Inverse problems in reflection seismology

The international oil industry spends about $4 billion/year acquiring reflection seismic data. A large survey collects a terabyte (1012) of data which is computer processed to a pixel volume of (103)3 = 109 bytes. At sea the energy source is usually an air gun while on land, the source is mostly buried dynamite, and sometimes, multiple trucks carrying sweep- frequency ground vibrators. At sea, a shot is fired every 10 seconds; echos are recorded along 6 km cables at about a thousand locations, each channel recording a signal of about 2000 floating point values. A typical marine survey contract whose result is shown in Figure 1, lasts a month or more and costs upward of $10M.