Analysis of Shallow Microearthquakes in the South Sebec Seismic Zone, Maine, 1989–1990

1992 ◽  
Vol 63 (4) ◽  
pp. 557-566 ◽  
Author(s):  
William E. Doll ◽  
Carol D. Rea ◽  
John E. Ebel ◽  
Sandra J. Craven ◽  
John J. Cipar
Keyword(s):  
New England ◽  
Satellite Images ◽  
Fault Plane ◽  
Seismic Zone ◽  
Fault Plane Solutions ◽  
Motion Data ◽  
First Motion ◽  
High Level ◽  
Surface Geology

Abstract Fifteen years of regional monitoring by the New England Seismic Network indicated a locally high level of seismicity near South Sebec, between the towns of Milo and Dover-Foxcroft in central Maine. Most of the events were located in a diffuse zone south of the distinctive, ENE trending Harriman Pond Fault (HPF) which is indicated by brittle deformation in outcrop and is represented as a depression in topographic maps and satellite images. A portable network consisting of both digital and analog instruments was deployed during the summers of 1989 and 1990 in order to characterize the pattern of the microearthquakes and to determine high-resolution epicenters, depths, and fault plane solutions. Seventy-three events were detected during the experiment, of which 28 could be located. Many of the events south of the fault lie along a NNW trending line which has no major expression in the surface geology. Only, a few of the events are subparallel to the HPF. The first motion data were insufficient for the determination of any fault plane solutions.

Microearthquakes in the Tihamat-Asir region of Saudi Arabia

1980 ◽  
Vol 70 (6) ◽  
pp. 2291-2293
Author(s):  
H. M. Merghelani ◽  
S. K. Gallanthine
Keyword(s):  
Saudi Arabia ◽  
Continental Crust ◽  
Red Sea ◽  
Fault Plane ◽  
Seismic Refraction ◽  
Earthquake Hazard ◽  
Tectonic Activity ◽  
Fault Plane Solutions ◽  
High Level ◽  
Asir Region

abstract During the course of a seismic refraction investigation in Saudi Arabia, an unexpected high level of microearthquake activity was detected near the border of the Red Sea and near the transition from oceanic to continental crust. The data is not adequate to determine fault plane solutions nor to relate the earthquakes to specific structures, but the existence of microearthquakes at this location suggest that there is a significant level of tectonic activity at a point 200 km from an axial trough of the Red Sea. These data, combined with other recent geological observations, may be an important clue to the understanding of continental rifting. The data suggest the need for a more thorough investigation of the earthquake hazard along the shores of the Red Sea.

Rampart seismic zone of central Alaska

1983 ◽  
Vol 73 (3) ◽  
pp. 813-829
Author(s):  
P. Yi-Fa Huang ◽  
N. N. Biswas
Keyword(s):  
Main Shock ◽  
Fault Plane ◽  
B Value ◽  
Aftershock Sequence ◽  
Strike Slip ◽  
Lithospheric Plate ◽  
Normal Faults ◽  
Seismic Zone ◽  
The West ◽  
Fault Plane Solutions

abstract This paper describes the characteristics of the Rampart seismic zone by means of the aftershock sequence of the Rampart earthquake (ML = 6.8) which occurred in central Alaska on 29 October 1968. The magnitudes of the aftershocks ranged from about 1.6 to 4.4 which yielded a b value of 0.96 ± 0.09. The locations of the aftershocks outline a NNE-SSW trending aftershock zone about 50 km long which coincides with the offset of the Kaltag fault from the Victoria Creek fault. The rupture zone dips steeply (≈80°) to the west and extends from the surface to a depth of about 10 km. Fault plane solutions for a group of selected aftershocks, which occurred over a period of 22 days after the main shock, show simultaneous occurrences of strike-slip and normal faults. A comparison of the trends in seismicity between the neighboring areas shows that the Rampart seismic zone lies outside the area of underthrusting of the lithospheric plate in southcentral and central Alaska. The seismic zone outlined by the aftershock sequence appears to represent the formation of an intraplate fracture caused by regional northwest compression.

scholarly journals Seismic evidence for the tectonics of Central and Western Asia

1959 ◽  
Vol 49 (4) ◽  
pp. 369-378
Author(s):  
A. E. Scheidegger
Keyword(s):  
Fault Plane ◽  
Stress System ◽  
Motion Direction ◽  
Fault Plane Solutions ◽  
Small Areas ◽  
Mountain Ranges ◽  
Central Asian ◽  
Western Asia ◽  
Tectonic Motion

Abstract A statistical analysis of the null axes of the fault-plane solutions of earthquakes in any one area permits determination of the average tectonic motion direction of that area. In the present paper this method has been applied to areas in central and western Asia for which several hundred fault-plane solutions are readily available in the literature. The investigation yields the result that (seismically) calculated tectonic motion directions in a series of small areas that are part of a larger unit are consistent with each other and that there is in every case an excellent correlation with the tectonic motion of the area as postulated from geological studies. This appears to justify completely the seismic method. The seismically determined tectonic motion in central Asia appears to be mainly in a north-south direction. The motion refers to the present time (since the earthquakes occur at the present time), but it is the same as that postulated in geology for an explanation of the folding of the central Asian mountain ranges. This demonstrates that the stress system which created the central Asian mountains is active at the present time.

scholarly journals DETERMINATION OF STRUCTURAL ELEMENTS INTENDED TO RESISTANCE AGAINST EARTQUAKE AND RENEWABLE ENERGY USAGE

2015 ◽  
Vol 1 (2) ◽  
pp. 85-90
Author(s):  
Poyraz Kağan ◽  
František Kulhánek
Keyword(s):  
Renewable Energy ◽  
Renewable Energy Sources ◽  
Working Environment ◽  
Seismic Zone ◽  
Structural Elements ◽  
Energy Usage ◽  
Preliminary Calculation ◽  
Innovative Solutions ◽  
High Level

The primary aim of office buildings is to provide a working environment with innovative solutions for the inclusion of needs of all positions including administrative and managerial workers. While offices can be appearing in almost any building; requirements complicate the construction. These requirements can be due to legal regulations, and technical needs. This study focuses on combined solutions via determination and preliminary calculation of structural components intended to resistance against earthquake and usage of possible renewable energy sources. The project building consists of 10 floors by way of application of reinforced concrete in conjunction with convenient application of heating, ventilating, and air conditioning (HVAC) systems, PV installation, high level of solar gain and interchangeable design. Static calculations are based on Turkish standards as Turkey is located over large seismic zone.

scholarly journals Theoretical Framework for Determination of Linear Structures in Multidimensional Geodynamic Data Arrays

2021 ◽  
Vol 11 (24) ◽  
pp. 11606
Author(s):  
Sergey Agayan ◽  
Shamil Bogoutdinov ◽  
Dmitriy Kamaev ◽  
Vladimir Kaftan ◽  
Maxim Osipov ◽  
...  
Keyword(s):  
Spatial Data ◽  
Satellite Images ◽  
Radioactive Waste Disposal ◽  
Multidimensional Data ◽  
Geological Environment ◽  
Tectonic Structures ◽  
Crustal Movements ◽  
Local Topography ◽  
High Level

The article addresses the issue of clustering of multidimensional data arrays with a noise using the methods of discrete mathematical analysis (DMA clustering). The theory of DMA clustering through the logical densities calculus is detailed, and the new algorithm Linear Discrete Perfect Sets (LDPS) is described. The main objective of the LDPS algorithm is to identify linearly stretched anomalies in a multidimensional array of geo-spatial data (geophysical fields, geochemistry, satellite images, local topography, maps of recent crustal movements, seismic monitoring data, etc.). These types of anomalies are associated with tectonic structures in the upper part of the Earth’s crust and pose the biggest threat for integrity of the isolation properties of the geological environment, including in regions of high-level radioactive waste disposal. The main advantage of the LDPS algorithm as compared to other cluster analysis algorithms that may be used in arrays with a noise is that it is more focused on searching for clusters that are linear. The LDPS algorithm can apply not only in the analysis of spatial natural objects and fields but also to elongated lineament structures.

scholarly journals Microearthquake Source Locations and Mechanisms: Ice Stream B, West Antarctica (Abstract)

1988 ◽  
Vol 11 ◽  
pp. 199-199
Author(s):  
S. Anandakrishnan ◽  
D. D. Blankenship ◽  
C. R. Bentley
Keyword(s):  
Depth Profile ◽  
Fault Plane ◽  
P Wave ◽  
West Antarctica ◽  
Precise Location ◽  
Fault Plane Solutions ◽  
Ice Flow ◽  
Ice Stream ◽  
Ice Stream B

An array of nine seismographic stations, each sensitive to all three components of motion, was deployed on Ice Stream B, West Antarctica, during the austral summer of 1985–86. The network was sensitive to high-frequency (=400 Hz) seismic activity within a 350 km2 area of the ice stream, and the deployment geometry allows the precise determination of depths for events beneath the 10 km2 array. Microearthquakes from both beneath and beside the ice stream were detected and recorded (Blankenship and others 1987). Inversion of P-wave and S-wave travel times and radiation patterns allows the determination of locations and fault-plane solutions for many of these events.We find that bottom events involve low-angle thrusting, in the down-stream direction, of ice or till; displacement is ∼½ cm per event over a (15 m)2 area. Such faulting is rare and releases an insignificant part of the total energy dissipated by ice flow. However, this is a possible mechanism for plucking of the ice-stream bed.Fault-plane solutions for most major surface events are consistent with the opening of tensional fractures oriented transverse to ice flow. Precise location of these events shows that they correspond to open crevasses, mapped by Vornberger and Whillans (1986), that are oriented transverse to ice flow.In addition, shear-wave splitting observed on some of the microearthquakes shows that the c-axes in the ice stream are slightly, but not strongly, anisotropic. Precise location of the sources requires the use of a detailed velocity-depth profile in the firn, which was obtained by seismic short-refraction studies (Anandakrishnan and others 1988, this volume). A density-depth profile calculated from these velocities agrees well with direct density measurements on a single core nearby (Alley and Bentley 1988, this volume).

Fault plane solutions for northeastern United States earthquakes

1981 ◽  
Vol 71 (6) ◽  
pp. 1875-1882
Author(s):  
Jay J. Pulli ◽  
M. Nafi Toksöz
Keyword(s):  
United States ◽  
New York ◽  
New England ◽  
Fault Plane ◽  
Local Stress ◽  
P Wave ◽  
Northeastern United States ◽  
Stress Concentrations ◽  
Fault Plane Solutions ◽  
Entire Area

Abstract Fault plane solutions for eight earthquakes occurring in the northeastern United States have been determined using P-wave first motions and a computer algorithm for picking all valid solutions. The predominant mechanism in the area is thrust faulting, however the direction of the P axis is not consistent throughout the entire area. In central New England (Maine-New Hampshire), the P axis trends nearly E-W. In southeastern New England, the P axis trends N-S to NE-SW. In the Adirondacks region of New York, the P axis trends NE-SW as previously reported by Yang and Aggarwal (1981). Although the stress distribution appears to be complicated, as in the Central United States (Street et al., 1974), an underlying E-W compressive stress may exist in the New England area. These small earthquakes may represent the response to local stress concentrations.

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