Detection of short-term slow slip events along the Nankai Trough, southwest Japan, using GNSS data
Detection of short-term slow slip events along the Nankai Trough, southwest Japan, using GNSS data
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DOI：
10.1002/jgrb.50222
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发表时间：
2013-06-01
影响因子：
3.9
通讯作者：
Obara, Kazushige
中科院分区：
文献类型：
--
作者：
Nishimura, Takuya;Matsuzawa, Takanori;Obara, Kazushige
我们检测到短期慢滑事件（SSE）以前只能观察到的倾斜和应变数据沿着南海海槽，日本西南部，使用GNSS（全球导航卫星系统）数据。使用赤池的信息标准在全球导航卫星系统时间序列中检测到的偏移有助于自动识别1996年6月至2012年1月期间运动方向与相对板块运动方向相反的207个事件。通过非线性反演检测到的位移，我们估计矩形故障模型的133个可能的和25个可能的短期SSE超过15年。SSE力矩幅值范围为5.5至6.3。大多数SSE断层模型位于菲律宾海板块俯冲界面上的非火山地震窄带中。大的SSE（矩震级，M-w，6）经常发生在四国西部和中部。累积滑动量沿走向沿着分布不均匀，总体上向东减小，最大滑动量（约50 cm）出现在四国西部。在纪伊海峡没有发现明确的短期SSE，但在伊势湾发生了几次短期SSE。这两个区域被称为震颤间隙。累积滑动的局部最大值填充了位于伊势湾的地震空区。短期SSE累积矩的长期率在2003年左右在四国东部增加了三倍，而在其他地区几乎是恒定的。与利用倾斜数据的短期SSE目录的比较表明，本研究和以前的研究都错过了一些沿着南海海槽沿着的SSE。结合大地测量数据对监测短期小扰动的时空分布十分重要。
We detected short-term slow slip events (SSEs) previously observable only with tilt and strain data along the Nankai Trough, southwest Japan, using GNSS (Global Navigation Satellite System) data. Offsets detected in GNSS time series using Akaike's information criterion helped automatically identify 207 episodes with a motion direction opposite to that of the relative plate motion from June 1996 to January 2012. By nonlinear inversion of the detected displacement, we estimated rectangular fault models for 133 probable and 25 possible short-term SSEs over 15 years. The SSE moment magnitudes range from 5.5 to 6.3. Most SSE fault models are located in a narrow band of non-volcanic tremors on the interfaces of the subducting Philippine Sea Plate. Large SSEs (moment magnitude, M-w, 6) often occur in western and central Shikoku. The cumulative slip is distributed heterogeneously along the strike, generally decreasing eastward with the maximum slip (similar to 50 cm) in western Shikoku. No definite short-term SSEs were found in the Kii Channel, but several short-term SSEs occurred in Ise Bay. Both regions are known as tremor gaps. The local maximum of the cumulative slip fills in the tremor gap located in Ise Bay. The long-term rate of short-term SSE cumulative moment increased by threefold around 2003 in eastern Shikoku, whereas it was almost constant in other regions. Comparison with short-term SSE catalogues using tilt data suggests that both this study and previous studies missed some SSEs along the Nankai Trough. A combination of geodetic data is important in the monitoring of the spatiotemporal distribution of short-term SSEs.