Development of real-time monitoring system using GPS Virtual Reference Station

该项目的主要目的是调查全球定位系统的虚拟参考站是否可用于地壳形变研究，并调查全球定位系统的其他运动学应用，高采样率可用于地壳形变研究。为此，在项目的第一年，我们购买了两台新的GPS接收器。然后我们每年在静冈大学进行VRS系统的实验。参考站来自周围的GeoNet站，我们通过移动电话上的商业网络从那里获得1秒的相位数据。我们使用Trimble的Total Control软件和我们通过该项目购买的3D-Tracker对获得的数据进行了后处理。初步结果显示，定位精度约为1-2厘米。因此，就精度而言，VRS用于地壳形变研究可能是可以接受的。然而，问题是数据采集，因为我们必须使用手机来获取参考数据。如果我们对现场位移进行持续和永久的观察，费用将高得令人无法接受。因此，作为该项目的结论，我们倾向于认为现在使用VRS GPS系统来连续监测地壳形变还为时过早。另一方面，GPS定位的运动学应用也有着广泛的应用。利用2003年东京地震时的1赫兹采样GPS数据，成功地探测到震中附近GPS测点的地震振动。数据分析采用GIMPSY软件进行离线处理。此外，实时动态GPS观测已被应用于利用GPS浮标进行海啸监测。该浮标于2004年4月部署在Muroto海角以南约13公里处。在Kii-Nanto-Oki地震发生时，该浮标能够探测到约10cn高的海啸。

The major purposes of the project were to investigate if Virtual Reference Station of GPS could be used for crustal deformation studies and to investigate other kinematic application of GPS high sampling rate could be used for crustal deformation studies. For this purpose, in the first year of the project, we purchased two new GPS receivers. Then we conducted experiments of VRS system every year at Shizuoka University. Reference stations were employed from surrounding GEONET stations from where we obtain 1-sec phase data through commercial network on the mobile phone. We made post-processing of the obtained data using Trimble's Total Control software and also using 3D-Tracker which we purchased through the project. Preliminary results showed about 1-2cm accuracy in positioning. Therefore VRS might be acceptable for crustal deformation studies in terms of accurracy. However, the problem is data acquisition because we have to use mobile phone for obtaining reference data. If we conduct continuous and permanent observation of the site displacement, it will be unacceptably expensive. Therefore, as a conclusion of the project, we are inclining to think that it would be premature to use the VRS GPS system for continuous crustal deformation monitoring. On the other hand, kinematic application of the GPS positioning has a wide variety of applications. 1-Hz sampling GPS data were used at the time of 2003 Tokachi earthqukae and we succeeded to detect seismic vibrations at the GPS sites nearby the hypocenter. The data analysis was made off line using GIPSY software. In addition, real-time kinematic GPS observation has been applied for tsunami monitoring using GPS buoy. The buoy was deployed about 13km south of Muroto Promontory in April 2004. The buoy enabled to detect tsunami of about 10cn height at the time of Kii-Nanto-Oki earthquake.