Seafloor acoustic ranging data across the North-Anatolian Fault, Marmara Sea, Turkey

in october 2014, a ranging network of 10 acoustic transponders was installed across an active segment of the north-anatolian fault, in the marmara sea at a depth of about 800 m, for up to 5 years (figure 1). this active fault segment is lacking any major seismic activity since the 18th century. the purpose of this acoustic ranging experiment was to determine whether this fault is continuously and aseismically creeping (i.e. slipping) or is locked and thus accumulating stress that could cause a large magnitude earthquake, few ten kilometers away from istanbul.the acoustic network comprised 4 transponders from the university of brest, france, and 6 transponders from the geomar institute, germany. the data available through this web site corresponds to the data collected by the 4 french stations only. they include sets of acoustic ranging between pairs of stations (i.e. two-way-travel times), in addition to sound-speed, temperature and pressure measurements at each station. the sampling rate varies with the data type, but is generally hourly (one or several samples every hour). these are the raw, unprocessed data. for instance, distances must be inferred from the two-way-travel times and sound-speeds.the experiment lasted until january 2018.data collection: in april 2015, the first set of acoustic ranging data, spanning a period of 6 months, was downloaded from the seafloor transponders using a modem from the sea surface (cruise pos484). in april 2016, a second set of acoustic ranging data, spanning one more year, was downloaded from the seafloor transponders, but only 3 of the transponders responded (cruise pos497). in may 2017, a third set of acoustic ranging data was downloaded from the seafloor transponders, but only 3 of the transponders responded (cruise yunus17). in january 2018, a last set was downloaded, but only 3 of the transponders responded (cruise yunus17). since the batteries were almost exhausted, two of the french transponders were retrieved from the seafloor (2002 and 2003, for which all the data had already been downloaded from the surface). the last two will be recovered in 2020 (2001 and 2004).more information about the acoustic network can be found in the paper by sakic et al. (2016; see reference below).

于2014年10月，在一处位于马尔马拉海北安纳托利亚断裂带活跃段的水下约800米深处，安装了一个由10个声波应答器组成的测距网络，该网络的使用期限为5年（见图1）。该活跃断裂带自18世纪以来未曾发生过任何重大地震活动。进行此次声波测距实验的目的是为了确定该断裂带是否持续且非地震性地缓慢滑动（即滑移），或者是处于锁定状态，从而积累可能引发大型地震的应力，而该地震可能发生在距离伊斯坦布尔数十公里之外。该声波网络包括来自法国布雷斯特大学的4个应答器和来自德国地球海洋研究所的6个应答器。本网站提供的数据仅对应于法国站点收集的数据。这些数据包括站点对之间的声波测距数据集（即往返旅行时间），以及每个站点的声速、温度和压力测量值。采样率随数据类型而变化，但通常为每小时一次（每小时一个或多个样本）。这些数据为未经处理的原始数据。例如，必须从往返旅行时间和声速中推断距离。实验持续至2018年1月。

数据收集：2015年4月，从海底应答器下载了第一组声波测距数据，时间跨度为6个月，使用的是海表面的调制解调器（航行号pos484）。2016年4月，从海底应答器下载了第二组声波测距数据，时间跨度再增加一年，但只有3个应答器响应（航行号pos497）。2017年5月，从海底应答器下载了第三组声波测距数据，但只有3个应答器响应（航行号yunus17）。2018年1月，下载了最后一组数据，但同样只有3个应答器响应（航行号yunus17）。由于电池几乎耗尽，两台法国应答器（2002年和2003年，所有数据均已从水面下载）被从海底回收。最后两台应答器（2001年和2004年）将在2020年回收。有关声波网络更详细的信息，请参阅Sakic等人于2016年发表的论文（参见以下参考文献）。