AS thunderous tones deepen, their power seemingly intensifies over frail barriers such as glass windows. Certain abrupt thunder peals often shatter windows into tiny fragments. In the apparent absence of thunderous tones we may observe the strong and continuous vibration of glass window panes during storms. A sudden eerie silence, and the window is shattered before our eyes.
Natural phenomena are prodigious generators of infrasound. The potent distal effects produced when natural explosions occur produce legendary effects. When Krakatoa exploded, windows were shattered hundreds of miles away by the infrasonic wave. Wind was not the causative agent of these occurrences, as no wind was felt or detected. Seismographic stations registered the blast, and barometers measured the shockwaves. The "ringing" of both earth and atmosphere continued for hours. It is believed that infrasound actually formed the upper pitch of this natural volcanic explosion, tones unmeasurably deep forming the actual "central harmonic" of the event. The island of Krakatoa was literally lifted into orbit in the fatal blast. Brilliant sunsets followed for many years thereafter, the sad memorial of all the souls who perished.
The power of explosives, in shattering and devastating property, lies in two zones. The first zone is that with which we are principally familiar; the actual blast site, where chemically released gases and metal fragments push back everything in their perimeter. The second less familiar zone extends very much further from the blast site than can be imagined. It is in the powerful sonic wave which expands outward that an equally destructive danger lies. Thick pressure walls of incredible momentum, interspaced with equally thick walls of reduced air pressure, travel far away from the blast site. The blast site is the small destructive zone by comparison. Few objects can survive this destructive tide.
Analysts contend that infrasound is composed of a very broad band of pitches. These tones of immense pressure and duration "accommodate" themselves when encountering resonant cavities. All such resonant cavities are "found and destroyed" when the proper pressure waves flow into their resonances. Rooms, halls, alleys, spaces among buildings, courtyard areas, cellars, subways, sewer chambers; all these burst open into flying fragments when infrasonic waves flood them. Infrasound is the cruel tonal giant, tearing open whatever it finds in its path.
Study reveals that the sudden shock wave of an explosion propels a complex infrasonic signal far beyond the shattered perimeter. Incoherent though such shockwaves may be, their destructive influence dissolves distant walls and windows seconds after the shrapnel has done its deadly work. Objects of all shapes, sizes, and compositions explode when the infrasonic impulse passes through their space. No shield can block infrasound. Physicists have studied the refuse which remains after an explosive charge has been detonated. Few materials can maintain their integrity. Those objects which manage to survive explosions are noteworthy as infrasonic "resistors". Screen reinforced concrete does not easily succumb to the infrasonic blasts of explosive charges.
The sound of Krakatoa exploding up into space, a vertical excess of one hundred miles, succeeded in blasting out windows at a thousand mile radius from the epicenter. Certain earthquake activities produce large and virtually insensate vertical displacements of the ground surface, in extreme instances amounting to a few feet per pulse. In this case, the ground becomes the surface of a drum, ringing out its deadly cadence at infrasonic pitch hours before the event. The ground undulates with infrasonic tones, an elasticity that eventually cracks under the heaving stress.
Ultralow pitch earthquake sounds are keenly felt by animals and sensitive humans. Quakes occur in distinct stages. Long before the final breaking release of built up earth tensions, there are numerous and succinct precursory shocks. Deep shocks produce strong infrasonic impulses up to the surface, the result of massive heaving ground strata. Certain animals (fish) actually can hear infrasonic precursors. Precursory shocks are silent, being inaudible in humans. Animals, however, react strongly to the sudden surface assault of infrasonic shocks by attempting escape from the area. Animals cannot locate the source and center of these infrasonic impulses, behaving in a pitiful display of circular frenzies. The careening motion of wild horses and other domestic animals indicates their fear and anxiety. Poor creatures, neither they nor we can escape the infrasonic source. Encounters with natural infrasound reveal their vast extent, covering hundreds of square miles of surface area.
Certain animals employ infrasound as weaponry. It has been known that certain whales are able to stun their prey with powerful blasts of inaudible sounds. Called "gunshots", whales focus these powerful blasts at large squid and other fish to paralyze and catch them. In some instances, they have been known to burst their prey apart by tonal projection alone. Human experience with these inaudible blasts have been reported. The distress calls emitted by little beached whales was sufficient to push a veterinarian back several feet in the water. Others have experienced these pressure waves, reporting that their hands could not be brought close to the sinal area of small whales because of their inaudible acoustic projections.
Infrasonic shocks produce characteristic pressure effects on structures and organisms alike. The sensation flattens the body. It  is as if one were struck with a solid invisible wall from which there is no escape. There are physiological effects as well. Anxiety, fear, extreme emotional distress, and mental incapacitation are all part of the unpleasant phenomenon. Notable among human exposures to quake-correlated infrasound is the precursory nausea which many report. This strong sensation leaves its more sensitive victims helpless. Feeling the momentary deep motion of the ground strata beneath them, numerous individuals have been used to report these sensations in a bizarre earthquake "alarm system". Unfortunately, physiological reaction to infrasound remains continuous, long after their irritating presence has ceased. The harmfully stimulating influence of infrasound renders physiology permeable and ultrasensitive to every available environmental sensation. The extreme irritability of infrasound victims has been noted.
Earthquake infrasound manifests only at intermittent intervals, producing drastic and sustained negative modifications of consciousness. The human organism continues to reel under intermittent infrasonic assault for numerous reasons. After less than a five minute exposure to low intensity infrasound of 10 cycles per second, dizziness will last for hours. Infrasound of 12 cycles per second produces severe and long lasting nausea after a brief low intensity exposure.
Surf pounds the shore, producing shocks of 16 cycles per second, just short of the true infrasound range. Ocean waves which pound the atmosphere across huge ocean areas produce an acoustic energy with a mean pitch of 16 cycles per second. The phenomenon of the "barisal guns, fog guns, lake guns" form a well documented bibliography of anomalous acoustic phenomena. These "booming" anomalous tonal phenomena are not isolated to one area or nation. Every nation has accounts of these sea-related mystery sounds. Some regions call them "bay detonations", since they come as abruptly explosive intonations from certain bay areas.
Some of these tones manifest their shocking tones at haphazard intervals. But there are those water-related booms which are periodic, residents near these sites being accustomed to their mysterious occurrence. The strange "explosive" sounds come at certain times of the day, at certain times of the month, and at certain times of the year. There are certain other related anomalous natural tones which ring, hoot, and buzz. Some have been likened to organ tones, tuba blasts, and the deep intonings of very large bells. Bay sizes, wave sizes, and geologic compositions of bays and shores have been woven into complex mechanistic attempts at explaining how these mystery sounds are being generated in certain environments.
The detonation may be caused by a sudden "slapping" of bay water by a singular wave having the "right" breadth and momentum, matching the natural resonant pitch of a bay. The underlying bay rock matrix may resound in the manner of a bell, gong, or cymbal. The geological composition of the bay plays the greater part of the effect, sudden winds or water surges knocking the natural "sounding board". These natural bay tones have great infrasonic content.
The infrasonic outputs of the mystery tones are significant. Each of these phenomena produce a range of very low pitch tones. These booming sounds have rattled windows and rocked some small towns. Animals are startled by their inaudible precursors, and humans are often dizzied after their manifestation for hours. In several areas, people are hospitalized by the "boom" related illnesses.
Waterfalls are notorious generators of infrasound. Numerous susceptible visitors at Niagara experience a peculiar nausea which is not associated with the normal fear of heights. Thundering cataracts produce strong infrasonic shocks to which mile exposure stimulates the common malady. Lake ice and glacial ice produce deep booming sounds which ring for hours, behaving as large tympanic surfaces. The thunderous sounds associated with these occurrences produces infrasound of pitch related to ice surface mass, breadth, and length alone. Antarctic research experienced nausea in relation to ice related sounds.
Tidal waves and other sudden variations of water surfaces produce large magnitude "seiche" waves. These have been sighted by ocean going ships, where oceanic surfaces have drastically changed elevation in an incredibly short time. Ships "drop" into such huge ocean troughs and rise again after the wave passes. In dropping, some have crashed to the very rock bottom of their bays, only to be lifted in pieces when the wave resurged. Film footage of the great and horrid Alaskan Earthquake (1964) reveals this devastating sea "drop-out".
Upon such lethal seiche tides, even in the fortunate absence of earthquakes, comes nausea and other coastal related illnesses. Large intensity infrasonic sea shocks have their powerful effect on the overlying atmosphere of their regions. These infrasonic shockwaves travel for long distances. Certain bays are known for the high incidence of such illnesses, the result of resonant baywater "heavings" which occur daily. Their sickening effects are seemingly "stored up" in physiology, lasting for hours. While these phenomena proceed from deep in the heart of earth, and on its surface, there are phenomena which generate infrasonic sources . . . from space.
Aerial earthquake sounds have been reported by observers. Such rushing, thrumming sounds seem to come from "everywhere" above the affected locale. Typical of infrasound, the sources cannot be accurately located.
When Krakatoa exploded, barometers fluctuated rapidly in short time intervals. It was recognized that a new means for detecting earthquakes and other earth movements had been found. The horrifying destruction of Krakatoa prompted the emergence of a new science. The rapid development of sensitive barometric instruments provoked the discovery of a whole new "infrasonic world".
The opposing nations of the Cold War years used barometers and seismographs in determining the relative explosive yield of periodic underground atomic blasts. Sensitive barometric detection gradually began searching the atmosphere and earth for infrasonic "events". Mysterious and sudden barometric variations indicates that natural infrasonic generation has a much wider source than the subterranean earth. Infrasounds associated with the Aurora Borealis are too numerous to mention, a well chronicled occurrence.
The aurora Borealis is heard to "swish, crackle, sizzle,  and . . . thunder". Quantitative analysts "cannot understand" how these sounds can be "heard" but not recorded. It is obvious that certain auroral sounds stimulate physiological responses which will never register in biologically unmodified electronic systems. Though debates continue when referring to higher auroral tones, the "thunder" of the aurora stimulates aerial infrasounds which can be measured.
Low level auroras have been actually seen and felt. The sounds and odors associated with this rare phenomenon are unmistakable. In one instance a chemist was fortunate enough to have lived, after witnessing the effect of auroral grounding throughout his laboratory. The incredible luminescence produced in several platinocyanides, electro-phosphorescent chemicals, were duly noted and reported. Another such incident involved the grounding of the aurora into an elevated radio tower. The radio engineer suddenly heard a crackling sound "from everywhere", was unable to transmit any signal power, felt completely electrified, smelled ozone everywhere, and heard the "crackling" sound. Numerous witnesses who saw the event, describing the colored column of light which suffused the tower, feared he might have been killed by its power.
The auroral high pitched sizzling sounds are augmented by deep and ominous thrumming. These deep tones sweep through the bodies of listeners who are fortunate enough to survive the dangerous encounter. These permeations produce an irritability and a dizzying nausea. These sounds were always equated with evil by the Eskimo. Their legends of the aurora are always fear-filled. The trademark of anxiety and dread highly characteristic of infrasonic influence, their tales also recount the "taking" of souls by the "ground walking" aurora. English observers reported that the aurora actually "swept along the ground" like a column descending from the sky. It took a multicolored appearance all along its meandering path.
Blasting through interplanetary space, solar flares assault the earth with a barrage of stupendous proportion. Their disturbing effect on electrical systems is historically noted. The appearance of electrical power surges during solar flare events has amounted to many hundreds or even thousands of amperes line-induced current. Northern lands design their power systems to accommodate these periodic manifestations of great power. Oil lines in northern lands must be carefully grounded and insulated to prevent the continuous induction of such harmful electrical surges. Standing arcs of brilliant blue current had been observed upon the surface of loose pipe joints during solar flares and strong auroral episodes.
Few writers have discussed the intermittent effects of solar flares on atmospheric pressure. The sudden changes noted in air pressure, which cover many thousands of square miles, are obviously sourced in the solar wind. The effect of this natural atmospheric assault has defined and disturbing influence on both the weather and human behavioral patterns. Some 139 solar flares were recorded between 1980 and 1983. There is a statistical 155 day periodicity in solar flares, a rhythm often violated by several interstitial flares. Principally used for predicting their expectable effect on radio communications, specific military observers monitor solar flares with continued concern. Correlations of flares with jet stream behavior is strong.
Jet stream behavior, in its meanderings and undulations across vast geographic regions, is not mysterious when considering the intermittent effect of solar flares and the normal "background"  bursting of the solar wind. Traveling at thousands of miles per hour, flare pressures aperiodically barrage the neutral atmosphere. The explosive influence of vast power shocks the entire weather system, electrically active flare disturbances violently disrupting all atmospheric processes. The very obvious outlines of flare contacts with the atmosphere can be traced as major pressure changes on weather maps. Solar flare impacts strike the earth like a bell. Auroras result, and have been correlated with thunderstorm activities.
But continual minor background disruptions also exist, propelled by the sun. In its normal process, solar expulsions do not arrive at the atmospheric boundaries as a homogeneous pressure wave. The arrival of solar products comes as a pressure wave of inconsistent density. This intermittent barrage induces harmonic atmospheric disturbances which continually modify and chaoticize emerging weather patterns. The effect is exactly like "thrumming" an evenly sanded drumhead with innumerable impacts. This imprint of "background" pressure waves, rattling daily upon the atmosphere from solar winds, can be seen as "Chladni" patterns on weather maps.
Both solar flares and the normal thrummings of the solar wind generate infrasonic pulses throughout the atmosphere. The infrasonic shockwaves of the aurora are normally not heard, but definitely sensed. Measurements have registered a continual infrasonic background noise level. This pressure energy emanates "from above" atmospheric strata, radiating downward in large patterns. Atmospheric infrasound is most strongly measured during daytime hours, a clear indication of their source in the intermittent expulsions of solar wind. Atmospheric infrasounds arrive at measuring stations with pitch between .67 and 1.5 cycles per second. Their pitch continuously oscillates between .67 and .83 cycles per second. These solar sourced infrasonic impacts very definitely correlate with sudden swings in human behavior, having very obvious sociological implications. The energetic content of atmospheric infrasound represents a vast and untapped potential.
Infrasound moves, unaffected, through and across both winds and storms. But wind and storm can generate infrasound. The powerful harmonic rotations of storms shears the atmosphere, radiating a cyclonic series of expanding infrasounds. The sense of impending fear which proceeds hurricanes is due to infrasonic emissions. The infrasound of seasonal winds and weather patterns produces illness in certain persons. Some individuals can hear the jetstream and its thunderous pitch, peaking between 30 and 40 cycles per second. More and more populations are reporting the persistence of ultralow pitch sounds which render them weak and fatigued. Having often unexplained sources, we find the bibliography flooded with cases of persistent "atmospheric . . .and underground sounds".
Victims of such infrasonic assaults report severe stomach upsets associated with such infrasounds. Persons who report these persistent "underground" rumbles often live in a very localized region. These loci have been as small as six miles in diameter. Wind shear action between the rapid jet stream (.75 miles per second) and more quiescent lower air strata might continuously generate this persistent infrasound. Natural infrasonic generation is difficult to determine in all cases where it has been detected. Clashing winds may produce such sustained low pitches by misunderstood "shearing" actions, similar to Von Karrman vortices.
Wind shearing may be modified by local topology. Mountain ranges of specific geometry may offer the most plausible explanation for infrasound in certain areas. Their obstructive presence among regionally prevailing winds may produced sustained aerial vortices from which infrasounds continuously radiate.
Why however does the infrasound focus on certain ground points? Some theorists claim that wind enters caverns, producing an immense artificial whistle of infrasonic resonant pitch. Careful examinations of these caverns reveals infrasonic pitch of 20 to 30 cycles per second which does not "register" on tape recordings. Some have suggested that these infrasounds are only sensed in physiology, being "electrostatic" in nature. They also claim that the incidence of ground-focusing infrasound is an electrical manifestation, the result of emerging terrestrial charges in highly localized regions.
How does sustained infrasound affect man-made structures? Gusting wind has often applied such instantaneous pressure  to man-made artifice that strong rock walls fall flat in tiny pieces. These sudden events often occur when winds seemingly ceased for an instance. During that brief interval, windows are often blown through, and walls are toppled by infrasonic impulse.
What is the sustained influence of infrasound on humans and human behavior? Mysterious desert humming sounds fill the night of nomads with superstitious dread. Deep, buzzing, and threatening, these continuous humming tones have produced anxiety and fear among Bedouins for centuries. The "ghost wails" appear in the mythology and folktales of the desert people.
But these deep and virtually inaudible humming tones are not confined to the desert plains, where they thrash among themselves across sandy dunes. The Mistral, the northward winds of the African continent, sweeps over the southern Mediterranean coast lands during late fall. These familiar hot winds emerge from their desert journeys with a strange power, lasting throughout the winter. These winds leave an indelible trace among exposed communities, a phenomenon which has been misunderstood for centuries.
The Mistral, weak in infrasonic intensity, does not wreak havoc with material structures. But the Mistral works its permeating harm nonetheless. For the inhabitants of certain coastal areas, the low intensity infrasound of the Mistral brings with it a peculiar seasonal anxiety and depression. In certain locations across the Mediterranean coast land there are individuals who suffer from "seasonal nervous exhaustion" and other "neurophysical maladies". It is known that whenever the Mistral blows, there will be increased emotional tension, depression, and irritability. The Mistral, in numerous cases, has produced fatalities.
Infrasound travels long distances, often exceeding one thousand miles, with virtually no attenuation. Its pressures thus arrive at great distances with the same force and intensity as when generated. A deadly pressure. The atmosphere sustains prolonged and powerful infrasonic vibrations. How natural conditions can systematically modify human behavior for protracted seasonal periods is frightening. How natural conditions can systematically modify large-scale social behavior for protracted seasonal periods is equally frightening. Not much acoustic power is required for infrasound to produce such extreme and sustained physiological symptoms.
Fohn winds are dry and warm southerly winds which traverse the Alpine regions of Europe. Fohn weather is characterized by clear skies, high visibility, and dry atmosphere. Studies of "Fohn weather" and the Mistral alike have revealed some intriguing and frightening statistical correlations. The biological effects of both Mistral and Fohn weather have been well documented. These include extreme irritability, accident-prone loss of objective judgement, slight disorientation, mild nausea, and diarrhea.
It is an established fact that sustained low intensity infrasound alters human behavior and health. Higher accident rates are correlated with pre-Fohn weather onset. This high accident rate rises until the establishment of Fohn weather, having been attributed to the infrasonic content of the winds.
Vibrating man-made structures stimulate the artificial generation of dangerous infrasound. When turns are made at 60 miles per hour, car chassis vibrations produce a peak infrasonic emission. Travel sickness can be associated with prolonged infrasonic exposure to any vibrating chassis. Cars, buses, trains, motorcycles, and jets alike each register hazardous intensities of infrasound. Each transportation mode has its characteristic infrasonic pitch, the necessary outcome of mechanical frictions and inertial resistances.
There is difficulty in recording and reproducing ultra deep tones for study and analysis. They have to be generated on site for experimental purposes. Theater-sized sound systems can never completely transmit all of the sensations associated with naturally occurring infrasound. But there have been instances where audiences have become frighteningly ill because of the accidental generation of infrasound in a theater space.
Of critical importance is the comprehension of human tolerances to infrasound. Military medical teams have long studied the effect of machine vibration on human judgement and behavior out of necessity. If jet pilots and rocket pilots alike evidence even minor errors in judgement through their exposure to infrasound, disaster can result. Certain critical errors in judgement and accuracy have in fact been noted during short flight times.
The powerful infrasonic vibrations of jet chassis absolutely saturate the bodies of pilots. Continually saturated with these infrasonic energies throughout their flight time, pilot reflexes are severely diminished. Military procedure recognizes this factor, and routinely limits flight time. It is known that excess infrasonic exposures endanger pilots and their flight missions. Pilot damaging effects include decrements in vision, speech, intelligence, orientation, equilibrium, ability to accurately discern situations, and make reasonable decisions.
For more reading on the man-made uses of Infrasound, consider "The Sonic Doom of Vladimir Gavreau".