The peak point of LURR and its significance

Abstract

SUMMARYThe Load/Unload Response Ratio (LURR) value fluctuates around one during the early stage of the seismogenic process and then rises and reaches its peak point before the occurrence of a strong earthquake; the strong earthquake however does not onset at that time, but after the peak point LURR decreases sharply at the eve of the main shock before the final event outbreak. Thus, the peak point of LURR is ahead of the occurrence of an earthquake. We denote the lead time as T 2 . The discovery of peak point for LURR and the relationship between T 2 and magnitude M is of great significance as the peak point is usually easy to determine and then we can predict the occurrence time for the coming event according to Equation (3) so that we can enhance the precision of time for earthquake prediction in terms of LURR from 'year' scale to 'month' scale. The variation of LURR around the Wenchuan earthquake and its lesson to us are depicted in the paper.

Testing the forecast of aftershocks: a simple method with an example of application

“…The result shows that the LURR-based forecasts, with delays of 50 and 100 transformed-time days, respectively, outperform random guess. The phenomena that earthquake does not occur just at the moment when the LURR ratio dramatically increases, but occurs after the LURR ratio recovers from its peak value, 8 as mentioned above, is shown by the curve with zero delay time which is near to the diagonal.…”

“…Details of the methodology and data of the forecast are described by Yin et al 8 The calculated LURR data for the forecast test are from the group of Yin. In methodology, the algorithm calculates the ratio of the number of seismic events during the Earth-tide loading phase and the unloading phase to identify the instability dur- ing the earthquake preparation.…”

“…Empirically, an earthquake does not occur just at the moment when the LURR ratio dramatically increases but occurs after the LURR ratio recovers from its peak value. 8 The targets for the forecasting are the TIP of the aftershocks above M S 5.0. The forecast was conducted for the two segments of the aftershock zone, namely the NE Longmenshan fault zone and the middle Longmenshan fault zone (or the SW part of the aftershock zone).…”

“…These were applied to an analysis of the Wenchuan aftershock sequence and the forecast of aftershocks based on the load-unload response ratio (LURR) approach. 8 …”

Study of the Potential Earthquake Risk in the Western United States by the LURR Method Based on the Seismic Catalogue, Fault Geometry and Focal Mechanisms

“…The LURR method has been studied for more than 20 years and has been improved year by year (YIN et al 1995(YIN et al , 2008b(YIN et al , 2010(YIN et al , 2013YU et al 2011). The LURR method has been tested by retrospective studies and applied to earthquake forecasting in some countries, such as China, USA, Japan, Australia, Iran, Sumatra, etc.…”