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 Seismic Damage Accumulation in Highway Bridges in Earthquake-Prone Regions

2015 ◽  
Vol 31 (1) ◽  
pp. 115-135 ◽  
Author(s):  
Jayadipta Ghosh ◽  
Jamie E. Padgett ◽  
Mauricio Sánchez-Silva
Keyword(s):  
Service Life ◽  
Damage Accumulation ◽  
Main Shock ◽  
Prediction Models ◽  
Time Window ◽  
Damage Index ◽  
Active Regions ◽  
Highway Bridges ◽  
Main Shocks ◽  
Aftershock Sequences

Civil infrastructures, such as highway bridges, located in seismically active regions are often subjected to multiple earthquakes, including multiple main shocks during their service life or main shock–aftershock sequences. Repeated seismic events result in reduced structural capacity and may lead to bridge collapse, causing disruption in the normal functioning of transportation networks. This study proposes a framework to predict damage accumulation in structures subjected to multiple shock scenarios after developing damage index prediction models and accounting for the probabilistic nature of the hazard. The versatility of the proposed framework is demonstrated on a case-study highway bridge located in California for two distinct hazard scenarios: (1) multiple main shocks during the service life and (2) multiple aftershock earthquake occurrences following a single main shock. Results reveal that in both cases there is a significant increase in damage index exceedance probabilities due to repeated shocks within the time window of interest.

Prediction of upcoming grand episodes of solar activity

2018 ◽  
Vol 13 (S340) ◽  
pp. 325-326
Author(s):  
G. L. Jayalekshmi ◽  
P. R. Prince
Keyword(s):  
Solar Activity ◽  
Active Regions ◽  
Phase Changes ◽  
Activity Level ◽  
Time Interval ◽  
The Sun ◽  
Strong Magnetic Fields ◽  
Periodicity Analysis ◽  
Long Time ◽  
Grand Minima

AbstractSunspots are active regions on the surface of the Sun having strong magnetic fields. Activity level of the Sun shows long-time scale phenomena known as grand episodes-Grand maxima and Grand minima. Present study examines grand episodes shown by sunspot numbers (1090-2017), using methods of wavelet transform and sinusoidal regression. Time interval analysed includes two grand maxima and four grand minima. Interval in between grand episodes are regular oscillations. Phase changes found from periodicity analysis clearly show the presence of upcoming grand episodes. The forthcoming grand episodes are suggested to be two grand minima which are likely to occur between the years 2100-2160 and 2220-2300.

scholarly journals A simple metric to quantify seismicity clustering

2010 ◽  
Vol 17 (4) ◽  
pp. 293-302 ◽  
Author(s):  
N. F. Cho ◽  
K. F. Tiampo ◽  
S. D. Mckinnon ◽  
J. A. Vallejos ◽  
W. Klein ◽  
...  
Keyword(s):  
Physical Meaning ◽  
Finite Time ◽  
Metastable Equilibrium ◽  
Lower Sensitivity ◽  
Time Interval ◽  
Finite Time Interval ◽  
Time Intervals ◽  
The Past ◽  
Local Clustering ◽  
Over Time

Abstract. The Thirulamai-Mountain (TM) metric was first developed to study ergodicity in fluids and glasses (Thirumalai and Mountain, 1993) using the concept of effective ergodicity, where a large but finite time interval is considered. Tiampo et al. (2007) employed the TM metric to earthquake systems to search for effective ergodic periods, which are considered to be metastable equilibrium states that are disrupted by large events. The physical meaning of the TM metric for seismicity is addressed here in terms of the clustering of earthquakes in both time and space for different sets of data. It is shown that the TM metric is highly dependent not only on spatial/temporal seismicity clustering, but on the past seismic activity of the region and the time intervals considered as well, and that saturation occurs over time, resulting in a lower sensitivity to local clustering. These results confirm that the TM metric can be used to quantify seismicity clustering from both spatial and temporal perspectives, in which the disruption of effective ergodic periods are caused by the agglomeration of events.

Responses of Two Tall Buildings in Tokyo, Japan, before, during, and after the M9.0 Tohoku Earthquake of 11 March 2011

2016 ◽  
Vol 32 (1) ◽  
pp. 463-495 ◽  
Author(s):  
Mehmet Çelebi ◽  
Yoshiaki Hisada ◽  
Roshanak Omrani ◽  
S. Farid Ghahari ◽  
Ertugrul Taciroglu
Keyword(s):  
Urban Areas ◽  
Main Shock ◽  
Nonlinear Behavior ◽  
Tall Buildings ◽  
Tohoku Earthquake ◽  
Ground Level ◽  
The United States ◽  
Time Interval ◽  
Long Period ◽  
Fundamental Frequencies

The 11 March 2011 M 9.0 Tohoku earthquake generated significant long duration shaking that propagated hundreds of kilometers from the epicenter and affected urban areas throughout much of Honshu. Recorded responses of tall buildings at several hundred km from the epicenter of the main shock and other events show tall buildings were affected by long-period motions of events at distant sources. This study presents behavioral aspects of 29-story and 30-story neighboring buildings in the Shinjuku area of Tokyo, Japan, as inferred from records retrieved from a sparse array of accelerometers deployed in the superstructures, at ground and 100 m below the ground level over a time interval covering before, during, and after the main shock. Such long-period effects are common in several regions of Japan as well as in the United States and in other seismically active countries. Permanent shifts in fundamental frequencies are observed. Drift ratios indicate possible structural nonlinear behavior occurred during the main shock. The need to consider risks to built environments from distant sources, including those in neighboring countries, is emphasized.

Questions on measurements of the Earth’s crustal strain on the basis of GPS data on geodynamic moves of plates after earthquakes

2017 ◽  
Vol 919 (1) ◽  
pp. 40-44
Author(s):  
S.A. Ganiyeva ◽  
J.T. Mehdiyev
Keyword(s):  
Atmospheric Pressure ◽  
Main Shock ◽  
Complete Removal ◽  
Time Interval ◽  
Strong Earthquakes ◽  
The Earth ◽  
Shallow Earthquakes ◽  
Triangular Network ◽  
Gps System

It is well-known that strong shallow earthquakes are usually accompanied with series of aftershocks which can be explained by non-complete removal of strains, collected in the center during the main shock. But in some cases after some time interval the repeated strong earthquake happens in the same place. There are different versions for such repeated earthquakes. It is obvious, that all existing versions require presence or accumulation of strain in the active zone after the main shock which stress out the actuality of development of theoretical and methodological basics for assessment of strains on the basis of experimental data on plates motion. The importance of geodynamic research of remained strain at the Earth crust after strong earthquakes by way of calculation of remained strain on the basis of data plates is noted. It is shown, that utilization of GPS system for determination of shifts of plates could lead to error caused by shifts of GPS stations due to various causes.The consideration of the case where the non-stability of atmospheric pressure is a prevailing factor is reasoned. The related formulas for calculation of strain of the Earth crust on the basis of GPS measurements in the triangular network are given.

scholarly journals Some possible correlations between electro-magnetic emission and seismic activity during West Bohemia 2008 earthquake swarm

Solid Earth ◽  
2010 ◽  
Vol 1 (1) ◽  
pp. 93-98 ◽  
Author(s):  
P. Kolář
Keyword(s):  
Seismic Activity ◽  
Earthquake Swarm ◽  
Electromagnetic Emission ◽  
Active Regions ◽  
Observation Time ◽  
Time Interval ◽  
Seismic Region ◽  
West Bohemia ◽  
Long Time ◽  
Electro Magnetic

Abstract. A potential link between electromagnetic emission (EME) and seismic activity (SA) has been the subject of scientific speculations for a long time. EME versus SA relations obtained during the 2008 earthquake swarm which occurred in West Bohemia are presented. First, a brief characterisation of the seismic region and then the EME recording method and data analysis will be described. No simple direct link between EME and SA intensity was observed, nevertheless a deeper statistical analysis indicates: (i) slight increase of EME activity in the time interval 60 to 30 min before a seismic event with prevalent periods about 10 min, (ii) some gap in EME activity approximately 2 h after the event, and (iii) again a flat maximum about 4 h after the seismic events. These results qualitatively correspond with the observations from other seismically active regions (Fraser-Smith et al., 1990). The global decrease of EME activity correlating with the swarm activity decay was also observed. Due to the incomplete EME data and short observation time, these results are limited in reliability and are indicative only.

scholarly journals The Spot Activity of FK Comae Berenices

1991 ◽  
Vol 130 ◽  
pp. 381-383
Author(s):  
Lauri Jetsu ◽  
Jaan Pelt ◽  
Ilkka Tuominen ◽  
Harold Nations
Keyword(s):  
Active Regions ◽  
Phase Coherence ◽  
The Other ◽  
Stellar Surface ◽  
Time Interval ◽  
Flip Flop ◽  
Non Linear ◽  
Spot Activity

AbstractThe active regions of FK Comae Berenices show a flip-flop behaviour, i.e. the concentrated part of spot-activity shifts exactly to the other side of stellar surface, and then remains on the same longitude for a time interval from a few years to a decade. The activity shows excellent phase coherence with respect to these two active longitudes separated 180 degrees from each other. FK Comae may provide a physical example of a non-linear dynamo, which shows surprisingly simple observational changes in the pattern of the magnetically induced spot configurations.

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.

Responses of a Tall Building with U.S. Code-Type Instrumentation in Tokyo, Japan, to Events before, during, and after the Tohoku Earthquake of 11 March 2011

2016 ◽  
Vol 32 (1) ◽  
pp. 497-522 ◽  
Author(s):  
Mehmet Çelebi ◽  
Toshihide Kashima ◽  
S. Farid Ghahari ◽  
Fariba Abazarsa ◽  
Ertugrul Taciroglu
Keyword(s):  
Urban Areas ◽  
Main Shock ◽  
Tall Buildings ◽  
Tohoku Earthquake ◽  
Time Interval ◽  
Long Duration ◽  
Reliable Assessment ◽  
And Performance ◽  
Code Type ◽  
Tall Structure

The 11 March 2011 M 9.0 Tohoku earthquake generated long-duration shaking that propagated hundreds of kilometers from the epicenter and affected tall buildings in urban areas several hundred kilometers from the epicenter of the main shock. Recorded responses show that tall buildings were affected by long-period motions. This study presents the behavior and performance of a 37-story building in the Tsukuda area of Tokyo, Japan, as inferred from modal analyses of records retrieved for a time interval covering a few days before, during, and for several months after the main shock. The U.S. “code-type” array comprises three triaxial accelerometers deployed at three levels in the superstructure. Such a sparse array in a tall structure limits a reliable assessment, because its performance must be based on only the average drift ratios. Based on the inferred values of this parameter, the subject building was not structurally damaged.

scholarly journals Time-predictable model applicability for earthquake occurrence in northeast India and vicinity

2011 ◽  
Vol 11 (3) ◽  
pp. 993-1002 ◽  
Author(s):  
A. Panthi ◽  
D. Shanker ◽  
H. N. Singh ◽  
A. Kumar ◽  
H. Paudyal
Keyword(s):  
Active Regions ◽  
Northeast India ◽  
United States Geological Survey ◽  
Time Interval ◽  
Plate Boundaries ◽  
Generation Model ◽  
Earthquake Occurrence ◽  
Earthquake Catalogues ◽  
Repeat Time ◽  
Earthquake Generation

Abstract. Northeast India and its vicinity is one of the seismically most active regions in the world, where a few large and several moderate earthquakes have occurred in the past. In this study the region of northeast India has been considered for an earthquake generation model using earthquake data as reported by earthquake catalogues National Geophysical Data Centre, National Earthquake Information Centre, United States Geological Survey and from book prepared by Gupta et al. (1986) for the period 1906–2008. The events having a surface wave magnitude of Ms≥5.5 were considered for statistical analysis. In this region, nineteen seismogenic sources were identified by the observation of clustering of earthquakes. It is observed that the time interval between the two consecutive mainshocks depends upon the preceding mainshock magnitude (Mp) and not on the following mainshock (Mf). This result corroborates the validity of time-predictable model in northeast India and its adjoining regions. A linear relation between the logarithm of repeat time (T) of two consecutive events and the magnitude of the preceding mainshock is established in the form LogT = cMp+a, where "c" is a positive slope of line and "a" is function of minimum magnitude of the earthquake considered. The values of the parameters "c" and "a" are estimated to be 0.21 and 0.35 in northeast India and its adjoining regions. The less value of c than the average implies that the earthquake occurrence in this region is different from those of plate boundaries. The result derived can be used for long term seismic hazard estimation in the delineated seismogenic regions.

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