Changes between Version 4 and Version 5 of OAF Research App
- Timestamp:
- Nov 2, 2015, 11:29:01 AM (9 years ago)
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OAF Research App
v4 v5 15 15 '''Once launched''', you’ll see a bunch of adjustable parameters on the left (see screen shot below); mouse over the titles to get more info on each. For now, just click '''“Fetch Data”''' to collect a weeks worth of aftershocks following the Nepal earthquake (the default), or enter any other '''USGS Event ID''' obtained from http://earthquake.usgs.gov/earthquakes (you sometimes have to dig a bit to find the IDs, which look something like “us20002qn7”). The default region used for collecting data is the two-step approach outlined in Jeanne’s doc (and with a min and max depth of 0 and 20 km, respectively). 16 16 17 At this point you can view a map of epicenters (under the '''Hypocenters''' tab ), a magnitude frequency distribution or MFD (under the '''Mag/Num Dist''' tab), and a plot of magnitudes as a function of time ('''Mag/Time Plot''' tab).There is also a '''Console''' tab that writes out some useful information, such as Mmaxc (the mode of the MFD, which is also shown in the MFD plot), and a '''Catalog''' tab which allows you to view the aftershocks in a 10-column format.17 At this point you can view a map of epicenters (under the '''Hypocenters''' tab, example shown below), a magnitude frequency distribution or MFD (under the '''Mag/Num Dist''' tab), a plot of magnitudes as a function of time ('''Mag/Time Plot''' tab), and a cumulative number of earthquakes plot ('''Cumulative Num Plot''' tab). There is also a '''Console''' tab that writes out some useful information, such as Mmaxc (the mode of the MFD, which is also shown in the MFD plot), and a '''Catalog''' tab which allows you to view the aftershocks in a 10-column format. 18 18 19 The next thing to do is to set the magnitude of completeness '''Mc''', which defaults to Mmaxc+0.5, and to set the '''Magnitude Precision''' (network rounding, where the default is 0.1; we have no way of getting this from ComCat, so work is needed if this is important). 19 [[Image(tutorial_hypocenters.png)]] 20 20 21 Then click '''“Compute b”''' and the maximum likelihood b-value will be set in the “b-value” parameter just below (and the fit will be added to the MFD plot). Either keep this b-value or change it to something else (the plot will update too). 21 The next thing to do is to set the magnitude of completeness '''Mc For Sequence''', which defaults to Mmaxc+0.5, and to set the '''Magnitude Precision''' (network rounding, where the default is 0.1; we have no way of getting this from ComCat, so work is needed if this is important). 22 23 Then click '''“Compute b”''' and the maximum likelihood b-value will be set in the “b-value” parameter just below (and the fit will be added to the MFD plot). Either keep this b-value or change it to something else (the plot will update too). An example MFD plot with the b-value added is shown below. A dashed line will also be added to the '''Cumulative Num Plot''' which estimates the number of earthquakes using generic aftershock parameters. These generic parameters are dependent on the tectonic regime of the mainshock. 24 25 [[Image(tutorial_b.png)]] 22 26 23 27 Next, fill in the range of values for the grid search we will do over the aftershock-parameters ('''a''', '''p''', and '''c'''), or leave at default values. To fix one of the parameters, set the min=max like the default for '''c'''. … … 25 29 Hit '''“Compute”''' and the maximum-likelihood values for '''a''', '''p''', and '''c''' will be filled in, and various marginal PDFs can be viewed under the '''Model PDFs''' tab. For example, you can see the resultant 2D PDF for '''p''' vs '''a''' in the following screen shot of the app: 26 30 27 [[Image( oaf_screenshot_1.png)]]31 [[Image(tutorial_pdf_timedep_mc.png)]] 28 32 29 Notice that the fit is not so good. Go back and set '''Mc''' as 4.5 rather than 4.95, click '''Compute b''' again, and then click '''“Compute”''' again. The 2D PDF looks better now: 33 At this point a black solid is added to the '''Cumulative Num Plot''' using these calculated aftershock parameters. 30 34 31 [[Image(oaf_screenshot_2.png)]] 35 The calculation applies a time dependent magnitude of completeness by default, with associated parameters ('''G''', '''H''', and '''Mcat'''). You can disable this feature and use '''Mc for Sequence''' instead by deselecting the '''Apply time dep. Mc''' parameter. The resultant 2D PDF for '''p''' vs '''a''' which uses constant '''Mc for Sequence''' is shown below. 36 37 [[Image(tutorial_pdf_reg_mc.png)]] 32 38 33 39 Finally, set the '''Forecast Start Time (Days)''' and likewise for the end time, click '''Compute''' below these settings, and go to the '''Forecast''' tab to see the results. If you want to see the numbers, click the '''Show Data''' option below the plot. … … 39 45 Things to add later include: 40 46 41 1) time-dependent '''Mc''' model (we need parameter values) 47 1) time-dependent '''Mc''' model (we need parameter values). '''Initial implementation done, needs further validation.''' 42 48 43 2) inclusion of generic parameters according to the Garcia, FE, or special regions (someone needs to give us those as well), and combined generic and sequence-specific forecasts. 49 2) inclusion of generic parameters according to the Garcia, FE, or special regions (someone needs to give us those as well), and combined generic and sequence-specific forecasts. '''Initial implementation done.''' 44 50 45 51 3) obtaining finite-rupture surfaces from ComCat (for collecting aftershocks)
