1. D. Di Giacomo, Bob Engdhal, D.A. Storchak and J. Harris
The ISC-GEM Global Instrumental Earthquake Catalogue ( ) for hazard purposes
D. Di Giacomo, Bob Engdhal, D.A. Storchak and J. Harris
BSM 2017, Reading, UK 1

2. Background www.isc.ac.uk/iscgem/
The ISC and a Team of International Experts released in January 2013 the ISC-GEM catalogue ( ), which provides basic earthquake parameters (location, moment magnitude, and, if available, moment tensor) along with corresponding uncertainties. This product is unique since it lists parameters obtained using the same techniques (to the largest extent possible) throughout the last 100+ years of instrumental seismology. It is available as CSV file (both main and supplementary catalogues) and also as KMZ (see Download & Legal). or

3. Background www.isc.ac.uk/iscgem/
In 2013 a short paper was published on SRL to announce the release of the ISC-GEM Catalogue, whereas in a PEPI special volume we describe in detail the various tasks accomplished to produce the catalogue:
Data collection
Relocation
Magnitude re-assessment
Bibliographic search of reliable seismic moments for events before 1976 (i.e., pre-GCMT) or

4. Phase and Amplitude Data Collection
Body/Surface Wave Amplitudes
Body Wave Arrival Times
Period
~10,000
~1,000,000
Quality station bulletins
DIGITALLY NOT AVAILABLE BEFORE THIS PROJECT
DIGITALLY AVAILABLE, ISC database
Major Sources of Phase Data:
Gutenberg Notepads ( ) and BAAS ( )
ISS Bulletins ( ) 4

5. Adding amplitudes from historical seismological bulletin
1906 San Francisco earthquake report from Göttingen (Germany) station bulletin.
The same report stored in digital format in the ISC database. Period and amplitude data finally available for magnitude recomputation.

6. Location improvements
More details in Bondár et al., PEPI 2015

7. Improvements in magnitude, especially Ms
ISC-GEM recomputed Ms
Ms from Abe’s catalogue
More details in Di Giacomo et al., PEPI 2015b

8. Summary of the ISC-GEM catalogue before extension started
Given the time and resources in the project we processed only selected earthquakes using time-variable cut-off magnitudes:
M ≥ 7.5 up to 1917 (plus significant quakes in continental regions with M ≥ 6.5);
M ≥ 6.25 between 1918 and 1959;
M > 5.5 from 1960 onwards.
~19,000 earthquakes were listed in the catalogue first release
Modified from Di Giacomo et al. (2015b)

9. Extension project Planned for 4 years;
Large number of earthquakes below ~6.2 is to be added before 1960;
Also current years (post 2009) to be added.
Data for recent years is taken from the ISC Bulletin, whereas for earthquakes before 1960 we need to digitise the relevant data for relocation and magnitude re-computation

10. First and second year extension: 1935-1959
Number of ISS events in the 1950s
Year
Number of earthquakes relocated
1950
438
1951
469
1952
560
1953
352
1954
316
1955
299
1956
311
1957
355
1958
530
1959
526
Totals
4156
Number of ISS events during
Year
Number of earthquakes relocated
1935
253
1936
260
1937
246
1938
302
1939
235
1940
233
1941
204
1942
184
1943
287
1944
228
1945
295
1946
388
1947
387
1948
441
1949
460
Totals
4403

11. Third year extension: 1920-1934
Number of ISS events during
Year
Number of earthquakes relocated
1920
105
1921 81
1922
1923
113
1924
129
1925
147
1926
249
1927
303
1928
274
1929
294
1930
267
1931
280
1932
214
1933
252
1934
226
Totals
3015
In the first three years of the Extension project we have:
Digitized over ~7,200 ISS pages with tabulated phase data;
This translates in over 1M phases between ( already digitally available from the Shannon tape)
Relocated earthquakes.
What about magnitude?
x7,200!!

12. First year extension: events with re-computed MS in the 1950s
Many ISS earthquakes in the 1950s fall below the ISC-GEM cut-off magnitude of 5.5, but rather than excluding completely those events we list them in the Supplementary Catalogue
Timeline of the re-computed MS in the 1950s

13. Second year extension: events with re-computed MS during 1935-1949
Many ISS earthquakes during fall below the ISC-GEM cut-off magnitude of 5.5, but rather than excluding completely those events we list them in the Supplementary Catalogue
Timeline of the re-computed MS during

14. Third year extension: events with re-computed MS during 1920-1934
Many ISS earthquakes during fall below the ISC-GEM cut-off magnitude of 5.5, but rather than excluding completely those events we list them in the Supplementary Catalogue
Timeline of the re-computed MS during
For the newly relocated events we have added ~225,000 amplitudes

15. Earthquakes already processed now with more MS stations
Maps of the “amplitude” stations added during the Extension project. The data added does not regard only earthquakes not processed before but also the ones already in the ISC-GEM catalogue
The increase in the NSTA contributing to the event MS is quite significant: whilst 42% of the original MS was obtained from NSTA ≤ 5, for the revised MS this percentage drops to ~5%. In addition, the added amplitude data also allowed us to gain 36 more MS values.

16. Summary after the third year extension
Before extension started
With extension during ,
Add bullet on the data collection, stress more all of them
BSM 2017, Reading, UK

17. Work in progress for
Earthquakes known and in ISC database from various sources
We are adding known earthquakes from ISA, Utsu, Karnik, SHEEC and other sources in the ISC database (e.g., 1904 Norway, 1905 Chamonix, 1906 South Wales, 1909 Benavente earthquakes are currently not in the ISC Bulletin).
ISS
BAAS
ISA
Gutenberg notepads,
Shide circulars
Individual station bulletins

18. Acknowledgements
64 Institutions in 48 countries, including the Royal Society, BGS and Blacknest in UK, make the annual membership subscriptions to the ISC.
14 international, public or commercial entities sponsor individual ISC projects:
CTBTO Link to ISC database
ISC-GEM Catalogue
International Station Registry
Aon Benfield,
Lloyd’s,
Guy Carpenter,
Catlin.
ISC Event Bibliography