HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) References Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by SBAR, M. L. Articles by AGGARWAL, Y. P. Search for Related Content GeoRef GeoRef Citation

The Adirondack, New York, earthquake swarm of 1971 and tectonic implications

LAMONT-DOHERTY GEOLOGICAL OBSERVATORY OF COLUMBIA UNIVERSITY, PALISADES, NEW YORK 10964

Abstract

An earthquake swarm was observed in the Blue Mountain Lake area of the southern Adirondacks from early May 1971 until the writing of this paper (late April, 1972). This swarm provided an unusual opportunity for a detailed field study of earthquakes and a determination of principal stress direction for a region within a lithospheric plate. Thousands of events were recorded, the largest of which had a magnitude of 3.6 and was felt as far as 80 km from the epicenter. A number of earthquakes were heard as well as felt—the smaller were heard, but not felt.

Thrusting mechanisms were determined from two composite fault-plane solutions. The solution for earthquakes above 2-km depth indicates faulting on a plane striking N12°W and dipping 25°E. The fault plane for the deeper events (between 2 and 3.5 km) strikes N31°E and dips 59°E.

The earthquake foci define a surface that dips gently to the east to a depth of 2 km and then steepens, in agreement with the composite fault-plane solutions. There is an indication that the shallower earthquakes may not represent renewed motion on a pre-existing fault, but may mark the generation of a new fault by a regional east-west compressive stress. The deeper events which occurred late in the sequence may represent the extension of the shallow fault and its deflection to an existing weakness. The axis of maximum compressional principal stress for the shallow composite fault-plane solution trends approximately east-west and is nearly horizontal. Geological and geophysical evidence is presented to support the hypothesis that the greatest principal stress in a zone extending from northern New York State to southern Illinois is compressive, large and horizontal, and trends nearly east-west.

This article has been cited by other articles:

				P. A. JOHNSON and M. L. SBAR A microearthquake study of southwest Utah-northwest Arizona: Transition between the Basin and Range Province and Intermountain Seismic Belt Bulletin of the Seismological Society of America, April 1, 1987; 77(2): 579 - 596. [Abstract] [PDF]

				G. LEBLANC and F. ANGLIN Induced seismicity at the Manic 3 reservoir, Quebec Bulletin of the Seismological Society of America, October 1, 1978; 68(5): 1469 - 1485. [Abstract] [PDF]

				R. B. HORNER, A. E. STEVENS, H. S. HASEGAWA, and G. LEBLANC Focal parameters of the July 12, 1975, Maniwaki, Quebec, earthquake--An example of intraplate seismicity in eastern Canada Bulletin of the Seismological Society of America, June 1, 1978; 68(3): 619 - 640. [Abstract] [PDF]

				J. G. ANDERSON and J. B. FLETCHER Source properties of a Blue MT. Lake earthquake Bulletin of the Seismological Society of America, June 1, 1976; 66(3): 677 - 683. [Abstract] [PDF]

				P. W. POMEROY, D. W. SIMPSON, and M. L. SBAR Earthquakes triggered by surface quarrying-the wappingers falls, New York sequence of June, 1974 Bulletin of the Seismological Society of America, June 1, 1976; 66(3): 685 - 700. [Abstract] [PDF]

				I. N. GUPTA Premonitory seismic-wave phenomena before earthquakes near Fairview Peak, Nevada Bulletin of the Seismological Society of America, April 1, 1975; 65(2): 425 - 437. [Abstract] [PDF]

				M. L. SBAR, R. R. JORDAN, C. D. STEPHENS, T. E. PICKETT, K. D. WOODRUFF, and C. G. SAMMIS The Delaware-New Jersey earthquake of February 28, 1973 Bulletin of the Seismological Society of America, February 1, 1975; 65(1): 85 - 92. [Abstract] [PDF]

				J. P. FLETCHER and J. G. ANDERSON First strong-motion records from a central or eastern United States earthquake Bulletin of the Seismological Society of America, October 1, 1974; 64(5): 1455 - 1465. [Abstract] [PDF]

				C. J. LANGER, M. G. HOPPER, S. T. ALGERMISSEN, and J. W. DEWEY Aftershocks of the Managua, Nicaragua, earthquake of December 23, 1972 Bulletin of the Seismological Society of America, August 1, 1974; 64(4): 1005 - 1016. [Abstract] [PDF]

				L. T. LONG Earthquake sequences and b values in the southeast United States Bulletin of the Seismological Society of America, February 1, 1974; 64(1): 267 - 273. [Abstract] [PDF]