Randomization test and its application

In this paper, one of the distribution-free tests — randomization test, is briefly described. It doesn’t need any distribution assumption and its related parameter estimation and is applicable to random and nonrandom sample. Then it is used to the test of migration of strong earthquakes on the Xianshuihe Fault Belt and “immunity” of large earthquakes in the large northern reigon of China. The test results show that there is 98.7% confidence degree for the migration of strong earthqueks on the Xianshuihe Fault Belt and “immunity” of earthqueks withM _S⩾8 toM _S⩾7 is significant in the large northern region of China. The obtained test results and the test method itself have certain application in the practice. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 484–489, 1993.     

On the analysis of self-similarity of earthquake sequence and its application in earthquake prediction

This paper has introduced the method of self-similarity analysis of time series into the analysis and study of earthquake sequence, and then researched its application in earthquake prediction. As parameter of earthquake time series, we can take the cumulated sum of the numbers of equivalent earthquakesQ=ΣN*, the numbers of equivalent earthquakeN*, maximum magnitudeM _max, average magnitudeQ=ΣN*, and the difference ΔN* between the numbersN* in two adjacent time intervals. The given method may be applied to analysis of long-period seismic sequences in different regions as well as to anlysis of seismic sequence in the aftershock region of strong earthquake. For making quantitative analysis the coefficient of self-similarity of earthquake sequence in order of timeμs was introduced. The results of self-similarity analysis were obtained for the earthquake sequences in North China, West South China, the Capital region of China, and for the East Yamashi region of Japan. They show that in period or half year to several years beforeM⩾7.0 andM⩾6.0 earthquakes occurred in these regions separately, the self-similarity coefficientμs calculated by using the above-mentioned parameters had remarkably anamalous decrease variations. The duration time ofμs anomaly depends on the earthquake magnitude and may be different from different regions. Therefore, the self-similarity coefficient in order of timeμs can be considered as a long-medium term precursory index. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 455–462, 1993.     

Interrelation among strong earthquakes and its application in seismic hazard analysis

The intterrelation among strong earthquakes and its application are emphatically studied in this paper. Taking North China seismic region as study area, we have investigated how a great earthquake influence other strong earthqukaes in neighbouring area? Does there exist earthqukae immunity phenomenon? If it exists, what distributional pattern did it has in space-time domain? The results show that occurrence of earthquakes withM⩾7 has cetain immunity phenomenon to earthquakes withM⩾6 in North China. Among others, the immunity area of earthquakes withM=8 is much larger than that ofM=7. For earthquakes withM⩾8, the immunity area to the earthquakes ofM=7 is larger than toM=6. Based on the above analysis, using some statistical methods, we gave the variational regularity of seismic immunity factor with space and time, and explored its concrete application in seismic hazard analysis. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 339–346, 1993.     

The middle-long term prediction of the February 3, 1996 Lijiang earthquake (MS=7) by the "criterion of activity in quiescence"

IntroductionIn the book Future CataS~ologr published in 1992, we proposed a viewpoiflt on using the"criterion of activity in quiescence" to predict big eathquake (MsZ7) (GUO, et al, 1992), and predicted in the book that in futore several years or in ten years a big earthquake (Ms27) will be possible to occur in the Zhongdian and nearby in Yunnan Province. In the 1994 nation-wide earthquake tendency consultation meeting we pointed out, once more, in the Zhongdian region of Yunnan Province…     

A discussion on the application ofb-value to the prediction of seismic tendency

In the estimation of seismic tendency, using Gutenberg-Richter’sb-value and using Hurst exponent are two commonly used methods. Based on the fractal geometry of earthquake time series, we point out that these two methods correlate to each other. In the perspective of fractional Brownian motion (FBM), an earthquake sequence withb>3/4 and that withb<3/4 have different dynamic properties. Foundation item: The MOST Project G1998040705. Contribution No. 01FE2010, Institute of Geophysics, China Seismological Bureau.     

Statistical testing of the relation between burst of aftershocks and strong earthquakes

According to geological tectonics and seismic activites this paper devided North China (30°–45°N, 105°–130°E) into four areas. We analyzed the North China earthquake catalogue from 1970 to 1986 (from 1965 to 1986 for Huabei, the North China, plain region) and identified forty-two bursts of aftershock. Seven of them occurred in aftershock regions of strong earthquakes and seventeen of them in the seismic swarm regions. The relation between strong earthquakes with the remaining eighteen bursts of aftershocks has been studied and tested statistically in this paper. The result of statistical testing show that the random probabilityp of coincidence of bursts of aftershock with subsequent strong earthquakes is less than six percent. By Xu’sR scoring method the efficacy of predicting strong earthquake from bursts of aftershock is estimated greater than 39 percent. Following the method proposed in the paper we analyzed the earthquake catalogue of China from 1987 to June, 1988. The results show that there was only one burst of aftershock occurred on Jan. 6, 1988 withM=3.6 in Xiuyan of Northeast China. It implicates that a potential earthquake withM _S⩽5 might occur in one year afterwards in the region of Northeast China. Actually on Feb. 25, 1988 an earthquake withM _S=5.3 occurred in Zhangwu of Northeast China. Another example is Datong-Yanggao shock on October 18, 1989 which is a burst of aftershock. Three hours after an expected shock withM =6.1 took place in the same area. Two examples above have been tested in practical prediction and this shows that bursts of aftershocks are significant in predicting strong earthquakes. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 273–280, 1991. Part of earthquake catalogue is from Jinbiao Chen, Peiyan Chen and Quanlin Li.     

Earthquake migration in East Asia mainland (I)—The migration of huge earthquakes and volcanic activity from West Pacific Trench to the Chinese mainland

The researches in this paper disclose a huge earthquake migration series that lasted more than one century—from the 17th century to the early day of the 18th, transverse migration of huge earthquake from West Pacific trench to the Chinese mainland, lasted about 134 a, the distance is about 2600 km, the velocity is about 19 km/a, and the direction of migration agrees with the direction of plate subduction and vertical to the strike of plate boundary. The migration has two branches. One extends westwards and terminates at the central longitude belt (Helanshan—Liupanshan fault zone) of the Chinese mainland, triggered the strongest seismicity episode in North China, including 4 earthquakes withM ⩾8.0. The other extends northwards, passing through Korea Peninsula, terminates at the north part of Heilongjian Province, and triggered the volcanic eruption activity in Changbaishan and Wudalianchi. The time-space linearity of migration is good. Its velocity is stable and its activity attenuates gradually. It is estimated that it is related with the disturbance of asthenosphere matters caused by the sudden acceleration of the subduction of the trench plate. There are two similar transverse migration series from 1498 to 1556 and from 1843 to 1927, and the velocities are 36.2 and 33.7 km/a respectively.     

Grouping occurrences being the fundamental feature of the strong earthquakes in Chinese mainland

ＧｒｏｕｐｉｎｇｏｃｃｕｒｒｅｎｃｅｓｂｅｉｎｇｔｈｅｆｕｎｄａｍｅｎｔａｌｆｅａｔｕｒｅｏｆｔｈｅｓｔｒｏｎｇｅａｒｔｈｑｕａｋｅｓｉｎＣｈｉｎｅｓｅｍａｉｎｌａｎｄＱｉｎ－ＺｕＬＩ（李钦祖）；Ｌｉ－ＭｉｎＹＵ（于利民）；Ｊｉ－ＹｉＷＡＮＧ（王吉易...     

The application of the method of reconstruction a phase space with higher dimensions to the study of seismic processes and earthquake prediction

The method of reconstructing a phase space with higher dimensions can be applied to analysing the observaiton data for studying the dynamic behavior of seismic processes and earthquake prediction. It is found that seismic processes are chaotic. So earthquakes could be determinately predicted only within the predictable period. Here, some related problems (e.g. several primary parameters and the relations among them, the relation between the quality of used data and analytical results, the relation between a reductive process of the fractal dimensions and earthquake prediction and so on) are discussed. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 470–476, 1993. This study was sponsored by the Chinese Joint Seismological Science Foundation under Contract NO. 9000007.     

Variations of the geomagnetic field and the geomagnetic effects of three earthquakes ( M s>5.0) in Jiangsu Province, China

Since 1979 the repeated observations and experiments of geomagnetic total intensity and vertical component have been carried out for ten years in the geomagetic network which is located in Jiangsu Province, China. Three earthquakes aboveM _s 5.0 occurred during the decade, and some seismomagnetic effects were observed. The observation results show that the anomalies of the vertical geomagnetic component can’t be observed untill some months before the earthquake (M _s>5.0) in this area. In this paper it is suggested that a densely distributed network for continuous observation of geomagnetic vertical component may catch seismomagnetic anomalies and thus improve earthquake prediction in the light of the geomagnetic measurements of the mid — or — low latitude locations. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 80–87, 1991. This study is sponsored by the Chinese Joint Seismological Science Foundation.     

Physical background on estimating b value

The G-R relation lgN=a-bM (1954) is an empirical formula used widely in the seismicity research. But the linearity of b curves has great difference in different time and space domains. An interested question in this paper is that in how large a space-time-strength domain the b value has certain physical connotation. This study told us that we can get optimal statistical results of b value in those space-time domains which can develop correspondent strong shocks with magnitude interval (M _s≥8.5, 8.0≤M _s<8.5, 7.0≤M _s<8.0). Thus, the possible seismogenic areas in which strong shocks with different magnitude intervals develop can be inferred in different regions of the mainland of China. Finally, some new problems are proposed, such as the delimitation of seismic province, the seismicity parameter determination in seismic hazard analysis and in earthquake predictions by using b value. Contribution No. 96A-0074, Institute of Geophysics, SSB, China.     

Atellitic thermal infrared brightness temperature anomaly image—short-term and impending earthquake precursors

Mechanism of satellitic thermo-infrared brightness temperature and temperature increaming is studied. Experiments are made with a gas sample taken around the epicenter area. The gas ample is pmved to contain green house gases such as CH₄, and CO₂ which have increased by tens of thousands of times. In addition, lab research slso pmes that CH₄, and CO₂ can obtain energy under the action of transient electric field and release heat, thus reeulting in a temperature increase of 2–6°C. Also a brief account of practices since 1990 is given; altogether 40 short-tenn and impending earthquake predictions have been made, with 9 precise ones whose three main factors of an earthquake are clearly depicted, and 12 fairly good ones. These predictions include 3 earthquakes ofM.⩾ 7, 4 ofM.⩾ 6.0 and the rest are mundM. 5.0. Yet there are earthquakes left out of prediction. Finally the evolutionwy processing characters of satellitic thermo-infrared brightness temperature and temperature increase before the Lijiang earthquake on Feb. 3, 1996 and Tangshan earthquake on April 14, 1998 are introduced in detail. The conclusion makes a study on the regularities of connection among time, space and stress when there appears the satellitic thermal-inlinred brightness tempera- and temperature increasing anomaly. Project supported by the State 863 High-Tech Project (Grant No. 863-2-7-4-18)     

Magnitude scale for the Central American tsunamis

Based on the tsunami data in the Central American region, the regional characteristic of tsunami magnitude scales is discussed in relation to earthquake magnitudes during the period from 1900 to 1993. Tsunami magnitudes on the Imamura-Iida scale of the 1985 Mexico and 1992 Nicaragua tsunamis are determined to bem=2.5, judging from the tsunami height-distance diagram. The magnitude values of the Central American tsunamis are relatively small compared to earthquakes with similar size in other regions. However, there are a few large tsunamis generated by low-frequency earthquakes such as the 1992 Nicaragua earthquake. Inundation heights of these unusual tsunamis are about 10 times higher than those of normal tsunamis for the same earthquake magnitude (M _s =6.9–7.2). The Central American tsunamis having magnitudem>1 have been observed by the Japanese tide stations, but the effect of directivity toward Japan is very small compared to that of the South American tsunamis.     

Fault deformation anomaly and intermediate and short-term prediction of the Jingtai M s=5.9 earthquake

The time-space distribution characteristics of fault deformation anomaly in the near-source region and its outlying zone in the seismogenic process of the Jingtai M _s=5.9 earthquake occurred on June 6, 2000 in Gansu Province is studied preliminarily. The distribution scope of fault deformation anomaly before the earthquake is wide, the anomaly shape is complicated and the pattern anomalous zone of fault deformation (strain) information index is obvious. The shape and amplitude of fault deformation anomaly in different regions differ significantly, which is closely related with the tectonic location of anomaly. The fault deformation anomaly of α, β, and γ phases along the western segment of Haiyuan fault zone shows the process from the quasi-linearity to non-linearity of fault movement in the near-source region, matches the high-value anomalous area of fault deformation (strain) information index, and reflects the high strain accumulation in the seismogenic region. However, the anomaly of abrupt jump and cusp with a large amplitude occurred in the areas far from the earthquake, such as Liupanshan fault zone which is the tectonic convergent section does not reflect the strain accumulation of its location, maybe it is a sign that the regional tectonic stress field is strengthened in the seismogenic process. Based on the above-mentioned facts and combined with the preliminary summary of experiences and lessons in the intermediate and short-term prediction of the Jingtai M _s=5.9 earthquake, we study and explore the application of fault deformation anomaly to earthquake judgment. Foundation item: National Key Basic Research Development Program (G1998040703 and G1998040705), and State Scientific and Technological Project of the “Ninth Five-Year Plan” (96-913-09-01-02-03 and 96-913-09-02-02-03), China.     

Regional characteristics of coda attenuation after the lancang-Gengma earthquake

In the light of the single scattering model of coda originating from local earthquakes, and based on the aftershock coda registered respectively at the 4 short period stations installed near the foci shortly after theM7.6 Lancang andM7.2 Gengma earthquakes, this paper has tentatively calculated the rate of amplitude attenuation and theQ _c-value of the coda in the Lancang and Gengma areas using a newly-founded synthetic determination method. Result of the study shows the rate of coda amplitude attenuation demonstrates remarkable regional differences respectively in the southern and northern areas. The southern area presents a faster attenuation (Q _c=114), whereas the northern area shows a slower attenuation (Q _c=231). The paper also discusses the reasons causing such differences. Result of the study also suggests a fairly good linear relation between the coda source factorA _o(f) and the seismic moment and the magnitude. Using the earthquake scaling law, the following formulas can be derived: lgM ₀=lgA ₀(f)+17.6,M _D=0.67lgA ₀(f)+1.21 and logM ₀=1.5M _D+15.79. In addition, the rates of amplitude attenuationβ _s andβ _m are respectively calculated using the single scattering and multiple scattering models, and the ratioβ _s/β_m=1.20−1.50 is found for the results respectively from the two models. Finally, the mean free pathL of the S-wave scattering in the southern and northern areas are determined to be 54 km and 122 km respectively by the relations which can distinguish between the inherentQ _i and scatteringQ _s, testify to this areas having lowQ-values correspond to stronger scatterings. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,14, 71–82, 1992. This study is partly supported by the Seismological Science Foundation of the State Seismological Bureau of China, and the present English version of the paper is translated from its Chinese original by Wenyi Xia, Seismological Bureau of Yunnan Province.     

The 1990 Zaisang earthquake of magnitude 7.3 in Kazakstan

The Zaisang earthquake (M _s=7.3) on June 14, 1990 occurred in the boundary between China and Kazakstan. During the great shock, 3 persons lost their lives, 30 people had been hurt and 340 houses collapsed. The intensity of the epicentre is VIII Degree. The economic losses equals to about 320 000 000 Yuan. This large earthquake was occurred on a new born fault, it belongs to main shock-aftershock type earthquake. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 360–365, 1993.     

Lg coda Q0 value and its relation with the tectonics in Chinese mainland and adjacent regions

We have collected 432 vertical component records from 45 stations of new CENC （China Earthquake Network Center） in Chinese mainland and adjacent regions. These records were used to calculate Q0 （Q at 1Hz） and η values of Lg coda from each station by the stack spectral ratio （SSR） method. Then the tomography method was applied to obtaining lateral variation of Q0 and η values in Chinese mainland and adjacent regions. The result indicates that Q0 value varies between 150 and 600 in the studied areas. Yunnan, southwest Sichuan, and northwest Myanmar show the lowest Q0 value （Q0〈240） and the crust of these regions is characterized by complicated crack and strong hydrothermal activity. The highest Q0 value （Qo〉510） exists in the border of southern Mongolia, Alxa and Ordos block. The η value varies between 0.45 and 0.75 in Chinese mainland and its adjacent regions.     

2017年新疆精河MS6.6地震遥感大气温度变化特征分析

在中国地震台网中心2016年底利用热红外遥感技术预测2017年新疆西部地区为潜在M_S 6.6±0.2地震危险区的基础上,分析2017年8月9日精河M_S6.6地震临震时段引潮力变化,并选用18时（UTC）中国大陆近地表50m高度处的遥感大气温度数据,以震前引潮力值最高点时刻（8月1日）为时间背景,获取地震前后（8月2~13日）连续的大气温度日增量分布图像,跟踪分析精河M_S6.6地震短临大气温度变化。结果显示：地震发生在天体引潮力由高峰—低谷连续周期变化的低谷时段,而大气温度变化过程显示,在全国大范围内,仅震中附近大气温度升高明显,其异常演化经历了起始—加强—高峰—衰减—再增强—发震—平静的动态过程。增温过程与潮汐变化具有同步性,这表明引潮力对本次地震具有触诱发的作用,而大气温度变化反映了本次地震地应力的变化过程,也说明在地震预测实践中,从中、短临多时间尺度综合分析遥感大气温度和引潮力变化,将有助于提高地震预测能力。     

The regional characteristics of seismic activity in China

ＴｈｅｒｅｇｉｏｎａｌｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｓｅｉｓｍｉｃａｃｔｉｖｉｔｙｉｎＣｈｉｎａＺｈｅｎ－ＬｉａｎｇＳＨＩ，ＪｉａｎＷＡＮＧａｎｄＸｉａｏ－ＤｏｎｇＺＨＡＮＧ（时振梁，王健，张晓东）（ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃｓ，Ｓ...     

The empirical relationships between M s, m b and M L for China and vicinity

Data from 753 earthquakes are used to determine a relationship between surface-wave magnitude (M _s) and bodywave magnitude (m _b), and from 541 earthquakes to determine a relationship between surface-wave magnitude (M _s) and local magnitude (M _L) for China and vicinity: M _s=0.9883 m _b-0.0420, M _s=0.9919 M _L-0.1773. The relationship of M _s versus m _b is obtained for 292 events occurred in the Chinese mainland in the time period from 1964 to 1996, 291 events occurred in Taiwan in the time period from 1964 to 1995 and 170 events occurred in the surrounding area. Standard deviation of the fitting is 0.445. Relationship of M _s versus M _L is obtained for 36 events occurred in the Chinese mainland, 293 events occurred in Taiwan, China and 212 events occurred in the surrounding area. The total amount is 541 events. Standard deviation of the fitting is 0.4673. The uncertainties of the converted M _s in different magnitude intervals can be estimated using complementary cumulative distribution function (CCDF). In the relationship of M _s versus m _b, taking ±0.25 as a range of uncertainties, in magnitude interval m _b 4.0–4.9, the probabilities for the converted M _s taken value less than (M _s-0.25) and more than (M _s+0.25) are 17% and 27% respectively. Similarly, we have probabilities for m _b 5.0–5.9 are 34% and 20% and that for m _b 6.0–6.9 are 11% and 47%. In the relationship of M _s versus M _L, if the range of uncertainties is still taken as ±0.25, the corresponding probabilities for magnitude interval M _L 4.0–4.9 are 22% and 38%, for M _L 5.0–5.9 are 20% and 15% and for magnitude interval M _L 6.0–6.9, are 15% and 29%, respectively. The relationships developed in this paper can be used for the conversion of one magnitude scale into another magnitude scales conveniently. The estimation of uncertainties described in this paper is more accurate and more objective than the usual estimation expressed by deviation. The estimations described in this paper indicate various dispersions in different magnitude intervals of original data. The estimations of uncertainties described by probabilities can be well connected with the total estimations of uncertainties in seismic hazard assessment.