Data Collection from Early Instrumental Seismological Bulletins for the ISC-GEM Global Instrumental Earthquake Catalogue D. Di Giacomo 1, J. Harris 1, A. Villaseñor 2, D.A. Storchak 1, E.R. Engdahl 3, G. Ferrari 4 1 International Seismological Centre, Thatcham, UK, 2 Institute of Earth Sciences Jaume Almera, ICTJA-CSIC, Barcelona, Spain 3 University of Colorado at Boulder, USA 4 Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Italy 1) Introduction As one of the global components of the Global Earthquake Model Foundation (GEM, we collected, digitized and processed an unprecedented amount of paper- based early instrumental seismological bulletins (stations or network) with fundamental parametric data for relocating and reassessing the magnitude of earthquakes that occurred in the instrumental period between 1904 and This effort was necessary in order to produce an earthquake catalogue with locations and magnitudes as homogeneous as possible. The parametric data obtained and processed during this work fills a large gap in electronic bulletin data availability. The instrumental data collected is limited to earthquakes selected according to three cut-off magnitudes: : Ms ≥ 7.5 and some smaller shallow events in stable continental areas; : Ms ≥ 6.25; : Ms ≥ 5.5. This new dataset complements the data freely available from the International Seismological Centre (ISC) Bulletin starting in To facilitate earthquake relocation, different sources have been used to retrieve body ‑ wave arrival times (e.g., International Seismological Summary, ). In total, ~1,000,000 phase arrival times were added to the ISC database for large earthquakes that occurred in the time interval 1904 ‑ With respect to the amplitude ‑ period data necessary to re ‑ compute magnitude, we considered the global collection of paper ‑ based station and network bulletins stored at the ISC and entered relevant station parametric data into the database. As a result, over 110,000 surface and body ‑ wave amplitude ‑ period pairs for re ‑ computing classical magnitudes M S and m b were added to the ISC database. 2) Phase data collection ( )  Gutenberg notepads ( ) and International Seismological Association (ISA) bulletins ( )  International Seismological Summary (ISS), References BAAS ( ). British Association for the Advancement of Science, Seismological Committee, quarterly issues. ISS ( ). International Seismological Summary, annual volumes. Engdahl, E.R., and A. Villaseñor, Global Seismicity: 1900–1999, in W.H.K. Lee, H. Kanamori, P.C. Jennings, and C. Kisslinger (Ed.), International Handbook of Earthquake and Engineering Seismology, Part A, Ch. 41, 665–690, Academic Press. Villaseñor, A. and E.R. Engdahl, Systematic relocation of early instrumental seismicity: Earthquakes in the International Seismological Summary for , Bull. Seism. Soc. Am., 97, ) Summary Overall amount of instrumental data gathered from different sources and used to produce the ISC- GEM catalogue, including modern period and data digitally available before this work (green colors). We consider the data added in this work a significant step forward on the way of improving any future study for earthquakes occurred in the early instrumental period. a) example of station parametric data from Göttingen (Germany) of the 1906 San Francisco earthquake and b) the same data entered in the ISC database. Each vertical segment represents the earthquake origin time for which station parametric data was added. The effect of WWI and WWII are clearly seen on the timeline plot. Poster S101PS.02 Example scans of the hand ‑ written Gutenberg notepads: a) station data for an earthquake occurred the in Bulgaria and b) for two earthquakes occurred in the Hindu-Kush region in October Manually added to the ISC database. For 67 large earthquakes selected in the period ~1,900 body ‑ wave arrival times for ~100 seismic stations from around the world were added.  Seismological Bulletin of the British Association for the Advancement of Science (BAAS), These bulletins are the predecessors of the International Seismological Summary (ISS), and are available in good quality printed form Manually added to the ISC database. For 45 large earthquakes selected in the period ~3,800 body ‑ wave arrival times for ~100 seismic stations from around the world were added. Example scan of the BAAS bulletin: station data for an earthquake occurred the Added to the ISC database in a semi-automatic way using optical character recognition (OCR) methods. OCR techniques are applicable to ISS Bulletins thanks to a fairly stable format. In the period ~620,900 body ‑ wave arrival times for ~850 seismic stations from around the world were added. Example scan of the ISS Bulletin: station data for an earthquake occurred the Part of the ISS data was already converted to digital form before the beginning of this work: Earthquakes in the ISS between were processed by Villaseñor and Engdahl (2007); Earthquakes with M S ≥ 7.0 were processed by Engdahl and Villaseñor (2002) to produce the Centennial Catalogue; A digital file (called Shannon tape) containing hypocentre and phase data for most of the earthquakes during  Japan Meteorological Agency (JMA) Bulletin, JMA Bulletin data was digitally available and made available to the ISC by Professor Hamada. The early JMA bulletin is in a computer-readable format and it was, therefore, possible to parse it automatically. About 270,000 from about 230 stations were used in the ISC ‑ GEM relocation procedure.  Overview of the phase data collection ( ) Distribution of the stations for which phase data were added before Each station is colour-coded by total number of arrivals added before Annual number of arrival times of P-wave (red) and S-wave type (blue) before 1960 collected from different. The annual number of P-wave (yellow) and S ‑ wave type (brown) manually added as part of the amplitude data entry task (described later) is also shown 3) Amplitude-period data collection ( ) A major drawback with the ISS and other data sources is the lack of the required data (e.g., amplitude, period and component information) for seismic phases useful for re ‑ computing classical magnitude scales such as M S and mb. In order to obtain magnitudes consistent with the relocated hypocentres, we needed to retrieve the necessary information from the early instrumental seismological bulletins. Annual number of surface wave (black) and vertical component P- wave (gray) amplitude-period measurements manually entered from seismological bulletins. A view of the ISC warehouse containing the original collection of early instrumental seismic station bulletins Map and timeline coverage for the seismic stations we added manually amplitude-period data for magnitude recomputation (see Poster S101PS.01) Station bulletins 270,000 (~110,000 amplitudes) Gutenberg/ ISA 1,900 BAAS3,800 ISS400,000 Shannon tapes 230,000 JMA270,000 ISS330,000 ISC11,000,000 (~2,500,00 amplitudes)