{"id":328,"date":"2013-04-08T05:54:00","date_gmt":"2013-04-08T05:54:00","guid":{"rendered":"http:\/\/ahay.org\/blog\/?p=328"},"modified":"2015-09-01T13:42:00","modified_gmt":"2015-09-01T13:42:00","slug":"program-of-the-month-sfnmo","status":"publish","type":"post","link":"https:\/\/ahay.org\/blog\/2013\/04\/08\/program-of-the-month-sfnmo\/","title":{"rendered":"Program of the month: sfnmo"},"content":{"rendered":"

sfnmo<\/a> implements normal moveout (NMO) correction, one of the most fundamental operations in seismic reflection data processing. <\/p>\n

The following example from jsg\/avo\/avo<\/a> shows synthetic data before and after NMO correction. <\/p>\n

\"\" \"\" <\/p>\n

NMO transforms prestack seismic gathers by stretching each trace according to the equation
\n$$t = \\sqrt{t_0^2 + \\frac{x^2}{v^2(t_0)}}\\;,$$
\nwhere $t$ is time before the correction, $t_0$ is time after the correction, $x$ is offset, and $v(t_0)$ is velocity specified in velocity=<\/strong> file. The NMO velocity can be picked (for example, with sfpick<\/a>) from velocity scans (for example, produced with sfvscan<\/a>). <\/p>\n

If s=<\/strong> file is provided, sfnmo<\/strong> uses Malovichko’s shifted-hyperbola approximation
\n$$t \\approx \\left(1-\\frac{1}{s(t_0)}\\right) + \\frac{1}{s(t_0)}\\,\\sqrt{t_0^2 + s(t_0)\\,\\frac{x^2}{v^2(t_0)}}$$
\nSee <\/p>\n