Slight Shocks Research Articles

Ramp-Wave Compression Experiment with Direct Laser Illumination on ShenGuang-III Prototype Laser Facility**Supported by the National Natural Science Foundation of China under Grant No 11305160.

Ramp-wave compression experiment to balance the high compression pressure generation in aluminum and x-ray blanking effect in transparent window is demonstrated with an imaging velocity interferometer system for any reflector (VISAR) on ShenGuang-III prototype laser facility. The highest pressure is about 500 GPa after using the multilayer target design Al/Au/Al/LiF and 1013 W/cm2 laser pulse illuminated on the planar Al target, which generates the spatial uniformity to over 500 μm on the ablation layer. A 2-μm-thick Au layer is used to prevent the x-ray from preheating the planar ablation Al layer and window material LiF. The imaging VISAR system can be used to record the abrupt loss of the probe beam ( nm) caused by absorption and reflection of 20-μm, 30-μm and 40-μm-thick Al, i.e., the blanking effect. Although there are slight shocks in the target, the peak pressure 500 GPa, which is the highest data up to now, is obtained with ramp-wave compression.

Housing Market Cycles A Disequilibrium Model and Its Application to the Primary Housing Market in Warsaw

This paper presents a simple disequilibrium model in the primary housing market, calibrated to the Warsaw market. Our aim is to point out that the primary housing market, due to the long construction process is always in disequilibrium, which has important policy implications. We discuss the last housing cycle and show how a combination of slight demand shocks with short-term rigid supply leads to strong fluctuations of house prices and new construction. The primary market can create a significant distress to the economy, because when house prices rise, this sector attracts capital and workers and is able to generate excessive supply, which finally can lead to the burst of the price bubble. The cyclical character is a permanent feature of the property market and can be explained by the inelasticity of supply. Market participants form price and demand expectations based on past observations. This causes frequent cycles that, under specific conditions, can lead to economic crises. We believe that the model describes the reality of the primary housing market better than equilibrium models do, so it can be useful for central banks and financial supervision institutions in the analysis of the impact of fiscal and monetary policy and regulations on the real estate market

Repairing a Mortgage Crisis: HOLC Lending and Its Impact on Local Housing Markets

Between 1933 and 1936 the Home Owners’ Loan Corporation purchased more than a million delinquent mortgages from private lenders and refinanced those loans for the borrowers. Its primary goal was to break the cycle of foreclosure, forced property sales and decreases in home values that was affecting local housing markets throughout the nation. We find that the volume of HOLC lending was related to measures of distress in local (county-level) housing markets and that these interventions increased 1940 median home values and homeownership rates, but not new home building.“[A] tremendous surge of residential building in the [last] decade… was matched by an ever-increasing supply of homes sold on easy terms [and only]… a small decline in prices was necessary to wipe out this equity. Unfortunately, deflationary processes are never satisfied with small declines in values. They feed upon themselves and produce results out of all proportion to their causes… In the field of real estate finance, particularly, we have depended so much upon credit that our whole value structure can be thrown out of balance by relatively slight shocks. When such a delicate structure is once disorganized, it is a tremendous task to get it into a position where it can again function normally.”1Henry Hoagland, 1935

Improvement of learning by cueing during postlearning paradoxical sleep

Rats were submitted to an active avoidance conditioning in a shuttle box with slight ear shocks used as conditioned stimulus (CS) preceding a foot shock. Three conditioning sessions were performed with a 24 h intersession interval. Animals were divided into 3 groups. After each session, the first group received the CS as cue during the first 6 phases of paradoxical sleep (PS) following learning. The second group received the CS as cue during 6 periods of wakefulness. The third group received no cue. Animals cued during PS showed a significant improvement in performances. The effect of cueing during the awake state appeared to be marginal compared to the clear-cut effects when the cue was presented during PS. A control experiment showed that the same ear shocks presented during PS were ineffective when they were not associated with the learning task (in this experiment a tone was used as CS during conditioning). These results are discussed in terms of memory reactivation during postlearning paradoxical sleep.

Dynamics of Subaqueous Gravity Depositional Processes

Clay-rich sediments, though commonly considered the least stable, possess greatest intrinsic bulk cohesion due to molecular and surface forces. Coarser materials derive stability from particle mass and physical packing; they, are essentially cohesionless. Intermediate silt and fine sand actually tend to be least stable; they are but weakly cohesive and commonly accumulate with open, mestastable packing. Hydrostatic pore pressure buoys saturated sediment masses slightly, reducing shear resistance. All fine sediments are susceptible to disturbance of their packing structures by forcible movement of fluids, thus slight shocks may deform metastable structure inducing gravity failure, even on half-degree slopes; such failures occur chiefly in areas of rapid deposition. Two fundamental dynamic boundaries distinguish elastic, plastic, and fluid behaviors. Plastic flow begins when the yield limit of cohesive sediment is exceeded; original stratification is preserved but contorted. Viscous fluid flow occurs if the liquid limit is exceeded; decreasing cohesion and churning destroy stratification and a suspension forms. This continuum of movements can be arrested at any point as is illustrated by the sedimentary record (load flows, contorted strata, pebbly mudstones). But if liquid limit is reached, cohesion normally deteriorates very rapidly by spontaneous liquefaction, almost inevitably producing a turbid suspension. This apparently accounts in part for the much greater abundance of graded bedding compared with contorted strata and pebbly mudstones. Inducement of mass failures results from disturbance by overloading, earthquakes, and hydraulic pressures (waves, tides, seepage). Turbidity currents may be initiated by mass movements, but also form by muddy rivers flowing into large bodies of water. Unfortunate misconceptions about turbidity currents have arisen, but repetitious graded bedding and displaced organisms or clastic materials are considered the most valid criteria of ancient turbidity current deposition. Volumetric importance of turbidity currents is difficult to estimate because of ambiguities among supposed criteria and destruction of graded bedding by normal currents.

One to One Correspondence between Etch Pits and Dislocations in KCl Crystals

Etch pits of KCl crystals obtained with dehydrated glacial acetic acid were observed. KCl is so soft, comparing with LiF, that dislocations are generated on it by slight mechanical shocks. Therefore, surfaces of KCl crystal are apt to be contaminated in the sense of the dislocation theory. It is supposed its depth usually reaches 100 µ or more and also most of these generated dislocations are surface half loops and isolated loops. One to one correspondence between etch pits and dislocations is discussed.

Earthquakes in Spain

Two Earthquake shocks caused some slight damage at Jativa, in Valencia, Spain, on May 23. No casualties are reported. Slight earthquake shocks are fairly frequent in southern Spain, which is part of the seismic zone stretching from the Atlantic Ocean at least to Turkey through the Mediterranean.

Seismological Data from India

THE Seismological Bulletin of the India and Ceylon seismological observatories for the period July-September 1939 has just been received. It has been published by the Government of India Meteorological Department under the direction of Dr. C. W. B. Normand. An average of eleven slight shocks and tremors daily was registered during July. It was estimated at the Colaba Observatory at Bombay that the earthquakes of July 12, 18, and 20 occurred near New Guinea, south of the Nicobar Islands and in the Pacific Ocean west of the Tonga Deep respectively. The latter probably had a depth of focus near 680 km. During August an average of ten earthquakes daily was recorded. The epicentre of the one on August 8 was in the ocean to the south-west of Ceylon, according to Colaba. It was felt over a large part of. Ceylon.

Sensitivity of Fish to Earthquakes

Two Japanese seismologists, Dr. Shinkishi Hatai and Dr. Noboru Abe, observed that catfish (Siluridse) in natural conditions showed signs of restlessness about six hours before earthquake disturbances were registered on their recording apparatus. Since catfish are, ordinarily, placid unresponsive creatures, experiments were made to test this seeming respon-siveness (Science Service, Washington, D.C.). Catfish placed in an aquarium were tested three times a day by tapping on the supporting table. When no earthquake was impending, the fish moved lazily or not at all; but about six hours before a shock the fish jumped when the table was tapped, and sometimes swam about agitatedly for a time before settling down upon the bottom again. Several month's testing showed that in a period when 178 earthquakes of all degrees of severity had been recorded, the fish had correctly predicted 80 per cent of the shocks. They showed no discrimination in their movements between slight local shocks and more serious distant shocks. The experimenters think that the catfish are made sensitive through electrical changes in the earth, since it was only when the aquarium was electrically earthed, through the drain-pipe, that they responded to a coming earthquake.

Societies and Academies

Societies and Academies

The San Francisco Earthquake of April 18

THIS disastrous earthquake was remarkable for its long duration and the rotatory character of the movement. As observed at Mare Island the first sign was a very faint, gentle rustling, the waves being the merest tremors; but after about a minute's duration they had grown to such proportions as to be felt by everyone. The violent phase lasted about forty seconds, and then the shocks died out, the last feeble tremors vanishing about three and a half minutes from the time of the first perception. The writer was favourably situated for noting the slightest disturbance, and had been awake some time before the first tremors were felt, and he could see the clock face at the beginning and end of the disturbance, which read about 5h. 11m. and 5h. 14m. 30s. Two of the four astronomical clocks at the Mare Island Observatory were stopped by having their pendulums thrown upon the ledge which carries the scale for measuring the amplitude of the swing. The time of the violent oscillation thus automatically recorded was 5h. 12m. 37s., Pacific Standard Time, eight hours slow of Greenwich. The waves were mainly from the south and south-south-west, and they seemed to turn to the west, giving the movement an elliptical, clockwise rotation. The pendulums of the two clocks which kept moving had their points rubbed against the swing index Of the ledge so violently that the metal of the index was brightened by the friction of the pendulum points, and the time thereby deranged more than twenty seconds. Except for the disturbance of objects on the ground, the earthquake seemed to be essentially noiseless. Other slight shocks have continued at irregular intervals for the past five days.

On the Cornish Earthquakes of March 29th to April 2nd, 1898

On March 29th and April 1st & 2nd, 1898, three slight earthquake–shocks were felt in the south of Cornwall. Their importance lies chiefly in the unusually clear evidence which they furnish, with regard to the origin of the double series of vibrations in one of the shocks, and to the continuous displacement of the seismic focus along the surface of the originating fault. It is possible that, at about the same time, there may have been other shocks or earth–sounds; but none, so far as I am aware, was noticed by more than one person. At Constantine, which is about 2 miles from the centre of the area chiefly affected, subterranean rumblings were heard on twelve occasions, ranging from six days before to three days after the principal earthquake on April 1st. Two other slight shocks, accompanied by a faint rumbling sound, were also observed on April 10th—one at Helston at 1.45 p.m., the other at Mabe at about 4.30 p.m. I have tried in vain to obtain other records of these reported shocks, and their seismic origin cannot, therefore, be regarded as established. Earthquake of March 29th, about 10.25 P.M. Of this earthquake I have only 9 accounts from 7 different places, namely, Crowan, Garras, ttelston, Mabe, Mawnan.Smith, Nancegollen, and St. Stythians ; while at 8 other places it is stated that neither shock nor sound was observed. The boundary of the disturbed area is indicated on the accompanying map (p. 2) by the broken–and–dotted line.

Curious Aerial or Subterranean Sounds

Is it not possible that the “Berisàl Guns” and “mist pouffers,” referred to by Prof. Darwin (p. 650), are merely earthquake sounds, the attendant shock being too slight to be otherwise perceptible? Nearly all earthquakes are accompanied by a rumbling sound, due, I believe, to the small and rapid vibrations proceeding chiefly from the margins of the area over which the fault-slip producing the earthquake takes place (Geol. Mag., vol. ix., 1892, pp. 208–218). In some districts (Comrie in Perthshire, East Haddan, in Connecticut, Pignerol in Piedmont, Meleda in the Adriatic, &c.), sounds without shocks are common during intervals which may last for several years, but slight shocks with sound occasionally intervene, as if the sounds and shocks were manifestations, differing only in degree and the method in which we perceive them, of one and the same phenomenon. In great earthquakes, the sound-area is confined to the neighbourhood of the epicentre; in moderate and slight shocks the sound-area and disturbed area approximately coincide, or the sound-area may even overlap the disturbed area. In the limiting case, the disturbed area vanishes, and the vibrations are perceptible only as sound.

The Earthquakes in Zante

THE following is a list of the shocks of earthquake at Zante, compiled from telegrams published in the Times and Standard:—January 31, at daybreak, the most destructive earthquake, of which, however, some warning must have been given, if we may judge from the comparatively small loss of life. Other slighter shocks followed during the day. February 1, 2 a.m., another severe shock, felt also in Cephalonia. February 2, two more violent shocks, one of which caused some fresh damage. February 3, further shocks, but less frequent and violent. February 5, another violent shock. February 6, continued shocks of slight intensity, followed by three more severe ones in the afternoon and evening. February 7, another violent shock in the morning, resulting in but little additional damage. February 8, some slight shocks. February io, some slight shocks in different districts. February II, I a.m., a somewhat severe shock, followed by a succession of shocks between 8 and 9 p.m. February 12, further shocks in the early morning, soon after midnight, and again at intervals during the day. February 13 or 14, renewed slight shocks, accompanied by loud subterranean rumblings. The Athens correspondent of the Times, telegraphing on February 20, says: “The shocks of earthquake continue at Zante, with varying degrees of violence. No serious damage is reported, but those who are compelled to live in the half-ruined or insecure houses are exposed to frequent alarms.” It is estimated that the total loss of property due to the shocks may exceed £600,000.

III.—On the British Earthquakes of 1890, with the exception of those felt in the Neighbourhood of Inverness

The most remarkable earthquakes of the year 1890 were those felt in the district round Inverness between November 15 and December 14. These have been described in a separate paper. The remaining earthquakes were of comparatively slight intensity. Two or three were felt during the night of June 25–26 within a very small area to the north-east of Leeds, and one at least in Kintyre on July 24. Several slight shocks at Invergarry and Feddan, in Inverness-shire, complete the list so far as known to me, with the exception of a doubtful shock at Tulliallan in Perthshire on January 6.It is hardly necessary to do more than refer here to the two supposed earthquakes felt on January 7 at and near Chelmsford. In a letter to “Nature,” I have given the evidence in full; and it appears to me sufficient to show that they were merely the reports of one of the great Woolwich guns.

Geographical Notes

IN a paper (accompanied by a map) in the last number of the Proceedings of the Royal Geographical Society, we are told by the author, Captain Langen, that the Key, or Ké, Islands derive their name from the native word Ké (pron. Kay), which signifies “What do you say?” The native tradition runs that when Macassar traders first landed there, and inquired in the Malay tongue after the name of the land they had set foot on, the Key natives answered “Kay?” which expression was mistaken by the questioners for the name of the islands; and under this name, which has been changed into “Key,” or “Ké,” we find them on charts of the East Indian Archipelago. The islands are very incorrectly laid down on all nautical charts, and Captain Langen's brother has taken great pains in drawing up a map according to his own survey, which is given in illustration of the paper. The group consists of two larger islands, of which the westerly one bears the name of Nuhu-roa, or Little Key, and the easterly one Ju-ud, or Great Key, surrounded by a number of smaller islands. There is no doubt that Great Key is geologically much older than Little Key and the other surrounding islands; it possesses elevations of from 2000 to 3000 feet, whilst Little Key and the other islands are very low. Great Key principally consists of a rocky and volcanic formation, whereas Little Key and the surrounding islands are formed of coral and interveined by flint and quartz. The traveller will find on the highest inland elevations of Little Key (200 feet) shells of various species, greatly damaged through long exposure to wind and weather. About thirty-five years ago, according to the most reliable chiefs, Little Key was raised out of the sea during the shocks of a severe earthquake, attended by a tidal wave; since then no earthquakes occurred until 1884, in the month of April. The members of the European settlement report that the day opened sultry and stifling, the sun shone till about 9 a.m., when the sky became overcast, and at 10 a.m. the first shock was felt, which caused our saw-mill, then in course of erection, to sway to and fro. No sooner had the workmen felt this first shock than they rushed out of the building, and after a short lapse of time two more slight shocks were felt, but fortunately without doing any serious damage. About half an hour's walk eastward from Doelah, is an extinct crater, filled with fresh water, of a great depth, and of a very dark blue colour. Every island belonging to the Key group is covered, down to the water's edge, with dense tropical jungle, gigantic creepers winding themselves from one tree to another, thus forming a close network and great impediment to travelling. These forests contain choice kinds of timber, which formed one of the principal inducements for the establishment of the present German colony.

Earthquake in South-West England

I HAVE just felt and heard the shock of an earthquake. The trembling of the earth was very great and the accompanying noise very loud, comparing it with one or two other slight shocks which I have before experienced in this district. I found the time to be 1.38 p.m. The time it lasted was several seconds. It was longer and louder than an ordinary clap of thunder when the lightning is not far off. A man reports that the slates of the cow-house were made to rattle.

Earthquake in South-West England

I BEG to inform you of the occurrence of two slight earthquake shocks here to-day, one shortly before 2 p.m., the ether near half an hour later. The direction of progress seemed to be from north-west to south-east—that is along the line of the deep and narrow valley. The tremor was sufficient to cause jangling of glass and earthenware, and of the slates covering the house. The usual rumbling noise accompanied the shocks.

Earthquake in the Andaman Islands

I SEE among the Notes in your last issue (p. 325) that there has been widespread seismic disturbance in Asia, including Ceylon, but unfortunately in no instance is the date given, which would have added very greatly to the value of the record. It may be interesting to give an extract from a letter I have just received from my brother, Mr. Harold Godwin-Austen, from Port Blair, Andaman Islands, which very probably was connected with the disturbance in Ceylon, and if so, it covered a very considerable area of the earth's surface, the distance being about 750 miles between the two places:—“Port Blair, January 2.—We had a very bad earthquake here on December 31, 1881, at 7.52 a.m. I thought the place was going to pieces. There has been a good deal of damage done to work and pucca (brick) buildings, and we had five high and low tides in three hours after the shock, and the sea did not quiet down all day. Since then we have had two or three slight shocks.”

Earthquakes in Iceland

IN NATURE, vol. xxi. p. 89, I see the earthquake which occurred in Iceland on September 24 last ascribed to “volcanic eruptions in the Krisuvik Mountains, a locality where eruptions have not been known within the memory of the present generation”. The use of the word “eruption” here is misleading, for though the earthquakes, which frequently occur at Krisuvik, are no doubt caused by volcanic action, nothing of the nature of an eruption, in the usual sense of the word, has been known to occur there within the historical period. The boiling springs, mud caldrons, and sulphur deposits, for which Krisuvik is noted, are, on the authority of Prof. Bunsen (Letters to Berzelius), to be ascribed to a pseudo-volcanic action occurring at comparatively slight depths. Though slight earthquake shocks have frequently occurred, during the last eighteen months, while I was at Krisuvik, I have never observed that they had any effect on the boiling springs and other thermal phenomena.