Crustal Deformation Abrupt And Short-term Earthquake Forecast

Short-term Earthquake Prediction (SEP) has been regarded as a difficult and complexscientific problem. In the past half century although seismologists over the worldhave done many works on SEP, there is no any significant gain with it. So the deeplyresearching for earthquake preparation, and exploring new way for SEP are importantand challengeable task.Based on the observed deformation data accumulated for many years, on resultsfrom experimental rock rupture in laboratory and on model of earthquake nucleationprocess, this paper have studied the relationships between deformation and seismicactivity And so did with earthquake preparation model, quantitative models amongthe Rapid Changes (RC) in deformations and earthquake 3-factors, methods forprediction and some concerned problems. Finally, some important achievements inearthquake preparation model and in SEP have been drawn as follows.l) The proposed concept of anomaly intensity gives a possible way to identifyanomaly scientifically.This concept of anomaly intensity based on the Fisher test method gives a probabilityto describe the anomaly property for a natural process.Analyzing anomaly intensity AF varying in an area, the differences ofrelationships between observed anomaly and seismic activity around a strongearthquake have been discussed, and an important precursor has also been found thatis the change in relationship between deformation anomaly and seismic activity.Among these anomalies the RC is obvious one.2) The RC may be caused by the pseudo-static accelerate propagation of fracture thatdriven by the inhomogeneous movement of deep masses.The differences among moments of RC in gravity, in crust deformation, and in ground water leveland the area of relative anomalies have demonstrated that the inhomogeneous movement of deepmasses may cause deformation, fracture instability, fracture rapid propagation and growth (creep).And the RC in ground water level will be founded by observations around ruPtUre fOrmed.So the earthquake preParing process may be divided to three stages: The initial crackdislocation (static) occurred in deep H1 at Tl moment. Then the crack dislocation began toaccelerae growth uP to the crust surface, while the crack propagation accelerates closed to thewave yelocity in deeP H2 at T2 moment. Finally while the dislocation could yet be propagated alocked fault zone or a jog met in the propagation direction, so an earthuake may be triggered.The dutalion from deeP Hl to deeP H2 can be aPproxinded.,The surface RC defOnnaion can be detected during all the process of pseudo-staticprOPagation. And its dUration is closed to the propagation period. FrOm the formula above,duration T is related to the scale of cormected fractUre. So the forecasted earthqake hasmagnitUde depending on the duraon days. As an examPle, comPared the duraon T of the tilt RCwith the maghtUde M we got the form1a:M=1 .36 log T (davs)+3.786M=1 .36 log T (davs)+3.7863) The reIation betWeen precursory RC and source/magnitude is estabIi8hed, anda proof of reducing dimension accomPanied with the earthquake preparationprocess is given. -The characters of deformation precursor field are differen in these RC proceSsqs. Thecloser the occurrence or source, the higher the amPlitude of RC is. The larger thearea with RC, the deePer the focal depth is and the greater the maghtude will be.The ePicener distance D from the sites of RC is withen 200bo with 95% cdrtaintyThe ti1t RC axnPlitude can give a more certainy prediction on the range of maghtudeM with maximum error 0.25 degree that makes the model a sighficat practice valuefor predicting the magnitUde or establishing the re1ation betWeen defOrmation andearthquake or analyZing the risk sitUation after an endquake.M= 0.57 log D bo + 1.l4 log I (grad+ ll.87This mode1 certified RC in deformation is inhomogeneous. AssUming theePicater disfore D, is constan, the formulation ofmaghtude M relat...