D. Di Giacomo 1 , J. Harris 1 , A. Villaseñor 2 , D.A. Storchak 1 , E.R. Engdahl 3 , G. Ferrari 4

1. Poster S101PS.02 D. Di Giacomo1, J. Harris1, A. Villaseñor2, D.A. Storchak1, E.R. Engdahl3, G. Ferrari4 1International Seismological Centre, Thatcham, UK, domenico@isc.ac.uk 2Institute of Earth Sciences Jaume Almera, ICTJA-CSIC, Barcelona, Spain 3University of Colorado at Boulder, USA 4Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna, Italy • International Seismological Summary (ISS), 1918-1959 1) Introduction As one of the global components of the Global Earthquake Model Foundation (GEM, http://www.globalquakemodel.org/), wecollected,digitizedandprocessedanunprecedentedamountofpaper-based early instrumentalseismologicalbulletins (stations or network) withfundamentalparametricdataforrelocatingandreassessingthemagnitudeofearthquakesthatoccurredintheinstrumentalperiodbetween1904and1970.Thiseffortwasnecessaryinordertoproduceanearthquakecataloguewithlocationsandmagnitudesashomogeneousaspossible.Theparametricdataobtainedandprocessedduringthisworkfillsalargegapinelectronicbulletindataavailability. The instrumental data collected is limited to earthquakes selected according to three cut-off magnitudes: • 1900-1917: Ms≥ 7.5 and some smaller shallow events in stable continental areas; • 1918-1959: Ms≥ 6.25; • 1960-1970: Ms≥ 5.5. • ThisnewdatasetcomplementsthedatafreelyavailablefromtheInternationalSeismologicalCentre(ISC)Bulletinstartingin1964. Tofacilitateearthquakerelocation,differentsourceshavebeenusedtoretrievebody‑wavearrivaltimes (e.g.,InternationalSeismologicalSummary,1918-1959).Intotal,~1,000,000phasearrivaltimeswereaddedtothe ISC databaseforlargeearthquakesthatoccurredinthetimeinterval1904‑1970.Withrespecttotheamplitude‑perioddatanecessarytore‑computemagnitude,weconsideredtheglobalcollectionofpaper‑based station and network bulletinsstoredattheISCandenteredrelevantstationparametricdataintothedatabase.Asaresult, over 110,000surfaceandbody‑waveamplitude‑periodpairsforre‑computingclassicalmagnitudesMSandmbwereaddedtotheISCdatabase. • 2) Phasedatacollection (1904-1959) • Gutenbergnotepads(1904-1912)andInternationalSeismologicalAssociation(ISA)bulletins(1904-1907) 3) Amplitude-period data collection (1904-1970) 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. Intheperiod1918-1959~620,900 body‑wave arrival times for~850seismicstationsfromaroundtheworld were added. 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 MS 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. Example scan of the ISS Bulletin: station data for an earthquake occurred the 1942-11-10. Data Collection from Early Instrumental Seismological Bulletins for the ISC-GEM Global Instrumental Earthquake Catalogue 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 Part of the ISS data was already convertedtodigitalform before thebeginningofthiswork: • Earthquakes in the ISS between 1960-1963 were processed by VillaseñorandEngdahl(2007); • Earthquakes withMS≥ 7.0wereprocessedbyEngdahlandVillaseñor(2002) to produce the Centennial Catalogue; • A digital file (called Shannon tape) containing hypocentreandphasedataformostoftheearthquakesduring1918-1942. 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. Map and timeline coverage for the seismic stations we added manually amplitude-period data for magnitude recomputation (see Poster S101PS.01). • JapanMeteorologicalAgency(JMA)Bulletin,1923-1970 Example scans of the hand‑written Gutenberg notepads: a) station data for an earthquake occurred the 1904-04-04 in Bulgaria and b) for two earthquakes occurred in the Hindu-Kush region in October 1908. Manually added to the ISC database. For67 largeearthquakes selected intheperiod1904-1912~1,900body‑wavearrivaltimesfor~100seismicstationsfromaroundtheworld were added. 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. 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. • Overview of the phase data collection (1900-1959) 4) 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. • Seismological Bulletin of the British Association for the Advancement of Science (BAAS), 1913-1917 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. For45 largeearthquakes selected intheperiod1913-1917~3,800body‑wavearrivaltimesfor~100seismicstationsfromaroundtheworld were added. Example scan of the BAAS bulletin: station data for an earthquake occurred the 1913-05-30. 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 Distribution of the stations for which phase data were added before 1960. Each station is colour-coded by total number of arrivals added before 1960. References BAAS (1913-1917). British Association for the Advancement of Science, Seismological Committee, quarterly issues. ISS (1918-1963). International Seismological Summary, annual volumes. Engdahl, E.R., and A. Villaseñor, 2002. 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, 2007. Systematic relocation of early instrumental seismicity: Earthquakes in the International Seismological Summary for 1960-1963, Bull. Seism. Soc. Am.,97, 1820-1832.