# Advanced Unified Earthquake Catalog for North East India
## 8 Discussion and Conclusions
For the four catalog periods, the magnitude of the completeness values is obtained using the EMR process. The \(\rm M_{c}\) value declined from 5.6 for 1737-1964 to 3.9 for 1964-2012, as projected by a rise in instrumentation for this area beginning in 1964. Improving \(\rm M_{c}\) has a major impact on the computation of the 'b' value and the assessment of the seismic hazard for a given location. Several earthquakes of \(\rm M_{wg}\geq 7.0\) occurred in this area between 1737 and 2012. The maximum time elapsed between the occurrences of a major earthquake (\(\rm M_{wg}\geq 7.0\)) was 18 years (1970-1988) in the 1737-2012 catalog. The last such occurrence happened in the area in 1988. The period of low seismic activity appears to have begun after 1988 and continues to this day. The study area has been subdivided into nine seismogenic zones considering \(\rm M_{wg}\) based earthquake catalogs, focal mechanisms, and fault types. '\(\rm M_{c}\)', 'b,' and 'a' values have been determined for each of these areas. The catalog data for the period 1897-2012 show that there have been no earthquakes of magnitude \(\geq 7.0\) in zones I, VI, or IX. Because zone IX is located between IV and VII zones in which big earthquakes have occurred, the probability of a big earthquake occurring in this zone is low in the immediate future. Based on these findings, a period of quiescence has been identified in seismogeneous zones I and VI for large-scale earthquakes. A complete and consistent unified seismic catalog has been developed in terms of \(\rm M_{wg}\) following a robust statistical procedure that could help to understand the seismicity of the region in a better way. Preparing a homogenized earthquake catalog by changing the original magnitude scales into seismic moment magnitude scale \(\rm M_{wg}\), an obstacle has been removed for seismic hazard assessment of the study region. Our analysis suggests that the use of the \(\rm M_{wg}\) scale improves seismicity parameters 'b' up to 30%, 'a' up to 17%, and '\(\rm M_{c}\)' up to 38% for the Northeast India region (Table 5). Hence, the variations in these parameters may have a significant impact on the seismic hazard results. Therefore, the use of the \(\rm M_{wg}\) scale is recommended for all practical cases. Conceptualization, R.D. and P.; data curation. R.D. and P.; formal analysis, R.D., P. and C.M. ; investigation, R.D. and P.; methodology, R.D. and P.; resources, R.D. ; software, R.D. ; validation, R.D. and P.; visualization, R.D. and P.; writing--original draft, R.D., P., C.M., S.J. and T.B. ; writing--review and editing, R.D., P., C.M., S.J. and T.B. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was supported by FONDECYT Grant 11200618. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** Body and surface wave magnitudes of earthquake data have been collected from ISC (International Seismological Center) U.K. ([[http://www.isc.ac.uk/search/Bulletin](http://www.isc.ac.uk/search/Bulletin)]([http://www.isc.ac.uk/search/Bulletin](http://www.isc.ac.uk/search/Bulletin))) (last accessed August 2012) and moment magnitudes have been collected from GCMT (Global Centroid Moment Tensor database, [[http://www.globalcmt.org/CMTsearch.html](http://www.globalcmt.org/CMTsearch.html)]([http://www.globalcmt.org/CMTsearch.html](http://www.globalcmt.org/CMTsearch.html))) (last accessed October 2012). Earthquake data of 9969 events for the time period 1897-2012 were compiled from various databases agencies (e.g. ISC, NEIC, GCMT, IMD, NEIST). Historical seismicity data were considered during 1897 to 1962 from Ref. [26]. **Acknowledgments:** We thank the Reviewers for their constructive comments, which largely improve the quality of this contribution. **Conflicts of Interest:** The authors declare no conflict of interest.