IPOC Creep

IPOC Creep is an array of 11 creepmeters installed along 4 active segments oft eh Atacama Fault Zone in Northern Chile. Installation of instruments started in 2008 within the framework of the Integrated Plate-boundary Observatory Chile (IPOC) and was completed in 2011. All installations are designed by the authors and follow a general concept, but are adapted to each site specifically. All the installed instruments use solid 12 mm thick invar rods as length standards, which are firmly attached to a concrete foundation in the hanging wall of the fault and pass through a PVC pipe to the footwall side of the fault where it is fixed to another concrete foundation. The creepmeters are buried at a depth of 30 - 70 cm, in order to increase the signal-to-noise ratio. We use a LVDT (linear variable differential transformer) with a range of 50 mm to monitor the relative displacement of the free end of the rod relative to the fixation point. Displacement is measured as voltage change and stored on a data logger with a sampling rate of 1/min (2008-2011 and 2/min (since 2011). Temperature at the rod is continuously measured with the same sampling rate to correct for thermal expansion and contraction of the length standard. The length of the instrument is dependent on the geometry at each site and ranges between 2 and 9 m. More specific information on each site can be found on http://www.ipoc-network.org/index.php/observatory/creepmeter.html .

The Data is stored as time series since the initial start of operation of each creepmeter until July 2016. Data format is asci and contains 4 columns:

1st column Date[D.M.Y]

2nd column Time [HH:MM:SS]

3rd column ReferenceSensor[V]The reference signal is a steady signal of 1V and fluctuations indicate general voltage fluctuations in the setup. By normalizing to the reference signal it is possible to correct for these voltage changes.

4th column CreepSensor[V]The measured voltage of the CreepSensor is linearly proportional to the actual displacement. It can be converted to micrometers as follows: Displacement(µm) = (CreepSensor(t2)[V] - CreepSensor(t1)[V]) * 10000.

IPOC蠕变仪阵列由11台蠕变仪组成，布设在智利北部阿塔卡马断裂带的4处活跃区段。2008年，依托智利板块综合边界观测站（Integrated Plate-boundary Observatory Chile, IPOC）项目启动仪器布设工作，并于2011年全部完成。所有装置均由本文作者自主设计，遵循统一的通用设计理念，但针对每个测点进行了个性化适配。

所有已安装的仪器均采用直径12 mm的实心因瓦合金杆作为长度基准，该杆牢固固定于断层上盘的混凝土基座中，并穿过PVC管延伸至断层下盘，最终固定于另一处混凝土基座。为提升信号信噪比，所有蠕变仪均埋设于地下30~70 cm深度处。我们采用量程为50 mm的线性可变差动变压器（linear variable differential transformer, LVDT）监测杆自由端相对于固定点的相对位移。位移以电压变化形式被采集，并存储于数据记录仪中，2008年至2011年间采样率为1次/分钟，2011年起调整为2次/分钟。同时以相同采样率连续监测杆体温度，用于校正长度基准的热胀冷缩效应。装置长度因各测点的地质几何条件而异，区间为2~9 m。各测点的详细信息可访问http://www.ipoc-network.org/index.php/observatory/creepmeter.html 查询。

本数据集存储了各台蠕变仪自投入运行至2016年7月的时间序列数据。数据格式为ASCII，包含4列信息：
1. 第1列：日期[日.月.年]
2. 第2列：时间[时:分:秒]
3. 第3列：参考传感器电压[V]：参考信号为稳定的1 V直流信号，其波动反映了整套装置的整体电压漂移。通过对参考信号进行归一化处理，可校正此类电压变化。
4. 第4列：蠕变传感器电压[V]：蠕变传感器的实测电压与实际位移呈线性正相关关系。可通过如下公式将其转换为微米级位移：位移(μm) = (CreepSensor(t2)[V] - CreepSensor(t1)[V]) * 10000。