 2013 (see last column notes also) id_dd: the hypoDD event identifier, allowing to directly connect to the Valoroso et al., 2013 full dataset IMPORTANT NOTE about st1 and st2 (below): the focal solutions are presented here based on the convention they where produced or published, so there are two different (but compatible) conventions for the fault plains orientation in the 3d space st1: for fty=HM or JG this is the strike of plane 1 (CMT convention) for fty=MP this is the strike of the dip direction of plain 1 (FPFIT convention) dip1: dip of plane 1 rk1: rake of plane 1 st2: for fty=HM or JG this is the strike of plane 2 (CMT convention) for fty=MP this is the strike of the dip direction of plain 2 (FPFIT convention) dip2: dip of plane 2 rk2: rake of plane 2 fty: flag to distinguish the type of solution, CMT=HM or JG, FPFIT=MP MW: only for HM, this columns reports also MW from Hermann et al., 2011

本数据集与2009年意大利亚平宁山脉中部发生的拉奎拉（L'Aquila）地震序列相关，包含以下三类数据：
1. 2782份经质量筛选的震源机制解：采用标准软件FPFIT（FPFIT）生成，基于2009年1月至12月记录的、自动检测并分析的前震与余震的初动极性自动测定结果（文件头标记fty为MP）。
2. 475份（共627份中筛选得到）经质量筛选的震源机制解：同样使用标准软件FPFIT生成，基于自动测定的初动极性，仅针对3204个ML≥1.9的地震，且采用基于局部三维层析成像速度模型计算的起跳角（Di Stefano等，2011），相关成果发表于Chiaraluce等，2011（文件头标记fty为JG）。
3. 165份（共181份中）区域矩张量解：针对ML≥3.0的地震，基于地面速度的宽频带波形反演得到，由Hermann等，2011发布（文件头标记fty为HM）。

本震源解数据集中共计3422个地震的震源位置，取自Valoroso等，2013发布的约64000次余震的高质量双差定位结果，该完整数据集已整体上传至Zenodo（Zenodo）平台。震源解与HypoDD（HypoDD）震源位置的关联，在可行情况下（如全部MP数据集）直接通过HypoDD事件标识符完成，其余情况则通过时空地震坐标匹配，并借助MySQL（MySQL）数据库实现。

本次共上传两个纯文本文件：其一以空格作为分隔符，其二以分号作为分隔符并带有.csv扩展名。下文将对文件头字段进行详细说明：
- "OT_Date"：发震时刻日期，格式为YYYY-MM-DD
- "OT_Time"：发震时刻时间，格式为HH:mm:ss.dcm
- "lat"：震源纬度，单位为度
- "lon"：震源经度（格林威治以东），单位为度
- "dep"：震源深度，单位为千米
- "ML"：取自Valoroso等，2013的局部震级（纯数值），详见最后一列备注
- "id_dd"：HypoDD事件标识符，可直接关联至Valoroso等，2013的完整数据集

重要备注（关于"st1"与"st2"）：
本数据集呈现的震源解遵循其生成或发布时采用的惯用规范，针对三维空间中断层平面的方位存在两种兼容的不同规范：
- "st1"：当"fty=HM"或"fty=JG"时，代表平面1的走向（采用CMT（CMT）规范）；当"fty=MP"时，代表平面1倾向方向的方位（采用FPFIT规范）
- "dip1"：平面1的倾角
- "rk1"：平面1的滑动角
- "st2"：当"fty=HM"或"fty=JG"时，代表平面2的走向（采用CMT规范）；当"fty=MP"时，代表平面2倾向方向的方位（采用FPFIT规范）
- "dip2"：平面2的倾角
- "rk2"：平面2的滑动角
- "fty"：用于区分解类型的标记，CMT类型对应"HM"或"JG"，FPFIT类型对应"MP"
- "MW"：仅适用于"HM"类型的解，该列包含Hermann等，2011发布的矩震级（MW）数值

搜集汇总

背景与挑战

背景概述

该数据集整合了2009年意大利拉奎拉地震序列的震源机制和定位数据，包含三种类型的震源机制（基于自动初动极性、局部速度模型和波形反演），总计3422个地震事件，并关联了高精度的HypoDD相对定位结果。数据集以文本文件格式提供，适用于地震学和地质构造研究，支持对地震序列的深入分析。