Cable Breaks Research Articles

Monitoring broken steel cables in moving elastomer belts

A practical method is described for detecting broken steel cables in flat elastomer belts. Cables are permanently magnetised by a preconditioning technique which results in externally fringing fields at a cable break. These fields are detected using passive monitoring coils above and below the surface of the moving belt. Voltages induced in coils by the motion of the fields are used to analyse the type and extent of failure in these important mechanical handling belts.

Sediment slides and turbidity currents on the Laurentian Fan: Sidescan sonar investigations near the epicenter of the 1929 Grand Banks earthquake

The epicenter area of the 1929 Grand Banks earthquake on the continental slope south of Newfoundland has been investigated using Sea MARC I, a deeply towed, midrange sidescan sonar with a 4.5-kHz subbottom profiler. Shallow slides pass downslope into debris flows on the muddy continental slope east of the epicenter. At the head of the Eastern Valley of the Laurentian Fan, west of the epicenter, arcuate slide scars cut undisturbed upper-slope sediment and lead downslope to a lineated erosional seabed. At a water depth of about 1600 m, this erosional seabed passes into extensive fields of 100-m-wavelength gravel waves situated on the broad, irregular valley floor. The gravel waves become better developed downslope and extend at least to water depths of 3000 m. All these morphological features appear fresh on the sidescan sonograms, suggesting that they date from the 1929 earthquake event, and the distribution of slides corresponds to the area of instantaneous cable breaks in 1929. The upper limit of erosion on valley walls suggests that the 1929 turbidity current was less than 300 m thick. Timing of cable breaks downfan suggests that flow velocities were sufficient to rework gravel deposits into large bedforms during waning flow stages over elevated areas of the valley floor. Similar cross-bedded coarse sands and gravels are common in ancient channel deposits.

Orleansville Turbidite: ABSTRACT

The Orleansville earthquake in 1954 produced a turbidity current on the Algerian Mediterranean margin and adjacent South Balearic basin sea floor which broke five telephone cables. The report of this event represented a cornerstone in the evolution of turbidity current theory. The resulting turbidite has been mapped on the Balearic abyssal plain for the purpose of relating flow paths and turbidite size, and areal extent to cable break locations. This study is based on 50 gravity cores. Figure The Orleansville turbidity current actually consisted of two currents which arrived simultaneously on the basin plain via two canyon mouths separated by 30 km. The merged turbidity currents flowed 170 km out on the basin-plain floor and covered an area of 8,000 km2. The turbidite is a tongue-shaped sediment body, 50 km wide, oriented northeast-southwest. It consists of a central band of 5-cm thick sand with a fringing 2 to 3-cm thick band of coarse to fine silt. Two of the cable breaks occurred on the abyssal plain at the extreme edge of the turbidite where the sediment is only 2 cm thick. An underlying turbidite of very similar dimensions to the Orleansville turbidite is separated from it by a 10 to 15-cm pelagic sequence. The consistent spacing between these two events in icates that although the Orleansville turbidity current broke telephone cables at its extreme margins, it caused no detectable erosion on the basin-plain floor. End_of_Article - Last_Page 641------------

Engineer's flexible arms: a method of increasing their rigidity.

A simple modification of the attachment of the terminal nipples to the central cable in an engineer's flexible arm is described. By its use, the cable breaks before the nipples are avulsed and greater tension can be employed than with conventional methods of fixation. The resulting increased rigidity much improves the reliability of such arms.

Turbidity Currents and Cable Breaks in the Western New Britain Trench

The western New Britain Trench is receiving abundant sediment from the west. Evidence for earthquake-triggered turbidity currents has been detected in the New Britain Trench through breaks in a submarine telephone cable in 1966 and 1968. The average velocity of the turbidity currents is 50 and 30 km/hr, respectively, assuming that the most likely single source of the turbidity currents is the Markham River delta at Lae, New Guinea. Bottom photographs and sediment samples support these conclusions. Deep-sea channels are present.

The channelized flow of turbidity currents with application to Monterey Deep-Sea Fan Channel

Whenever a turbidity current is confined to a channel its upper surface has a cross-channel slope, owing to the combined effects of the Coriolis and centrifugal forces. This cross-channel surface slope for channel full flows may cause a difference in the heights of the levees that have developed on opposite sides of the channel. An equation is developed that balances the Coriolis and centrifugal forces against the pressure force that results from the surface slope. This equation can be used to calculate curves of average velocity versus density, the two variables in the equation, and the two principal unknowns of turbidity current flow. The autosuspension mechanism of turbidity current flow provides a lower limit on the range of permissible velocities and, hence, by way of the equation, on the range of densities. Grain-to-grain friction becomes prohibitively large for densities greater than about 1.18 g/cm3 so that an upper limit is placed on the range of permissible densities and velocities. The slope equation is applied to fathograms of twelve crossings taken along a 100-km stretch of the channel that extends from Monterey submarine canyon off the coast of central California and crosses Monterey fan. This portion of channel consists of a large meander curving to the right followed by a broad curvature of the channel to the left. The cross-channel surface slope of the flow, as reflected in the difference in the heights of the levees, behaves as expected in response to the combined Coriolis and centrifugal forces. Solutions of the slope equation for the twelve crossings, in view of the permissible densities, give velocities ranging between 600 and 2000 cm/sec. This agrees in magnitude with the velocities obtained from ordered sequences of submarine cable breaks. Calculations of curves of velocity versus density with a modification of the Bagnold [1962] equation, based on the concept of autosuspension and utilizing different channel parameters, agree favorably with the results obtained with the cross-channel slope equation. Using velocities deduced from the levee height differences, it is found that a reasonable range of Pleistocene slump volumes in Monterey Canyon is capable of generating channel-full turbidity currents of adequate length and time of passage. The simultaneous solution of the cross-channel slope equation and the Bagnold equation, assuming a wide range of sediment discharge rates, indicates that there has not been a substantial amount of erosion of the channel since the levee height differences were developed.

Treatment by atrial-triggered pacemaker.

Fifty-four patients with heart block were treated with the atrial-triggered pacemaker, which was implanted without thoracotomy. An atrial detector-electrode was placed in the mediastinum by means of media-stinoscopy, except in a few cases where an intra-atrial detector electrode was inserted by transvenous technique. The patients were treated for 14 months on the average, with very satisfactory results. Nineteen patients had their pacemaker changed after an average of 15 months. This type of pacemaker seems to have no greater tendency to failure than the fixed rate type. There were no cable breaks or other defects of the electrodes. The advantages of synchronous pacemaker treatment were discussed and the importance of normal atrial activity was emphasised. On the basis of the results of treatment and of haemo-dynamic studies, indications were established for the use of atrial-triggered pacemaker.

Specialized Apparatus for Testing Subway Cars

Methods of making tests of a varied nature on subway cars are described and details of pieces of apparatus are given. Instrumentation for recording braking tests is discussed and followed by discussion of rapid distance recording. A novel form of speedometer is detailed and its special drive mechanism is described. A brief comment on accelerometers is followed by opinions on the criteria for desirable current-voltage recorders. The need for time synchronization of paper charts and a method of providing every recorder simultaneously with an accurate comrnon time scale trace is described. Conmments on common temperature measurements and a description of a little known method of high temperature recording follow. A simple duty cycle meter and a device for detecting partial breaks in cables are discussed, followed by a synopsis of a few other devices used in Toronto.

The Yallahs Basin: A sedimentary basin southeast of Kingston, Jamaica

The Yallahs Basin lying at a depth of 1,300 m is about 100 km 2 in area and contains approximately 500 m of sediments. It is structurally controlled and probably fault bounded. It has been filled by resedimentation of noncarbonate material from two gravel fan deltas and, to a lesser extent, by carbonate from the Jamaican island shelf. After the basin was filled slides and turbidity currents from the more active of the two deltas cut the Yallahs canyon down some 200 m and back 16 km across the basin. Seismic profiling shows that two series of sediments occur in the basin, one laid down before the canyon was cut and one after. A short core from the upper series shows a well-graded sequence of sands and silts. Cable breaks indicate that the three main sediment sources are still active.

APPLICATION OF THEORY TO AN ATLANTIC TURBIDITY‐CURRENT PATH

SUMMARYSome results of turbidity‐current theory are applied to analyses of turbidite layers in cores from the route of a large turbidity current of sheet‐flow type. Novel features are that current velocity is estimated from the sediment sizes deposited, and the lateral spreading of the current is considered. An approximate quantitative picture of the current is obtained. It is compared with the turbidity current which caused the Grand Banks cable breaks.

Congo Submarine Canyon

In May, 1957, a brief survey of the Congo Submarine Canyon was conducted from the Research Vessel VEMA. The canyon was found on the continental slope near the seaward limit of earlier surveys and traced to the west for 150 miles. Where the survey was discontinued, in depths of 2,200 fathoms, the leveed canyon was still a prominent feature. At the 550-fathom contour the canyon is about 5 miles wide at its rim and 500 fathoms deep. The canyon is V-shaped and echoes from the thalweg are usually recorded after the echoes from the steep walls. The outer parts of the canyon, in depths exceeding about 1,800 fathoms, are bounded by huge natural levees. In 1963 a 30-mile-long section of the canyon was surveyed 150 miles west of the 1957 study. Four biological trawls and ten sediment cores were collected from the canyon region. One trawl in 2,140 fathoms contained abundant tree leaves and a rich fauna. The canyon cores contain silt, sand, and organic debris. The canyon was discovered in 1886 by a cable route survey. Between 1887 and 1937 the Luanda-Sao Thome cable broke 30 times in the canyon. Breaks occurred most frequently during months of maximum river discharge and consequently at the times of greatest bed-load discharge. Cable breaks were limited to periods of years when the river channel was undergoing major changes in position and depth. The cable breaks which occurred up to 120 miles seaward of the river mouth are attributed to turbidity currents generated at the river mouth at times of maximum bed-load transport. These turbidity currents flowed down the continental slope, eroding the deep slope canyon and building the natural levees of the continental rise, and eventually spread out on the Angola Abyssal Plain. In contrast to oth r great rivers, the Congo is not building a subaerial delta; virtually its entire bed load is being carried by turbidity currents via the Congo Submarine Canyon to the great Congo Cone on the floor of the Angola Basin.

Grand Banks Slump: GEOLOGICAL NOTES

A seismic reflection profile in 1961, south of Grand Banks, showed a huge gravity slump on the continental slope near the first of a sequence of delayed cable breaks believed to be due to a turbidity current from the 1929 earthquake. This great slump could explain the instantaneous cable breaks near the epicenterter. Sedimentary cores show generally a gray layer over a thick red layer, but in channels inferred to be made by turbidity currents associated with the Grand Banks earthquake the gray layer is thinner or absent. The change in color is thought due to the red sediments having been abruptly cut off from their source, perhaps by glacial retreat or sea-level rise.--G.D.C

Remarks on the Grand banks turbidity current

The hypothesis is discussed that a turbidity current caused the breaks in the submarine telegraph cables lying down-slope of the epicentral area of the 1929 Grand Banks earthquake. An inspection of the bottom topography makes it appear impracticable for the turbidity current to have approached, from the north, and to have caused several of the cable breaks ascribed to it. Though the hypothesis of a turbidity current is able to account for the fact that the cables were broken in sequence from north to south, it is not able to explain why distant breaks on one and the same cable occurred simultaneously. The direction chosen by the turbidity current indicated by the cable breaks is to the left of the general direction of the slope, whereas it should be slightly to the right of the slope, in view of the action of the deflecting force of the earth's rotation. It is demonstrated that a turbidity current with a limited length should rapidly lose suspension in the rear and become considerably thinner and slower.

High-velocity turbidity currents, a discussion

The possibility of the transport of coarse material by turbidity currents is discussed. The difficulties in regarding such currents as responsible for the cable breaks following the 1929 Grand Banks earthquake are pointed out.

Discussion on “The localization of exposed breaks in submarine cables”

Discussion on “The localization of exposed breaks in submarine cables”

The localization of exposed breaks in submarine cables

This paper gives a brief description of the methods used in localizing breaks in submarine cables, and an account of measurements made with the purpose of verifying the laws relating to breaks. From these, and similar measurements, certain conclusions are drawn which, when applied to break tests, should reduce errors in localization.As a result of a study by the author of the laws governing break tests, a new method is presented of computing the resistance to a break from measurements made in a known manner.

Saint Lawrence (Cabot Strait) Submarine Trough

Introduction The Saint Lawrence estuary or submarine valley extends inland to the vicinity of the city of Quebec. In its upper portion it is fairly shallow, but from a point near the mouth of the Saguenay out to the edge of the continental shelf, 750 miles away, there is a submarine trough, most of which is between 100 and 300 fathoms deep (Figure 1). One large tributary of the trough extends up towards the Strait of Belle Isle and has a branch on the north side of Anticosti Island. The Grand Banks earthquake of November 19, 1929, which produced 63 breaks in the transatlantic cables, had its epicenter just outside the Saint Lawrence trough. Studies of this earthquake have led Prof. J. W. Gregory, Dr. Arthur Keith, and Dr. E. A. Hodgson to conclude that the trough is a fault graben.2 Previously it had been considered by others to have . . .

Sea-Bottom Samples from the Cabot Strait Earthquake Zone

Research Article| June 30, 1931 Sea-Bottom Samples from the Cabot Strait Earthquake Zone1 E. M. KINDLE E. M. KINDLE Search for other works by this author on: GSW Google Scholar GSA Bulletin (1931) 42 (2): 557–574. https://doi.org/10.1130/GSAB-42-557 Article history received: 19 Jan 1931 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation E. M. KINDLE; Sea-Bottom Samples from the Cabot Strait Earthquake Zone. GSA Bulletin 1931;; 42 (2): 557–574. doi: https://doi.org/10.1130/GSAB-42-557 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract IntroductionThe bottom samples discussed in this paper represent 24 stations in the region southwest of the Grand Banks where many cable breaks were caused by the earthquake of November 18, 1929. These samples were obtained by the cable repair ships, the John W. Mackay and the Faraday; 17 were sent to me by Mr. A. E. Powell, vice-president of the Commercial Cable Company, and I am indebted to Prof. D. S. McIntosh, of Dalhousie University, Halifax, Nova Scotia, for the opportunity of studying five others.All the sediments included in this study fall in the class of terriginous deep-sea deposits, coming from depths ranging from 400 to 2,000 fathoms. The fact that 12 cables were broken, some of them in many places, by the heavy earthquake of November, 1929 (figure 1), lends especial interest to the samples of sediment forming the sea-bottom on which this havoc was wrought.The . . . This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Method for Finding Cable Breaks

Method for Finding Cable Breaks

Method for Finding Cable Breaks

Method for Finding Cable Breaks