EXTENSION of the ISC-GEM GLOBAL INSTRUMENTAL EARTHQUAKE CATALOGUE

Transcription

1 EXTENSION of the ISC-GEM GLOBAL INSTRUMENTAL EARTHQUAKE CATALOGUE Dmitry A. Storchak, Domenico Di Giacomo, Bob Engdahl, Antonio Villaseñor and James Harris August 2014 ESC, Istanbul, Turkey 1

2 International Seismological Centre, ISC Prof. John Milne ( ) set up in 1964 to continue the work of the ISS and BAAS (from early 1900s) international, non-profit, non-governmental based in UK staff Supported by: 62 Member-Institutions worldwide, including 33 in Europe with 2 in Turkey (AFAD and Kandilli) Grants: CTBTO, FM Global, GEM, Lighthill, NSF, USGS Sponsors: Reftek August 2014 ESC, Istanbul, Turkey 2014 Grants 27% Memberships 73% 2

3 ISC data products: ISC-GEM Catalogue August 2014 ESC, Istanbul, Turkey 3

4 ISC-GEM Global Instrumental Earthquake Catalogue ( ) ISC-GEM Catalogue: warm colors shallow quakes : MS 7.5 worldwide + smaller shallow events in stable continental areas : MS 6¼ : MS August 2014 As compared to the ISC Bulletin that serves many fields of Geophysics, the ISC-GEM Catalogue is specifically built for the purpose of seismic hazard assessment: ~19,000 homogeneous hypocentre locations and MW estimates with the estimates of uncertainty covering 110 years period prepared using uniform location and magnitude determination techniques, using original arrival time measurements ESC, Istanbul, Turkey 4

5 ISC-GEM: improvement in length of period August 2014 ESC, Istanbul, Turkey (Storchak et al., 2014) 5

6 ISC-GEM: improvement in data availability The work on the ISC-GEM Catalogue required digitising of a large volume of data that has not been available electronically in the past. (Storchak et al., 2014) August 2014 ESC, Istanbul, Turkey 6

7 ISC-GEM: improvement in data availability ISC- GEM Catalogue : warm colors shallow quakes courtesy of Ross Stein, USGS 2011 Land Scan DB: The brightness of white indicates the populakon density Google Earth August 2014 ~4,000 downloads from ~1,000 unique IP-addresses in 15 months ESC, Istanbul, Turkey 7

8 ISC-GEM: improvement in earthquake location before ISC-GEM Location maps and cross-sections in the Arica region (Bondár et al., 2014). As a result of consistent relocation of hypocentres with the same technique (EHB+ISC) and velocity model (ak135) we observe tighter clustering of earthquake hypocentres, better focusing, many regional tectonic features are illuminated August 2014 ESC, Istanbul, Turkey 8

9 ISC-GEM: improvement in magnitude homogeneity We used GCMT M W and recomputed ISC MS determinations of the modern period to build regression curves that were later applied to obtain M W proxies in the early period before GCMT. (Di Giacomo et al., 2014) August 2014 ESC, Istanbul, Turkey 9

10 ISC-GEM: improvement in magnitude homogeneity (Storchak et al., 2014) We assigned an M W magnitude value (direct or proxy) with an estimate of uncertainty to each earthquake in August 2014 ESC, Istanbul, Turkey 10

11 ISC-GEM: comparison to Centennial catalog (*) ISC-GEM: all hypocentres in have been recomputed using the same: location technique velocity model Centennial: a lot fewer earthquakes were re-located ISC-GEM: Magnitude type: all M W from just 4 comparable sources: direct GCMT, direct Bibliog, M S, mb Centennial: 5 different types of magnitude from 14 sources (*) Centennial Catalog: Engdahl, E.R., and A. Villaseñor, Global seismicity: In International Handbook of Earthquake and Engineering Seismology, Part A, edited by W.H.K. Lee, H. Kanamori, P.C. Jennings and C. Kisslinger. Academic Press, August 2014 ESC, Istanbul, Turkey 11

12 ISC-GEM: PEPI special volume, 2014, imminent Storchak et al., The ISC-GEM... Introduction, Phys. Earth Planet. Int., in press, doi: /j.pepi Di Giacomo et al., ISC-GEM... Data collection from early instrumental seismological bulletins, Phys. Earth Planet. Int., in press, doi: /j.pepi Bondár et al., ISC-GEM... Location and seismicity patterns, Phys. Earth Planet. Int., in press, doi: /j.pepi Di Giacomo et al., ISC-GEM... Re-computed MS and mb, proxy MW, final magnitude composition and completeness assessment, Phys. Earth Planet. Int., in press, doi: /j.pepi Lee, W.H.K. and E.R. Engdahl, Bibliographical search for reliable seismic moments of large earthquakes during to compute MW..., Phys. Earth Planet. Int., in press, doi: /j.pepi August 2014 ESC, Istanbul, Turkey 12

13 ISC-GEM: Completeness August 2014 ESC, Istanbul, Turkey 13

14 ISC-GEM: Extension plans for 4 years August 2014 ESC, Istanbul, Turkey 14

15 ISC-GEM: Extension plans for 4 years The work is planned for 4 years Large number of earthquakes M W 5.5-6¼ is to be added in early instrumental period Current years to be added August 2014 ESC, Istanbul, Turkey 15

16 Project year 1, data years , work in progress Hypocentres in the ISS ISC- GEM, M>=6.25 ISC- GEM Extension, M>= Phases in the ISS ISC- GEM, M>=6.25 ISC- GEM Extension, M>= August 2014 ESC, Istanbul, Turkey 16

17 Project year 1, data years , work in progress Amplitudes sourced from paper- based bullefns ISC- GEM, M>=6.25 ISC- GEM Extension, M>= StaFons reporfng amplitudes ISC- GEM, M>=6.25 ISC- GEM Extension, M>= August 2014 ESC, Istanbul, Turkey 17

18 ISC-GEM Extension Sponsors 62 ISC Members from 45 countries Joining soon: August 2014 ESC, Istanbul, Turkey 18

19 Homogeneity and long time span are the key characteristics ~4,000 downloads from ~1,000 unique IP addresses in 15 months Large amount of parametric station measurement data will soon become digitally available We invite and gladly take into account comments and suggestions Summary The ISC-GEM catalogue is a specialised ISC product designed We maintain the log of changes and publically acknowledge all for assessment of seismic hazard help received from colleagues We published a special PEPI volume to describe the procedures used in creating the catalogue We are extending the catalogue to improve its completeness in the early instrumental period We invite new sponsors from seismic engineering field to help us with the massive amount of work on historical seismic bulletins August 2014 ESC, Istanbul, Turkey 19