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Noda S.,Earthquake Disaster Prevention Laboratory | Yamamoto S.,Earthquake Disaster Prevention Laboratory | Sato S.,Earthquake Disaster Prevention Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2012

The Shinkansen Earthquake Early Warning system rapidly estimates earthquake parameters from a single station data. Epicenter locations in this system are estimated utilizing the Principal Component Analysis and the B-δ method. This paper proposes new methods to improve the performance of epicenter estimation by introducing variable time windows, instead of the conventional fixed time window. It was found that the new method improved the accuracy and speed of the back-azimuth estimation by 28% and 0.25 seconds respectively. Speed of estimation of the epicentral distance was improved by approximately 1.32 seconds, compared with the conventional method. Source


Iwata N.,Earthquake Disaster Prevention Laboratory | Yamamoto S.,Earthquake Disaster Prevention Laboratory | Korenaga M.,Earthquake Disaster Prevention Laboratory | Noda S.,Earthquake Disaster Prevention Laboratory | Ito Y.,Earthquake Disaster Prevention Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2013

At present, in case of earthquakes with tremors exceeding the operational control threshold, walking patrols must inspect seismographs for each relevant track section, to ensure safety. In order to resume train operations more rapidly after restrictions have been imposed on train operations due to an earthquake, a working model system was developed which can accurately estimate seismic motion just after the earthquake. This system makes facilitates decision making for earlier resumption of traffic following the earthquake. By obtaining seismic information not only from railway operator's seismographs but also from public data sources in quasi-real-time, this system estimates the distribution of the shake over meshed planes and extracts the seismic motion at any given chainage point along the target railway section being evaluated. Source


Yamamoto S.,Earthquake Disaster Prevention Laboratory | Sato S.,Earthquake Disaster Prevention Laboratory | Iwata N.,Earthquake Disaster Prevention Laboratory | Korenaga M.,Earthquake Disaster Prevention Laboratory | And 2 more authors.
Quarterly Report of RTRI (Railway Technical Research Institute) (Japan) | Year: 2011

The earthquake early warning system was put into operation in Japan in order to stop Shinkansen trains as rapidly as possible before the strike of large tremors, in the case of an earthquake. The present paper overviews current earthquake early warning system configuration and functions and evaluates the accuracy of epicenter estimation by that same system by using the latest datasets. The estimation error (rms) of epicentral distance in the present system is 0.324 on a logarithmic scale. By re-determination of the coefficients of correlation equation for estimation, it was confirmed that the estimation error was reduced by 13%. Source

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