Recent Studies on the increase in Seismicity in the Antarctic Plate: Observations from BB Seismological Observatory (MAIT) at Maitri, Antarctica

The permanent Seismological Observatory was established in 1997 at Maitri in Central Dronning Maud Land, East Antarctica (70 °45' South 11 °43' East) primarily to monitor the seismicity in and around Antarctica, the space and time distribution of earthquake occurrences and obtain hypocentral parameters, magnitudes of earthquakes, velocity inversion for underground structure and earthquake source mechanism. The observatory has been upgraded during 25th Indian Silver Jubilee Scientific Expedition to Antarctica (December 2005 to February 2007) and 26th Indian Antarctic Expedition (IAE) with the new generation Geotech KS-2000M Seismometer and Smart 24R digitizer. During the 27th IAE the Seismic Observatory was further upgraded by adding Reftek 130 seismic system. Uninterrupted good quality digital Broad Band Seismic data is continuously being acquired. The SEISAN 8.1 software was used for final processing and analysis of about 300 earthquakes recorded. During the year 2006 the tele-seismic events, and quite a number of regional earthquakes of the order of 4 to 6.0 magnitude within Antarctic Plate, 23 in South Sandwich Islands, 7 in Scotia Sea, 2 in Macqurie Islands and 23 in Mid Oceanic Ridges in the Indian Ocean were recorded. 48 earthquakes of the magnitude above 4.5 from the nearby South Indian Ocean, South of South Africa, Chile, Argentina, Bolivia and about 40 earthquakes of the magnitude above 5.0 from the Indonesian Region were analysed. An earthquake of magnitude Ms=7.3 from the seismically active region of South Sandwich Islands Δ =16.5 °, Mb=7.8 earthquake from Tonga Islands and Mb=7.2 earthquake from Java were the large earthquakes that were recorded. Along with this the MOHO depth beneath MAIT was also estimated to be about 40km using receiver function analysis. All the analysed monthly data was reported to the I.S.C., U.K.,Global Data Centre for the final processing and inclusion in the yearly ISC Seismic Bulletin. The increasing seismic activity in and around Antarctic plate and along the oceanic ridges in the Indian Ocean confirms the emerging deforming zone between 75 ° East and 100 ° East longitude estimated by IERS in their plate characteristics in the Indian Ocean between India and Antarctica. All the results give an insight into the spreading rates of the ridges and reorganization of Plate Boundaries.