# Earthquake Research Institute of the University of Tokyo ERI The Earthquake Research Institute (ERI) of the University of Tokyo has archived analog seismograms recorded on mechanical seismographs operated by ERI and its predecessors between 1881 and 1993. The first observation started in 1880 by J. A. Ewing at Hitotsubashi (Tokyo Imperial University) and continued until 1923. ERI was established in 1925. Seismograms were recorded at various buildings of the University of Tokyo, Tsukuba Observatory, and Wakayama seismological network. The collection includes maregrams and seismograms from a a few foreign networks - Taiwan, [Canada](../organizations/cnsn), and [WWSSN](../organizations/wwssn). ## Stations Only select records from the Wakayama Microearthquake Network have been scanned. See Satake et al. (2020) for a list of stations with curated microfilm records from the University of Tokyo, Tsukuba Observatory, Wakayama Seismological Network, and other locations. ### Wakayama Microearthquake Network The Wakayama microearthquake observatory was established in 1964 at ERI as a network of 10 high‐gain electromagnetic seismographs targeting microearthquakes: * T=1s, V=12,000–18,000 * pen recording on paper at 4mm/s **Stations with scans available** **Station**|**Component**|**Start Year**|**End Year**|**Number of Records** :--- | :---: | :---: | :---: | :---: Kumano |UD |1966 |1982 |5,532 Sarutani| UD |1964 |1982| 6,201 Kainokawa| UD| 1964| 1982| 6,305 Oishiyama| UD |1969, 1972 |1974 |3,318 Shichikawa | UD | 1964 | 1969 | Iinan |UD |1964 | 1970 | UD, up–down. ## Instrumentation ### Wakayama Microearthquake Network electromagnetic high-gain (short period) ### Other Ewing circular, vertical Hagiwara Imamura (strong motion) Ishimoto (accelerometer) Omori (seismograph and tremometer) Press-Ewing Tremometer Wiechert horizontal, vertical Wood-Anderson ## Recording Medium ### Wakayama Microearthquake Network ink on paper ### Other ink on paper photographic film photographic paper smoked paper ## Data Availability ### Microfilm In addition to the original analog seismograms, ERI maintains extensive archives of microfilm data. **ERI** Additional information about the microfilmed seismogram archives at the ERI can be obtained from the [Historical Seismogram Search System](http://wwweic.eri.u-tokyo.ac.jp/susu/en/index.html). **Foreign Seismograms** Access the list (station and date) of foreign seismograms available for: * [Taiwan](http://wwweic.eri.u-tokyo.ac.jp/record-W/taiwan-e.html). Includes station reports, meteorological data, seismic bulletins, and earthquake reports. Seismograms (pdf) of select Taiwan earthquakes recorded in Japan. * [Canada](http://wwweic.eri.u-tokyo.ac.jp/canadaseis/canada.html). The Earthquake Research Institute maintains ~1800 rolls of 35 mm films from 23 stations of the Canadian seismograph network between 1982-1989 *availability unconfirmed*. See also [Canada](../organizations/cnsn). * [WWSSN](http://wwweic.eri.u-tokyo.ac.jp/wwssn/filmlist.html). WWSSN microfilms of 167 stations between 1963-1988. See also [WWSSN](../organizations/wwssn) **Mareograms** * [Mareogram data](http://wwweic.eri.u-tokyo.ac.jp/tsunamidb/index.html) ### Scanned Images Images are available for some stations in the Wakayama Microearthquake Network (see list above). This is an ongoing project. **no. available** | **format** | **dpi** | **color** | :---: | :---: | :---: | :---: | TIFF | 400 | View data at: [http://wwweic.eri.u-tokyo.ac.jp/wakayama/](http://wwweic.eri.u-tokyo.ac.jp/wakayama/) ### Vectorized Data A database of digitized historical records and seismogram images for major earthquakes (~35) from 1920-1949 has been constructed. Plans are to make the data available via the [National Museum of Nature and Science](http://www.kahaku.go.jp/) and [ERI](http://www.eri.u-tokyo.ac.jp/) (Murotani et al., 2020). Earthquakes digitized include: * 1923 Kanto * 1944 Tonankai * 1946 Nankai ## Contact For more information about this collection, please contact: ## References Murotani, S., K. Satake, H. Tsuruoka, H. Miyake, T. Sato, T. Hashimoto, and H. Kanamori (2020). A Database of Digitized and Analog Seismograms of Historical Earthquakes in Japan, Seismol. Res. Lett. 91, 1459–1468, doi: https://doi.org/10.1785/0220190287. Satake, K., H. Tsuruoka, S. Murotani, and K. Tsumura (2020). Analog Seismogram Archives at the Earthquake Research Institute, the University of Tokyo, Seismol. Res. Lett. 91, 1384–1393, doi: 10.1785/0220190281. *Website links above last accessed 3 Feburary 2020.*