zmap a tool for analyses of seismicity patterns typical applications ...

More documents

Recommendations

Info

. Another date of interest is 1980, because at this time approximately, improvements in analysis techniques took place in all of California. The period before it is not clean (Figure 2.3), thus we compare the rate in the periods 1972-1978 to those in 1980-1985 (the end of the clean period following the 1980 change, Figure 2.3). The rate comparison of these periods shows an even more dramatic magnitude shift (Figure 2.7) of at least DM=–0.5 units. In this case, the shift was accompanied by an increase in reporting of small earthquakes. These two phenomena, magnitude shifts and increased reporting of small events, are often seen at the same time, because a single change in the operating procedure generated both. The conclusion is that the earthquake catalog for Parkfield can hardly be used for seismicity rate studies. The fact that the two FMD curves show the same slope before and after the disastrous changes in 1980 (Figure 2.7D) suggests that the catalog can still be used for b-value studies. Figure 2.7: Comparison of the rates as a function of magnitude for two periods, which are printed at the top. The rate change took place in 1978/80 along the Parkfield segment of the San Andreas fault. Details same as in Figure 2.5. The magnitude shift was at least dM=-0.5 units. Another method to evaluate the homogeneity of reporting as a function of time, is to inspect cumulative number curves. In a network where no magnitude shifts have taken place but more small earthquakes are reported in recent years because of improvements in the operations, the key to selecting the widest magnitude band which has been reported homogeneously, is to define the smallest magnitude for which constant numbers have been reported. This assumes that in a rather large area the production of events is stationary, on average. Such a case is shown in the comparison for the Parkfield network (Figure 2.8). The improvement of reporting is seen to be restricted to M
cumulative number curve for M>1. events is approximately straight, whereas the curve for all magnitudes shows a kink upward at the time of the improvement (Figure 2.8). Figure 2.8: Comparison of cumulative number of events for earthquake M >= 1.0 (blue) and M , 1.0 (red). The legend was added manually. It could be a mistake to rely solely on cumulative number curves for evaluating homogeneity, because in the Parkfield catalog the selection of an intermediate magnitude for cutoff (M=1.2, in this case) results in a cumulative curve with relatively constant slope, whereas the plots for M>1.5 and for M
Page 1 and 2: ZMAP A TOOL FOR ANALYSES OF SEISMIC
Page 3 and 4: INTRODUCTION This cookbook is aimed
Page 5 and 6: Figure 2: Seismicity map of the ent
Page 7 and 8: Save new mat-file: At this point it
Page 9 and 10: Narrowing the target of investigati
Page 11 and 12: Figure 11: Resolution map with the
Page 13 and 14: Articles in which tools discussed i
Page 15 and 16: Figure 2.2: Genas1 window. The cumu
Page 17 and 18: Figure 2.5: Comparison of the rates
Page 19: this case, the routine found that a
Page 23 and 24: Second: One may want to know the am
Page 25 and 26: Figure 3. 5: Z-menu window. Choosin
Page 27 and 28: each node and calculates for every
Page 30 and 31: Again the grid is chosen by using t
Page 33 and 34: Articles in which tools discussed i
Page 35 and 36: Figure 4.2: b-value maps of souther
Page 37 and 38: Figure 4.5: (a) Magnitude of comple
Page 39 and 40: Changes of b-values as a function o
Page 41 and 42: CHAPTER V Stress Tensor Inversions
Page 43 and 44: Inverting for the best fitting stre
Page 45 and 46: of S1 as a bar, and color codes the
Page 47 and 48: Using Gephart’s code An alternati
Page 49 and 50: #define VARIANCE_30 30 change to: #
Page 51 and 52: depicts the misfit value f. Please
Page 53 and 54: Lu, Z., M. Wyss, and H. Pulpan, Det
Page 55 and 56: • First rename mydata into a: a =
Page 57 and 58: CHAPTER VII Tips an tricks for maki
Page 59 and 60: Now lets change the axes setup. Sel
Page 61 and 62: Alternatively, you can print from t
Page 63: Working with interpolated color map

zmap a tool for analyses of seismicity patterns typical applications ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?