SEISMICITY ANOMALIES OF M 5.0+ EARTHQUAKES IN CHILE DURING 1964-2015

The study of magnitude-frequency distribution of earthquake hazards in a region remains a crucial analysis in seismology. Its significance has varied from seismicity quantification to earthquake prediction. The analysis of seismicity anomalies of magnitude M => 5.0 earthquakes in Chile from 1964 to 2015 was undertaken by the present study with a view of reporting the trend of earthquake occurrences in the region. Chile has an area of about 756, 950 km2 with an extensive coastline of approximately 6,435 kms. It is situated in a highly seismically and volcanically active zone with a long, narrow strip of land between the Andes Mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east and the Drake Passage in the far south. Of a total of 3,893 earthquakes that have been documented historically, magnitudes Richter 5.0 to 5.9 represent 92.6%, magnitudes 6.0 to 6.9 represent 6.8%, magnitudes 7.0 to 7.9 represent 0.6%, and magnitudes 8.0 to 8.9 about 0.1%. The quantity of earthquakes (a-value) revealed an estimate of 8.4. The b-value was estimated using Gutenberg-Richter (GR) and the Maximum Likelihood Estimation (MLE) methods. The estimated b-value using GR and MLE methods are 0.97 and 1.1 respectively, with an estimated average b-value ≈ 1. The present studies supprort the conclusion that Chile is seismically very active and prone to the recurrence of moderateto- great earthquakes in the future.