National Geophysical Research Institute Research Articles

Surface-wave and body-wave magnitudes of some Sino-Soviet nuclear explosions and earthquakes

abstract Body-wave and surface-wave magnitudes have been determined for Sino-Soviet nuclear explosions and earthquakes in nearby regions using National Geophysical Research Institute's seismological observatory data. On a Ms versus mb plot, the two are clearly distinguished. The following relations hold good between Ms and mb. M S = 0.70 m b + 1.88 for earthquakes , and M S = 1.06 m b − 1.46 for explosions . A comparison with an analogous study involving only continental seismic paths for North American explosions and earthquakes shows that our findings are consistent for earthquakes whereas for explosions, NGRI Ms values are systematically lower.

Results of airborne magnetometer profile from offshore Mangalore to offshore Madras (India) along the 13th degree parallel

A study is made of an airborne magnetometer profile from 130 km offshore Mangalore to 60 km offshore Madras approximately along the 13th degree parallel obtained in May 1967 by the National Geophysical Research Institute. The total length of the profile is about 770 km. A Bouguer gravity anomaly profile along same traverse over the land section has been also studied along with the magnetic profile.

Proceedings of the Symposium on Upper Mantle Project

Book Review| December 01, 1968 Proceedings of the Symposium on Upper Mantle ProjectJanuary 4–8, 1967. Published by the Geophysical Research Board, National Geophysical Research Institute, Hyderabad, India. 540 + xxxviii + iv pages, $5.00 K. Naha K. Naha Department of Geology and Geophysics University of CaliforniaBerkeley, California Search for other works by this author on: GSW Google Scholar Author and Article Information K. Naha Department of Geology and Geophysics University of CaliforniaBerkeley, California Publisher: Seismological Society of America First Online: 03 Mar 2017 Online Issn: 1943-3573 Print Issn: 0037-1106 Copyright © 1969, by the Seismological Society of America Bulletin of the Seismological Society of America (1968) 58 (6): 2073. https://doi.org/10.1785/BSSA0580062073A Article history First Online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation K. Naha; Proceedings of the Symposium on Upper Mantle ProjectJanuary 4–8, 1967. Published by the Geophysical Research Board, National Geophysical Research Institute, Hyderabad, India. 540 + xxxviii + iv pages, $5.00. Bulletin of the Seismological Society of America 1968;; 58 (6): 2073. doi: https://doi.org/10.1785/BSSA0580062073A Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyBulletin of the Seismological Society of America Search Advanced Search This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Gravity Anomalies and the Godavari Rift, India

A Bouguer anomaly map of the Godavari valley region extending from the deltas of the Krishna and Godavari rivers has been prepared by using data of the Survey of India and National Geophysical Research Institute. A gravity “low” of the order of 50 milligal is associated with the Godavari valley. A comparison of this map with the geologic map of India and the paleogeographic maps of the Gondwana periods by Fox (1931) and Ahmad (1961) indicates the Godavari structure continues northwestward at least up to 23° N. Godavari valley appears to be a rift, according to the definition of a rift valley given by Girdler (1963). Its average width is 50 km and its lateral extent, as indicated by gravity and paleogeographic data, may be of the order of 800 km. The valley floor may lie at depths ranging from 3 to 4 km. The gravimetric and geologic data do not indicate extension of the Godavari valley structure into the sea. However, it appears to have its counterpart in the basins on the western and northwestern coasts of Australia. It is suggested that the Godavari rift developed along a zone of weakness inherited from the Archean orogenies. It appears that after the Eparchean interval, but prior to the deposition of the Cuddapahs, tensional forces must have developed that caused formation of the graben, according to a mechanism proposed by Vening-Meinesz and Heiskanen (1958).