scholarly journals Damage Assessment of an SRC Frame-Core Tube Structure under the Action of a Main Aftershock Sequence

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Peng Wang ◽  
Qingxuan Shi ◽  
Feng Wang ◽  
Siusiu Guo
Keyword(s):  
Main Shock ◽  
Vulnerability Index ◽  
Aftershock Sequence ◽  
Time Interval ◽  
Demand Model ◽  
Core Tube ◽  
Repair Work ◽  
Damage Data ◽  
Probabilistic Seismic Demand ◽  
Tube Structure

Historical seismic damage data show that most strong earthquakes are accompanied by multiple intense aftershocks. In general, the time interval between the main shock and the aftershocks is relatively short, and structure repair work is often not completed before the aftershocks occur. For a structure that has suffered damage from the main shock, the aftershock will further aggravate the damage and even cause complete collapse. Based on the incremental dynamic analysis (IDA) method, this paper establishes a probabilistic seismic demand model for the SRC framework-core tube structure and plots the vulnerability curve of a structure under the action of the main aftershock sequence, which occurs following the actions of frequent earthquakes, fortification earthquakes, and rare earthquakes. The structure vulnerability matrix and the vulnerability index are used to evaluate the seismic performance of a structure. This study found that the occurrence of aftershocks leads the structure to a more unfavourable failure state. Taking the vulnerability index as an evaluation parameter, the structural vulnerability index when subjected to an intensity 8 earthquake under the action of the main aftershock is approximately 10% larger than under the action of a single main shock. Meanwhile, the SRC frame-core structure designed according to the current Chinese specifications meets the expected seismic fortification target, even after being acted upon by the main aftershock ground motion sequence.

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.

A fault model for the Nahanni earthquakes from aftershock studies

1990 ◽  
Vol 80 (6A) ◽  
pp. 1553-1570 ◽  
Author(s):  
R. B. Horner ◽  
R. J. Wetmiller ◽  
M. Lamontagne ◽  
M. Plouffe
Keyword(s):  
Stress Drop ◽  
Main Shock ◽  
Fault Zones ◽  
Aftershock Sequence ◽  
Aftershock Activity ◽  
Thrust Faulting ◽  
Rupture Plane ◽  
To Come ◽  
Activity Mechanism ◽  
Secondary Fault

Abstract Relative locations of 323 large aftershocks (M 3.0 or greater) in the period from 5 October 1985 to 25 March 1988 show that the Ms 6.6 event on 5 October 1985 initiated at 62.208°N, 124.217°W, about 2.5 km northeast of the Ms 6.9 main shock on 23 December 1985. The overall aftershock distribution suggests the October rupture was primarily a west-dipping, low-angle thrust. In subsequent aftershock activity, the main rupture plane was marked by a distinct quiescent area of about 200 km2 that persisted until the 23 December event. Most of the stress drop and slip occurred in this area. Following the 23 December rupture, a similar sized quiescent zone was also observed; however, it was only evident during the first 24 hr of the aftershock sequence, and the area was about 50 per cent too small to yield the overall stress drop. The additional area appeared to come from secondary rupture zones that developed coincident with the main shock rupture. Precise locations of 182 small (M 3.0 or less) aftershocks recorded during a third field survey from 12 to 21 September 1986 indicated at least one and probably three high-angle faults. Composite mechanism solutions showed thrust faulting except in a region directly south of the main shock rupture areas where there is a bend in one of the secondary fault zones and a concentration of aftershock activity. Mechanism solutions calculated for five of the largest aftershocks in the same region also indicated a similar variability. Development of secondary fault zones explained the increased complexity of the December event and may also provide an explanation for the vertical peak acceleration exceeding 2 g that was recorded about 10 sec after the December rupture initiated.

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.

Aftershock sequence and focal parameters of the February 28, 1969 earthquake of the Azores-Gibraltar fracture zone

1972 ◽  
Vol 62 (3) ◽  
pp. 699-719 ◽  
Author(s):  
A. López Arroyo ◽  
A. Udías
Keyword(s):  
Canary Islands ◽  
Fracture Zone ◽  
Main Shock ◽  
Fault Plane ◽  
Aftershock Sequence ◽  
Strike Slip ◽  
Strait Of Gibraltar ◽  
Wide Region ◽  
Focal Parameters ◽  
Source Mechanism Solution

Abstract The earthquake of February 28, 1969, which occurred about 500 km west of the Strait of Gibraltar, was felt over the entire Iberian Peninsula, in a wide region of Morocco, and south to the Canary Islands. It had a long sequence of aftershocks continuing for at least 10 months, but, nevertheless, most of the energy seems to have been liberated in the main shock of which the mb was 7.4. The source mechanism solution indicates a fault plane striking N 67°W and dipping 68°SW, with motion principally of the strike-slip type. There also is some overthrusting. The horizontal extent of faulting is of the order of 90 km.

Observations of the Coyote Lake, California earthquake sequence of August 6, 1979

1980 ◽  
Vol 70 (2) ◽  
pp. 559-570 ◽  
Author(s):  
R. A. Uhrhammer
Keyword(s):  
San Francisco ◽  
Fault Zone ◽  
Strong Earthquake ◽  
Main Shock ◽  
B Value ◽  
Aftershock Sequence ◽  
The South ◽  
The North ◽  
Temporal And Spatial Characteristics ◽  
Largest Aftershock

abstract At 1705 UTC on August 6, 1979, a strong earthquake (ML = 5.9) occurred along the Calaveras fault zone south of Coyote Lake about 110 km southeast of San Francisco. This strong earthquake had an aftershock sequence of 31 events (2.4 ≦ ML ≦ 4.4) during August 1979. No foreshocks (ML ≧ 1.5) were observed in the 3 months prior to the main shock. The local magnitude (ML = 5.9) and the seismic moment (Mo = 6 × 1024 dyne-cm from the SH pulse) for the main shock were determined from the 100 × torsion and 3-component ultra-long period seismographs located at Berkeley. Local magnitudes are determined for the aftershocks from the maximum trace amplitudes on the Wood-Anderson torsion seismograms recorded at Berkeley (Δ ≊ 110 km). Temporal and spatial characteristics of the aftershock sequence are presented and discussed. Some key observations are: (1) the first six aftershocks (ML ≧ 2.4) proceed along the fault zone progressively to the south of the main shock; (2) all of the aftershocks (ML ≧ 2.4) to the south of the largest aftershock (ML = 4.4) have a different focal mechanism than the aftershocks to the north; (3) no aftershocks (ML ≧ 2.4) were observed significantly to the north of the main shock for the first 5 days of the sequence; and (4) the b-value (0.70 ± 0.17) for the aftershock sequence is not significantly different from the average b-value (0.88 ± 0.08) calculated for the Calaveras fault zone from 16 yr of data.

scholarly journals On the validity of the regional time and magnitude predictable model in China

1999 ◽  
Vol 42 (5) ◽  
Author(s):  
C. Qin ◽  
E. E. Papadimitriou ◽  
B. C. Papazachos ◽  
G. F. Karakaisis
Keyword(s):  
Physical Meaning ◽  
Main Shock ◽  
Active Regions ◽  
Time Interval ◽  
Tectonic Loading ◽  
Simplified Form

A simplified form of the "regional time and magnitude predictable model" gives the time interval, T, between two successive mainshocks in a region and the magnitude, Mf, of the following mainshock by the relations: logT=cMP+a; Mf=CMp+A, where Mp is the magnitude of the preceding mainshock, a, A are constants which depend on the minimum considered mainshock and on the region's tectonic loading (moment rate). The physical meaning of the model is that the larger the magnitude of the preceding main shock, Mp, the longer the time, T, will be till the occurrence of the next one and the smaller its magnitude, Mf. This means that parameters c and C are positive and negative, respectively, when the model has been found valid for a certain area. In order to examine if the above model is appropriate to describe the seismicity behavior in the area of China, a detailed inspection was carried out aiming to show if the estimated values of parameters c and C favor the model. The results show that c tends to the global value 0.33, obtained by Papazachos and Papadimitriou (1997), and that C tends to be within the range [-0.30, -0.23]. The results, which favored the model, greatly outnumber those that do not follow it, the latter being concentrated around the boundaries of the seismically active regions. It is concluded that the results, which favor the model, obviously dominate the whole territory of China.

scholarly journals The aftershock sequence of the Kamchatka earthquake of November 4, 1952

1958 ◽  
Vol 48 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Markus Båth ◽  
Hugo Benioff
Keyword(s):  
Aftershock Sequence ◽  
Stress System ◽  
Time Interval ◽  
Aftershock Activity ◽  
Kamchatka Earthquake ◽  
Strain Release ◽  
Release Curve ◽  
Mohorovičić Discontinuity ◽  
Total Average ◽  
Northern Japan

Abstract Aftershock epicenters of the Kamchatka earthquake of November 4, 1952, are distributed over an area approximately 1,030 kilometers in length by 240 kilometers in width. Assuming that this distribution represents the active strain zone, the total average strain, average elastic energy, and average stress of the rocks before slip were 11.9 × 10−5, 1.35 × 102 ergs/cm.3, and 12.6 kg/cm.2, respectively. The strain-release curve of the sequence has been constructed using observations from Uppsala and Kiruna. The data include more than 400 shocks with magnitudes 6.0 and greater which have occurred up to December, 1956. The curve exhibits three segments each of the form ΣJ1/2 = A + B log t, where J is the energy and t is the time measured from the time of the principal earthquake. The slope B changes abruptly at t = 0.4 days and at t = 195 days, the latter change being particularly pronounced. Moreover, this was accompanied by other evidence suggesting a change in mechanism. The coefficients B have almost the exact ratio of 1 : 2 : 5 in the three intervals 0-0.4, 0.4—195, and after 195 days. The aftershock activity has its highest concentration in the vicinity of the principal earthquake and tapers off toward both ends of the active fault segment. The majority of the aftershocks have clear pP impulses occurring generally 9 to 13 sec. after P, indicating that the foci were in or close to the Mohorovičić discontinuity. The rate of strain accumulation and release for the time interval from 1897 to 1956 for the entire Kamchatka-northern Japan stress system shows a slow decrease with time. Comparison of the rate of the entire system with that of the aftershock sequence leads to an approximate estimate of the possible duration of the sequence.

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