So instead of being proud of our accomplishments, perhaps we are better off being skeptical that our accomplishments are as great as we think they are. There are many ways to make the data look better for the wrong reasons. For example, we should not conclude that a surface-consistent solution is correct just because it makes the data look better. As scientists, we need to be skeptical about our results in order not to fall into traps of irrational thinking. However, the assumptions built into these methods are highly simplistic and in a strict sense are known to be false. Decades-old surface-consistent methods allow the processor to turn these unknowns into knowns. The seismic processor’s job is to remove the unknown effects of statics, scaling and waveform distortions from the millions of seismograms that typically comprise each seismic dataset. The near-surface of the earth has a serious blurring effect on the image of the targets at depth that we really want to resolve clearly. The seismic data is acquired with sources and receivers on the surface of the earth so the irregular, inhomogeneous, unconsolidated near-surface layers distort the wavefields going down from the sources as well as the reflected wavefields coming up to the receivers. Land seismic exploration can be a frustratingly inaccurate science. Furthermore, in both cases the lack of definitive evidence is no reason for not clinging strongly to belief in the truth of the conclusions. In both the political and geophysical situations, definite conclusions need to be made despite the lack of hard and fast evidence. But in this case Rumsfield’s efforts to infer definite conclusions about the existence of weapons of mass destruction from a mass of evidence that was largely inaccurate, insufficient and inconsistent shares an uncanny similarity to the job that geophysicists do when processing and interpreting seismic exploration data, especially in land scenarios where seismograms typically contain more noise than signal. We are, after all, scientists who come to an understanding of nature from evidence of what is true rather from what we want to be true.
We geophysicists and geologists are generally not eager to compare ourselves with politicians.
But there are also unknown unknowns, the ones we don’t know we don’t know.” We also know there are known unknowns that is to say we know there are some things we do not know. Famously, United States Secretary of Defense Donald Rumsfeld in February 2002 made the following statement in response to the lack of evidence linking the government of Iraq with weapons of mass destruction: “…as we know, there are known knowns there are things that we know that we know.
0 kommentar(er)
