Earthquakes of the Western United States

IF the reader will compare the general features of the continent of North America with those of Europe, he will perceive that the two continents differ very widely. Europe is a bundle of peninsulas grouped around a central mass which is divided into several distinct areas by trenchant geographical lines. North America is a land mass of singularly even contour, with but three or four well-marked geographical areas, whose boundaries are generally less distinctly drawn than those of Europe. The effect of these peculiarities of contour on the physical conditions or climate of the different regions of the two continents is easily seen, and has been frequently dwelt upon by geographers. In North America the climate varies less within a given geographical range than in any other continent, except possibly Africa. In Europe the variation as we pass from point to point is greater than on any other portion of the earth’s surface.

That the climate should correspond with the surface is not at all remarkable, though the observer cannot but be surprised to find that variety in the manifestation of the earthquake forces seems to be equally dependent on the degree of complication of the surface, — that where the land mass is broken up into many distinct geographical areas the action of the seismic forces is more irregular than where the divisions are few and simple. In Europe the limitation of the severest shocks to certain well-defined areas, the juxtaposition of regions of great earthquake activity and regions where such activity is almost unknown, is very remarkable. It is less than a thousand miles from Lisbon, the seat of some of the most terrible catastrophes ever produced by the internal forces, to Paris, where we have no reason to believe that two stones were ever separated by an earthquake shock. Midway between Portugal and Iceland, two regions of the most intense earthquake activity, lies Ireland, from which we have hardly a movement recorded. From the unshaken plains of Southern Russia to the earthquake region of the Caspian, a country really accursed by earthquakes, is less than eight hundred miles.

We must wait many centuries before we can have a sufficiently extensive record of American earthquakes to enable us to know their geographical distribution as well as we know that of European earthquakes ; still, we can discern the general laws of their distribution quite well. It is, in the first place, evident that the continent of North America, at least excepting the southward prolongation on the west side of the Gulf of Mexico and the Caribbean Sea, is far more uniformly subject to earthquakes than the European area. Excepting the Hudson’s Bay country, Florida, Newfoundland, and some other areas, from which our information is too limited to enable us to take them into consideration, we may say that tins continent is far more uniformly affected by earthquake-producing forces than Europe. There are no such areas as Portugal, Calabria, or Canton Valais, where an earthquake focus is bordered by regions rarely and slightly influenced by seismic forces. Shocks of moderate energy are, however, very far from rare over nearly the whole of the known surface of North America. The region just about New York City, with a good part of the surface of the adjoining Long Island and some of the valleys of the Alleghenies, are probably among the points of least disturbance. A few points, such as the region about the mouth of the Merrimack River, Haddam in Connecticut, and New Madrid on the Mississippi River, once promised to become the seats of local disturbances ; but it has been a century and a quarter since the Newburyport earthquakes ceased to occur, the Haddam disturbances have gradually become less frequent, and New Madrid was the seat of continued shocks only for two years after the great earthquake of 1811.

The general law that earthquake disturbances are least likely to occur in the regions longest elevated above the sea is at least approximately verified in America, and it seems quite likely that longer observation will entirely confirm it. If we limit our observations to the earthquakes of the present century — and it is only during this time that any considerable portion of the continent’s surface has been subjected to simultaneous observation,— we are led to believe that the intensity of earthquakes as well as their frequency increases as we pass from the Atlantic toward the Pacific Ocean ; Western New England and Northern New York, the longest elevated of any area of equal size in the United States, having been the least disturbed, the Mississippi valley having been the seat of more numerous and intense movements, while the Pacific slope exceeds both, at least in the frequency of the severe shocks.

The earthquake area of the Mississippi valley is the only one of the three known North American areas outside of Mexico which has been observed to sympathize with the movements of the Caribbean region. The connection is very slight, there being only one or two rather questionable cases in which a shock has affected portions of the two continents at the same time. The isolation of the two Americas is apparently quite as perfect as is the separation of North America and Europe. The Caribbean Sea and the Gulf of Mexico are far more effectual barriers to the passage of shocks than the Mediterranean. Many shocks have passed the latter, affecting regions both to the north and south of its waters.

The first recorded shock which affected the Mississippi valley occurred in the summer of 1776, — day and month unknown. The only account of it is from Mr. John Heckewelder, a missionary of the United Brethren, on the Muskingum River in Ohio. It happened about 8 A. M., and its duration is asserted to have been two or three minutes. “ The southwest side of the house was raised with such violence that the furniture was nearly overturned. It was accompanied by a subterranean rumbling noise. The cattle were frightened by the shock, and the Indians continued after it to apprehend some great disaster of which they conceived this to be the precursor.”

The next shock occurred in the year 1791 or 1792,— tradition has not preserved the year with certainty,—in April or May, about 7 A. M. Furniture in houses was agitated by the jar. The shock was preceded by a rumbling noise in the earth, which seemed to come from the west. The course of this movement was evidently the same as that of the great shocks of 1811. The region where the shock was felt was confined to the northern and eastern parts of Kentucky. There were at that time few settlements farther west, and it may have had a wider range without being observed.

At 3 A. M. on the 8th of January, 1795, a considerable shock was felt at Kaskaskia, in the Territory of Illinois and in the part of Kentucky to the south. Its direction was, like that of the preceding, from west to east, its duration about one minute and a half. A subterranean noise accompanied the shock. Two other shocks should be mentioned. One, at Niagara Falls, occurred at 6 A. M. on the 26th of December, 1796. It came from the northwest, was very slight, and affected the vicinity of the Falls over a radius of about fifty miles. Another occurred near the site of the city of Chicago, in 1804, at ten minutes past two on the 24th of August. It seems to have been quite a strong shock, though we have no accurate description of it. It was felt as far east as Fort Wayne in Indiana, nearly two hundred miles distant. As with the preceding shocks, the impression left upon the minds of the observers was that it came from the west. Although the last two earthquakes were not felt over any portion of what is properly called the Mississippi basin, they were still within the earthquake area which we have named from the great river.

For more than seven years after the shock of 1804 there is no record of any movement of the earth in the Mississippi valley. Without premonitory shocks, and without those varied atmospheric symptoms which are so generally supposed to indicate the approach of a great subterranean disturbance, there occurred on the night of the 16th of November, 1811, a great and long-continued earthquake, which shook a larger area than any known shock except the Lisbon convulsion of 1755, and which in intensity was probably not surpassed by the movements which produced that great calamity.

The thinly-peopled condition of the region along the banks of the Mississippi, which precluded this great earthquake from producing any great loss of human life, has also made our accounts of the phenomena very imperfect. This latter result is the more to be regretted, inasmuch as there can be no doubt that many of the events of that convulsion were without a parallel in the history of earthquake shocks. The valleys of the great rivers of the world, at least the parts immediately adjacent to their banks, are rarely the seats of earthquake shocks of great severity. The Amazons, the Nile, the great rivers of Asia, even the Danube, the Po, and the Rhone, of Europe, have been very slightly affected by earthquake shocks. The course of a great river like the Mississippi must be much affected by a severe earthquake. Without the intervention of external disturbances the stream is constantly wandering over the plain through which its varying channel is cut. A slight accident, such as the sinking of a wreck or the lodging of a few sticks of floating timber, may so disturb the regular system of curves in which the water flows, that the position of the banks in its course for miles below the point of disturbance will have to be changed before the equilibrium is restored. The sedimentary matter deposited by the overflows of the stream — which in the case of the Mississippi constitutes the great accumulation, from ten to one hundred miles wide and many hundred feet deep, through which the stream cuts its inconstant course — is not a compact mass, but in its structure frequently as loose and incoherent as an artificial filling. The settling which necessarily takes place when this matter is consolidated by sudden and violent agitations of the mass must greatly affect both the surface of the deposit and the course of the river. This irregular subsidence will doubtless account for many of the peculiar movements which occurred during the shocks ; while the violence and extent of the movements thus dependent upon the sudden consolidation of the soil makes one suspect that it may have been centuries since the valley had been submitted to a similarly intense movement. The foregoing considerations will materially aid the reader in understanding the perplexing accounts of the events of the earthquake of 1811.

Owing to the fact that the region of greatest observed violence was in the country immediately about the village of New Madrid, on the west bank of the Mississippi, about fifty miles below the mouth of the Ohio, this earthquake is commonly known in history as the New Madrid shock ; but the evidence leads us to suppose that the true centre of the shock was farther to the west. The first shocks were evidently not vertical at New Madrid, but seemed to come from some point beyond the line of the most western settlements. The Indians describe even more terrible effects of the convulsion in the region between the Mississippi and the great plains, — forests overthrown, rocks split asunder, and other indications of great violence,—than were observed at any place near the river. Everywhere the first movements seemed to come from the west, so that we are obliged to refer the origin of this earthquake, as that of many other earthquakes of the same area, to some centre of disturbance lying between the Mississippi River and the Rocky Mountains. Now that population is spreading over all that region, we shall doubtless yet know, possibly by sad experiences, the true seat of the several disturbances of which we have evidently observed only the westward prolongations.

The first movements of the shock of 1811 were observed by parties of travellers on the Mississippi River; it occurred at about 2 A. M. and was exceedingly violent; we are so fortunate as to have from the pen of an English traveller, Mr. Bradbury, a botanist of some celebrity, a clear account of the occurrences of that night and the several succeeding days during which his voyage towards New Orleans carried him through the disturbed region. At the time of the earthquake this traveller was sleeping in his boat, which was moored to the bank of a small island just above the point known as the Devil’s Channel, near the Chickasaw Bluffs. This point is about one hundred and fifty miles below the village of New Madrid, and rather beyond the centre of the shock.1 Bradbury’s account is one of the most vivid descriptions of the effects of this earthquake extant, and we cannot do better than to transcribe a portion of it: “In the night I was awakened by a most tremendous noise, accompanied by an agitation of the boat so violent that it appeared to be in danger of upsetting. Before I could quit the bed, or rather skin, upon which I lay, the four men who slept in the other cabin rushed in and cried out in the greatest terror, 'O mon Dieu ! Monsieur Bradbury, qu’est ce qu’il y a!’ I passed them with some difficulty, and ran to the door of the cabin, where I could distinctly see the river as if agitated by a storm ; and although the noise was inconceivably loud and terrific, I could distinctly hear the crash of falling trees and the screaming of wild fowl on the river, but found that the boat was still safe at her moorings. I was followed out by the men and the patron, still in accents of terror inquiring what it was. I tried to calm them by saying, 'Restez-vous tranquils; c’est un tremblement de terre ! ’ which they did not seem to understand.” “By the time we could get to our fire, which was on a large flag in the stern of our boat, the shock had ceased ; but immediately the perpendicular banks, both above and below us, began to fall into the river in such vast masses as nearly to sink our boat by the swell they occasioned ; and our patron, who seemed even more terrified than the men, began to cry out, ' O mon Dieu ! nous périrons !’ I wished to consult with him as to what we could do to preserve ourselves and the boat, but could get no answer except, ‘ O mon Dieu ! nous perirons !’ and ' Allons à terre ! allons à terre ! ’ As I found Mr. Bridge the only one who seemed to have retained any presence of mind, we consulted together and agreed to send two men with a candle up the bank in order to examine if it had separated from the island, a circumstance that we suspected from hearing the snapping of the limbs of some drift trees which were deposited betwixt the margin of the river and the summit of the bank. The men on arriving at the edge of the river cried out, ‘Venez aà terre! Venez à terre!’ and told us there was a chasm formed already, so wide that it would be difficult to pass it to attain firm ground. Immediately after the shock we noticed the time, and found it was near two o’clock. It was now nearly half past, and I determined to go ashore myself, after securing some papers and money, and was employed in taking them out of my trunks, when another shock came on, terrible, but not equal to the first. Morin, our patron, called out from the island, ‘Monsieur Bradbury, sauvez-vous ! sauvez-vous ! ’ I went ashore and found the chasm really frightful: it was not less than four feet in width ; besides, the banks had sunk at least two feet. I took the candle, and examined to determine its length, and concluded that it could not be less than eighty yards ; and where it terminated the banks had fallen into the river. I now saw clearly that our lives had been saved by mooring to a sloping bank. Before we had completed our fire we had two more shocks, and they occurred during the whole night at intervals of from six to ten minutes, but slight in comparison to the first and second. I had already noticed that the sound which was heard at the time of every shock always preceded it by about a second, and that it always proceeded from the same point and went off in an opposite direction. I now found that the shock came from a little northward of east and proceeded to the westward.2 At daylight we had counted twentyseven shocks during our stay on the island, but still found the chasm so that it could be passed. The river was covered with drift-timber, and had risen considerably, but our boat was still safe. Whilst we were waiting till the light became sufficient for us to embark, two canoes floated down the river, in one of which we could perceive some Indian corn and some clothes ; we considered this a melancholy proof that some of the boats we passed the preceding day had perished. Our conjectures were afterwards confirmed, as three had been overwhelmed and all on board had perished. I gave orders to embark, and we all went on board. The men were in the act of loosening the fastenings, when a shock occurred, nearly equal to the first in violence. The men ran up the bank in order to save themselves on the island ; but before they could get over the chasm a tree fell close by them and stopped their progress. The bank appeared to me to be rapidly moving into the river, and I called out to the men in the boat, ‘Coupez les cordes !' On hearing this, the two men ran down the bank, loosed the cords, and jumped into the boat.” The party landed again a few miles down the river, where the bank seemed more secure. While they were getting breakfast there were three more shocks; one was so violent that the party found it very difficult to keep their feet; the last came as they were about to re-embark, and one man was nearly precipitated into the river by the giving-way of the bank on which he stood. At eleven o’clock occurred another severe shock, which, says our author, “ seemed to affect us as sensibly as if we had been on land. The trees on both sides of the river were violently agitated, and the banks fell in in. several places, carrying with them innumerable trees, the crash of which falling into the river, mixed with the terrible sound attending the shock and the screaming of the geese and other wild fowl, produced an idea that all nature was in a state of dissolution.” Bradbury’s party experienced repeated shocks during the following days. They found the people at the settlements they passed distracted with terror and filled with the belief that the end of the world was at hand. The rapid current of the stream soon carried the travellers beyond the region affected by the shocks. During the six days of their course through the shaken region, they experienced several dozen shocks, most of great severity, and yet the phenomena witnessed by these travellers were produced by the shocks where they were of far less power than they were at New Madrid and other points nearer the focus of the earthquake.

We have but one other account of the experiences of persons travelling on the river. This is contained in a letter from William Shaler to his friend Samuel L. Mitchell, and published by the latter in his account of this earthquake. The statements were gathered by the writer of the letter from the patron of a Kentucky boat which had descended the Mississippi during the disturbances. The description relates to the shocks which occurred during the first part of the month of February. The events recounted are so extraordinary that we transcribe a part of the account: “On the 7th of last February, at 3 o’clock A. M., being moored to the bank of the Mississippi about thirteen miles above New Madrid, he was awakened by a tremendous roaring noise, felt his vessel violently shaken, and observed the trees over the bank falling in every direction and agitated like reeds on a windy day, and many sparks of fire emitted from the earth. He immediately cut his cable and put off into the middle of the river, where he soon found the current changed and the boat hurried up stream for about the space of a minute with the velocity of the swiftest horse; he was obliged to hold his hand to his head to keep his hat on. On the current’s running its natural course, which it did gradually, he continued to proceed down the river, and about daylight came to a most terrific fall, which he thinks was at least six feet perpendicular, extending across the river, and about half a mile wide. The whirls and ripplings of this rapid were such that his vessel was altogether unmanageable and destruction seemed inevitable; some of the former, he thinks, were at least thirty feet deep, and seemed to be formed by the water’s being violently sucked into some chasm on the river’s bottom. He and his men were constantly employed in pumping and bailing, by which, and the aid of Providence, he says, he got safe through. As soon as he was able to look round he saw whole forests on each side fall prostrate, to use his own comparison, ‘like soldiers grounding their arms at the word of command.’ On his arrival at New Madrid he found that place a complete wreck, sunk about twelve feet below its level, and entirely deserted; its inhabitants and those of the adjacent country, who had fled there for refuge, were encamped in the neighborhood. He represents their cries as truly distressing. A large barge, loaded with five hundred barrels of flour, besides other articles, was split from end to end and turned upside down upon the bank. Of nearly thirty loaded boats, only this and one more escaped destruction ; the water ran twelve feet high, and threw many of them a great many rods on shore ; several lives were lost among the boatmen. Another fall was formed about eight miles below the town, the roaring of which he could distinctly hear at New Madrid. He waited five days for the fall to wear away. During that time the earth was constantly trembling at intervals of about five minutes. He observed many fissures in the earth, below the town, five or six feet wide, extending in length out of sight, and one side several feet lower than the other. On the fifth day, he passed the lower fall, which had worn away to a practicable rapid. He felt a succession of shocks until he came down to Plum Island.” Other statements corroborate this statement of the reversion of the current of the Mississippi, and the formation of barriers across its course, over which the river broke in cataracts. On many accounts these are among the most surprising results of earthquake action ever recorded.

It is difficult to estimate the intensity of these long-continued shocks. The buildings along the banks of the Mississippi at that time were entirely of wood; even the chimneys, which generally are built of stone, at that early day in the West were usually constructed of small logs of wood notched and fitting into each other at the corners. This mode of building with notched logs was used also in constructing the houses and out-buildings, which were almost always of one story, and rarely exceeding fifteen feet in height. It would be impossible to imagine a style of building better suited to withstand such shocks ; nothing but the most violent movements would affect such structures ; yet there can be no doubt that the houses of New Madrid were ruined by the convulsion, and that over a wide area most of these substantial huts were so shaken as to become uninhabitable. The people of that region, as soon as their first terror was over, abandoned their dwellings and resorted to the forests. In order to secure themselves against the risk of falling into the fissures which were so frequently formed, they felled trees so that their trunks would be transverse to the general direction which the fissures took, and built tents upon platforms which they constructed on those broad foundations.

While these facts afford an idea of the intensity of the shocks, they do not enable the reader to conceive of the tremendous effects of the repeated convulsions on the surface of the earth. Many considerable tracts of land were submerged ; at other points dams were thrown across the smaller confluents of the Mississippi, forming lakes, some of which remain to the present day. Reelfoot Lake, near the Mississippi River, in the State of Kentucky, a body of water about fifty miles in length and from one to two miles and a half wide, was formed by a “ sand blow,” or the eruption of a great amount of sand, which dammed the waters of the stream, heaping them up until they found a new channel by passing into the Obion River.3 This extensive body of water had no existence until the earthquake shock. The valley was thickly wooded, and to this day, in the shallow parts of the lake, the dead cypresses stand in great numbers, their trunks blackened by the hunters’ fires, the flames of which are wafted by the wind from the high grass of the shore and spread from tree to tree over the water.

Although nearly sixty years have elapsed since the earthquake occurred, and although the soil on which its chief force was spent is of a loose texture, Which renders the obliterating effect of time on all irregularities of surface peculiarly great, one can still find in a day’s journey frequent evidences of the action of those terrible shocks. In the southwest corner of Kentucky the “earth-cracks ” may be traced at many points, the fissures being from twenty to seventy feet wide and from one to four feet deep. In Obion County, Tennessee, where the effects were still more violent, depressions are even now visible one hundred feet deep, and varying from a few feet to one hundred feet wide. They are said to have had more than twice this depth when originally formed. Many of these fissures were produced by the escape of gases, which broke forth with all the violence of volcanic eruptions, throwing out great quantities of sand and water. There seems reason to believe that, although no indications of the coming shock were perceived in the atmospheric condition of the night on which it occurred, a very sudden change succeeded the earthquake : within five minutes after the first movement, the heavens, which had been peculiarly clear and serene, became overcast, and the air was filled with a dense vapor, which had a disagreeable smell and produced a difficulty of breathing. This condition of the air continued until the break of day, before which several other shocks occurred ; it then cleared up. Soon after sunrise another shock of great violence succeeded, which overthrew the chimneys which had withstood the preceding movements, and rocked the houses very violently. The darkness immediately returned, and the terrified inhabitants fled from their homes. There seems no doubt that there were sudden flashes of fire at the moment of each shock. This, as well as the statement of the sudden change in the condition of the atmosphere, does not rest upon the authority of one observer, but is supported by so many independent observations that it cannot be considered doubtful. The formation of vapor does not seem difficult to account for ; the tremendous character of the movement of the soil must have generated a great deal of heat. There is also abundant evidence that large quantities of hot water were ejected from the fissures in the earth. These agents may have been sufficient to have produced the result. The electric flashes which accompanied the shocks have been observed in the case of most shocks of extreme violence occurring during the night-time. There can be no doubt that an immense amount of frictional electricity is evolved by the intense movements of the soil attendant on earthquakes of great violence, and it is quite natural that this should discharge itself into the atmosphere in lightning-flashes. These peculiar electrical and atmospheric phenomena were limited to the region of greatest observed disturbance, in the vicinity of New Madrid.

Our space will not allow us to trace in detail the various effects of this earthquake in different parts of the Mississippi valley. The physical effects were not observed over one fiftieth part of the region shaken. The scanty and illiterate population has left us only the most imperfect records of what they saw, yet enough remains to make it certain that since human history began the earth has rarely been shaken by a more tremendous convulsion.

The continuance of the shocks was as remarkable even as their violence or the peculiar phenomena they induced. From the morning of the 16th, to the 28th of December, sixty-seven shocks were counted. A competent observer, Dr. Robertson, a government surveyor, then living at St. Genevieve on the Mississippi River, about fifty miles below St. Louis, counted over five hundred shocks, when he became weary and abandoned the task. During the fourteen months succeeding the first shock, not a single day passed without a considerable movement of the earth, and often many shocks occurred within a few hours. After the expiration of a year the disturbances became more rare and lost their destructive violence, but another twelvemonth passed before the movements ceased to occur. During the first part of the series of shocks the centre of the disturbance seemed to be in the region lying to the west of New Madrid ; but the point of greatest frequency gradually moved eastward, until it was near the mouth of the Wabash River, in the Ohio valley. Here, over a region about twenty miles in diameter, a succession of shocks occurred for more than two years, during which time only a few days passed without bringing a distinct movement. Most of the oscillations were of such a slight character as not to be felt outside of this narrow district. The following account of the movements of the earth observed at Cincinnati, Ohio, will give the reader an idea of the force of the convulsion at a point on the extreme limit of the area disturbed, where shocks were reduced to the merest tremblings, which near their origin were of extreme violence. It is from the pen of Dr. Daniel Drake, an acute observer, who has supplied us the only connected and carefully recorded observations made upon the shock. The extract is from the Appendix to Drake’s Natural and Statistical View of Cincinnati: —

“ December 16, 1811. — At twentyfour minutes after two o’clock A. M., mean time, the first shock occurred. The motion was a quick oscillation or rocking, by most persons believed to be from west to east, by some south to north. Its continuance, taking the average of all the observations I could collect, was six or seven minutes. Several persons assert that it was preceded by a rumbling or rushing noise, but this is denied by others, who were awake at the commencement. It was so violent as to agitate the loose furniture in our rooms, open partition-doors that were fastened by falling latches, and throw off the tops of a few chimneys in the vicinity of the town. It seems to have been stronger in the valley of the Ohio than in the adjoining uplands. Many families living on the elevated ridges of Kentucky, not more than twenty miles from the river, slept during the shock ; which cannot be said, perhaps, of any family in town.

“ About three o’clock, or about fortyfive minutes after the first, a slight vibration was felt.

“ At twenty minutes after seven o’clock A. M. of the same day occurred a moderate rocking, apparently southwest and northeast, of about one minute’s duration, terminating in a strong throe of a few seconds. This was unattended by any sound in the earth or atmosphere.

“Thirty minutes past seven A. M., a slight oscillation.

“ Between ten and eleven o’clock A. M., another of the same force.

“ 17th. — At fifteen minutes before twelve, a vibration stronger than the last.

18th. — About thirty minutes past eleven, a moderate agitation.

“31st. — Between four and five o’clock, a few gentle rockings.

‘January 3, 1812. — A slight vibration between two and three o’clock A. M.

“ From the 3d to the 22d no vibration strong enough to attract general notice occurred ; and it was generally believed in Cincinnati that the earth hereabouts was quiet. Others however assert that they felt many slight agitations, which undoubtedly was the case, for during that period shocks were every day felt along the Mississippi.

“23d. — About nine o’clock A. M. a great number of strong undulations occurred in quick succession. They continued four or five minutes, having two or three quick exacerbations during that time. An instrument, constructed on the principle of that used in Naples at the time of the memorable Calabrian earthquakes, marked the direction of the undulations from south-southeast to north-northwest. This earthquake was nearly equal to that which commenced the series, on the 16th ultimo.

“27th. — At forty-five minutes past eight A. M.. a solitary heave, as strong as any single throe on the 23d.

“February 4. — About four o’clock P. M., a pretty strong agitation.

“5th and 6th.— During these days and the nights preceding them many slight jars and tremors were perceived by the aid of delicate plumb-lines. They were also perceptible to those persons who were at rest in situations favorable for nice observation.

“7th. — At forty-five minutes past three o’clock A. M., several alarming shocks in rapid succession. The instrument already mentioned indicated the three principal heaves to be from the southwest, the south-southwest, and north-northeast. The last greatly surpassed any other undulation ever known in this place. It threw down the tops of more chimneys, made wider fissures in brick walls, and produced vertigo and nausea in a greater number of people, than the earthquakes of either the 16th of December or the 23d of January. It was said by some that this earthquake was preceded by a light and noise ; but this was denied by others who were awake and collected in mind and senses.

“8th. — During most of this day the earth was (to borrow a term from chemistry) in a state of ebullition, as the gyration and other agitation of pendulous bodies indicated.

“About eight p. M., a slight agitation.

“ At thirty minutes after eight o’clock P. M., another vibration ; its continuance was nearly a minute.

“ At forty minutes after ten o'clock, a shock considerably stronger than either of the preceding. It was observed to produce in suspended and elevated bodies a very sensible degree of trembling, but no oscillation, indicating perhaps a vertical, instead of the horizontal motion of the previous shocks. Immediately before this shock I had the pleasure of hearing, for the first time, a noise such as preceded, according to the report of some of our citizens, most of the principal earthquakes. It was a peculiar, faint, dull, rumbling or rushing sound, near the horizon, to the southwest. It seemed to approach, but not to arrive at the place of observation, and after continuing four or five seconds was succeeded by the shake. During the remainder of the night and the next day the earth was in the same state of tremor which it suffered on the 5th and 6th. “10th. — About four o’clock r. M., a gentle vibration.

“ 11 th. — About one o’clock A. M., another.

“ 11th.— About six o'clock A. M., another.

“ 13th.— About ten o'clock A. M., another.

“ 13th. — About two o’clock p. M., another.

“ 16th.— About ten o’clock p. M., another.

“ 17th. — At forty minutes after three o'clock A. M., a stronger shock ; the undulation was south-southeast and northnorthwest. About this time a great number of slight tremors and agitations were perceived.

“20th. — Between ten and eleven p. M., a slight shock.

“21 st.—At thirty minutes past twelve o’clock A. M., a short but stronger shock.

“ 22d. — Between three and four A. .m., another slight vibration: these three oscillations were south and north.

March 3. — A few slight rockings about thirty minutes past six o'clock A. M.

loth. —A stronger vibration about eight o’clock p. M.

“ 11th.—A slighter vibration between two and three o’clock A. M.

“April 30. — A moderate agitation.

May 4. — About eleven o'clock A. M., a slight shock.

“ 10th. — About eleven o'clock P. m., a slight shock.

June 25.— In the night, a slight shock.

“26th. —About eight o’clock A. M., a slight agitation.

September 15. — At the dawn of day, a moderate vibration.

“December 22.—About three o'clock, another.

“March 6, 1813. — About ten o’clock P. M., a very slight shock.

“December 12, — Between ten and eleven o’clock A. M., another.

December 12. — Between three and four o'clock p. M., another.”

In the variety as well as the range of its effects in different parts of the continent of North America, this convulsion can only be compared with the Lisbon earthquake. As in that memorable convulsion, the greater shocks of this earthquake, while diminishing gradually in force as we pass from the centre of disturbance to more distant regions, exhibited some peculiar features in their intensity at different points. The shocks were felt as far as the shores of Lakes Michigan and St. Clair on the north, to the Atlantic on the east, and the Gulf of Mexico on the south ; but it was only the first movement and possibly one or two of the heavier shocks which occurred in the first year of the disturbance which extended their effects so far. The others were really local in character. The region shaken by the shocks of average force, although extensive, was much more limited than that affected by the severest movements. On the east, it reached Cincinnati, where over one hundred distinct shocks were felt; on the north it extended to the northern border of Illinois ; and on the south to the point where the Mississippi enters the State of Louisiana.

The eastward extension of the greater shocks was much hindered by the Alleghany Mountains. This range interposed a barrier to the propagation of the movement, such as has frequently been noticed in connection with the shocks which have affected Central and Southern Italy, where the mountains limit the shocks in a remarkable degree. The movement of the shocks of the first day was felt, though indistinctly, as far as Richmond, Virginia, and Washington. They were not perceived farther north on the coast line, nor were any of the subsequent shocks noticed. From Columbia, South Carolina, southward, as we pass from under the protection of the Alleghany range, we find the effects of the shocks more intense. At the last-named city, plastering fell from the ceilings, and great terror was produced by the shocks. At Charleston, the church - steeples rocked so that the bells rang continuously ; during December seven shocks were felt. At Knoxville, on the western side of the mountains, the shocks were violent, and attended, as at many other points, with flashes like lightning. It would require a volume to recapitulate the recorded effects of these shocks at different points ; we have given enough to enable the reader to form a conception of the nature of this grand convulsion. To the geologist, the most remarkable features are, that a convulsion of such violence and long continuance should have occurred at a region so remote from points of volcanic eruption, and in a country where so large a portion of the surface is formed of rocks, which seem to have been but little affected by the forces coming from beneath. But there are other considerations which cannot fail to interest the general reader even more than these scientific speculations; namely, what are the probabilities of a repetition of such a catastrophe in that region, and what would be the effects of such movements on the works of man ?

To the first of these important questions only a qualified answer can be returned. As before stated, the occurrence of such a shock in a region like the Mississippi valley, on the borders of a great river, is probably unprecedented in the history of earthquakes; but, as it has occurred, all analogies indicate the probability of its recurrence within a century. In all those countries which have been visited by great convulsions, where observation has extended over a great length of time, it has been found that their visits may be expected as often as about once in a hundred years. If such a convulsion should revisit that region in its present populous condition, the destruction of life and property would be terrible indeed. In no portion of the world are the buildings less fitted to withstand such shocks. To feeble walls of great height, and with slight transverse supports, are added massive stone copings and heavily loaded floors. The architect’s work is deemed to be the nice adjusting of strength to strain, so that nothing is left for contingencies. The seismologist can have no doubt that the recurrence of a series of earthquakes like those of 1811, 1812, and 1813 would ruin many of the cities of the Mississippi valley. St. Louis, Memphis, Cairo, Nashville, the towns along the Ohio River below Cincinnati, and the cities generally within two hundred miles of New Madrid, would suffer terribly by a return of those movements which convulsed the region half a century ago. An earthquake which could render loghouses uninhabitable would play havoc with the flimsy structures which prevail in our Western cities. It is sincerely to be hoped that the conclusions of science may prove without foundation, and that this warning may be found to have as little basis as it will have effect ; but the cautious man, building in a region which had been shaken as this region has been, would try to give his Walls the strength of Roman masonry, and avoid all unnecessary elements of weakness in his buildings.

After the land in the Mississippi valley had ceased to vibrate with the frequently recurring shocks of the New Madrid earthquake, there came a long period of repose. Indeed, for nearly forty years only the most feeble tremors, occurring at long intervals, served to remind the people of the valley that the forces of the earthquake still existed under their feet. In February, 1857, there occurred a shock more violent than any since 1813. No damage was done to buildings, nor were any effects traced on the surface of the earth. Those people who had experienced the shocks of 1811 to 1813 were much frightened at the prospect of a similar calamity ; but the mass of the population was unaffected by it. The work of collecting the records necessary to the formation of a catalogue of the earthquakes of the Mississippi valley remains to be done, so that it is not possible to present here a list of these shocks. This is the less to be regretted, inasmuch as they afford little matter calculated to interest the general reader.

  1. There are reasons for believing that, although the centre, or, to use the especial language of the science, the seismic vertex, of the New Madrid shocks was at the outset much to the west of the Mississippi, it gradually moved eastward, until, towards the close of these movements, in 1813, it had travelled over two hundred miles in this direction, being then near the mouth of the Wabash River on the Ohio. The first movements at New Madrid were probably nearer horizontal than vertical ; after some days however, the accounts say, the ground bounded up and down.
  2. This direction, it seems from the precision of statement, may have been determined with a compass, but it differs so widely from that assigned to the shocks by other accounts that I am tempted to believe it a mistake.
  3. This expanse of water includes Obion Lake, which is on the same level and seems to have been formed at the same time and by the same barrier.