Tangshan Earthquake Research Articles

Temporal and spatial variation characteristics of present stress field in the northern area of North China

From focal mechanism solutions of the earthquakes in the northern part of North China during the period of 2002∼2006, the directions of principal stress axes in 4 stress sub-districts are analyzed using a grid test method. The characteristic of present crustal stress directions is discussed. Based on this result and on the focal mechanism solutions calculated for some events in the period of 1977∼1998, in combination with some other study results, the temporal variation of present crustal stress directions in the northern part of North China is investigated. The results confirm that the direction of crustal principal stress in some regions had somewhat rotated after the 1976 Tangshan M7.8 earthquake. The mean P axes of the focal mechanism solutions rotated clockwise not only in Tangshan sub-district, but also in Beijing and Xingtai sub-districts after the Tangshan earthquake. In Beijing and Xingtai sub-districts the orientations of principal stress axes in the period of 2002∼2006 are consistent with that before the Tangshan earthquake, implying that the stress orientations has rotated back to the state before the Tangshan earthquake in these two sub-districts. The directions of the mean P axes are nearly E-W in Tangshan sub-district since the M7.8 earthquake. The present stress field in the sub-district northwest to Beijing, or in the western part of the Zhangjiakou-Bohai fault zone, is relatively stable during the time period concerned in this study. Because of the limitation of data, this paper only states a possible variation of stress field in the northern part of North China in the recent decades.

Impact of intensity and loss assessment following the great Wenchuan Earthquake

The great Wenchuan Earthquake occurred on May 12, 2008 in the Sichuan Province of China, and had a magnitude of 8.0. It is the most serious earthquake disaster in China since the great Tangshan Earthquake (Ms=7.8, July 28, 1976). According to official reports, there were 69,225 deaths, 379,640 injuries and 17,939 missing as of Aug. 11, 2008. The China Earthquake Administration quickly sent hundreds of experts to the field immediately after the event, to investigate the damage and assess the economic losses. This paper emphasizes the impact of seismic intensity and presents a preliminary loss assessment. A brief description of the geological features of the affected region is provided, followed by a summary of the earthquake damage. An isoseismal map is developed that shows that the high intensity region is distributed like a belt around the seimogenic fault, and that the epicentral intensity reached XI (Chinese Intensity Scale, similar to the Modified Mercalli Scale). The direct economic loss resulting from the earthquake is 692 billions RMB (about 100 billions US$).

Seismic images under the Beijing region inferred from P and PmP data

In this study a new tomographic method is applied to over 1500 high-quality PmP (Moho reflected wave) travel-time data as well as over 38,500 high-quality first P-wave arrivals to determine a detailed 3D crustal velocity structure under Beijing and adjacent areas. Results of detailed resolution analyses show that the PmP data can significantly improve the resolution of the model in the middle and lower crust. After the PmP data are included in the tomographic inversion, our new model not only displays the tectonic feature appeared in the previous studies, but also reveals some new features. The Zhangjiakou-Bohai Sea fault zone (Zhang-Bo zone) is imaged as prominent and continuous low-velocity (low-V) anomalies in the shallower crust, while in the middle and lower crust it shows intermittent low-V anomalies extending down to the uppermost mantle. Furthermore, the pattern of low-V anomalies is different along the Zhang-Bo zone from the southeast to the northwest, indicating that there exist large differences in the dynamic evolution of Taihangshan and Yanshan uplifts and North China depression basin. Prominent low-V anomalies are visible under the source area of the 4 July 2006 Wen-An earthquake (M 5.1), suggesting that the occurrence of the Wen-An earthquake is possibly related to the effect of the crustal fluids probably caused by the upwelling of the hot and wet asthenospheric materials due to the deep dehydration of the stagnant Pacific slab in the mantle transition zone. The fluids in the lower crust may cause the weakening of the seismogenic layer in the upper and middle crust and thus contribute to the initiation of the Wen-An earthquake. This is somewhat similar to the cause of the 1695 Sanhe-Pinggu earthquake and the 1976 Tangshan earthquake in the region, as well as the 1995 Kobe earthquake in Japan and the 2001 Bhuj earthquake in India.

An Algorithm of Fault Parameter Determination Using Distribution of Small Earthquakes and Parameters of Regional Stress Field and Its Application to Tangshan Earthquake Sequence

AbstractIt is known that clustered small earthquakes often occur in the fault plane vicinities of large earthquakes. Based on the simulated annealing and Gauss‐Newtonian nonlinear inversion algorithms, we develop a robust algorithm to estimate fault plane parameters of strong earthquakes such as strike, dip, and location using data of densely populated small events. Rake angle of the fault plane is further inferred from regional tectonic stress parameters. This method can also be employed for determination of fault plane parameters of an active fault using data of densely populated small earthquakes.We apply the algorithm to investigate the fault planes of the 1976 Tangshan, Luanxian, and Ninghe earthquakes and the Lulong fault, using precisely relocated earthquakes which occurred near the earthquake rupture zone between 1 April 2002 and 31 May 2006, and obtain the parameters of strike, dip, location, and rake angle of these fault planes. Our estimated fault planes are close to the results of previous studies, attesting the validity of our method. In addition, we discover an aligned seismic belt east of the Luanxian seismic zone trending NE‐SW, which can be ascertained as a fracture zone. The faulting parameters of the fracture zone such as the strike, dip and rake are determined accurately. It is still an open question whether the Luanxian and Ninghe faults have ruptured during the Tangshan earthquake sequence, answers to the question await for further multi‐disciplinary studies and bear great significance for the understanding of dynamic processes of the Tangshan earthquake sequence.

The 1998Mw5.7 Zhangbei‐Shangyi (China) earthquake revisited: A buried thrust fault revealed with interferometric synthetic aperture radar

The 1998Mw5.7 Zhangbei‐Shangyi (China) earthquake is the largest to have occurred in northern China since the large 1976Ms7.8 Tangshan earthquake. Due to its proximity to Beijing, the capital of China, it has therefore gained a lot of attention. A great number of studies have been conducted using seismic and geodetic data, but few are able to identify conclusively the orientation of the primary fault plane for this earthquake. In this paper, two independent ERS synthetic aperture radar interferograms are used to determine precisely the location and magnitude of coseismic surface displacements (∼11 cm in the radar line of sight). Modeling the event as dislocation in an elastic half‐space suggests that the earthquake is associated with a buried shallow NNE‐SSW oriented thrust fault with a limited amount of lateral displacement, which is consistent with seismic intensity distribution and aftershock locations.

Seismic response analysis of the deep saturated soil deposits in Shanghai

The quaternary deposits in Shanghai are horizontal soil layers of thickness up to about 280m in the urban area with an annual groundwater table between 0.5 and 0.7m from the surface. The characteristics of deep saturated deposits may have important influences upon seismic response of the ground in Shanghai. Based on the Biot theory for porous media, the water-saturated soil deposits are modeled as a two-phase porous system consisting of solid and fluid phases, in this paper. A nonlinear constitutive model for predicting the seismic response of the ground is developed to describe the dynamic characters of the deep-saturated soil deposits in Shanghai. Subsequently, the seismic response of a typical site with 280m deep soil layers, which is subjected to four base excitations (El Centro, Taft, Sunan, and Tangshan earthquakes), is analyzed in terms of an effective stress-based finite element method with the proposed constitutive model. Special emphasis is given to the computed results of accelerations, excess pore-water pressures, and settlements during the seismic excitations. It has been found that the analysis can capture fundamental aspects of the ground response and produce preliminary results for seismic assessment.

Managing Disasters: The Role of Local Government

In major disasters, local communities are often on their own for several hours or days. Local governments can play a key role in taking the initiative to protect their citizens. This essay compares the experience of New Orleans before, during, and after the catastrophe of Hurricane Katrina with the performance of Qinglong County, China, during the Tangshan earthquake of 1976. Qinglong County exemplifies local government taking initiative in risk assessment, decision making, operations, information sharing, and communications.

Seismogenic Tectonic Environment of 1976 Great Tangshan Earthquake: Results from Dense Seismic Array Observations

On July 28, 1976, the great Tangshan earthquake that shook the whole world took place in the Tangshan area of the Hebei Province, China. A big incomprehensible question is why such a tremendous earthquake took place in the Paleo-craton area in North China? It would be worth considering whether a similar event will reoccur in the Tangshan region. In this study, using the receiver function inversion technique and teleseismic P waveform data recorded at the Capital Circle Seismic network and our movable seismic array, we investigated the 3-D S-wave velocity structure of the crust and upper mantle down to 60 km beneath Tangshan area. Our results manifest that (1) the media beneath the Tangshan block cut by active faults are very different from the adjacent area, and all of the active faults surrounding the Tangshan block was through the whole crust; (2) in the upper and middle crust, there exist obvious heterogeneous low-velocity media beneath the Tangshan earthquake region; the crust-mantle boundary has an obvious block uplift and, in comparison with both sides, the top anomalous uplift of the upper mantle beneath the Tangshan block reaches to 10 km, and the upper mantle beneath has an anomalous heterogeneous structure; (4) beneath the Tangshan earthquake region, there are probably massive intrusions derived from the upper mantle, which form the low-velocity body in the upper and middle crust. Because of our results having much higher resolution than previous results, some new features of the crust and upper mantle velocity structure could be shown in this study; (5) the locations of destructive earthquakes are not random and are related closely to their deep structure of the crust and upper mantle. This provides a possibility of correctly estimating the location of destructive earthquakes. On the basis of our results, we discuss the dynamic genesis of the Tangshan earthquake. We consider that the main dynamic source for the Tangshan earthquake is the vertical movement of the upper mantle, which leads to the exchange of material and energy between the crust and the upper mantle. The horizontal stress field plays only a subordinate role. This observation facilitates our understanding of why the Tangshan earthquake with the magnitude greater than 7.0 occurred within the Paleo-craton area of North China. A problem worth considering is whether there is a possibility that same magnitude events will reoccur in the Tangshan region.

Successful Earthquake Mitigation in Qinglong County during the Great Tangshan Earthquake: Lessons for Hurricane Katrina in the United States

More than 246,000 people were killed in the 1976 Tangshan Earthquake. In Qinglong County, despite the collapse of 180,000 buildings, no deaths were attributable to the earthquake and its aftershocks. The case of Qinglong County illustrates excellent coordination among public administrators, scientists and citizens and features pro-active policies, local government initiative, thorough implementation, delegation, information sharing, and citizen participation. These lessons are applied to the response to Hurricane Katrina in the United States in 2005.

Analysis of the risk factors of upper urinary tract dilatation due to spinal cord injury

To evaluate the urodynamic risk factors of upper urinary tract dilatation (UUTD) secondary to spinal cord injury (SCI). Ninety-six SCI patients of Tangshan earthquake were divided into 2 groups by ultrasonography: 16 SCI patients (group A) with UUTD and 80 SCI patients (group B) without UUTD received urodynamic test. Responses were evaluated using single and multiple analysis after examination. The incidence of male was significantly higher than that of female. Residual urine volume, maximum cystometric capacity, detrusor leak point pressure and the incidence of bladder low compliance in group A were significantly higher than those in group B. There were no significant differences in age, the incidence of detrusor hyperreflexia, relative safe bladder capacity, the incidence of detrusor-sphincter dyssynergia, maximum flow rate and maximum urethral closure pressure between 2 groups. Bladder low compliance was cardinal risk factors according to Logistic regression analysis. An early urodynamic examination and treatment for SCI patients are important to prevent from bladder low compliance and upper urinary tract damage.

State Vector: A New Approach to Prediction of the Failure of Brittle Heterogeneous Media and Large Earthquakes

The concept of state vector stems from statistical physics, where it is usually used to describe activity patterns of a physical field in its manner of coarsegrain. In this paper, we propose an approach by which the state vector was applied to describe quantitatively the damage evolution of the brittle heterogeneous systems, and some interesting results are presented, i.e., prior to the macro-fracture of rock specimens and occurrence of a strong earthquake, evolutions of the four relevant scalars time series derived from the state vectors changed anomalously. As retrospective studies, some prominent large earthquakes occurred in the Chinese Mainland (e.g., the M 7.4 Haicheng earthquake on February 4, 1975, and the M 7.8 Tangshan earthquake on July 28, 1976, etc) were investigated. Results show considerable promise that the time-dependent state vectors could serve as a kind of precursor to predict earthquakes.

GENERATION OF ARTIFICIAL EARTHQUAKE MOTION RECORDS USING WAVELETS AND PRINCIPAL COMPONENT ANALYSIS

In the last century alone two to three million people died in earthquakes; More than 240 000 perish in Tangshan earthquake in China, 20 000 in the Izmit [Ikeya, 2004] 50 000 in India Bhuj earthquake, 100000 in Sumatra and 90000 in Pakistan earthquakes. Earthquake engineering has progressed to the stage where it is now computationally practical and desirable to perform a dynamic analysis of most civil engineering structures. Such an analysis requires the engineer to create an accurate analytical model of the structures as well as prescribe an earthquake input excitation. The design earthquake input excitation for the site under consideration is usually prescribed in the form of response spectra or in the form of an ensemble of artificial earthquake acceleration time histories. There is every need for generating artificial accelerograms since recorded accelerograms are very limited at site. This paper proposes five neural network based models for the generation of artificial earthquake and response spectra using wavelet transforms (WT) and principal component analysis (PCA) where the recorded accelerograms are limited at site of interest. The proposed model is compared with Lee and Han's model. The data for 25 earthquakes are taken for training and 4 for testing. Just like response spectra, this is also a convenient way of obtaining the design solution to a structural dynamics problem and is certainly an important tool.

Earthquakes and archeology: Neocatastrophism or science?

The recent number of devastating, large earthquakes serve as a tough reminder that geophysicists remain unable, after decades of continuous and frustrating efforts, to predict not only where but also when and how big such events will be. These recent earthquakes include those in Pakistan (8 October 2005), Sumatra (26 December 2004, 3 March 2005), Iran (20 June 1990, 10 May 1997, 26 December 2003), India (29 September 1993, 26 January 2001), and Turkey (17 August 1999), and China (the 1976 Tangshan earthquake responsible for at least 300,000 fatalities).This difficulty in predicting earthquakes can be traced, in part, to the absence of sufficient temporal data about the occurrences of large past earthquakes. In this case, sufficient means a time period that spans, for a given area, several large events, typically over a period of several millennia or more. Written records can provide a more or less complete record only for the past several hundred years. Excavations across geologic faults can provide paleoseismic information but only in special geological settings. Archeological evidence for past catastrophic earthquakes has been emerging as a third important source of data that should be considered. The authors of this article have been pursuing this avenue of research for several decades.

Seismic rehabilitation and analysis of Chaohe earth dam

Stability of earth dams during earthquakes has been a major concern for geotechnical engineers in seismic active regions. Liquefaction induced slope failure occurred at the upstream slope of a major earth dam in the suburb of Beijing, China, during the 1976 Tangshan Earthquake. The gravelly soil with loose initial condition liquefied under relatively small ground vibration. In recent years, a major seismic rehabilitation project was carried out on a similar earth dam nearby using dumped quarry stone. Seismic stability analysis was carried out using model test, finite element simulation, and pseudo-static slope stability program after taking into account the influence of excess pore pressure.

The Resilient city: how modern cities recover from disaster

For as long as they have existed, cities have been destroyed - sacked, shaken, burnt, bombed, flooded, starved, irradiated, and pillaged - in almost every case they have risen again. Rarely in modern times has a city not been rebuilt following destruction, be it natural or man-made. The Resilient explores urban disasters from around the globe and the ongoing restoration of urban life. It examines why cities are rebuilt, how a vision for the future gets incorporated into a new urban landscape, and how disasters have been interpreted and commemorated in built form. An international cast of historians, architects, and urban studies experts looks at a diverse group of cities that have suffered traumas, including: the Oklahoma City bombing; Chicago's great fire of 1871; San Francisco's earthquake and fires of 1906; Washington's invasion by the British during the War of 1812; Berlin and Warsaw in World War II; Gernika's bombardment during the Spanish Civil War, Jerusalem's rebuilding following centuries of destruction; Mexico City's 1985 earthquake; China's Tangshan earthquake; Tokyo's earthquake, fires, and WWII bombardment; Beirut in the 1990s wars; and South Central Los Angeles following the Rodney King beating. In so doing, they bring to light the experiences these resilient cities share, while underscoring that no two cities have recovered in the precisely the same way. This book will appeal to anyone interested in cities, among humankind's most durable artifacts and enduring forms of communal life.

A newly discovered major fault of the 1976 Tangshan earthquake in China

A newly discovered major fault of the 1976 Tangshan earthquake in China

Fine three-dimensional P-wave velocity structure beneath the capital region and deep environment for the nucleation of strong earthquakes

A detailed 3-D P-wave velocity model of the crust and uppermost mantle under the capital region is determined with a spatial resolution of 25 km in the horizontal direction and 4–17 km in depth. We used 48750 precise P-wave arrival time data from 2973 events of local crustal earthquakes, controlled seismic explosions and quarry blasts. These events were recorded by 123 seismic stations. The data are analyzed by using a 3-D seismic tomography method. Our tomographic model provides new information on the geological structure and complex seismotectonics of this region. Different patterns of velocity structures show up in the North China Basin, the Taihangshan and the Yanshan Mountainous areas. The velocity images of the upper crust reflect well the surface geological, topographic and lithological features. In the North China Basin, the depression and uplift areas are imaged as slow and fast velocity belts, respectively, which are oriented in NE-SW direction. The trend of velocity anomalies is the same as that of major structure and tectonics. Paleozoic strata and Pre-Cambrian basement rocks outcrop widely in the Taihangshan and Yanshan uplift areas, which exhibit strong and broad high-velocity anomalies in our tomographic images, while the Quaternary intermountain basins show up as small low-velocity anomalies. Most of large earthquakes, such as the 1976 Tangshan earthquake (M 7.8) and the 1679 Sanhe earthquake (M 8.0), generally occurred in high-velocity areas in the upper to middle crust. However, in the lower crust to the uppermost mantle under the source zones of the large earthquakes, low-velocity and high-conductivity anomalies exist, which are considered to be associated with fluids, just like the 1995 Kobe earthquake (M 7.2) and the 2001 Indian Bhuj earthquake (M 7.8). The fluids in the lower crust may cause the weakening of the seismogenic layer in the upper and middle crust and thus contribute to the initiation of the large crustal earthquakes.

Automatic recognition of damaged town buildings caused by earthquake using remote sensing information: Taking the 2001 Bhuj, India, earthquake and the 1976 Tangshan, China, earthquake as examples

In the high-resolution images, the undamaged buildings generally show a natural textural feature, while the damaged or semi-damaged buildings always exhibit some low-grayscale blocks because of their coarsely damaged sections. If we use a proper threshold to classify the grayscale of image, some independent holes will appear in the damaged regions. By using such statistical information as the number of holes in every region, or the ratio between the area of holes and that of the region, etc, the damaged buildings can be separated from the undamaged, thus automatic detection of damaged buildings can be realized. Based on these characteristics, a new method to automatically detect the damage buildings by using regional structure and statistical information of texture is presented in the paper. In order to test its validity, 1-m-resolution iKonos merged image of the 2001 Bhuj earthquake and grayscale aerial photos of the 1976 Tangshan earthquake are selected as two examples to automatically detect the damaged buildings. Satisfied results are obtained.

On the long-term seismic hazard analysis in the Zhangjiakou–Penglai seismotectonic zone, China

The Zhangjiakou–Penglai seismotectonic zone (ZPSZ) lies in the northern part of North China and extends along the Zhangjiakou–Beijing–Tianjin–Bohai Bay–Penglai–Yellow Sea. It is about 900 km long and some 250 km wide in a northwest direction. The great Sanhe-Pinggu ( M S=8.0) earthquake occurred on September 1679 and the Tangshan ( M S=7.8) earthquake on July 1976 caused serious economic and life losses. According to some differences in crust structure and regional tectonic stress field, the ZPSZ is divided into western and eastern segment by the 117°E line for study on long-term seismic hazard analysis. An analysis of Gutenberg–Richter's empirical relation of earthquake-frequency and time process of historic and recent earthquakes along the eastern and western segments shows that the earthquake activity obeys a Poisson process, and these calculations indicate that the earthquake occurrence probability of M S=6.0–6.9 is 0.77–0.83 in the eastern segment and the earthquake occurrence probability of M S=7.0–7.9 is 0.78–0.80 in the western segment of the ZPSZ during a period from 2005 to 2015.

Crustal heterogeneity and seismotectonics of the region around Beijing, China

A detailed three-dimensional (3-D) P-wave velocity model of the crust and uppermost mantle under the Chinese capital (Beijing) region is determined with a spatial resolution of 25 km in the horizontal direction and 4–17 km in depth. We used 48,750 precise P-wave arrival times from 2973 events of local crustal earthquakes, controlled seismic explosions and quarry blasts. These events were recorded by a new digital seismic network consisting of 101 seismic stations equipped with high-sensitivity seismometers. The data are analyzed by using a 3-D seismic tomography method. Our tomographic model provides new insights into the geological structure and tectonics of the region, such as the lithological variations and large fault zones across the major geological terranes like the North China Basin, the Taihangshan and the Yanshan mountainous areas. The velocity images of the upper crust reflect well the surface geological and topographic features. In the North China Basin, the depression and uplift areas are imaged as slow and fast velocities, respectively. The Taihangshan and Yanshan mountainous regions are generally imaged as broad high-velocity zones, while the Quaternary intermountain basins show up as small low-velocity anomalies. Velocity changes are visible across some of the large fault zones. Large crustal earthquakes, such as the 1976 Tangshan earthquake ( M=7.8) and the 1679 Sanhe earthquake ( M=8.0), generally occurred in high-velocity areas in the upper to middle crust. In the lower crust to the uppermost mantle under the source zones of the large earthquakes, however, low-velocity and high-conductivity anomalies exist, which are considered to be associated with fluids. The fluids in the lower crust may cause the weakening of the seismogenic layer in the upper and middle crust and thus contribute to the initiation of the large crustal earthquakes.