1755 Lisbon Earthquake, 1964 Alaska Earthquake, Alaska, Alaska Earthquake, earthquake hazard, geology, Great Lisbon Earthquake, horizontal acceleration, impacts of earthquakes, long distance earthquake impacts, Norway, nuclear energy, nuclear hazard, nuclear spent fuel pools, nuclear waste, Portugal, seiche, seismic surface waves, Spent Fuel Pools, Tibet, UK, US Gulf Coast
Earthquake induced seiches are interesting because of the risks to nuclear spent fuel pools, and because they show that, depending on geology, impacts from earthquakes can be felt almost 7,000 km, over 4,000 miles away!
“A [seismic] seiche is the sloshing of a closed body of water from earthquake shaking. Swimming pools often have seiches during earthquakes.” http://earthquake.usgs.gov/learn/glossary/?term=seiche
The Great Alaska Earthquake of 1964 made water slosh on the US Gulf Coast! The 1950 Tibet earthquake impacted water in Norway and the UK!
Local Impacts of the 1964 Alaska Earthquake:
“Because both seiches and seismic intensity depend on the horizontal acceleration from surface waves, the distribution of seiches may be used to map the seismic intensity that can be expected from future local earthquakes.” http://pubs.er.usgs.gov/publication/pp544E
“If you have observed water sloshing back and forth in a swimming pool, bathtub, or cup of water, you may have witnessed a small-scale seiche (pronounced saysh). On a much grander scale, the same phenomenon occurs in large bodies of water such as bays and lakes. A seiche may occur in any semi- or fully-enclosed body of water.” http://oceanservice.noaa.gov/facts/seiche.html
Seismic seiches are standing waves set up on rivers, reservoirs, ponds, and lakes when seismic waves from an earthquake pass through the area. They are in direct contrast to tsunamis which are giant sea waves created by the sudden uplift of the sea floor.
The term seismic seiche was first coined by Anders Kvale in 1955 to describe oscillation of lake levels in Norway and England caused by the Assam [Tibet] earthquake of August, 1950. But this was not the first time that seismic seiches had been observed. The first published mention was after the great earthquake of November 1755 at Lisbon, Portugal. An article in Scot’s Magazine in 1755 described seiches in Scotland in Loch Lomond, Loch Long, Loch Katrine and Loch Ness. They were also seen in English harbors and ponds and were originally described in the Proceedings of the Royal Society in 1755.
Earthquake effects recorded by surface-water gages were first noticed by A.M. Piper of the U.S. Geological Survey (USGS). He reported that two of six gauges on the Mokelumne River in California showed a slight fluctuation caused by the December 20, 1932 earthquake at Lodi, California. Since then many seiches resulting from earthquakes have been recorded. Kvale made a detailed study of 29 seiches recorded in fiords and lakes in Norway and four seiches on reservoirs in England, all caused by the 1950 Assam earthquake. Frank Stermitz, a USGS scientist, reported readings from 54 stream gages that recorded seiches caused by the Hebgen Lake, Montana, earthquake of 17 August 1959. These were in Montana, Wyoming, Idaho, and Alberta, Canada – the most distant seiche being 545 kilometers from the epicenter.
Seismic waves from the Alaska earthquake of 28 March, 1964, were so powerful that they caused water bodies to oscillate at many places in North America. Seiches were recorded at hundreds of surface-water gaging stations – although they had rarely been reported following previous earthquakes. Indeed, four seiches were observed in Australia.
Some of the 1964 seiches were very large. Waves as high as 1.8 meters were reported on the Gulf Coast – probably because they were generated in resonance with the seismic surface waves.
Arthur McGarr and Robert C. Vorhis studied the continental distribution of seiches produced by the Alaska earthquake. They divided the seiches into two groups – those that occurred in Alaska itself and those that occurred outside the State.
The Alaska seiches were not wholly seismic, but were caused by landslides, submarine slides, tsunamis, and tilting – as well as by seismic surface waves. It was therefore difficult to isolate a particular mechanism for seiches produced within the epicentral region. At teleseismic distances (greater than 1000 kilometers) from the epicenter, inelastic effects are unimportant and seiches are generated solely by seismic surface waves.
After the 1964 Alaska earthquake, the southeastern part of the United States had by far the greatest density of seiches. Other high density areas included north and central New Mexico, eastern Kansas, and the region at the southern tip of Lake Michigan. The areas west of the Rockies, the Middle Atlantic States and New England experienced few or no seiches.
The 1964 distribution does not have any obvious dependence on distance or azimuth from the epicenter. But it does seem to have definite regional patterns, which reflect the influence of major geologic features:
The density of seiches is roughly proportional to the thickness of surface sediments, for example, in the Mississippi Delta region.
Thrust faults apparently provide a favorable environment for seiche generation. The relationship is especially clear in Georgia, near the Brevard thrust zone, in the Ouachita Mountains, and also in the Valley and Ridge province of Tennessee and Alabama.
Seiche locations were also controlled by structural uplifts and basins – such as the Williston and Michigan basins.
Abridged from Earthquake Information Bulletin, January-February 1976, Volume 8, Number 1.” (Emphasis added) http://earthquake.usgs.gov/learn/topics/seiche.php
“Seismic seiches from the March 1964 Alaska earthquake: Chapter E in The Alaska earthquake, March 27, 1964: effects on hydrologic regimen Professional Paper 544-E
This report is Chapter E in The Alaska earthquake, March 27, 1964: effects on hydrologic regimen. For more information, see: Professional Paper 544. By Arthur McGarr and Robert C. Vorhis
Seismic seiches caused by the Alaska earthquake of March 27, 1964, were recorded at more than 850 surface-water gaging stations in North America and at 4 in Australia. In the United States, including Alaska and Hawaii, 763 of 6,435 gages registered seiches. Nearly all the seismic seiches were recorded at teleseismic distance. This is the first time such far-distant effects have been reported from surface-water bodies in North America. The densest occurrence of seiches was in States bordering the Gulf of Mexico.
The seiches were recorded on bodies of water having a wide range in depth, width, and rate of flow. In a region containing many bodies of water, seiche distribution is more dependent on geologic and seismic factors than on hydrodynamic ones. The concept that seiches are caused by the horizontal acceleration of water by seismic surface waves has been extended in this paper to show that the distribution of seiches is related to the amplitude distribution of short-period seismic surface waves. These waves have their greatest horizontal acceleration when their periods range from 5 to 15 seconds. Similarly, the water bodies on which seiches were recorded have low-order modes whose periods of oscillation also range from 5 to 15 seconds.
Several factors seem to control the distribution of seiches. The most important is variations of thickness of low-rigidity sediments. This factor caused the abundance of seiches in the Gulf Coast area and along the edge of sedimentary overlaps. Major tectonic features such as thrust faults, basins, arches, and domes seem to control seismic waves and thus affect the distribution of seiches. Lateral refraction of seismic surface waves due to variations in local phase-velocity values was responsible for increase in seiche density in certain areas. For example, the Rocky Mountains provided a wave guide along which seiches were more numerous than in areas to either side. In North America, neither direction nor distance from the epicenter had any apparent effect on the distribution of seiches.
Where seismic surface waves propagated into an area with thicker sediment, the horizontal acceleration increased about in proportion to the increasing thickness of the sediment. In the Mississippi Embayment however, where the waves emerged from high rigidity crust into the sediment, the horizontal acceleration increased near the edge of the embayment but decreased in the central part and formed a shadow zone.
Because both seiches and seismic intensity depend on the horizontal acceleration from surface waves, the distribution of seiches may be used to map the seismic intensity that can be expected from future local earthquakes.” http://pubs.usgs.gov/pp/0544e/ http://pubs.er.usgs.gov/publication/pp544E (Emphasis added)
“INTERPRETATION OF SEICHE DISTRIBUTION
RELATION TO GEOLOGIC FEATURES
The influence of major geologic features on the distribution of seiches became apparent when seiche locations were plotted on the tectonic map of the United States (U.S. Geol. Survey and Am. Assoc. Petroleum Geologists, 1962). A simplified version o f this map is shown as plate 1.
In all but three areas of North America-the northeast end of the Mississippi Embayment, the area near Miami, Fla., and the Great Valley of California-the density of seiches seems to be roughly proportional to the thickness of low-rigidity sediments. Extreme examples of this density distribution are shown by the concentration of seiches in the Mississippi Delta region along the Gulf Coast of Louisiana, where sediment thickness is maximum, and by near absence of seiches on the Canadian Shield, where sediments are almost nonexistent. Along the Gulf Coast eastward and westward from Louisiana the regular decrease in number of seiches as the deposits become thinner is particularly striking. The anomalously high density of seiches near Miami and the anomalously low densities at the head of the Mississippi Embayment and in the Central Valley of California are discussed on pages El9 and E20.
Thrust faults apparently provide a favorable environment for the generation of seiches. The relationship is especially clear in Georgia, where seiches were recorded at gages on the Brevard Rome, Towaliga, and Whitesfone” The entire article is here: http://pubs.dggsalaskagov.us/webpubs/usgs/p/text/p0544e.pdf
McGarr, Arthur, and Vorhis, R.C., 1968, “Seismic seiches from the March 1964 Alaska earthquake: U.S. Geological Survey Professional Paper 544-E, p. E1-E43, 1 sheet, scale 1:5,000,000.” (Emphasis our own)