A new method for coseismic offset detection from GPS coordinate time series

Currently,the extraction of coseismic offset signals primarily relies on earthquake catalog data to determine the occurrence time of earthquakes.This is followed by the process of differencing the average GPS coordinate time series data,with a time interval of 3 to 5 days before and after the earthquake.In the face of the huge amount of GPS coordinate time series data today,the conventional approach of relying on earthquake catalog data to assist in obtaining coseismic offset signals has become increasingly burdensome.To address this problem,we propose a new method for automatically detecting coseismic offset signals in GPS coordinate time series without an extra earthquake catalog for reference.Firstly,we pre-process the GPS coordinate time series data for filtering out stations with significant observations missing and detecting and removing outliers.Secondly,we eliminate other signals and errors in the GPS coordinate time series,such as trend and seasonal signals,leaving the coseismic offset signals as the primary signal.The resulting coordinate time series is then modeled using the first-order difference and data stacking method.The modeling method enables automatic detection of the coseismic offset signals in the GPS coordinate time series.The aforementioned method is applied to automatically detect coseismic offset signals using simulated data and the Searles Valley GPS data in California,USA.The results demonstrate the efficacy of our proposed method,successfully detecting coseismic offsets from vast amounts of GPS coordinate time series data.

第三腰椎横突综合征患者肌骨超声表现及误诊情况分析

目的分析第三腰椎横突综合征患者的肌骨超声表现及误诊情况。方法前瞻性选取2017年5月—2020年12月河北省中医院收治的120例第三腰椎横突综合征患者作为观察组,另取同期该院健康体检者120例作为对照组,评价超声检查指标的可重复性,比较两组超声检查指标的差异。结果对照组患者L_(3)、L_(4)、L_(5)部位多裂肌厚度和横断面积的可重复性信度系数均>0.8,肌骨超声的可重复性较强。观察组患者L_(3)、L_(4)、L_(5)部位的多裂肌厚度、横截面积小于对照组(P<0.05)。观察组患者肌骨超声诊断前的误诊主要以腰肌劳损、肾结石为主,其次为股外侧皮神经炎和肾绞痛。结论第三腰椎横突综合征患者肌骨超声检查主要为多裂肌厚度和横截面积的差异,其误诊以腰肌劳损和肾结石为主。