Quotation from EIC Seismological Note #139
We estimated coseismic motion of the 11 GEONET stations in the Kushiro-oki earthquake (Mj=8) occured around 19:50 of Sep. 25, 2003. The rtnet software wth precise point positioning (PPP) strategy was used for the purpose. The RTNET PPP estimate with IGS final products (satellite orbit and clock) showed coseismic motion of GEONET stations with clear delay of iarrival of seismic wave depending on beseline length between epicenter and GEONET stations. The RTNET PPP estimate with IGU predicted products showed the similar variations with IGS's with a few offsets.
| Event | Mj Magnitude JMA | Time UTC (MJD) | Time (JST) |
| 1st (target) | 8.0 | 09-25_19:50 (52907.8264) | 09-26_04:50 |
| 2nd (biggest aftershock) | 7.4 | 09-25_21:08 (52907.8806) | 09-26_06:08 |
| 3rd~ | 6.X | 09-26 (next day) |
| Station code | DN (mm) | DE (mm) | DU (mm) |
| Continuous data available | |||
|---|---|---|---|
| 0121 | -211.3 | 116.8 | -38.1 |
| 0133 | -180.9 | 295.7 | -51.9 |
| 0142 | -122.7 | 420.1 | -122.5 |
| 0508 | -106.9 | 83.8 | -5.3 |
| 0518 | -261.3 | 208.2 | -61.0 |
| 0521 | -390.6 | 317.5 | -115.1 |
| Data missing | |||
| 0019 | -154.4 | 628.7 | -191.1 |
| 0138 | -469.6 | 586.4 | -166.0 |
| 0144 | -161.8 | 610.2 | -213.1 |
| 0532 | -387.9 | 836.8 | -202.6 |
| 0793 | -467.1 | 674.1 | -298.0 |
| IGS Final | IGU Observed | IGU Predicted | Orbit | < 5 cm | ~5cm | ~10cm | Clock | < 0.1 ns (3 cm) | ~0.2 ns (6 cm) | ~5 ns (150cm) |
|---|
Figure: Distribution map of GEONET stations with 1Hz dataset in the DOY 268 in 2003.
Figure: Periods of available dataset for the used 11 GEONET stations.
| Strategy | RTNET PPP w/ IGS final | RTNET PPP w/ IGU predicted | |
|---|---|---|---|
| Observation m | Pseudorange, Phase (L3) | Pseudorange, Phase (L3) | |
| Satellite orbit | IGS final products, 15min | IGU predicted products, 15min Pure real-timei | |
| Satellite clock | IGS final products, 15min | from clock solutions | |
| PCV model | consider GEONET monument | ||
| Ocean tide loading | GOTIC 2 | ||
| Satellite Information | SATELLIT. | ||
| Satellite Problem | SAT_2003.CRX | ||
Figure: GEONET stations used for satellite clock estimation. RTNET estimate the satellite clocks based on IGU predicted orbit (accuracy is about 10cm). The optimized number of stations for the purpose of real-time ZTD estimation is about 20.
Figure: Coseismic motion for the 11 GEONET stations in RTNET PPP w/ IGS final products. Click here to see larger plots in new window (_blank).
Figure: Coseismic motion for the 10 GEONET stations in RTNET PPP w/ IGU predicted orbit and estimated satellite clock. Click here to see larger plots in new window (_blank).
Feasibilities
- [Yes] Infrastructure of real-time data collections in GEONET
- [Yes] Relatively ceaper computation power (Pentium 4 or Athlon 64)
- [Yes] Satellite clock estimation and PPP positioning
- => Yes, Feasible!
Seismology
- New research opportunities using the dense "GPS Seismometer".
Geodesy
- Real-time monitoring crustal deformation due to earthquakes.
- Improve clock estimation. Global network will help to prevent gaps of satellite clock due to satellite rising and setting in regional network estimation.
- Remove stations in earthquake regions to avoid errors of clock estimations due to sudden coordinate changes.
- Availability of 1Hz data
- Interesting to see more high sampling dataset
GPS Solutions Inc. : developer of rtnet
IGS : International GNSS Service
GSI : Geographical Survey Institute
NGS : Nippon GPS Solutions
NIED 2003 09
ERI Tokachi-oki
NIED HI-NET
GEONET