Aftershock Sequence of the 2011 Virginia Earthquake Derived from the Dense AIDA Array and Backprojection

2019 ◽  
Vol 109 (1) ◽  
pp. 19-33 ◽  
Author(s):  
G. D. Beskardes ◽  
Q. Wu ◽  
J. A. Hole ◽  
M. C. Chapman ◽  
K. K. Davenport ◽  
...  
Keyword(s):  
Aftershock Sequence ◽  
Virginia Earthquake

The Norris Lake Earthquake Swarm of June Through September, 1993; Preliminary Findings

1994 ◽  
Vol 65 (2) ◽  
pp. 167-171 ◽  
Author(s):  
L.T. Long ◽  
A. Kocaoglu ◽  
R. Hawman ◽  
P.J.W. Gore
Keyword(s):  
Earthquake Swarm ◽  
Building Stone ◽  
Aftershock Sequence ◽  
Average Depth ◽  
Induced Earthquakes ◽  
Epicentral Area ◽  
Event Recorder ◽  
Significant Damage ◽  
The 1950S ◽  
Recreational Lake

Abstract During the summer of 1993, the residents in the Norris Lake community, Lithonia, Georgia, were bothered by an incessant swarm of earthquakes. The largest, a magnitude 2.7 on September 23, showed a normal aftershock decay and occurred after the main swarm. Over 10,000 earthquakes have been detected, of which perhaps 500 were felt. The earthquakes began June 8, 1993, with a 5-day swarm. The residents, accustomed to quarry explosions, suspected the quarries of irregular activities. To locate the source of the events, a visual recorder and a digital event recorder were placed in the epicentral area. Ten to 20 events were detected per day for the next three weeks. The swarm then escalated to a peak of over 100 per day by August 15, 1993. Activity following the peak died down to about 10 events per day. The magnitude 2.7 event of September 23 was followed by a normal aftershock sequence. The larger events were felt with intensity V within 2 km of their epicenter, and noticed (intensity II) to a distance of 15 km. Some incidents of cracked wallboard and foundations have been reported, but no significant damage has been documented. Preliminary locations, based on data from digital event recorders, suggest an average depth of 1.0 km. The hypocenters are in the Lithonia gneiss, a massive migmatite resistant to weathering and used locally as a building stone. The epicenters are 1 to 2 km south-southwest of the Norris Lake Community. The cause of the seismicity is not yet known. The earthquakes are characteristic of reservoir-induced earthquakes; however, Norris Lake is a small (96 acres), 2 to 5m deep recreational lake which has existed since the 1950s.

scholarly journals Seismicity, focal mechanism, and stress tensor analysis of the Simav region, western Turkey

2020 ◽  
Vol 12 (1) ◽  
pp. 479-490
Author(s):  
Ahu Kömeç Mutlu
Keyword(s):  
Moment Tensor ◽  
Aftershock Sequence ◽  
Movement Direction ◽  
Normal Faults ◽  
Normal Faulting ◽  
Stress Inversion ◽  
Western Turkey ◽  
Stress Orientations ◽  
Extension Direction ◽  
Inversion Analysis

AbstractThis study focuses on the seismicity and stress inversion analysis of the Simav region in western Turkey. The latest moderate-size earthquake was recorded on May 19, 2011 (Mw 5.9), with a dense aftershock sequence of more than 5,000 earthquakes in 6 months. Between 2004 and 2018, data from earthquake events with magnitudes greater than 0.7 were compiled from 86 seismic stations. The source mechanism of 54 earthquakes with moment magnitudes greater than 3.5 was derived by using a moment tensor inversion. Normal faults with oblique-slip motions are dominant being compatible with the NE-SW extension direction of western Turkey. The regional stress field is assessed from focal mechanisms. Vertically oriented maximum compressional stress (σ1) is consistent with the extensional regime in the region. The σ1 and σ3 stress axes suggest the WNW-ESE compression and the NNE-SSW dilatation. The principal stress orientations support the movement direction of the NE-SW extension consistent with the mainly observed normal faulting motions.

Aftershock sequence of the 9 May 1989 Canary Islands earthquake

1996 ◽  
Vol 255 (1-2) ◽  
pp. 157-162 ◽  
Author(s):  
M.J. Jiménez ◽  
M. García-Fernández
Keyword(s):  
Canary Islands ◽  
Aftershock Sequence

scholarly journals Intermediate-term forecasting of aftershocks from an early aftershock sequence: Bayesian and ensemble forecasting approaches

2015 ◽  
Vol 120 (4) ◽  
pp. 2561-2578 ◽  
Author(s):  
Takahiro Omi ◽  
Yosihiko Ogata ◽  
Yoshito Hirata ◽  
Kazuyuki Aihara
Keyword(s):  
Aftershock Sequence ◽  
Ensemble Forecasting

The San Salvador Earthquake of October 10, 1986—Seismological Aspects and Other Recent Local Seismicity

1987 ◽  
Vol 3 (3) ◽  
pp. 419-434 ◽  
Author(s):  
Randall A. White ◽  
David H. Harlow ◽  
Salvador Alvarez
Keyword(s):  
Main Shock ◽  
Fault Plane ◽  
Vertical Plane ◽  
Aftershock Sequence ◽  
Central American ◽  
Fault Plane Solution ◽  
San Salvador ◽  
The North ◽  
Volcanic Chain ◽  
Plane Solution

The San Salvador earthquake of October 10, 1986 originated along the Central American volcanic chain within the upper crust of the Caribbean Plate. Results from a local seismograph network show a tectonic style main shock-aftershock sequence, with a magnitude, Mw, 5.6. The hypocenter was located 7.3 km below the south edge of San Salvador. The main shock ruptured along a nearly vertical plane toward the north-northeast. A main shock fault-plane solution shows a nearly vertical fault plane striking N32\sz\E, with left-lateral sense of motion. This earthquake is the second Central American volcanic chain earthquake documented with left-lateral slip on a fault perpendicular to the volcanic chain. During the 2 1/2 years preceeding the earthquake, minor microseismicity was noted near the epicenter, but we show that this has been common along the volcanic chain since at least 1953. San Salvador was previously damaged by a volcanic chain earthquake on May 3, 1965. The locations of six foreshocks preceding the 1965 shock show a distinctly WNW-trending distribution. This observation, together with the distribution of damage and a fault-plane solution, suggest that right-lateral slip occurred along a fault sub-parallel with Central American volcanic chain. We believe this is the first time such motion has been documented along the volcanic chain. This earthquake was also unusual in that it was preceded by a foreshock sequence more energetic than the aftershock sequence. Earlier this century, on June 08, 1917, an Ms 6.4 earthquake occurred 30 to 40 km west of San Salvador Volcano. Only 30 minutes later, an Ms 6.3 earthquake occurred, centered at the volcano, and about 35 minutes later the volcano erupted. In 1919 an Ms 6 earthquake occurred, centered at about the epicenter of the 1986 earthquake. We conclude that the volcanic chain is seismically very active with variable styles of seismicity.

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