The following paper contains a summary of the historical record, so far as it is available in accessible references and a list of 206 dates on which earthquake shocks have occurred since 1606 B.C.
Some account of the geographical conditions which appear to be related to the distribution of seismic activity follows, and it is indicated that there are at least three distinct earthquake provinces in Palestine and Syria. The southern one corresponds to the plateau of Palestine and is of moderate activity. A central one comprises the arcs of the Lebanon and Anti-Lebanon ranges and centers in Damascus. The northern one coincides with the distinct arcs between Homs and Aleppo. A fourth, which may be regarded as belonging to Asia Minor, is the arc of the Giaour Dagh and Cyprus that has been the origin of the many destructive shocks recorded in the history of Antioch.
The Palestine earthquake of July 11, 1927, is described from personal observation, and it is pointed out that it exhibited a major and two minor centers of destructive intensity.
Building conditions he Palestine are presented in accordance with data collected during inspection of structures wrecked by the earthquake. Acknowledgments are here made to the British authorities for the cordial assistance constantly given the writer in his studies.
The article closes with suggestions of the nature of the geologic problems involved in the earthquake activity and the extraordinary depression of the Dead Sea trough.
It is illustrated by two diagrammatic maps and twenty photographs by the author.
From time immemorial Palestine and Syria have been afflicted by earthquakes. Not that there is precise statement of fact in ancient writings; it is not to be expected that the people of antiquity would have had or could have preserved definite records; but there are many references in the traditions from which Old Testament history sprang, and in the Old Testament itself, which either suggest the occurrence of earthquakes or state clearly the fact of their occurrence. A good illustration of the effect of storm, flood, and earthquake upon the ancient mind is found in the Epic of Izdubar, which was inscribed upon clay tablets some 2000 years before Christ and was in all probability a folktale of far greater antiquity. The epic describes the Deluge in a manner closely parallel to the account given in Genesis and it has been discussed by Suess, who explained the flood as a coincidence of cyclonic rainfall with an earthquake wave. We may quote from his carefully revised translation of the original cuneiform inscription
"Now when the sun had made the appointed time, a voice spoke: in the evening the heavens will rain destruction. The appointed time is arrived, spoke the voice, in the evening the heavens will rain destruction.
Then arose Mu-seri-ina-namari from the foundations of the heavens, black clouds in the midst thereof Ramman caused his thunder to roar, while Nebo and Sarru advanced against each other, the "thronebearers" stride over mountain and plain. The mighty plague god unfetters the hurricanes Adar causes the canals to overflow unceasingly. The Anunnaki cause floods to rise, the earth they Uptake to tremble through their Cozener, Ramman's great billow ascends to the sky: all light is consumed in darkness.
Brother looks no more for brother, men trouble no longer about each other. In heaven the gods fear the deluge, and they seek a retreat, they ascend to the heaven of the god Anu. spike a dog in his litter, the gods Crouch together at the railings of heaven.
It would be difficult to describe more graphically the helplessness of men, their utter terror and confusion before those natural forces, which caused even the gods to "crouch together at the railings of heaven." The line which refers to the trembling of the earth may allude to experiences of earthquakes or may be but a poetic expression. In any case the description shows clearly the manner in which men regarde d, and for that matter, many still do regard great natural catastrophes.
In the Old Testament itself there are many figurative phrases which may be interpreted as descriptions of earthquakes or their effects, as in Numbers 16 :31, where it says: "And it came to pass, as he [Moses] made an end of speaking all these words, that the ground slave asunder that was under them; and the earth opened her mouth, and swallowed them up, and their households." Or in I Samuel 14:15: "And there was a trembling in the camp, in the field, and among all the people; the garrison, and the spoilers, they also trembled; and the earth quaked; so there was an exceeding great trembling." Or still more definitely in Kings 19:11: ".And, behold, the Lord passed by, and a great and strong wind rent the mountains, and brake in pieces the rocks before the Lord; but the lord was not in the wind; and after the wind an earthquake; but the Lord was not in the earthquake; and after the earthquake a fire; but the Lord was not in the fire; and after the fire a still small voice."
Montessus de Ballore, a great seismologist and a devout Catholic has discussed the biblical references to earthquakes with a phenomena between those events that should be regarded as natural phenomenon simply and those which should be considered as miraculous or divine. The distinction is not sharp, for the orthodox Catholic interpretation permits the assumption that God may have used all earthquake or other activity of natural forces to accomplish His purpose, as for instance in the punishment of Sodom and Gomorrah. If, as tradition has it, those cities in the Vale of Siddim were situated by the Salt or Dead Sea near its southern end, they may very possibly have been buried beneath one of the great landslides which have occurred there and the slide may have been caused by an earthquake. The rationalist may rest the explanation at that point; the orthodox may attribute the whole occurrence to the divine purpose; and argument avails nothing since the minds of men react differently to the facts, according to their inborn tendencies Montessus therefore had no difficulty as a seismologist in discussing the various disasters or triumphs (as when the walls of Jericho fell) and he analyzes them with scholarly understanding. Interesting though it would be to review many of the instances he considers, we must be content to note that there is abundant evidence that earthquakes were among the natural phenomena with which the patriarchs of Israel were acquainted.
Lists of earthquakes have been compiled from many. and diverse sources. The oldest known to me was by an Egyptian, As-Soyuti by name, about the beginning of the tenth century. Having experienced an earthquake in Egypt .As-Soytuti was impelled to impress his countrymen with a realization of the divine wrath from which they had suffered; but in the kindness of his heart he desired to soften the lesson by showing them that others had been far more severely punished. He may have exaggerated somewhat. l lis compilation, being wholly from Arabic sources, supplements those compiled from Christian chroniclers to an important degree, nevertheless. No complete translation appears available, but his list of shocks has been published in English by the Asiatic Society of Bengal.
Ecclesiastic histories and studies carried out by earnest Fathers of the church, who sought reverently to fathom the divine purpose of repeated catastrophes, furnish data for lists that cover the first 1,800 years of our era. The Abbe Perrey, a professor in the faculty of sciences at Dijon a hundred years ago, made an extensive compilation of all the records he could find and prepared the catalogue known by his name, which is the principal reference work on the seismology of Europe. His final contribution, published in 1849, took in the regions we now designate as the Near East: Turkey, Greece, Asia Minor, Mesopotamia, Syria, Palestine, and Egypt, as well as the islands of the Mediterranean and of the Grecian archipelago.
Professor G. L. Arvanitakis, a student of the meteorology of Palestine, regarding whose activities no other information is available, in 1904 published a catalogue of earthquakes which evidently represents very extensive research in ancient and modern chronicles. Whereas the other lists, except Mallet's, give no dates for the era before Christ, he cites the year and place of occurence of ten earthquakes from 1470 to 24 B.C.
A somewhat more discursive statement than any of the three catalogues cited was prepared by a French author, Monsieur J. D. Tholozan, and was published in the Cognates Rendus of the French Academy in 1879. Various other references make it possible to complete the list fairly satisfactorily down to the current year. There are, however, probably some earthquakes noted in the scientific records of recent decades which have not been included in these less exhaustive catalogues. Mallet's great catalogue furnished fourteen dates not included in the earlier ones, four of them being biblical records, 900 B.C. or earlier, and several others apparently representing duplicate records of one occurrence.
From all these sources we have arranged a list which includes every shock noted for Palestine and Syria, omitting none that is listed but not including detailed accounts of destruction, many of which seem greatly exaggerated, nor the numerous references to the original sources. For these data the reader should consult the works cited below.
Other references to special occurrences of earthquakes in Palestine may be found in the great "Bibliografia General de Temblores," by Montessus de Ballore, and some additional data were secured during and since my recent visit to Palestine.
The following list gives the year of occurrence, a reference to the work in which it is cited, and the place. The authorities are indicated in the list by thier initials, as follows: .A, As-Soytlti (Sprenger); Ar, Arvanitakis; B, Blankenhorn; C. Chaplin; P, Perrey; V, Vigouroux (Legendre); M,Mallet.
[Table Missing This section did not scan well]
The latest information was received recently in a personal letter froth the Director of the Meggido Expedition, Mr. P. T. Guy. Megiddo is situated on the south edge of the Plain of Esdralon, close to the line of a thrust fault which traverses Mount Carmel. Mr. Guy incloses clippings from the Palestine Weekly regarding two slight shocks felt in Jerusalem and describes his observations of a later one at Meggido.
Jerusalem, January 18. 1928. "On Wednesday morning at 8:10 a slight shock was felt in Jerusalem. It was particularly noticeable in the upper floors of houses."
Jerusalem, January 25, 1928. during the slight shock which was felt in Jerusalem on Wednesday morning a crack was caused in one ( the walls of Al Aqsa mosque."
Megiddo, February 27, 1928, 8:15 p.m., Mr. Guy wrote:
"I cannot vouch for the accuracy of our clocks here,but at 7:58 p.m., just as we were finishing dimmer, there was what I should call a severe shock. Quite as severe as the Nablus shock. I timed it carefully! and it lasted for sixteen seconds from first to last. The shock of this morning was easier to analyze, because we were on the upper floor, this evening we were on the ground floor, and the movements were more confused. Direction was more or less the same as this morning, hut perhaps more W. SW. and E.NE I could not separate tide oscillations, which were closer together and more rapid that this miming; they also seemed to me to lee more violent, weather calm, hut raining. The rain is becoming heavier as I write. Barometer at 8:01 p.m. was 29.65, and is still at that. Wind had been blowing hard and gustily throughout the flay, and the calm which I have mentioned set in, I think, only after 7 p.m.. Wind is now rising again. No damage at all, I am glad to say, and I cannot but feel that we are fortunate."
Inspection of the foregoing list shows that it is very incomplete That might be expected. Only major shocks would be recorded by casual observers of the course of Nature and even such records would he affected by all the chances and mischances of human affairs. The contacts of Europe with the Orient varied with the fortunes of Rome the division of theEastern Empire from the Western, the advances and retreats of Asiatic armies the counter--movements of the Crusades, and the rising or falling tide of commercial and intellectual intercourse. It would be interesting to seek out the historic causes for some of the larger breaks in the list of earthquakes, as for instance the almost complete lack of information for the ninth and tenth centuries, but it would carry us too far afield.
There was much that was local and even individual in the keeping of the record. Antioch "the Beautiful" has a reputation for excessive earthquake activity. It is written that the city has been "thrown down" or ''ruined'' or "destroyed" twenty-seven times in eighteen centuries. That is, three times in every two hundred years. Does this mean that the site is one of peculiar activity ? It probably does, but we must also bear in mind that the city was one in which the congestion of population Greatly increased the chances of a major disaster and from which news of the event would surely spread throughout the East and West.
Occassionally a coincidence emphasized the importance of a particular shock. For instance the year 589 appears in many histories as one of great disaster. It happened that an earthquake, which undoubtably was very destructive, occurred during the visit of the Patriarch Gregory to Antioch to confront the governor of the city, Asterius. The latter was killed, while the Saint escaped. Sixty thousand people are said to have perished in the disaster, and the hand of God was seen in the ordering of the events. Historians have not failed to note the occurrence.
Let us nevertheless list the number of . A.D., as follows:
|First century||1-100||2 earthquakes|
|Second century||101-200||2 earthquakes|
|Third century||201-300||4 earthquakes|
|Fourth century||301-400||11 earthquakes|
|Fifth century||401-500||10 earthquakes|
|Sixth century||501-600||20 earthquakes|
|Seventh century||601-700||3 earthquakes|
|Eighth century||701-800||7 earthquakes|
|Ninth century||801-900||2 earthquakes|
|Tenth century||901-1000||0 earthquakes|
|Eleventh century||1001-1100||5 earthquakes|
|Twelfth century||1101-1200||14 earthquakes|
|Thirteenth century||1201-1300||4 earthquakes|
|Fourteenth century||1301-1400||2 earthquakes|
|Fifteenth century||1401-1500||1 earthquakes|
|Sixteenth century||1501-1600||2 earthquakes|
|Seventeenth century||1601-1700||2 earthquakes|
|Eighteenth century||1701-1800||7 earthquakes|
|Nineteenth Century||1801-1900||4 earthquakes|
Upon this showing it seems improbable that the great, apparent range of frequency should be wholly clue to tack of information and this doubt is reinforced by the fact that the data have been assembled from widely different sources. Perrey depended chiefly on European chroniclers; As-Soyuti on Arabic writers; and Tholozan on Arabic and Persian. Where they agree on the date of a Catastrophe (which is seldom) or cite nearly the same year we regard the evidence as confirmatory. It has somewhat the same significance when they agree negatively.
From this point of view it seems probable that seismic activity in the Near East has been spasmodic. It increased during some centuries and decreased during other centuries. Rhythmic change is characteristic of Nature's processes. In this instance it points to the gathering of a variable force or of the existence of variable conditions governing . the working of the force that produces earthquakes. Whatever the source of energy and whatever the mechanism through which it acts the effect is irregular. The power gathers slowly, the resistances rise gradually, the balancing forces increase during decades or even a century. The lead is with the active source and eventually that pressure surpasses the limit of passive opposition. The structure yields, not once only, but repeatedly at relatively short intervals. The action over, mountains have been pushed Up by an insignificant amount, the elastic rocks have vibrated under their movement and the dwellings of men have collapsed. Self-centered, self- conscious, ignorant, and superstitious, men flee before the gods. But they return inevitably to the ruins, where water and fertile soil, beauty and balmy airs, commerce, wealth, and ease invite them. And they forget.
Very great difference exists, according to the records, between the seismicity of northern Syria and that of Palestine. Montessus, whose map we reproduce, illustrates the fact by the size of circles which mark centers of historic earthquakes. In considering the facts suggested in that way the reader should bear in mind the effect of concentration of population which makes the cities appear as centers. Any earthquake spreads, of course, over a wide area around the place of great destruction and may have been more intense in some desert region where it leaves no mark. It would be easy to convey the idea that there is some relation between the southern and northern regions, but in fact they are quite distinct. They are not so far apart, it is true, that a very violent shock in the one might not be perceived in the other, nor is it improbable that similar conditions may cause both to be active during one and the same tend of years, but they are seismically and structurally separate.
This separation was first brought to my attention by the Palestine earthquake of 1927. It was quite severe there and was naturally thought to have been even more vigorous in Syria. When no reports came from the French authorities it was inferred that they were negligent, but the inference was not justified. There had been no earthquake north of Palestine on that occasion.
Some account of the geography and of the geologic structures which underlie the surface is necessary to an understanding of the relations of the earthquake belts of Palestine, Syria, and Persia. We may enter by way of Palestine. Palestine is a plateau, which has well-defined limits except toward the south. East of it lies the Dead Sea and the Jordan Valley. North of it is the Plain of Esdralon. West of it is the Mediterranean, which is not quite full enough to flood the narrow coastal plain. The general altitude of the flat top of the plateau is between 2,000 and 2,600 feet above sea level. Jerusalem stands on a summit, a low hill, similar to many others which have at one time or another been occupied as defensible city sites. There during all the warring centuries men walled themselves in. Thence they went forth to till their fields in the adjacent, upland valleys. They were fortunate if an earthquake found them abroad, outside of their beehive of a city. They were fortunate or unfortunate, according to the side of the quarrel they happened to have espoused, if perchance an earthquake threw down the walls of a besieged city, as presumably was the case when Joshua took Jericho.
Matching the Palestine plateau, but lying east of the Dead Sea and Jordan Valley is the Transjordan plateau, a bench on the Arabian highland. The Palestine and Transjordan plateaus are completely separated by the profound trough of the Dead Sea, in which the surface of the water lies 1,200 feet below sea level.
In both of these plateaus the geologist notes that the rocks are strata of marine limestone or sandstone, which have been uplifted without appreciable disturbance. In general the beds lie nearly as flat as when they were deposited beneath the sea. Closer inspection shows, it is true, that they have been bent and crushed along certain lines, but the compression is not the obvious thing. One would infer that a great force, a swelling perhaps, had raised the whole mass of either plateau gradually. One would not at once arrive at the conclusion that the deepseated foundations of the regions were being crushed as in a vise and that the squeezed masses were moving in the direction of least resistance, that is vertically upward. Study of the structures has, however, led me to that conclusion, and I would attribute the earthquakes that shake Palestine to yielding within the body of the plateau or to the slipping of the whole plateau upon the shearing planes that underlie it.
North of the Palestine plateau is the lowland which stretches from west to east, from the Mediterranean to the Jordan, and comprises the Plain of Esdralon and the Valley of Jezreel. It would extend eastward beyond the Jordan, as it once did, if it had not been covered and heaped up by thick lavaflows. They form the upland of Bashan, ranging northeastward along the southern slopes of Mount Sermon toward Damascus. Earthquakes impinge on the margins of the low country, Esdralon and Jezreel, but they do not originate within it. It is a non seismic zone between Palestine and northern Syria.
We must now take a long step. Even a Roman centurion may have thought it a long march from Jerusalem to Antioch, whether he went by the coast road by Acre and Beirut, or by the valley road Up the Jordan, past Baalbek, and down the Orontes, or still farther inland via Damascus and Aleppo. Whichever way he went he passed earthquake- shaken cities or may have experienced an earthquake. Arrived at Antioch he was near the mouth of the Orontes, but not in the main valley of that river. By one of those seemingly arbitrary accidents of topography, which are not uncommon in broken (faulted) mountain regions, the stream, after flowing northward for a hundred miles, turns west and southwest like a fish hook and enters the Mediterranean. The last few miles of its course lie in another valley which comes down from the northeast, from Marash in Persia. Marash and Antioch are situated a hundred miles apart at the eastern base of a long, curving mountain range, the Giaour Dagh. From its northern end near Marash the height curves toward the southwest and, if we prolong it into the Mediterranean continues in Cyprus in the sweep of the Kyrenia Range. It is a typical mountain arc and is a single structural feature, although very possibly broken by one or more faults in the submerged section.
The Giaour Dagh and the Kyrenia Range look down on fated cities. Marash is not often mentioned in earthquake chronicles, but it has been ruined. Antioch is conspicuous for the frequency and violence of the shocks from which it has suffered. And the ancient city of Salamis, situated on the east coast of Cyprus just south of the Kyrenia Range, was repeatedly and disastrously shaken. Tile mountain arc skirts a very active earthquake zone. It outlines the northwestern margin of the earthquake province of Syria or it may be regarded as the southeastern border of the active region in Asia Minor. Geologically the Giaour Dagh belongs to Asia Minor. Historically Antioch is Syrian.
Between Antioch and Palestine, between the valley of extreme quaking and the plateau where earthquakes are rare, there lie two groups of mountains and valleys. In a general way the heights trend north and south, but they are curved and arch westward toward the Mediterranean. Those of the northern group extend from Antioch two hundred miles to the south and rise to about 6,000 feet above sea level. the southern group consists of the mighty Lebanon and Anti- Lebanon ranges, 9,000 feet high. The grandeur of the Lebanon, seen from the Mediterranean near Beirut or Tripolis, the sublimity of snow-covered Mount Hermon in the Anti-Lebanon, pervade both ancient and modern descriptions. Both of these groups of ranges have earthquake histories. At the northern end of the northern group and on the east side of the curve is Aleppo, second only to Antioch in disastrous story. On the curve of the southern group lies Damascus, also repeatedly shaken. Between them is Homs or Hams, with a similar record. These mountains are actively growing and the elastic rocks beneath them snap from time to time, whenever the growing strain exceeds the sum of the passive resistances.
The records which have been preserved depend for their completeness upon the historical and commercial importance of the cities. No one noted the frightened camels of the desert, nor the terror-stricken Bedouins. It was only when a beehive of political, commercial, cultural activity was disturbed or destroyed that the fact was chronicled. But it happens that city sites are apt to be situated on lines of high earthquake intensity. The latter very commonly follow the base of a mountain, from which flow the life-giving waters, the essential element. The slopes of the outwash are appropriate for irrigation; the soil is fertile. The gorge behind is easily defended against invaders; yet it brings caravans from beyond the range. On the other side stretches the desert. The site is inevitably determined by its fitness and though visited again and again by disastrous shocks it must continue to be occupied. Men herd together in helpless ignorance today even as they have during past millenniums.
In the earthquake records of Palestine, Jerusalem is mentioned more often than any other city, as might be expected. It is there that the interest and the learning centered. It happens, however, that the village of Ramleh is named four times to nine for Jerusalem, a fact which is not explained by its size or importance. Ramleh is at most a small city, situated in the coastal plain of the Mediterranean, not far from Jaffa. It and the neighboring town of Ludd or Lydda stand on low chalk hills that rise slightly above the plain and afford a convenient dwelling-place for the peasants who till the fertile fields round about.
Neither does the site of Ramleh arouse in the mind of the geologist any suspicion that he should expect earthquakes to be dangerous there rather than anywhere else, at Jaffa for instance. When confronted with the record he can only infer that the line of the coast is determined approximately by a fault, which separates the basin of the Mediterranean from the plateau of Palestine and which here runs east of the actual seashore, causing the chalk to project sufficiently to form the line of hills.
Attention was called to this apparently isolated active point by the earthquake of July 11, 1927, which was quite as severe at Ramleh and Ludd as anywhere else. Jaffa on the other hand was not damaged. Other cities along the coast, Gaza to the south and Haifa to the north, had escaped. The violence at Ramleh and Ludd was very local.
Jerusalem, walled in on its rocky promontory between the gorges of the Hinnom and Kedron, had received a strong shock. So had Hebron, twenty miles to the south, and Nablus, thirty miles to the north. These three cities are on the crest of the plateau, on the axis which might be supposed to correspond to an axial fault within the uplift, though no fracture is visible in the surface. The inference which connects the vigor of the shock with a structural feature is strengthened by the greater severity of the earthquake in the Mount of Olives. The Mount is a broad ridge, but a mile east of Jerusalem. it ranges from south to north on the axis of a fold, which assumes the character of a fault in its northern extension. The greatest damage occurred on that axis.
Jericho in the valley of the Jordan is about seven miles east of the escarpment which marks the outcrop of the Mount of Olives fault. The distance is considerable, and it is probable that the shock would not have done much damage in the village (it cannot now be called a city) if it were not founded on alluvial soil. As it was, the destruction was notable.
Jericho lies north and somewhat west of the Dead Sea. It would be natural to infer that the vigor of the earthquake was connected with the great fault that bounds that extraordinary trough along its western side, and one would expect to find evidence of intense disturbance along the high cliffs. But it was not so. The prison-convent of Marsaba, located at the head of the inaccessible gorge by which the Ke dron descends directly to the Dead Sea, experienced only a slight tremor Broken stone heaped opon its massive walls, was not shaken down. 
Thus the scene of the earthquake was mainly limited to the Palestine plateau. The disturbance appeared to have originated in the southwest, probably beneath the Mediterranean, and had been propagated into the mass of the plateau along internal fault planes. Wherever they came to the surface the shock attained destructive intensity. It was a fresh demonstration of the well-known effect of structural features.
The limitation of effect to the Palestine plateau was not absolute, however. There were two very unexpected and rather inexplicable areas of violence beyond the boundaries of that mass.
One of them involved only the village of Reineh north of Nazereth. Reineh is situated on the road from Nazareth to Tiberius in the hilly country beyond the Plain of Esdralonl. There seems to be nothing to distinguish its site from the numerous similar ones occupied by similar villages round about. But Reineh was practically destroyed, while no other town in the vicinity suffered any damage. The peculiarity of the situation of Reineh is emphasized ho the fact that the place was similarly destroyed in the earthquake of 1837. l he description of the position is exact and leaves no doubt regarding the identity of "Rani" with Reineh. The condition is clearly permanent and the villagers were well advised in August 1927 in moving their homes from the ancient site to a neighboring hillside. It is impossible to say, however, whether the change to a few hundred yards away will save them from some future visitation.
The other unusual appearance of local activity was at some distance to the east of Palestine, beyond the Jordan Valley in Transjordania. Here on the high plateau are the cities of Ammon and Es Salt, forty to fifty miles from Jerusalem. They were both of them destructively shaken. A great part of Es Salt was destroyed completely and most of the houses in Amman were rendered dangerous. The distance between the two places is about ten miles and this gives an indication of the local limitation of the marked activity, although it may have extended out indefinitely into the uninhabited desert.
The distribution of intensity which has been described was no doubt related to the actual vigor of the shock at the places named, but there were local conditions which greatly modified the action on buildings, the apparent intensity. Prominent among these were foundation conditions, exposure or local position, and the nature of the buildings themselves .
The effect of foundation conditions has often been described. Jericho undoubtedly suffered because it is built on alluvium. Nablus was divided into three sections. Two of them, the northern and southern sides of the town, were scarcely damaged. The central strip was very badly ruined. The former stood on the rocky slopes on either side of the little valley in which the town is situated. The middle zone was piled up on the alluvium and on the debris of former earthquake ruins, an unstable support for massive walls of mud and stone, three or four stories high. It would be well for future generations if that strip could be cleared and turned back into olive orchards.
Among the examples of unfavorable exposure were the Mount of Olives and Es Salt. While the destruction on the Mount was in large part due to the fault within the ridge, it was increased by exposure to the east. Habitations on that far side, the side away from the advancing surface wave of the earthquake, were subjected to its full intensity unrestrained by any mass to impede its emergence into the air. Es Salt, over in Transjordania, was built on two hills, one sloping south, the other east. The damage was greater on the latter, for there again the emerging vibrations met with no check.
Some account of the building conditions in Palestine and of their relation to the destructiveness of earthquakes, past and future, is given in the following paragraphs.
Any engineer who has observed the building practices in Palestine may well wonder how Solomon's temple was put together. Certainly there was no Gothic balance behind its magnificence. Samson need not be credited with superhuman strength for the destruction of the temple of Dagon. All things are relative, and the force he exerted is to be measured by the weakness of the structure. Semetic engineering is a very weak, if not a negligible, factor. Only the Romans and the Crusaders have left enduring monuments in Palestine.
The native building materials of Palestine are stone, mud, and rubbish. In ancient days wooden posts and beams were available, but they have vanished from the deforested land, where no young tree can survive to the stature of a shrub unless protected by efficient policing against the Arab, shivering in the bitter cold of the winter. or against the omnipresent goat. Lime for mortar is too expensive for ordinary use, for though limestone is abundant, the fuel wherewith to burn it is scarce and costly. Cement is only for the European.
Stone, mud, and rubbish: Given those materials, how would you go to work to make substantial three- or four-story buildings and roof them? You might rely on stone alone, quarrying and piling it in such huge blocks that even an earthquake can scarcely dislodge them; that is what the Romans did. Or you might insist on mortar in which to set the stone, wringing the cost of it from the conquered peoples; that is what the Crusaders did. But if you were an Arab or an Israelite you would do neither of these things. You would take the easier way of laying the stone in thick walls of mud and of filling in with rubbish wherever it would not be seen. It is to be remembered that mud itself is not to be had in unlimitted quantity, for it requires water.
The primitive wall throughout the East was a mud wall. It is still the common resource. Galore pretentious structures are faced with stone and the facing often presents the appearance of blocks accurately dressed to smooth bearing surfices, but it is a sham. The edges on which the blocks adjoin are but an eighth to a quarter of an inch wide; they rest on that narrow edge; behind it they are chipped to a rude pyramidal form, which is stuck into the mud or rubbish. Walls of this kind are from two to three feet thick or more. In the old, closely built-up sections of an ancient city, a Jerusalem or a Nablus, they are piled up with the most extraordinary disregard for support. A Western explorer penetrates the labyrinths of cubicles with astonishment and grooving fear, especially after an earthquake has done its work on them.
On invitation of the British representative at Nablus I accompanied him on a tour of inspection of the ruined portion of that city a few days after the recent shock. In the heart of the stone beehive was the quarter occupied by many generations of Samaritans, a small tribe isolated in the very city of their birth by the intense religious prejudice that has always pursued them. When they increased in numbers they neither would nor could expand among their neighbors. They could only build higher, could only pile another stone cubicle on the roof. The passage and the stair must come off the narrow, crowded room below. The planning was haphazard occasional, suited to the immediate need, but it endured for centuries. And so did the dirt in the dark, foul-smelling corners. I sympathized with the health officer, who was of our party. "Tear it down, let in light and air." "But it is their property, it is all they have, we can't pay for the whole place," was the answer. And so only that which was absolutely dangerous because it might fall and crush them could be torn down.
Thinner stone walls are being put up by newcomers in the land. They are twelve to eighteen inches thick and present faces of dressed stone on both sides, but they are hollow shams, like the thicker walls. The stones are beveled as in the others and are more or less firmly stuck into mud. There is no bond between the two facings, no headers extend through the wall from outside to inside. Yet these walls, like all others in Palestine, are bearing walls, carrying all the loads of floors and roofs.
In the lack of any wood except that which is imported, the use of steel beams is not uncommon in modern construction. They can be used to span wide spaces and to take heavy loads. But even so they are simply set in the walls, without any precautions to tie them in place. A beveled stone slipping from its niche, even though undisturbed by an earthquake tremor, is sufficient to cause collapse of the floor. The complete destruction of the Winter Palace Hotel at Jericho, with loss of life, was due to this kind of construction. It was a palace of mud. It is dust. Conspicuous among the buildings ruined by the earthquake of July, 1927, was the great hospice of the Order of St. John, endowed by the Kaiserin Augusta Victoria and finished i n 1910. It stood on the Mount of Olives, a conspicuous, monumental structure, which should have been of the firmest construction. But it proved to have been so only in part. An outer wall, reaching only to the second floor, the great tower, and a long row of slender chimneys were constructed with care. Cement was used in the wall and possibly in the tower and chimneys. The only failure in these parts of the composite building was the cracking of the belfry walls near the top of the tower. Throughout the rest of the edifice the thick and seemingly massive walls were of mud, faced with stone or plaster. They cracked in every direction and large masses fell into the rooms or outside. This structure stood almost over the Mount of Olives fault, near the eastern edge of the plateau, where the exposure was most unfavorable. The reaction of its different parts to the shock demonstrated plainly the folly of cheap building practices and the adequacy of good construction.
The building problem is a very serious one in Palestine and also in Syria. Western people and Western moneys are flowing into the countries under the British and French mandates. The Zionists are building a new city, Tel-el-vir, as a suburb to Jaffa. It is a beautiful city to look at, but it is not built to withstand an earthquake. Jerusalem is spreading out in suburbs which are not put up to withstand an earthquake of any severity. The risks are growing rapidly with the increase in population and wealth, and no one knows whether or not or when a destructive earthquake may strike.
At a meeting of British officials in Jerusalem in August, 1927, the problem of building to resist earthquakes was discussed with technical knowledge of the prevailing practices and in the light of the then recent experience. It was the opinion of that conference that certain regulations, which should be embodied in a building code, would go far toward reducing the damage from any future shock to a minillltlm. It was recognized that the economic conditions and the established habits of the country would inevitably dictate a continuance of the practice of building stone walls with mud for mortar, and that even where an owner might be willing to use lime or cement the general inefficiency of labor would handicap his effort to build more securely. But it could be provided by regulation that:
It is of interest to note some striking survivors of past disasters, since from them we may learn why they have resisted the shocks that have overthrown other parts of the same structures.
Visitors to Baalbek are astounded to see the group of six huge columns standing and still supporting the entablature, which by all the laws of momentum should have swung them beyond their balance if it had ever been swagged to and fro. They are apt to conclude that the temple has not been subjected to earthquakes since it was destroyed. Perhaps they recall the fact that it was demolished by Theodosius the Great in the last decade of the fourth century and that Saracens and Mongols later worked their will on it. These historical facts throw some doubt upon the extent of earthquake damage suffered by the structures, whose ruins now stir our wonders but the records show that the valley has been shaken repeatedly and the stability of the Great Six, as we may call them, is indeed most astonishing. It is surprising, however, merely because we fail to realize the stabilizing effect of the huge mass of the entablature. It has stood still while the columns have swung to and fro at their bases with the earth. At no time has the movement of the foundations carried the base beyond the circle within which it supported the center of gravity; at no time has the slow, pendulum-like swing of the column been exaggerated by the quicker vibration of the earth to the degree when it would carry it too far. One may see the effect any day in Palestine as the women swing along with vigorous strides steadying their heavy water jars on their heads. The conditions have been demonstrated in the Vibration Laboratory at Stanford University in wrecking a frame under a load. At first rigid, the frame communicates the vibrations to the superimposed load, but when the joints have been strained and the load is sufficiently increased the latter remains relatively immovable. The distortion developed in the lower part of the frame is then extreme, but there is comparatively little tendency to throw the top.
A different effect is evident when the entablature has been thrown without carrying the column with it. The latter then remains free at the top but fixed at the bottom and its segments may rotate out of alignment as they tilt up on an edge.
In walls we may observe the effects of incoherence as contrasted with the fissures which are of common occurrence in our more firmly cemented ones. Stones laid up with a thin layer of mud in the joints arc practically loose from one another as are the great blocks of the megalithic Roman structures The individual blocks dance apart on all the joints and every vertical contact tends to become a window slit. At Baalbek we may observe that size is no protection; stones three by four by six feet and even four by six by twenty feet, more or less, and weighing forty tons or more, have been jostled far apart. They bear witness to long-continued, violent shocks, even more positively than do the fallen columns, for the latter may have been thrown down by men, but man-power could not have disjointed the walls. In Jerusalem and other cities the strength of a honeycomb structure was demonstrated. The pressure of population within the fortified hive caused the streets to be built over, often for considerable distances, and the arches that span them are of solid masonry. They support heavy superstructures and exert a corresponding thrust against the houses.on either side. The effect is that of very strong partition walls within a large structure. The whole resists firmly. Failure can begin only in the foundations, by shearing which extends upward, cracking the walls. Failure can be caused only by a severe earthquake, but if it occur there could be no escape for the thousands in the hive. These conditions lend a certain credibility to the estimates of tens of thousands lost in the great disasters.
The Dead Sea lies so far below sea level, in a trough so straight and narrow, that it has always challenged the attention of intelligent curiosity. How does it happen that a section of the earth's crust should have sunk so deep or should have remained at so low a level during the dislocations that the crust has suffered. The alternative suggests two different assumptions. If it has sunk so deeply, then it formerly stood on a level with the plateaus that now stand high above it. If, on the other hand, it has lagged behind, the plateaus have been raised from its level to their actual elevation.
Simple as this alternative seems, it divides two schools of geologic theory. The one, which is prevailingly European, holds that gravity is the dominant force to which we must ascribe all displacements of sections of the earth's crust. It follows that any considerable block must sink in, if it moves at all. Not only must the Dead Sea strip have sunk in, but also the bottom of the Mediterranean basin and the bottom of the Atlantic basin also. When followed out to its logical result, the assumption that gravity alone can produce material changes of level leads to the conclusion that the entire surface of the earth must formerly have stood as high at least as the great plateaus of the continents, if not even level with the mountain tops. There is an extreme assumption, such for instance as that the summit of Mount Everest represents the height of the original surface of the entire globe, from which even the most consistent supporters of the gravitative theory recoil. In general, however, they do not hesitate to assume the collapse of great continents which they suppose once occupied the sites of the Atlantic, Pacific, and Indian oceans, and they do not ask themselves where were the waters of the oceans when the hollows were occupied by the theoretical continents. This school regards it as demonstrated that the basin of the Mediterranean was formed in a relatively recent geologic period by the breaking up and collapse of a land which occupied its site, and it also thinks that the Dead Sea trough has originated in the subsidence of a narrow strip of the crust. The assumption is that an arch spanned the entire width of the section between the Mediterranean a nd Arabia and that the keystone of the arch fell in, forming the trough.
A moment's thought will show that the keystone of an arch can sink only if the arch be stretched Tension is an essential prerequisite. Now tension is the opposite of compression and the two kinds of stress cannot exist in the same body at the same time in the same direction. There is abundant evidence in the mountains of Syria and also of Palestine that the ranges have been thrust up by compression. Those who would recognize tension are therefore obliged to assume that there have been two successive episodes of activity: first, the mountainous regions were compressed, the strata were folded sheared, and thrust over each other; and later the crust broke up and foundered under a tensile stress and the pull of gravity.
It is possible to account for the sequence of a tensile stress following a compressive stress in the earth's crust by assuming that the globe is shrinking sufficiently to leave the outer shell partially unsupported. The effect would be to set up a horizontal crushing force in the crust and to cause it to buckle, fold, and ride up on itself. If, however, the shortening thus produced were not adequate to maintain contact between the shell and the shrinking interior, then sections of the latter would collapse and sink till they reached foundations.
This is an old theory, well known and supported by great names in geology, Dana and Suess. But ha the light of modern research it meets with great difficulties, such as the evidence of the solidity of the earth and the inadequacy of any possible shrinkage to account for the measured shortening of the crust in the intensely folded and overthrust mountain ranges.
This is not the place for a general discussion of geologic theories. There are many modifications of the extreme European view just described, which more or less adequately meet the difficulties. But we may here place in Opposition to that view one which recognizes another and a sometimes greater force than gravity, that is, the mollecular force of crystallization.
The ancient phrase "dead as a stone" survives from the times of our ignorance of chemical reactions. Stones consist of minerals, and minerals are chemical compounds which depend for their stability upon a balance of forces. If that balance be disturbed, as for instance by raising the mineral to a high temperature under great pressure and in the presence of superheated steam, the molecules rearrange themselves in adaptation to their environment and in so doing they exert forces which may greatly exceed the attraction of gravity. Rocks which have been buried deep beneath the surface, but which have been exposed by uplift and erosion, show evidences of these changes. They have recrystallized in elongated forms, demonstrating that they shortened in one direction and extended in another. In thus changing form in the solid crust of the earth the mass which recrystallized must have pushed other masses aside, and the effect would be to lift overlying sections of the crust or to fold and crush adjacent segments. The forces which may thus be brought into play are competent to raise mountains and to elevate continental plateaus.
The mechanics by which we may explain the movements of mountain ranges under either of the foregoing theories again lie outside the scope of this paper. Those who wish to pursue the study will find the geology of Syria and Palestine discussed in papers by Kober, Krenkel, and Willis.
We are here concerned with the action of enormous forces and may reasonably speculate on their origin.
In an earthquake an enormous amount of energy is suddenly released. One estimate, for instance, is that a single shock in a few seconds set free sufficient energy to run the largest British battleship at full speed for 38,000 years. It is generally agreed that elastic compression is the only condition by which such a store of energy can accumulate in the rocks of the earth's crust, and it is further regarded as essential to its release that the masses should have been distorted elastically and shall snap back into position like enormous steel springs. The mountain ranges of northern Syria, where earthquakes have been most frequent and most violent, have been strongly folded and are being overthrust, that is are being squeezed up and pushed forward by compression. In that region the compression which seismic theory requires as a source of energy is demonstrated by the geologic structure.
Earthquake activity has been more moderate in the Palestine plateau, and the evidences of compression are also less obvious. They nevertheless exist and are illustrated in the accompanying block diagram. It is assumed that a pressure is exerted from beneath the Mediterranean, that it extends horizontally through the deep foundation rocks of Palestine and Transjordania and is resisted by the mass of the Arabian continental block. The effect upon the Palestine plateau is to crush its foundations, causing it to bulge upward and swell. The block is also thrust upward as a whole upon a curved surface that divides it from the Dead Sea block. We may designate that surface a ramp. A similar effect is produced under the Transjordan plateau, the Dead Sea block being thrust under it. These movements are supposed to be related to the extrusion of large flows of lava that have come Up in Transjordania and around the northern margin of that plateau.
The condition of compression being thus analyzed, the distribution of the effects observed in the shock of July, 1927, is explained by the structures that have been suggested. It seems probable that there was a local movement on a fault which follows the coast and which reacted in the immediate vicinity of Ramleh. Displacements on one or more internal faults, within the Palestine block, caused the vibrations which shook Hebron, Jerusalem, and Nablus. Send the elastic waves, transmitted through the Dead Sea block without causing any displacement on the ramps that bound it, occasioned a slip within the Transjordan block in the vicinity of Es Salt and Amman. The isolated damage at Reined is evidence of elastic strain and local release in that northern district.
The centers of high intensity lie within an area which measures one hundred miles in width from east to west and one hundred fifty miles in length from north to south. Considering this as the surface of a block, which may reasonably be assumed to extend to a depth of thirty miles (taking that to be the minimum thickness of the layer in which compression is set up) we would have a mass equivalent of 450,000 cubic miles under pressure and in a state of elastic strain. It is not a homogeneous, coherent mass. On the contrary it is composed of many different kinds of rocks, forming an intricate mosaic and divided by numberless shearing planes. In general the friction on the planes prevents the pyramidal segments from slipping one on another, but the pressure rises, the elastic strain increases, the weaker segments give, and the concentrated strain causes a local snap. The elastic waves radiate through the mass and there, where they find the hair trigger set, they start a second or third snap). The adjustments relieve the most intense strains, but the relief is very local. The conditions which develop the pressure continue to act, and the critical state must from time to time be reached and relieved again and again. History and reason agree in demonstrating the truth of the saying: "Once an earthquake region always an earthquake region."
Edouard Suess, "The Face of the Earth" (English translation), 1, 29, 1904. References to authoritative texts are there given.
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Fernando de Montessus de Ballore. "La Sismologia en la biblia," Boletin del Servicio Seismologico de Chile, 11, 27-158, 1915.
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Fernando de Montessus de Ballore, "Les Tremblements de Terre— Geographic Seismologique," pp. 155-159, and Fig. 20, 1906.
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Exaggerated reports of great fissures in the ground near Jerusalem, of immense dust clouds, and other startling phenomena were current in the city after the shock, but there was little evidence of their actuality. The limestone plateau on which the city stands is not as firm as a granite ledge. The rock consists of fissured limestone, and the blocks have been loosened by the slow processes of superficial agencies as well as by occasional earthquake shocks. The branching canyon of the Kedron has nearly precipitous walls. It is therefore not surprising that the blocks should separate and that fissures should appear, nor that dust should rise from them in the arid season. Even so the fissures were few and far between.
There was an interesting incident which demonstrates the growth of a legend among the ignorant. A photograph was sold in Jerusalem showing the volcano in the Dead Sea from which the earthquake must have started. For several days its authenticity was not questioned. A positive statement by a geologist that there was no volcano in the Dead Sea had no effect. Not until it was proved that the view was one of the volcano Stromboli, taken by a passing tourist, and developed by an enterprising photographer who saw and seized his opportunity, did even the intelligent portion of the community abandon the pleasing legend. It is more than likely that the mythical volcano will reappear in some "Arabian Nights' " tale of the earthquake.
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Max Blankenhorn, "Das Erdbeben im Juli, 1927, ha Palastina, ' Zeitschrift des Deutschen Palaistina Vereins, 50, 288-29X, 1927, this article gives details of the local phenomena and personal observations communicated by German residents in letters to the author. It is suggested that the epicenter was located h the Jordan Valley, but the author does not fed convinced that its position has been ascertained. The evidence of several centers, presented ha the article herewith, explains the uncertainty attaching to the interpretation of the seismograms, which might well yield an average result and locate the center north or northeast of Jerusalem.
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The effects of the shock in the Jordan Valley were somewhat spectacular and have led to exaggerated accounts of the severity of the earthquake in that vicinity. The alluvium of the river banks is saturated with water to within a short distance from the surface and consists of unconsolidated mud. There is a growth of trees, which appears the more luxuriant because of the contrast with the barren, desert hills. Masses of the soil slid into the river, damming it so that it overflowed. The slides along the banks were followed by others so that cracks and channels appeared at some little distance from the stream. The slides carricd the trees with them. giving the impression of uprooting the growth. The effects suggested great force, hut they were very superficial and involved nothing more than the sliding of masses of mud held together by roots.
The strand of the Dead Sea at its northern end showed no evidence of notable rise or fall, when examined a few days after the shock. It is possible. however, that the shaking of the delta produced some sliding on the steep front by which it slopes into the heavy water and caused a disturbance of level.
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L. Kober, "Geologische Forschungen in Vorderasien," Dewlkschrif ten der mathematischen-naturwissnlschaftlichen Klasse der Akademie der Wissenschaften, Wien, 91, 383-424, 1915.
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E. Krenkel, "Der Syrische Bogen," Centralblatt fur Mineralogie, pp. 274-281 and 301-313, 1924.
E. Krenkel, "Geologie Afrikas," Erster Teil, 52-124, 1925.
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Bailey Willis, "The Dead Sea Trough—Rift Valley or Ramp Valley ?" Bulletin of the Geological Society of Americas, 39, No. 2 (in press), 1928.
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