九. 重大自然灾害的综合预测及灾害链

(负责人：耿庆国 曾小苹 秦保燕)

Comprehensive Prediction and Chain of Disasters of

Significant Natural Disasters

(Conveners: GENG Qingguo ZENG Xiaoping QIN Baoyan)

1.Comprehensive Prediction and Research of Great Disasters for the Sustainable Development of China

Geng Qingguo

(Information Center, CSB Beijing 100081)

Abstract

It is not isolated for the occurrence of all kinds of natural disasters, but there is certain relationship between disasters underground, on the earth’s surface and on the ground. For the implementation of the strategy of “Sustainable Development”, it will be a significant and urgent scientific research task for the comprehensive prediction and forecast, prevention and resistance of great natural disasters which may occur in the period of the tenth 5-year plan, and also an essential and fundamental project for society stabilization, economy development and states prosperity.

2. Possible connection between the “mantle plume” phenomenon and the seismo-magnetic Effect

Zeng Xiaoping1  Lin Yunfang1  Xu Chunrong2
1) Institute of Geophysics, China Seismological Bureau, Beijing, China, 100081
2) Institute of Dynamic Crust, China Seismological Bureau, Beijing, China, 100085

Abstract

In the 1990’s, international scientists of earth science confirmed the existence of “mantle plume” which is the gushing-up of the mass in the core at the core-mantle boundary.  This phenomenon may be regarded as the motion of the electric-conducting fluid in the geomagnetic field B and thus satisfies the dynamic equation of the magnetic fluid mechanics. The time of dissipation and the spatial scale of prominent change of the magnetic field have been calculated. And we found they corresponded fairly well with the time of occurrence and the spatial scale of the geomagnetic anomalies before the Ms = 6.0 ~ 7.8 strong earthquakes in Southwest China and North China from 1970 to l999.  Therefore the concept of the model of magnetic effect of the spiral gushing-up of the mass of mantle plume in the core during the seismogenic process is put forward.

3. The Discriminant Criteria of Abnormal Modulated Ratio

YANG Yi 1     QIN Baoyan 2
1  Graduate school at Beijing, University of  science and technology of China, Beijing,100039
2  Seismological Institute of Lanzhou,  Lanzhou, 730000

The method of modulated ratio of small earthquakes is widely  used for earthquake prediction research. Using the prior discriminant criteria of abnormal modulated ratio, the false forecasting ratio is high. According  our research, the criteria is modified:
In a time-space window,  Rm≥<Rm>+sigma，and Rm>0.38,  N≥Nmin
Here, Rm and N is the modulated ratio and earthquake frenquency respectively; <Rm> is  the  average value of  Rm  for many years and sigma  is the mean square deviation,  Nmin is the specified minium number of earthquake frenquency.

4. The Nature Disasters with the Climatic Cooling and Its Period

Chen Dianyou Yang Xuexiang

(Changchun University of Science and Technology, Changchun 130026)

Abstract

The global warming and cooling may vary with the Earth’s orbital obliquity, orbital eccentricity and perihelion motion. It provides evidence for the orbital forcing of geomagnetic field intensity and energy liberation of inner core. The solar wind makes the inner core vibrate periodically between the north hemisphere and south hemisphere. It controls the earth’s tectonic movement and the change of geomagnetic field intensity.

If the earth is characterized by the symmetry, the earth will follow the fluid static equation

When

Then

This result means that there is larger pressure in the earth than that people imagine. The earth can be expanding with the decrease of the gravitational constant G in a large scale. It also makes the earth cold.

The project(No.4974228)supported by NSFC.

Keywords global cooling, orbital cycle, solar wind, inner core vibration, geomagnetic field intensity.

5. Orbital Modulation of the Earth's Magnetic Field Intensity and Periods of Natural Disasters

Yang Xuexiang Chen Dianyou

(ChangChun University of Science and Technology, ChangChun 130026)

Abstract

J.E.T.Channell, et al suggested that geomagnetic field intensity may vary with the Earth’s orbital obliquity (centered on a period of ~41kyr)、orbital eccentricity (~100kyr) and perihelion motion (~21kyr) as a result of effect of obliquity、eccentricity and perihelion motion on precessional forces in the Earth’s core (Nature,1998,394:464~468).They provide evidence for the orbital forcing of geomagnetic field intensity.

The Earth’s rhythm is controlled by the intermittent energy liberation in the Earth. In the Earth’s core, there exists not only huge thermal energy, but huge rotational energy. They are the internal causes of energy liberation. Astronomical factor makes the Earth’s inner core vibrate periodically, makes the Earth’s orbit, the Earth’s volume, the Earth’s ellipticity, speed of the Earth’s revolution and rotation change periodically, it is the external cause of the intermittent energy liberation. As concerns the differential rotation of the Earth’s inner core, the solar wind makes the Earth’s magnetic field form external tail and internal tail. The inner core moves contrary. It may effect the exchange of core-mantle angular momentum and lead to the eruption of the mantle plumes, so it controls the energy exchange in CMB. It is the reason for the correspondence of the natural disasters one by one with the astronomical periods 、geological cycles and change of the Earth’s magnetic field intensity.

The project (No.49774228) supported by NSFC.

Keywords magnetic field intensity, natural disasters inner core vibration, astronomical period

geological cycles

6. The strain field of tectonic block in North China

Ting Chen, Caijun Xu, Jingnan Liu

The school of geoscience, Wuhan Technical University

of Surveying&Mapping

430079

Abstract

As the relative positioning accuracy of GPS has been improved to ~, GPS measurement is used to study the horizontal crustal deformation and tectonic activity. Repeated GPS surveys have been carried out in North China in 1992,1995 and 1996 respectively. This paper analyses the current crustal horizontal strain rate with the GPS measurements of 1995 and 1996. GPS baselines are processed by GAMIT (King and Bock,1995) and the GPS network is adjusted by POWERADJ Ver2.0 (Jingnan Liu,1996) within ITRF framework.

As the network occupies a big area, rotation and strain are expressed with spherical coordinate. Consider two points and , whose north,east and vertical direction are and . If the motions are tangent to surface everywhere, then the velocity at r can been expressed as the following:

~

the first term is velocity around ；A symmetry strain rate tensor and an anti-symmetry rotation tensor produce the second term. According to least square method we can get the rotation and strain rate at r with three or more geodetic points.

From the strain rate we get the maximum principal strain rate, area expansion & contraction etc, with which we analyses the strain in North China. Earthquake danger maybe exists where the maximum Strain (compression) is.

7. Prediction of Earthquake Risk for the South-Central Shanxi by Using Gravity Data & Deep Sounding Information

QIN jianzeng LI qinglin et al.

(Geophysical Prospecting Centre, CSB, Zhengzhou, 450002, China)

Abstract

In this paper, the repeatedly gravity measurment data in south-central Shanxi area are analyzed in detail, considering various disturbance factors, such as temperature, atmosphere, groundwater, altitude variation of the station, ect. The analysis shows that an apparent anomaly occurred in the local gravity fileld before the earthquake and recovered after the earthquake.

After the Linyi earthquake , an apparent gravity anomaly have been occurring in south-central Shanxi region since 1999. The gravity anomly is proved by using short-cycle repeatly gravity measurement; The results of deep sounding information in this region reveal that the local upper mantl is uplifted. This upwarping of upper mantle possibly relates to local gravity high and local grwvity low.

According to the anomaly patten, amplitude and lasting time of gravity variation, it is con-

sidered that it has got into middle preparation period of medium-strong earthquake, for this reason, it is thought that there is earthquake risk in south-central Shanxi in future several years, considering earthquake migration in Shanxi province.