Craters, scaling

Hypervelocity Impact Dependence of Crater Dimensions on Impact Velocity. Craters in copper and lead, produced by hypervelocity impact, were measured and the dimensions correlated with impact vel. The results indicate that craters scale with ca the 1.7 power of vel, in agreement with computer physics results based upon hydrodynamic calculations... 

Grieve R. A. E. and Cintala M. J. (1992) An analysis of differential impact melt-crater scaling and implications for the terrestrial record. Meteoritics 27, 526-538. 

Event 1 Explosion—Ammonium nitrate. Azote de France Factory, Toulouse, France (September 21, 2001). 30 killed (7 off-site), 800 hospitalized, 2,400 injured, shock wave of 3.4 on the Richter scale, 50-foot crater resulted 500 homes uninhabitable and 85 schools or colleges damaged chemical releases and structural damages at other facilities (Dechy et al. 2004). 

In an optical micrograph of a commercially available nitinol stent s surface examined prior to implantation, surface craters can readily be discerned. These large surface defects are on the order of 1 to 10 p.m and are probably formed secondary to surface heating during laser cutting. As mentioned above, these defects link the macro and micro scales because crevices promote electrochemical corrosion as well as mechanical instability, each of which is linked to the other. Once implanted, as the nitinol is stressed and bent, the region around the pits experiences tremendous, disproportionate strain. It is here that the titanium oxide layer can fracture and expose the underlying surface to corrosion (9). 

Depth scale calibration of an SIMS depth profile requires the determination of the sputter rate used for the analysis from the crater depth measurement. An analytical technique for depth scale calibration of SIMS depth profiles via an online crater depth measurement was developed by De Chambost and co-workers.103 The authors proposed an in situ crater depth measurement system based on a heterodyne laser interferometer mounted onto the CAMECA IMS Wf instrument. It was demonstrated that crater depths can be measured from the nm to p,m range with accuracy better than 5 % in different matrices whereas the reproducibility was determined as 1 %.103 SIMS depth profiling of CdTe based solar cells (with the CdTe/CdS/TCO structure) is utilized for growing studies of several matrix elements and impurities (Br, F, Na, Si, Sn, In, O, Cl, S and ) on sapphire substrates.104 The Sn02 layer was found to play an important role in preventing the diffusion of indium from the indium containing TCO layer. 

Figure 10.9 Reflectance spectra obtained from Earth-based telescopes for small (< 5 km diameter) areas within the Copernicus crater on the Moon (from Pieters et al., 1985). Left reflectance scaled to unity at 1.02 im right residual absorption after continuum removal. Spectra are offset vertically, (a) Wall and (b) floor areas containing orthopyroxene are deduced to be of noritic composition (c) floor containing pyroxene and glass is an area of extensive impact melt and (d) central peak containing olivine is deduced to be troctolite.

Figure 9.19 Scale analysis of North Sea houting from Ijsselmeer lA-ICP-MS, a) photograph of a scale, b) part of a scale with laser craters obtained by LA-ICP-MS measurement in line scan modus, c) Sr Ca ratio for nine North Sea houting caught in Ijsselmeer in 2001/2002. The results were sorted into three different types A Fish that only lived in freshwater B Fish that lived for a fairly long period in fresh water, then moved to sea water and returned to fresh water where they were caught C Fish that obviously moved quickly to sea water after hatching (period from hatching in fresh water until the arrival in the sea was to short to measure a ratio that normally indicates fresh water) and returned to...

In this chapter, we will examine craters created from ground-level bursts, above-surface bursts, and buried bursts. We will find methods to scale from existing databases that wilt allow us to correct for the type of explosive as well as the type of ground medium. 

The way we can apply this to crater dimension prediction is to use the ratio of the cr of the material in question to cr of a material for which you have known scaling data. An example follows ... 

Use the scaling data for surface bursts to scale crater dimensions for aboveground bursts. Correct these data for ground medium and explosive type, but also correct the explosive equivalent weight by the ratio of percent energy coupled at height of burst to 33% (% coupled at HOB = 0). Combined with the equation shown in Figure 29.6, this becomes... 

Stephenson, D., Small Scale Cratering Studies in Sand/Clay Soil, E. H. Wang C.E.R.F./UNM for Defense Nuclear Agency and Air Force Weapons Laboratory, AFWL TR-73-99, August 1979. 

Chabai, A. J., Influence of Gravitational Fields and Atmospheric Pressures on Scaling of Explosion Craters, Impact and Explosion Cratering, (pp. 1191-214), Pergamon Press, New York, 1977. 

---