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Surface distortion and rupture permits field emission from liquid surfaces at field strengths less than those effective for equally smooth solid surfaces. An approximate mathematical theory of the rupture of a plane liquid surface in a uniform electric field has been developed. The relation between initial distortion, rupture time, and field strength has been calculated for fields large compared to that which just renders the surface unstable. This critical field is ${E}_{m}=2{\ensuremath{\pi}}^{\frac{1}{2}}{(\ensuremath{\rho}gT)}^{\frac{1}{4}}=53$ kv ${\mathrm{cm}}^{\ensuremath{-}1}$ for mercury, where $\ensuremath{\rho}$ is density and $T$ is surface tension. Typically, the theory shows that a hump initially 4\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}5}$ cm high and of diameter 9\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$ cm will lead to rupture in 5\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}6}$ sec. in a field of ${10}^{6}$ v ${\mathrm{cm}}^{\ensuremath{-}1}$. Relative to initial humps in the surface whose linear dimensions vary inversely as the square of the field, the time to rupture varies inversely as the cube of the field strength. This calculation shows that a lowered sparking potential to liquid mercury can be ascribed to surface rupture and shows that it is possible that surface rupture plays a part in Beams' low field emission from liquid mercury. Possible application of the theory to the high field condition at the cathode spot of the Hg arc is not clear.

The San Miguel, Baja California Norte, earthquakes of February 9 and 14, 1956, were felt over most of northern Baja California and parts of southern California. They originated on the San Miguel fault. This newly named fault runs from the southern end of the Sierra Juárez, near the eastern end of the Agua Blanca fault, about N 60° W across the Álamo Plain. At least twelve miles of surface rupture occurred along this line during the February shocks. Cracks were uniformly open and arranged en échelon, stepping to the left. Magnitude of displacement was variable, but the direction was always right-lateral and up to the northeast. Surface evidence indicates that the fault is nearly vertical. A zone of springs, linear hills and valleys, displaced drainage, and closed basins extends beyond the zone of surface rupture for fifty miles northwest to the vicinity of Guadalupe. The main shock of February 9 occurred close to the northwest projection of the surface trace; the two major aftershocks on February 14 were near the southeast projection. This implies progressive faulting from northwest to southeast, similar to the southwest-to-northeast faulting in the Arvin-Tehachapi earthquake. Slides occurred on the steep slopes of the Sierra Juárez. Temporary warm springs were formed a few miles from the fault, and near-by existing springs had variations in their flow. Total property loss was small because there were few objects to be damaged. The six-building community of San Miguel, astride the fault, was severely hit: three adobe houses were destroyed and a frame schoolhouse was shifted from its inadequate foundations. Two brush shacks were relatively undamaged. Elsewhere, adobe and unreinforced concrete block structures suffered varying degrees of damage, most of which has gone unrepaired. The most common form of damage was cracking upward and outward from lintels. The principal damage in and around the Álamo Plain, the area of surface rupture, was apparently from the shock of February 9. Beyond the southeast end of the surface trace, the only reported damage was from the aftershocks of February 14.

The Buyin-Zara earthquake of 1 September 1962 originated on the Ipak fault and it was felt over most of Northern Iran. This newly named fault and its branches run for 64 miles, from Ipak, about W-05°-N, across the mountains south of Buyin, to Takhrijin, 4 miles west of Ab-i-Garm. During the earthquake of September 1, 1962 and its aftershocks, at least 64 miles of surface rupture occurred progressively along this line, and at leas two stages of progressive faulting were involved. Most probably, one from Rudak from where the fracture progressed east to Ipak, and a deeper fracture, with very weak surface evidence from Indrejin progressing east to Tofak. The earthquake killed 12,225 and injured 2,776 persons. It damaged beyond repair 21,310 houses and killed 35% of the livestock in the area. The maximum intensity of the shock did not exceed IX MM. Small landslides and rock falls occurred on steep slopes and temporary springs were formed.