Crater radius

Ra is the apparent crater radius (L) and the dependent variable, or crater parameter that we will attempt to predict. 

Figure 29.4. Crater radius versus charge weight for a broad range of explosives types and weights.

The cratering efficiency found from Table 29.1 is 0.75, and now the crater radius can be estimated as... 

Solving Eq. (29.5) for crater radius with this HOB correction yields a radius of only 0.65 ft. Following a rough rule of thumb that crater depth is about one-half the radius, this crater would be only about 4 in. deep. 

K, pressure gradient in soil (F/L ) and Ra, apparent crater radius (L). 

The dependence of crater radius and crater depth upon the depth of burst for a 1 kilo ton explosion in dry soil is shown in Fig. 9.5. Also shown are the range of... dimensions possible from a surface burst to the approximate maximum for an... 

Tlhe Sedan thermonuclear detonation in July 1962 created the largest A man-made crater ever produced by a single explosive. Approximately 7.6 million tons of earth were moved by this detonation to produce a crater with a radius of 608 feet and a depth of 323 feet (9). Fifty-eight percent of the crater mass or 4.8 million tons of desert alluvium were ejected from the crater during the detonation and distributed somewhat symmetrically around the ground zero point to a distance of 6000-7000 feet (1). 

If the expl is buried deeper in the earth than its radius of rupture, there is then formed a roughly circular depression, known as camouflet, considerably greater in vol than the expl chge producing it. Soft, low-density soil is lifted, scoured, and blown away more easily than firm or rocky earth formation. An expln in soft, swampy ground produces a relativ ely huge crater... 

Cross Section of Typical 2-lined Crater HRR = horizontal radius of rupture V HR = vertical radius of rupture. 

Let US examine the effect of dirt type first. A large number of explosive tests as well as a series of very near surface nuclear shots have been condueted on very different types of geology. From these experiments, statistical values for cratering efficiency, Eqk, as a function of geological type were determined. The efficiency, cr, is related to crater volume. This same number can be used in relation to radius as well as depth in the form cr > since the volume of a crater is roughly proportional to the cube of its linear dimensions. Table 29.1 gives cr values for various geological materials. 

Mercury is an important part of the solar system puzzle, yet we know less about it than any other planet, except Pluto. Mercury is the smallest of the terrestrial planets (0.05 Earth masses) and the closest to the Sun. Its relatively high density (5.4 g cm ) indicates that it has a large metallic core (—3/4 of the planet s radius) compared to its silicate mande and crust. The existence of a magnetic field implies that the metallic core is stiU partly molten. The surface is heavily cratered like the highlands of the Moon, but some areas are smooth and less cratered, possibly like the lunar maria (but not as dark). Its surface composition, as explained in the next section, appears to be low in FeO (only —3 wt.%), which implies that either its crust is anorthositic (Jeanloz et al., 1995) or its mande is similarly low in FeO (Robinson and Taylor, 2001). 

All of Neptune s six innermost satellites are very dark, having albedos of 0.065 or less. Proteus, the largest and outermost of the newly discovered satellites, had details on its surface imaged. It is heavily cratered, with a 93 mi (150 km) diameter crater visible there. Proteus turns out to be somewhat larger than Nereid and has a mean radius of 250 mi (400 km) images of Proteus indicate it to be decidedly non-spherical. The images indi-... 

The continuing activity of Mt. Erebus releases substantial amounts of volcanic particulates and gases into the atmosphere. In addition, a variety of salts are forming on rock surfaces and in the regolith in the area of the summit. The discharge of water vapor by fuma-roles on the summit plateau has caused the growth of spectacular ice towers and warm ground that occurs south of the Main Crater and elsewhere within a radius of less than 1,000 m of its rim. 

The Cover Depth Parameter. The total mass of rock material thrown into the surroundings is unquestionably a direct function of the crater volume produced by the explosion. The crater dimensions (depth, radius, volume) depend primarily on the depth and to some extent on the rock quality. 

V is the wear volume, b the diameter of the wear crater and R the radius of the ball. The... 

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