The KiK-net database processed using an automated ground motion processing protocol

The Kiban-Kyoshin network (KiK-net) is one of two strong motion seismograph networks constructed in Japan following the 1995 Kobe earthquake. The KiK-net network has more than 650 stations that cover most the Japanese territory. Each station has two collocated instruments at the ground surface and at a borehole at depths that are typically 100 m or 200 m. This allows for an empirical evaluation of the site response at each station.
The ground motions recorded by the KiK-net stations are available to researchers all over the world through the following website http://www.kyoshin.bosai.go.jp/. The availability of such database is extremely important for research related to earthquake engineering and engineering seismology because of: 1) the large number of records in the database; 2) the uniform distribution of the recording stations over a large area; and 3) the availability of measurements for the shear wave velocity profiles at most stations. Nevertheless, using the data is not an easy task because the motions are uploaded to the website in a raw format and many of the important metadata associated with the ground motions are not provided (e.g., moment magnitude). Hence, processing these records and collecting its metadata are necessary steps to enable their use in engineering applications.
The database presented here consists of about 157,000 KiK-net strong ground motion records that were automatically processed using a protocol described in detail by Dawood et al. (2014). The automated protocol includes the selection of corner frequencies for band-pass filtering. In addition, a comprehensive set of metadata was compiled for each record. As a part of the metadata collection, two algorithms were used to identify dependent and independent earthquakes. Earthquakes are also classified into active crustal or subduction type events; most of the GM records correspond to subduction type earthquakes.

基班-强震台网（KiK-net，全称Kiban-Kyoshin network）是1995年阪神大地震后日本布设的两套强震动观测台网之一。该台网拥有超过650个观测站点，覆盖日本绝大部分领土。每个站点均配有两台同址安装的仪器，分别置于地表与深度通常为100米或200米的钻孔内。这一设计可实现对每个站点场地响应的实证评估。
KiK-net站点记录的强震动数据可通过以下网址向全球研究人员开放获取：http://www.kyoshin.bosai.go.jp/。该数据库的开放对于地震工程与工程地震学相关研究具有极为重要的意义，原因如下：1）数据库内记录数量庞大；2）观测站点在大范围内均匀分布；3）绝大多数站点均可提供剪切波速剖面测量数据。然而，直接使用这些数据并非易事：原始数据均以未处理的格式上传至该网站，且多数强震动记录的关键元数据（如矩震级）并未附带提供。因此，对这些记录进行处理并收集其元数据，是使其能够应用于工程场景的必要前提。
本文所呈现的数据库包含约15.7万条KiK-net强震动记录，这些记录均采用Dawood等人（2014年）详细阐述的标准化处理流程完成自动处理。该自动处理流程包含带通滤波截止频率的选取环节。此外，研究人员还为每条记录编制了一套完整的元数据集。在元数据收集过程中，研究人员采用了两种算法来区分相关地震与独立地震。地震还被划分为活动地壳型与俯冲带型两类；绝大多数强震动记录均对应俯冲带型地震。