scholarly journals Reappearance of Characeristic Seismicity Pattern in the Tokai and Tonankai Regions (Seismic Activity Change in the Tokai Region: Part 6)

2010 ◽  
Vol 63 (2) ◽  
pp. 83-95
Author(s):  
Shozo MATSUMURA
Keyword(s):  
Seismic Activity ◽  
Activity Change ◽  
Seismicity Pattern ◽  
Tokai Region

SEISMIC ACTIVITY CHANGE PRECEDING THE SUMATRA GIANT EARTHQUAKE SERIES, 2004M9.0, 2005M8.6, AND 2007M8.5

2009 ◽  
Vol 03 (01) ◽  
pp. 17-24
Author(s):  
SHOZO MATSUMURA
Keyword(s):  
Stress Concentration ◽  
Seismic Activity ◽  
Plate Boundary ◽  
Activity Change ◽  
Locked Plate ◽  
The Real ◽  
Giant Earthquake ◽  
Induced Stress ◽  
Earthquake Series ◽  
Significant Change

The seismicity along the Sunda trench was examined from the viewpoint of whether or not any significant change preceded the major earthquakes. Based on the seismicity of M5 and greater earthquakes, a growth of activated zones with time approaching the final breakage was detected. These activated zones well predicted the positions of the real asperities for the following 2004 M9.0, 2005 M8.6, and 2007 M8.5 events. Such a feature in seismicity change can be explained by introducing an assumption that a quasi-static slip progressed on a weakly locked plate boundary prior to the final breakage, and resulted in an activation corresponding to the induced stress concentration. At present, there are two activated zones unresolved. Accepting the limit in validity of the above hypothesis, I would like to give warnings for imminent earthquake occurrences in these zones.

Seismic activity on the southern Calaveras Fault in central California

1980 ◽  
Vol 70 (4) ◽  
pp. 1181-1197
Author(s):  
William H. Bakun
Keyword(s):  
Seismic Moment ◽  
Seismic Activity ◽  
Main Shock ◽  
San Andreas Fault ◽  
San Jose ◽  
Central California ◽  
Seismicity Pattern ◽  
San Andreas ◽  
Fault Trace ◽  
The Right

abstract Cumulative seismic moment ΣM0 for earthquake on 50-km-long creeping section of the Calaveras Fault from near Mount Hamilton southeast to San Felipe Lake correlates with mapped fault-trace characteristics. In general, ΣM0 is lower at the left-stepping offset in the trace at the south end of Anderson Lake and along linear segments of the fault than near right-stepping offsets and bends in the trace and intersections of the Calaveras with other faults. Rupture expansion for the August 6, 1979 Coyote Lake sequence main shock, 10 km NNE of Gilroy, California, was unilateral to the southeast (Archuleta, 1979) away from the right-stepping offset in the fault trace near its epicenter. Rupture expansion for the two felt shocks (ML 4.2 and ML 3.9) on August 29, 1978 located 112 km apart near Halls Valley east of San Jose was unilateral for each away from the other, suggesting the existence of a rupture-expansion blocking discontinuity between them. The correlations of seismic activity and fault-trace characteristics are similar to those for shocks along the creeping section of the San Andreas Fault in central California and suggest that the specific “stuck” and “creeping” patch model of Bakun et al. (1980) developed for the San Andreas is applicable to the creeping Calaveras Fault as well. Cumulative seismic moment (January 1, 1969 to August 6, 1979) within the 16-km-long 1979 Coyote Lake sequence aftershock zone was less than that near the fault-trace discontinuities at its ends. Microearthquakes along the Calaveras Fault near the Coyote Lake aftershock zone increased before the sequence beginning with a cluster on June 22, 1978 near the southeast end of the aftershock zone. A similar seismicity pattern preceded the August 29, 1978 shocks and the ML 4.5 May 8, 1979 shock near Halls Valley.

Seismicity, tectonism, and surface faulting in the western United States during historic time

1966 ◽  
Vol 56 (5) ◽  
pp. 1105-1135 ◽  
Author(s):  
Alan Ryall ◽  
David B. Slemmons ◽  
Larry D. Gedney
Keyword(s):  
United States ◽  
Seismic Activity ◽  
Western United States ◽  
Seismic Zone ◽  
Seismicity Pattern ◽  
Seismic Zones ◽  
Historic Time ◽  
Before And After ◽  
High Level ◽  
Large Earthquakes

Abstract Maps of tectonic flux are presented for the conterminous United States west of longitude 109°W, for periods of time before and after 1932, and for the entire historic period through 1961. The most active continuous seismic zone in this region during historic time extended over 750 km, from a point off the California coast near Ventura to Winnemucca in north-central Nevada. Although this zone is characterized by a discontinuous line of historic surface faulting, it is neither sharply defined by, nor closely related to structures along its path that are generally considered to be the major tectonic elements of the region. The broad areal extent of this, and five other active zones, suggests that the tectonic processes causing earthquakes and surface faulting in the western United States are distributed over broad regions, and are not confined to geologic or physiographic provinces. Seismicity maps for different periods indicate that seismic activity in some areas has shifted with time. Within major seismic zones, gaps in the seismicity pattern are filled in by successive large earthquakes. Recurrence curves support a high level of activity for the Ventura-Winnemucca zone, and they indicate a lower rate of activity for the San Andreas fault zone than for other areas in the region studied. Recurrence curves for the central California area indicate that the rate of activity in a given region may remain practically constant over periods at least as long as a century, whether or not large earthquakes occur in the region during those periods. There appears to be a general correlation between observed shear or slippage, and the seismicity of any given region. Based on these results, it is proposed that, where historic faulting has occurred in areas with little or no historic seismic activity, such faulting is due to the propagation of fractures into the inactive areas from adjoining seismic zones.

Change in seismic activity in the Tokai region related to weakening and strengthening of the interplate coupling

2006 ◽  
Vol 417 (1-2) ◽  
pp. 17-31 ◽  
Author(s):  
Akio Yoshida ◽  
Kohji Hososno ◽  
Toshimitsu Tsukakoshi ◽  
Akio Kobayashi ◽  
Hiromi Takayama ◽  
...  
Keyword(s):  
Seismic Activity ◽  
Interplate Coupling ◽  
Tokai Region
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