ISC-GEM Global Instrumental Earthquake Catalogue (1900-2009)
Creators: name: Storchak, Dmitry A.
name: Di Giacomo, Domenico
name: Bondár, István
name: Harris, James
name: Engdahl, Eric R.
name: Lee, Willie H.K.
name: Villaseñor, Antonio
name: Bormann, Peter
name: Ferrari, Graziano
Publisher: name: GEM Foundation, Pavia, Italy
Year: 2012
Subjects: Instrumental catalogue
Earthquakes
Magnitude
Relocation
Depth
Hazard assessment
Risk assessment
GEM

description: GEM Technical Report 2012-01
description: Geological, Earthquake and Geophysical Data
description: This report describes the ISC-GEM Global Instrumental Earthquake Catalogue (1900-2009) created on the request and with sponsorship from the GEM Foundation. * The ISC-GEM Global Instrumental Earthquake Catalogue (1900-2009) is a major step forward on the way to improve characterization of spatial distribution of seismicity, magnitude frequency relation and maximum magnitudes within the scope of GEM. * With a few exceptions, parameters of this catalogue are the result of computations based on the original reports of seismic stations and observatories. * We made every effort to use uniform location and magnitude determination procedures during the entire period of the catalogue: - In earthquake location, we used a combination of the EHB depth determination technique and the new ISC procedures that use a multitude of primary and secondary seismic phases from the IASPEI Seismic Phase List and the ak135 velocity model and take into account the correlated error structure. - In determination of earthquake magnitude, where possible, we used direct MW values from Global CMT project for the period 1976-2009. In addition, 1,127 high quality scientific papers have been processed to obtain directly measured values of M0 and MW for 970 large earthquakes during 1900-1979. In all other instances we computed MW proxy values based on our own determination of instrumental surface or body wave magnitudes using updated regression models. - It has to be noted that a computation of MW proxy values based on regressions from other types of magnitudes does not bring similarly reliable results as compared to a direct measurement of MW based on the original waveform analysis. It is, nevertheless, a necessary measure since the direct measurement of MW using historical analogue waveforms on a global scale is beyond the scope of this project. * A number of important additional benefits have been achieved during this project: - The entire ISC collection of historical paper-based seismic station bulletins was reviewed, indexed and catalogued for further works. Indexes of similar collections at USGS/Berkeley were used in filling the gaps in the ISC collection. - A large number of seismic phase arrival times, body and surface wave amplitude measurements have been made electronically available on a global scale that have never been available on a global scale prior to this project. - A large number of more accurate network MS and mb magnitudes have been computed for large earthquakes that either had no magnitude estimate or the estimates were previously based on single or unreliable station data. * In our work we consulted and were observed by experts from the IASPEI and, where possible, followed the IASPEI seismic standards. * We put together an excellent team of professionals in the field and gave training to a group of technical personnel without whom the work on this project would have been impossible to complete. These personnel members are a valuable asset of this project and their experience can be used if further work was to be planned. * Although the ISC-GEM Catalogue is a major accomplishment, we nevertheless believe that further work is necessary to enhance its qualities: - Firstly, neglecting to update the ISC-GEM Catalogue beyond 2009 would seriously hamper the GEM community efforts of testing and refining of the earthquake forecasting models. - Secondly, it is well known that in seismic hazard studies the effect of small to moderate size earthquakes is not negligible. This is especially the case in densely populated and industrialized areas. This calls for further improvement of completeness of the reference catalogue to be extensively used by GEM community for many years to come. - Thirdly, it has to be noted that we really have no magnitude estimates for many events in our main original source of historical data before 1964 – the ISS Catalog. Some of these events in the first part of the 20th century could be large enough to have caused damage. The work of including many more earthquakes recorded at teleseismic distances and bringing previously unavailable station amplitude data from historical station bulletins would greatly contribute to more accurate consequent analysis of global earthquake hazard and risk.