3:45 PM - 4:00 PM
[HDS08-09] Verification of “Past” seismic intensity and estimation of “Future” ground motion by “Present-day” seismic observation: The Yanesen area
Keywords:observational seismology, historical earthquake, estimation of seismic intensity
We aim to clarify the details of “Future” disastrous earthquakes and ground motions in the Tokyo metropolitan area based on the investigation of “Past” ground motion by using “Present-dat” seismic observation (e.g., Ishise et al., 2020).
In the last fiscal year, we surveyed and collected various historical documents on earthquake damage caused by the 1855 Ansei-Edo Earthquake in the Hokuso area. Then, based on the results of the survey, we conducted seismic observations in the area and reported that the regional variation in seismic intensity of moderate-size earthquakes is consistent with that of the Ansei-Edo Earthquake (Ishise et al., 2021). And since last fall, we have been conducting the same kind of survey and seismic observation in the Yanesen area, as in the Hokuso area. In this study, we introduce the observational study and share a vision of the future.
“Past” ground motion
(1) Survey of historical documents:
Through this survey, we discovered new historical document about the earthquake damage to Tennoji temple cause by the 1855 Anse-Edo earthquake. The newly discovered document includes 13 descriptions of the damage within the temple.
(2) Re-examination of reported historical documents:
We re-examined historical documents used to estimate the seismic intensity map of the Ansei-Edo earthquake. As a result, we found out that some of the location information needed to be corrected.
“Present-day” seismic observation
Since last September, we have been conducting temporary seismic observations using 19 seismometers in the Yanesen area. The locations of seismometers were selected based on analyses of historical documents. Seismic observations will continue until March 2021.
Tentative waveform analysis using some of data shows regional variations in amplitude and frequency components at each site. After the completion of the temporary observation, we plan to quantitatively examine the relative seismic intensity distribution obtained from this observation and the seismic intensity distribution inferred from the analyses using historical documents.
“Future” earthquakes and the ground motion:
The seismological objective of this study is to predict the ground motion of future disastrous earthquakes, such as M7-class earthquakes in the Tokyo metropolitan area. To help with this, we plan to estimate detail site amplifications based on the present-day seismic observations to help make more realistic seismic intensity predictions. To do this, it is essential to develop a seismic observation network. Therefore, we are considering the construction of a super dense seismic network using seismic data obtained by Meso-net and SUPREME.
It is also important to know the distribution of strong motion caused by earthquakes as soon as possible after the occurrence of an earthquake. If seismometers are installed in advance at each site, they will be useful for in determining evacuation routes and priority of rescue operations. Furthermore, it is possible to start rebuilding livelihoods without survey by experts. In order to consider the construction of such a seismological observation system, we are conducting a pilot observation, which will be reported later.
In the last fiscal year, we surveyed and collected various historical documents on earthquake damage caused by the 1855 Ansei-Edo Earthquake in the Hokuso area. Then, based on the results of the survey, we conducted seismic observations in the area and reported that the regional variation in seismic intensity of moderate-size earthquakes is consistent with that of the Ansei-Edo Earthquake (Ishise et al., 2021). And since last fall, we have been conducting the same kind of survey and seismic observation in the Yanesen area, as in the Hokuso area. In this study, we introduce the observational study and share a vision of the future.
“Past” ground motion
(1) Survey of historical documents:
Through this survey, we discovered new historical document about the earthquake damage to Tennoji temple cause by the 1855 Anse-Edo earthquake. The newly discovered document includes 13 descriptions of the damage within the temple.
(2) Re-examination of reported historical documents:
We re-examined historical documents used to estimate the seismic intensity map of the Ansei-Edo earthquake. As a result, we found out that some of the location information needed to be corrected.
“Present-day” seismic observation
Since last September, we have been conducting temporary seismic observations using 19 seismometers in the Yanesen area. The locations of seismometers were selected based on analyses of historical documents. Seismic observations will continue until March 2021.
Tentative waveform analysis using some of data shows regional variations in amplitude and frequency components at each site. After the completion of the temporary observation, we plan to quantitatively examine the relative seismic intensity distribution obtained from this observation and the seismic intensity distribution inferred from the analyses using historical documents.
“Future” earthquakes and the ground motion:
The seismological objective of this study is to predict the ground motion of future disastrous earthquakes, such as M7-class earthquakes in the Tokyo metropolitan area. To help with this, we plan to estimate detail site amplifications based on the present-day seismic observations to help make more realistic seismic intensity predictions. To do this, it is essential to develop a seismic observation network. Therefore, we are considering the construction of a super dense seismic network using seismic data obtained by Meso-net and SUPREME.
It is also important to know the distribution of strong motion caused by earthquakes as soon as possible after the occurrence of an earthquake. If seismometers are installed in advance at each site, they will be useful for in determining evacuation routes and priority of rescue operations. Furthermore, it is possible to start rebuilding livelihoods without survey by experts. In order to consider the construction of such a seismological observation system, we are conducting a pilot observation, which will be reported later.