| Project/Area Number |
17200021
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (A)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Statistical science
|
|---|
| Research Institution | The Institute of Statistical Mathematics |
|---|
Principal Investigator |
OGATA Yosihiko The Institute of Statistical Mathematics, Department of Statistical Modeling, Professor (70000213)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TANEMURA Masaharu The Institute of Statistical Mathematics, Department of Statistical Modeling, Professor (80000214)
TAMURA Yoshiyasu The Institute of Statistical Mathematics, Department of Data Science, Professor (60150033)
HIGUCHI Tomoyuki The Institute of Statistical Mathematics, Department of Statistical Modeling, Professor (70202273)
SATO Seisho The Institute of Statistical Mathematics, Department of Data Science, Associate Professor (60280525)
TODA Shinji The Institute of Statistical Mathematics, National Institute of Advanced Industrial Science and Technology Active Fault Research Center, Senior Research Scientist (80313047)
|
|---|
| Project Period (FY) |
2005 – 2007
|
| Project Status |
Completed (Fiscal Year 2007)
|
| Budget Amount *help |
¥35,750,000 (Direct Cost: ¥27,500,000、Indirect Cost: ¥8,250,000)
Fiscal Year 2007: ¥9,490,000 (Direct Cost: ¥7,300,000、Indirect Cost: ¥2,190,000)
Fiscal Year 2006: ¥14,170,000 (Direct Cost: ¥10,900,000、Indirect Cost: ¥3,270,000)
Fiscal Year 2005: ¥12,090,000 (Direct Cost: ¥9,300,000、Indirect Cost: ¥2,790,000)
|
|---|
| Keywords | Immediate aftershock forecast / ETAS models / Stochastic declustering / Space-time ETAS model / Seismicity anomalies / Precursory slow slip / Geodetic anomalies / SASesis2006 FORTRAM programs / ETASモデル / 相対的活発化・静穏化現象 / クーロン破壊ストレス変化 / 前駆的非地震性すべり / GPS基線系列 / 階層ベイズ時空間ETASモデル / 点過程解析用ソフトウェア / Neyman-Scott cluster models / 変化点問題 / 地震検出率 / 余震の確率予測 |
|---|
| Research Abstract |
Seismic quiescence and activation, as the precursors to large earthquakes, have attracted much attention among seismologists. Of particular interest is the hypothesis that the stress-changes transferred from a rupture or silent slip in one region can cause seismic changes in other regions. However, the clustering feature of earthquakes prevents us from detecting the seismicity change due to stress change transferred from other region because successive earthquakes are triggered by complex mechanisms under heterogeneous fractal media. Nevertheless, we can use the statistical empirical laws as a practical method for predicting earthquake clusters. Thus, the objective of this research is to demonstrate that diagnostic analysis based on fitting the Epidemic Type Aftershock Sequence (ETAS) model to regional seismicity can be helpful in detecting exogenous stress changes there. In particular, the changes due to silent slips are usually so slight that one can barely recognize systematic anoma
… More
lies in seismicity without the aid of the ETAS model.
The ordinary short-term occurrence rate of earthquakes in a region is well predicted using the ETAS model of triggering earthquakes. Any anomalous seismic activity, such as quiescence and activation, can be quantified by identifying significant deviation from the predicted rate. Thus we have successfully made a number of case studies. For example, such anomalies are revealed to have occurred during the three year period leading up to the 2004 Chuetsu Earthquake of Magnitude 6.8, central Japan. The quiescence and activation, which took place in the region of negative and positive increments of the Coulomb Failure Stress, respectively, were possibly caused by silent slip on the focal fault plane, or its deeper extension with a lower dip angle.
Such slip is further supported by transient crustal movement around the rupture source. The time series records of many baseline distances between the permanent GPS stations significantly deviated from the predicted linear trends, mostly with the deviations consistent with the coseismic horizontal displacements of the GPS stations due to the Chuetsu Earthquake. Furthermore, a deeper extension of the mainshock fault plane, with a lower dip angle, can explain the more cases of the observed baseline deviations in comparison with the theoretical displacement. The cumulated precursory slip is estimated to be roughly equivalent to M6in the moment magnitude. Less
|
