Seismological Observatory at Maitri, East Antarctica

Antarctica is the world's greatest natural laboratory and attracts scientists from across the globe for research. It provides a stable platform for carrying out a wide range of scientific investigations. Being far away from major industrial regions, Antarctica remains one of the most unpolluted areas on Earth, making it an ideal location to monitor environmental and climatic changes affecting the entire planet.

Antarctica is the coldest, windiest, and stormiest continent in the world, covering an area of about 14 million square kilometres. It is often called a “pulsating continent” because its size changes with the seasons. During winter, the ocean surrounding the continent freezes, and sea ice expands hundreds of kilometres outward. As summer approaches, this ice breaks up and retreats.

Locations of major permanent and seasonal research stations across Antarctica operated by different countries.

The continent has extremely harsh terrain and severe climatic conditions. The world's lowest recorded temperature of -89.6 °C was measured here near the geomagnetic pole. Wind speeds can exceed 250 km per hour, and blizzards may last for several days, reducing visibility to only a few metres. Nearly 98% of Antarctica is covered by a thick ice sheet, with ice thickness ranging from about 800 metres to 4.5 kilometres. The remaining 2% of the land is exposed as small rock outcrops and mountain ranges.

At present, about 30 countries are actively involved in scientific research in Antarctica. These countries are signatories to the Antarctic Treaty, which is mandatory for operating research stations on the continent. The population at Antarctic research stations varies seasonally, with around 4000 scientists and support personnel during summer and about 1000 during the winter months (around June). The primary objective of the Antarctic Treaty is to ensure that Antarctica is used exclusively for peaceful purposes and scientific research, in the interest of all humanity, and that it does not become a source of international conflict.

Indian Antarctic Scientific Expedition

India created history in 1982 when a team of 21 scientists landed on the frozen continent of Antarctica to carry out scientific research. The first Indian Antarctic Scientific Expedition focused on studies in geology, geophysics, meteorology, geomagnetism, oceanography, and biology, operating from a temporary base camp. The expedition stayed for a short period of 10 days, marking the beginning of India's polar science programme. During the Second Indian Antarctic Expedition, efforts were made to identify a suitable site for establishing a permanent research station. Site selection proved to be a challenging and highly debated task. The initially selected location was rejected after aerial surveys revealed the presence of developing fissures in the ice. After detailed and extensive surveys, a stable area of about 10 km in diameter was finally selected for setting up the research station (coordinates: 70°45'52” S, 11°44'03” E). In the Third Indian Antarctic Expedition, India established its first permanent research station, Dakshin Gangotri, on a stable ice shelf approximately 150 metres thick, free from crevasses and fissures, with the Wohlthat Mountain Range to the south. However, Dakshin Gangotri was later abandoned after India's second station became operational, as it was gradually buried under ice.

Maitri Research Station, India's second permanent Antarctic base, located in the Schirmacher Oasis (70°45'58″S, 11°43'56″E), about 100 km inland from the Antarctic ice shelf.

India's second permanent research station, Maitri, was completed in 1989. Maitri is located on exposed rocky terrain in the Schirmacher Oasis, a mountainous region of Antarctica. The station can accommodate about 25 personnel during the winter months. Maitri supports research in a wide range of disciplines, including earth sciences, glaciology, atmospheric sciences, communication, medicine, human physiology, and cold-region engineering. In March 2013, India commissioned its third permanent Antarctic research station, Bharati. Bharati is located near the Larsemann Hills in northeast Antarctica (coordinates: 69° S, 76° E) and represents a major advancement in India’s polar research capabilities. With three permanent research stations, India became the ninth nation in the world to operate multiple permanent scientific bases in Antarctica.

Broadband Seismograph Installation at Maitri, Antarctica

The broadband seismograph installed at Maitri Research Station, Antarctica, is shown in Figures 3 and 4. The system consists of a three-channel broadband digital seismometer of force-balance feedback type, designed for low noise performance and a large dynamic range. The instrument operates over a wide frequency bandwidth of 0.0083 Hz to 50 Hz, with a sensitivity of 2000 V/m/s and a power consumption of approximately 1.3 W.

As the seismometer is sensitive to diurnal temperature variations, it is enclosed within a thermal shielding cover to ensure stable performance under extreme Antarctic environmental conditions.

The Data Acquisition System (DAS) is a three-channel, 24-bit broadband seismic recorder. It is compact, lightweight, and consumes low power. The DAS is equipped with six input/output connectors and an LCD display, and operates with an input voltage range of 10-16 V DC. The system provides a dynamic range greater than 135 dB, enabling high-quality seismic data recording. Seismic data recorded by the DAS are stored locally on a 4 GB compact flash card and are periodically transferred via FTP to the National Centre for Polar and Ocean Research (NCPOR) data server in Goa for further analysis and archiving.

Accurate timing and positioning are provided by a Global Positioning System (GPS) receiver, which uses signals from a constellation of 24 satellites. The GPS supplies precise time information and station coordinates, which are embedded in the digital seismic data. A 1 Hz timing pulse is also transmitted serially to the DAS for synchronization. The GPS unit is powered by a 12 V DC supply from the DAS.

Building on this setup, the first figure further demonstrates the complete deployment process of the broadband seismic station at Maitri, including field logistics, station infrastructure, and real-time data monitoring. It highlights how the sensor is integrated with the data acquisition system, power supply, and timing unit, and how continuous seismic data are recorded and monitored within the station under extreme polar conditions.

Installation of the broadband seismic station at Maitri Research Station, Antarctica, showing vault preparation, sensor deployment, thermal protection, and data acquisition and monitoring setup.

Following this, the second figure provides a broader perspective of the operational environment supporting the seismic station at Maitri. It illustrates the surrounding station infrastructure, logistical support, and field operations that enable sustained seismic monitoring. Together, these elements demonstrate how scientific measurements are maintained over long periods despite the severe climatic and environmental challenges of Antarctica.

Operational environment and logistical infrastructure supporting broadband seismic monitoring at Maitri Research Station, Antarctica.

Seismicity of Antarctica: Observations and Monitoring

Seismicity in Antarctica and the surrounding Southern Ocean has been evaluated using earthquake data compiled by the International Seismological Centre (ISC) for the period 1964 onwards. For many decades, Antarctica and its surrounding oceans were considered largely aseismic regions of the Earth. Although earthquakes do occur in Antarctica, they are relatively infrequent compared to other tectonically active regions. However, with the development of global seismic networks and the deployment of local seismic arrays by various countries, a significant number of tectonic earthquakes have now been detected in and around the Antarctic continent.

Antarctica and the surrounding oceanic region are divided into 13 seismic zones, including three continental and ten oceanic regions. As in other parts of the world, most tectonic earthquakes occur along narrow belts that mark the boundaries between crustal plates. In addition to tectonic activity, Antarctica experiences seismic signals generated by natural cryospheric processes, such as ice and snow movement, commonly referred to as ice quakes. Many tectonic earthquakes observed along the Antarctic coastline are believed to be caused by stress accumulation in the crust following large-scale deglaciation.

The National Geophysical Research Institute (NGRI) established a permanent seismological observatory at Maitri Research Station (70°45'58″ S, 11°43'56″ E), located in the ice-free Schirmacher Oasis, during the XVII Indian Scientific Expedition to Antarctica (1997). The primary objective of this observatory was to monitor seismicity in Antarctica and the surrounding Southern Ocean, including the Indian Ocean region. Initially, both analogue and digital short-period seismometers were installed. These were later upgraded to a high-resolution, three-component digital broadband seismometer in January 2001, during the XX Indian Scientific Expedition to Antarctica.

Since its inception, the Maitri seismological observatory has been in continuous operation. Seismic data were initially pre-processed at Maitri and subsequently analysed at NGRI using the SEISAN software package. The recording of both teleseismic and regional events at Maitri has provided a comprehensive understanding of seismic activity in and around Antarctica. Seismic data collected were contributed to the ISC for inclusion in the global earthquake bulletin. This dataset represents an important benchmark for present and future Antarctic seismic research and serves as a valuable resource for the global Earth science community. In 2026, the Broadband Seismological Station at Maitri, East Antarctica, was successfully linked via satellite to CSIR-NGRI, Hyderabad, enabling continuous near real-time seismic data streaming, archival, and remote state-of-health monitoring of the seismograph.

At present, the Maitri seismological observatory is also a part of the Antarctic Seismic Web Resource (AnSWeR). A broadband seismograph installed at Maitri in 1997 continues to operate in continuous recording mode. Despite long-term success, challenges remain in ensuring robust and accurate recordings under extreme polar conditions. One of the key scientific objectives is to develop reliable procedures to effectively discriminate tectonic earthquakes from ice-quakes, thereby improving the efficiency of seismic data analysis.

The implementation of such advanced seismic analysis programmes in the Antarctic and Southern Ocean regions by the National Centre for Polar and Ocean Research (NCPOR) will significantly strengthen India's role in polar geoscience research. These efforts will help ensure India's continued leadership among nations engaged in Antarctic scientific exploration.

List of CSIR-NGRI Members Participated in Indian Antarctica Expeditions

Name of member (CSIR-NGRI)	Year of Participation	Indian Antarctica Scientific Expedition (IASE)	Remarks
Dr. H. K. Gupta	-	3	Expedition Leader
I. Prasada Raju	1998-1999	17	Member
Saurabh Barua	1999-2000	18	Member
YVVBSN Murthy	2000-2001	19	Member
L. Premkishore	2001-2002	20	Member
SVRR Rao	2002-2003	21	Member
G. S Srinivas	2003-2004	22	Member
A. Akilan	2004-2005	23	Member
A. Nageshwara Rao	2005-2006	24	Member
SVRR Rao	2006-2007	25	Member
L. Prem Kishore	2006-2007	25	Expedition Leader
G. S Srinivas	2007-2008	26	Member
Venkatravudu Manchem	2008-2009	27	Member
A. Nageshwara Rao	2009-2010	28	Member
Amit Kumar Bansal	2011-2012	31	Member
Satish Saha	2012-2013	32	Member
Satish Saha	2013-2014	33	Member
Saroj Kumar Mondal and Tirupati .M	2014-2015	34	Member
Sateesh Chandrapuri	2015-2016	35	Member
Amit Kumar Bansal	2016-2017	36	Member
M. Shekar	2017-2018	37	Member
Amit Kumar Bansal	2018-2019	38	Member
Srinivas Dakuri	2019-2020	39	Member
Amit Kumar Bansal	2022-2023	42	Member
V. Rageswara Rao	2023-2024	43	Member
Venkatesh Vempati	2025-2026	45	Member

Ongoing Research Activity

1. Environmental Effects on Broadband Seismic Noise: A Year-Long Assessment from Maitri Station, Dronning Maud Land, East Antarctica

This study presents a year-long analysis of broadband seismic noise recorded at the Maitri seismic station in East Antarctica during 2023. Using probabilistic power spectral density methods, the study shows that Maitri operates in a consistently low-noise environment, with seismic noise levels remaining within global reference limits. Strong seasonal variations in microseismic noise are observed, with higher amplitudes during austral summer due to reduced sea-ice cover and increased Southern Ocean wave activity. Short-period noise remains low throughout the year, indicating minimal anthropogenic influence, while long-period variations reflect wind and temperature effects. Overall, the results confirm Maitri as a high-quality seismic observatory and a valuable site for monitoring environmental and ocean-cryosphere interactions in Antarctica.

(a) Location and seismic noise characteristics of the Maitri broadband seismic station, East Antarctica, showing station location, (b) probabilistic noise levels, and (c) seasonal variation across different period bands.

2. Shear Wave Velocity Structure beneath Maitri station in Dronning Maud Land, East Antarctica

The shear-wave velocity structure beneath the Maitri seismic station in East Antarctica was investigated using joint inversions of ambient seismic noise, as illustrated in the figure. The velocity models derived from Rayleigh wave ellipticity (RWE) and multimode surface-wave dispersion reveal a low-velocity near-surface layer associated with ice and sediments, a higher-velocity igneous layer in the upper crust, and a mafic lower crust. A pronounced increase in shear-wave velocity at depths of ~30-35 km marks the crust-mantle boundary (Moho). The close agreement between different inversion approaches highlights the robustness of the results and demonstrates the effectiveness of single-station ambient noise methods for imaging crustal structure in remote polar regions.

Shear-wave velocity structure beneath the Maitri seismic station derived from joint inversion of ambient-noise data, highlighting crustal layering and the Moho at ~30-35 km depth.

3. Seismic anisotropy and mantle dynamics beneath Maitri Station in central Dronning Maud Land, East Antarctica

This study investigates upper-mantle seismic anisotropy beneath the Maitri station in Dronning Maud Land, East Antarctica using shear-wave splitting analysis of both core-refracted phases (SKS, SKKS, PKS, PKKS) and direct S-waves recorded between 2013 and 2017. The results show a consistent north-east-south-west-oriented fast polarization direction with an average delay time of about 1 second, indicating a coherent anisotropic structure beneath the station.

The observed anisotropy aligns closely with regional magnetic anomalies, geological lineaments, and the continental margin, suggesting that it primarily reflects frozen lithospheric fabric rather than present-day mantle flow. This fabric is interpreted as a remnant of major Precambrian tectonic events and Gondwana breakup-related deformation, preserved within the Antarctic lithosphere. The strong agreement between anisotropy patterns at Maitri and nearby stations highlights long-term crust-mantle coupling and provides important constraints on the tectonic evolution of East Antarctica.

Shear-wave splitting results at the Maitri station plotted over magnetic anomaly data, showing individual and mean anisotropy measurements, comparison with nearby stations and earlier studies, and their relation to absolute plate motion.