scholarly journals Characterizing the Foreshock, Main Shock, and Aftershock Sequences of the Recent Major Earthquakes in Southern Alaska, 2016–2018

2020 ◽  
Vol 8 ◽  
Author(s):  
B. G. Bukchin ◽  
A. S. Fomochkina ◽  
V. G. Kossobokov ◽  
A. K. Nekrasova
Keyword(s):  
Control Parameter ◽  
Empirical Distribution ◽  
Scaling Law ◽  
Plate Boundary ◽  
Scaling Properties ◽  
Second Moments ◽  
The Pacific ◽  
Unified Scaling Law ◽  
Aftershock Sequences ◽  
Integral Estimation

For each of three major M ≥ 7.0 earthquakes (i.e., the January 24, 2016, M7.1 earthquake 86 km E of Old Iliamna; the January 23, 2018, M7.9 earthquake 280 km SE of Kodiak; and the November 30, 2018, M7.1 earthquake 14 km NNW of Anchorage, Alaska), the study considers characterization of the foreshock and aftershock sequences in terms of their variations and scaling properties, including the behavior of the control parameter η of the unified scaling law for earthquakes (USLE), along with a detailed analysis of the surface wave records for reconstruction of the source in the approximation of the second moments of the stress glut tensor to obtain integral estimation of its length, orientation, and development over time. The three major earthquakes at 600 km around Anchorage are, in fact, very different due to apparent complexity of earthquake flow dynamics in the orogenic corner of the Pacific and North America plate boundary. The USLE generalizes the classic Gutenberg-Richter relationship taking into account the self-similar scaling of the empirical distribution of earthquake epicenters. The study confirms the existence of the long-term periods of regional stability of the USLE control parameter that are interrupted by mid- or even short-term bursts of activity associated with major catastrophic events.

On Prediction and Unified Correlation for Decay of Vertical Buoyant Jets

1979 ◽  
Vol 101 (3) ◽  
pp. 532-537 ◽  
Author(s):  
C. J. Chen ◽  
C. H. Chen
Keyword(s):  
Kinetic Energy ◽  
Scaling Law ◽  
Flow Characteristics ◽  
Heat Fluxes ◽  
Buoyant Jets ◽  
Numerical Result ◽  
Plume Region ◽  
Unified Scaling Law ◽  
Rate Of Dissipation ◽  
Decay Behavior

A differential turbulence model is used to predict the decay behavior of turbulent buoyant jets in a uniform environment at rest. The turbulent stresses and heat fluxes are modeled by the algebraic expressions while the differential transport equations are solved for the kinetic energy of turbulence, k, the rate of dissipation of turbulence kinetic energy, ε, and the fluctuating temperature T′2. The numerical result correlated with a unified scaling law was shown to fall into a single curve for the flows beyond the zone of flow establishment. The flow characteristics are then classified into a non-buoyant region, an intermediate region and a plume region. The predicted results show that the buoyant jets is accelerated in the zone of flow establishment. Equations for decay of velocity, density, and turbulent quantities are given from the non-buoyant region to the plume region for both plane and round buoyant jets.

scholarly journals On the enigmatic birth of the Pacific Plate within the Panthalassa Ocean

2016 ◽  
Vol 2 (7) ◽  
pp. e1600022 ◽  
Author(s):  
Lydian M. Boschman ◽  
Douwe J. J. van Hinsbergen
Keyword(s):  
Triple Junction ◽  
Tectonic Evolution ◽  
Plate Boundary ◽  
Pacific Plate ◽  
Plate Tectonic ◽  
Point Location ◽  
Marine Magnetic Anomalies ◽  
The Pacific ◽  
History Of ◽  
Ridge System

The oceanic Pacific Plate started forming in Early Jurassic time within the vast Panthalassa Ocean that surrounded the supercontinent Pangea, and contains the oldest lithosphere that can directly constrain the geodynamic history of the circum-Pangean Earth. We show that the geometry of the oldest marine magnetic anomalies of the Pacific Plate attests to a unique plate kinematic event that sparked the plate’s birth at virtually a point location, surrounded by the Izanagi, Farallon, and Phoenix Plates. We reconstruct the unstable triple junction that caused the plate reorganization, which led to the birth of the Pacific Plate, and present a model of the plate tectonic configuration that preconditioned this event. We show that a stable but migrating triple junction involving the gradual cessation of intraoceanic Panthalassa subduction culminated in the formation of an unstable transform-transform-transform triple junction. The consequent plate boundary reorganization resulted in the formation of a stable triangular three-ridge system from which the nascent Pacific Plate expanded. We link the birth of the Pacific Plate to the regional termination of intra-Panthalassa subduction. Remnants thereof have been identified in the deep lower mantle of which the locations may provide paleolongitudinal control on the absolute location of the early Pacific Plate. Our results constitute an essential step in unraveling the plate tectonic evolution of “Thalassa Incognita” that comprises the comprehensive Panthalassa Ocean surrounding Pangea.

scholarly journals Distribution of the Pacific/North America motion in the Queen Charlotte Islands-S. Alaska plate boundary zone

2003 ◽  
Vol 30 (14) ◽  
Author(s):  
Stéphane Mazzotti ◽  
Roy D. Hyndman ◽  
Paul Flück ◽  
Alex J. Smith ◽  
Michael Schmidt
Keyword(s):  
North America ◽  
Plate Boundary ◽  
Boundary Zone ◽  
Queen Charlotte Islands ◽  
The Pacific ◽  
Plate Boundary Zone

scholarly journals Complex networks of earthquakes and aftershocks

2005 ◽  
Vol 12 (1) ◽  
pp. 1-11 ◽  
Author(s):  
M. Baiesi ◽  
M. Paczuski
Keyword(s):  
Complex Networks ◽  
Time Windows ◽  
Scaling Law ◽  
Relative Strength ◽  
Modern Theory ◽  
Significant Information ◽  
Data Set ◽  
Scale Free ◽  
Main Shocks ◽  
Aftershock Sequences

Abstract. We invoke a metric to quantify the correlation between any two earthquakes. This provides a simple and straightforward alternative to using space-time windows to detect aftershock sequences and obviates the need to distinguish main shocks from aftershocks. Directed networks of earthquakes are constructed by placing a link, directed from the past to the future, between pairs of events that are strongly correlated. Each link has a weight giving the relative strength of correlation such that the sum over the incoming links to any node equals unity for aftershocks, or zero if the event had no correlated predecessors. A correlation threshold is set to drastically reduce the size of the data set without losing significant information. Events can be aftershocks of many previous events, and also generate many aftershocks. The probability distribution for the number of incoming and outgoing links are both scale free, and the networks are highly clustered. The Omori law holds for aftershock rates up to a decorrelation time that scales with the magnitude, m, of the initiating shock as tcutoff~10β m with β~-3/4. Another scaling law relates distances between earthquakes and their aftershocks to the magnitude of the initiating shock. Our results are inconsistent with the hypothesis of finite aftershock zones. We also find evidence that seismicity is dominantly triggered by small earthquakes. Our approach, using concepts from the modern theory of complex networks, together with a metric to estimate correlations, opens up new avenues of research, as well as new tools to understand seismicity.

Seismic coda Q and scaling law of the source spectra at the Aeolian Islands, southern Italy

1983 ◽  
Vol 73 (1) ◽  
pp. 97-108
Author(s):  
E. Del Pezzo ◽  
F. Ferulano ◽  
A. Giarrusso ◽  
M. Martini
Keyword(s):  
Southern Italy ◽  
Scaling Law ◽  
Coda Wave ◽  
Corner Frequency ◽  
Volcanic Complex ◽  
Coda Q ◽  
Aeolian Islands ◽  
Scaling Properties ◽  
Linear Pattern ◽  
Seismic Coda

abstract The model developed by Aki and Chouet for the coda wave generation and propagation has been used to calculate the quality factor Q for the zone of the Aeolian Islands, southern Italy, in the frequency range of 1 to 12 Hz, and the scaling properties of the seismic spectrum in the magnitude range of 0.4 to 4.7. The Q found for the Aeolian area has a frequency dependence of the form Q = qfv. The absolute values of Q seem to be dependent on the station and location of the seismic events, confirming the strong lateral heterogeneities in the geological structure beneath the Aeolian Arc. A temporal variation has been noted in the Q calculated at Vulcano station (VPL) in a period of 3 weeks soon after the occurrence of a main shock of ML = 5.5 located near the station. The scaling behavior of this sequence is similar to that obtained in two areas of California and one portion of Japan, with a corner frequency that remains constant with an increasing seismic moment between magnitudes 1 and 4. It differs substantially from the scaling properties of the Hawaian earthquakes that show a linear pattern, without an increase of the stress drop with magnitude. The fact that Vulcano is an active volcano seems not to influence the scaling properties of the seismic sequence localized very near it. It probably indicates that the aftershocks used for calculating the scaling law are generated out of the volcanic complex Lipari-Vulcano, in a zone with a good capability of accumulating the stress.

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