Summary List files contain basic geographic and geologic information for volcanoes thought to have been active in the last 10,000 years (Holocene). The data include a unique volcano number, volcano name, location, latitude and longitude (in decimal degrees), summit elevation (in meters above sea level), volcano type, status, and the time range of the last recorded eruption. More detailed descriptions of the data elements, plus more information on the volcanoes and their eruptions, can be found below and in "Volcanoes of the World" (Simkin and Siebert, 1994). The book provides a discussion of the many cautions that are so easily stripped away from an electronic database, such as the incomplete and uneven nature of the historical record, and the large uncertainties surrounding many older eruption dates. The accuracy of the record varies enormously from one region to another (and one century to another), and the sea-floor volcanism that dominates our planetary magma budget is scarcely represented in this data set.
The volcano numbering system, developed by the Catalog of Active Volcanoes of the World (CAVW) in the late 1930s and used in all their catalogs, is geographic and hierarchical. The first two numerals identify region, the next two identify subregion, and the last two or three (after the hyphen) identify individual volcanoes in that subregion.
Original CAVW volcano numbers have been retained, where possible, to aid cross-referencing, but this has required, for the many volcanoes added since CAVW publication, the interpolation of 3-digit volcano numbers between 2-digit CAVW numbers. Volcanoes bearing numbers identical to those used by the CAVW carry an "=" symbol at the end of the number to facilitate reference to the CAVW for fuller descriptions. When we have added a volcano between those already numbered, we have added a third numeral. Thus Lipari, between Stromboli (0101-04=) and Vulcano (0101-05-), is given the number 0101-041 rather than the next available two-digit number at the end of the Italian subregion. This scheme permits natural geographic sequencing of volcanoes while retaining original CAVW numbering. Letters have been added at the end of a very few individual volcano numbers to designate volcanoes thought likely to be interconnected yet sufficiently separated that one cannot be clearly designated a subfeature of another. The grouping is shown by using the same volcano number in each case, with letters at the end of each individual number in the group. When adding numbers in regions not previously numbered by the CAVW, and when renumbering in regions such as the Canary Islands and the western United States, we have used only two numerals for the individual volcano number but have designated the fact that it cannot be found under this number in the CAVW by adding a "-" in the last place. Crater Lake, in the Cascade Range of Oregon, for example, is numbered 1202-16- here, but was not included in the CAVW.
With few exceptions, we have used the names listed by the compilers of the CAVW, the contributors to the IAVCEI post-Miocene data sheets, and individual volcanologists reporting on additional volcanoes. We have preferred broader island names, locatable on standard maps, rather than crater names locally used to identify the full island volcano, and we have dropped modifiers, such as "Mount," when they seemed unnecessary. We have used square brackets, however, to indicate alternative names that are widely encountered in the literature (e.g. "Cerro Azul [Quizapu]" in Chile). For Japanese volcanoes we have listed the more widely used Hepburn style of spelling. Readers familiar with older spellings of Indonesian names will note that newer official names are used here, so that TJ, DJ, J and OE appear as C, J, Y, and U, respectively. We have excluded special characters from other languages that would strain our already-overburdened computers.
A few names have also been changed from the CAVW to reflect the broader time coverage of this compilation. Historically active features that are clearly part of a larger feature active in Holocene time have been listed under the larger feature. For example, the CAVW lists volcano number 0603-31= as Bromo; however, Bromo is but one of several youthful features in Tengger caldera, so we have used the caldera name. An extension of the time coverage problem is the grouping problem mentioned above. Amboy, a solitary cinder cone 200 km east of Los Angeles, is entered as a single volcano, and so is the Michoacan-Guanajuato Field, made up of nearly 1,000 cinder cones dotting a 200 x 200 km area in Mexico. Clearly not all "volcanoes" are equal, and caution must be used in any serious counting of them.
The location consists of the "subregion" designated by the CAVW compilers (and identified by the third and fourth digits of the volcano number, but we have added a more general location name where useful for identification.
Geographic coordinates are listed in decimal parts of a degree. This facilitates both computer manipulation of data and rapid estimation of distances between points (one degree of latitude being equal to 111 km). To retain some indication of the accuracy of original locations, when converting from minutes and seconds we have listed 3 digits to the right of the decimal point only where seconds were originally specified. We list 2 digits if only degrees and minutes were given in the original (e.g., 71°41' = 71.68° whereas 71°41' 01" = 71.684°). Readers should also beware of obviously generalized locations such as X.00° or Y.50°. When different references give different positions for the same volcano, we attempt to determine which is most reliable, and list that location here. For some regions, where our growing archive of topographic maps permits, we have obtained more precise locations than given in older sources. Newly obtained maps for the Kurils and Kamchatka, for example, have permitted correction of deliberately mislocated volcano positions that were a cold war artifact. Note that some locations are the center point of broad volcanic fields (indicated by an asterisk), and that even at individual volcanoes the coordinates given do not necessarily match the eruption site. Tens of kilometers may separate eruptive centers of a single volcano, particularly in large caldera complexes and rift settings.
Distribution of the world's volcanoes with respect to latitude has gained wide interest because of the relationship between large volcanic eruptions and climate. Major explosive eruptions drive volcanic ash and gas tens of kilometers into the stratosphere where, because fine ash and aerosol particles settle slowly and are not washed out by rain, they may be distributed around the globe by stratospheric circulation. For months or years before settling back to Earth, then, this layer of volcanic aerosol acts as a solar radiation filter, lowering temperatures on the Earth below it. The extent to which this process has affected global climate in the past is a matter of considerable scientific debate, but the fact that individual eruptions can affect climate is established (the catastrophic eruption of Indonesia's Tambora in 1815, for example, contributed to a lowering of global temperatures that brought June snow-storms to New England and widespread crop failure to northern latitudes). The Earth's rotation strongly influences stratospheric circulation patterns and therefore any concentration of the world's volcanoes by latitude is important in assessing their effect on global climate.
Two thirds of the volcanoes are in the northern hemisphere and only about one fifth are between 10°S and the South Pole. The northern hemisphere concentration reflects the fact that two-thirds of the world's land area is also north of the equator, but nevertheless indicates the greater vulnerability of the northern hemisphere to volcanically induced climate change.
The most northerly volcano in our list is an unnamed submarine volcano in the Arctic Ocean only 192 km from the North Pole. Three eruptions have been attributed to this site. The next most northerly volcano, on Jan Mayen island and 2104 km from the pole, has been recently quite active with vigorous eruptions in 1970 and early 1985.
The southernmost historically active volcano is Mount Erebus, 1387 km from the South Pole on Ross Island, Antarctica. This volcano was erupting violently when first seen by Ross, in 1841, and is active today with a molten lava lake that has been circulating in its summit crater since at least 1972. The many young cinder cones of the Royal Society Range, 80 km closer to the pole are probably Holocene, and local ash layers have been found in glaciers, but no eruptions have been dated.
No significant concentration of volcanoes by longitude is obvious, but over 1000 volcanoes (or two-thirds of those listed) lie around the Pacific Ocean margin forming the well known "Ring of Fire." Linear belts of volcanoes are a striking feature of the planet and they reflect, in most cases, convergence of the major tectonic plates that make up the Earth's outer shell.
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Plate Tectonics: schematic cross-section illustrating processes (Simkin et al., 1994). Artist José F. Vigil. |
These vast plates, moving at speeds of only a few centimeters per year, form a shifting jig-saw puzzle with the major earthquake and volcano belts marking the unrest at plate boundaries. Where plates converge, with the thinner plate normally being thrust down under the thicker, a line of volcanoes grows above (and as a result of) the under-thrusting. Because this type of volcanism is normally both explosive and near (if not on) land, we have a reasonably complete listing of these volcanoes (approximately two-thirds of this file). The spreading apart of major plates, however, is characterized by the relatively nonexplosive outpouring of fluid lava and commonly takes place one or more kilometers below the surface of the ocean. Consequently we have a very incomplete record of this important type of volcanism. Rift volcanism forms only 5% of our eruption file and is dominated by those few regions, such as East Africa and Iceland, where the spreading apart of plates takes place above sea level. The remainder of our file--less than a tenth of the total--represents volcanism within major plates rather than at their boundaries. This takes place when deep "hot spots" penetrate the overlying crust and old volcanic products are carried slowly away from the volcanic center by the moving plate. Although our record of intraplate volcanism is probably better than that for the volcanism of spreading ocean ridges, we no doubt miss many examples, particularly from the sea floor.
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Pie diagrams contrasting the volcanism that we see with that we don't (Simkin and Siebert, 1994). Left diagram shows proportion of documented historical eruptions from subduction zones (black), mid-ocean ridges (stipple), and hotspot settings (white). Right diagram shows proportion of annual magma budget in the same settings (with same symbols). |
Elevation of each volcano's highest point is listed in meters above or below sea level. Elevation for the same volcano may differ because of different surveying techniques or because of volcanological changes (e.g. the 400 m change in Mount St. Helens' summit height in 1980). As with latitude and longitude, when separate values for the same feature appear in different references we display here the one that seems to be most reliable. When unable to resolve a difference any other way, we normally display the more recent figure. Most elevations, both in the CAVW and original references, are given in meters, but when we have had to convert from other units we have attempted to retain a measure of the original's accuracy by rounding the conversion to the same number of significant figures as in the original. Thus a 2,600 ft elevation, apparently rounded to the nearest 100 ft, is listed here as 790 m rather than the 792 m figure that is the exact metric equivalent (but implies more accuracy than in the original measurement).
Less than 4% of the listed volcanoes, most of them submarine, have elevations unknown to us. Submarine volcano elevations (or depths) are particularly unreliable because changes are often rapid, dramatic, and unrecorded. We normally list the most recent elevation when several are given, but caution should be used with all submarine volcano elevations.
Roughly 30% of the volcanoes in our list are within 1,000 m of sea level, roughly 60% are within 2,000 m and about four-fifths are within 3,000 m of sea level. Less than 100 volcanoes have elevations above 5,000 m (16,400 ft): most of these are in the South American Andes and nearly two-thirds of the total are in that chain's central segment (15-28°S).
The highest volcano with historical eruptions is Llullaillaco (volcano number 1505-11=) in the northern Chilean Andes. Its elevation is 6,739 m and three eruptions were recorded there in the second half of the last century. Active fumaroles, however, mark the summit crater of Nevado Ojos del Salado, 267 km to the south of, and 148 m higher than, Llullaillaco. The youthful nature of Nevado Ojos del Salado suggests that its lack of historical eruptions stems only from its remote location, and it is rightfully the world's highest volcano. The only higher mountain in the Americas, Argentina's Aconcagua at 7,021 m, was listed as active by Darwin during the voyage of the Beagle, but Chilean colleagues tell us that the mountain is not a volcano and its height results from imbricate thrust faulting.
The deepest submarine volcano in our list has less significance because the record is so poor. Seawater not only hides eruptions from view, but its weight also provides enormous pressure on the deep-sea floor, inhibiting (and often prohibiting) the explosive release of volcanic gases that frequently calls attention to shallow submarine eruptions. A few historical reports, however, give some credence to explosive volcanism on the deep-sea floor: 1955 activity at 4000 m near Hawaii (1302-10=), 1865 activity at 4200 m west of the Azores (1801-04=), uncertain 1852 activity at 5300 m in the central mid-Atlantic (1805-04=), and an 1850 event at about 6000 m depth off Taiwan. Non-explosive volcanism regularly takes place at great depths on the ocean floor, as shown by photography of fresh volcanic features at depths of ~ 5 km in the Cayman Trough, Caribbean Sea, but our record of it is exceedingly scanty.
Volcanoes come in a variety of shapes and sizes. Under the heading of type, we have attempted to characterize the morphology of each volcano. An individual volcano may be composed of a variety of landforms, such as when a stratovolcano is truncated by a caldera that is itself filled by lava domes and pyroclastic cones--but we show only the most prominent feature here. We have followed the CAVW entry in most cases, although little attempt has been made to standardize usage. Profiles are illustrated here, but the reader should consult a volcanological textbook for further description (and recognize that different volcanologists have used different terms for the same features). Interest in the landforms of other planets has prompted a more quantitative approach to the morphology of Earth's volcanoes. Lacking a standardized nomenclature, however, we have generally listed the volcano types as given in the various sources used in our compilation.
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Types of volcanoes (Simkin and Siebert, 1994). Schematic profiles are vertically exaggerated by 2:1 (shaded) and 4:1 (dark) from the data of Pike (1978). Relative sizes are only approximate, as dimensions vary within each group. |
This element states, essentially, the most persuasive reason for including each volcano in this compilation. A "historical" eruption, documented during or shortly after observation, is the best evidence for inclusion. We list more than 540 volcanoes with historical eruptions, the criterion used by many people terming a volcano "active." However, we have tried to provide more even coverage of the globe's volcanoes, many of which carry no written record until 80 centuries after the first historically documented eruption in our file (Central Turkey, in 6200 BC). To do this we have included 183 volcanoes with dated eruptions during the last 10,000 years, as determined by techniques, such as "Radiocarbon" dating. For volcanoes with different eruptions dated by different techniques, we have entered under Status the technique that seemed to confirm Holocene activity most certainly. We should mention, however, that the "Anthropology" status covers volcanoes with undated (but recent) activity described in native legends as well as activity dated by buried artifacts.
The remaining Status categories cover the many volcanoes (about half of our file) for which Holocene eruptions have not been dated, but are either likely or possible. These status categories will be discussed in order of decreasing certainty.
First in certainty for undated eruptions comes the variety of general evidence lumped together under "Holocene" status. These locations, although without dated products, are virtually certain to have been active in postglacial time. Evidence includes: (1) volcanic products overlying latest Pleistocene glacial debris, (2) youthful volcanic landforms in areas where erosion should have been pronounced in many thousands of years, and (3) vegetation patterns that would have been far richer if the volcanic substrates were more than a few thousand (or hundred) years old. We have included in this category volcanoes mapped by original authors simply as "Holocene" or "postglacial." Some subjectivity is involved in this assignment, and the compiler is dependent upon the field experience of the original author. Many early investigators, unaware of slow erosion rates in arid regions, described lava flows as "extremely fresh, probably erupted within the last few hundred or few thousand years," but later radiometric dating has shown them to be Pleistocene or even older. We have generally required strong evidence for entry under this category, but more than 500 volcanoes bear "Holocene" status in our file, and roughly another 100 (with distinctly less certainty) are identified as "Holocene?" (marked with a query symbol).
Many volcanoes with obviously recent, but undated, eruptions are still visibly hot, as evidenced by surface thermal features displayed in the Status category. "Fumarolic" locations are those characterized by steam and volcanic gas, or fume, reaching the surface. Temperatures are near the boiling point of water and a substantial supply of groundwater is necessary. Previously we used the word "Solfataric" for Status when sulfur dominated the volcanic gases, but we have since encountered inconsistencies with this usage and have combined it with "Fumarolic" here. When the volume of water is large compared to steam and gas, however, the words "Hot springs" are used. A "Fumarolic" or "Hot springs" status is assigned, however, only where we have seen no explicit evidence for Holocene eruptive activity.
Our least certain Status category, "Uncertain", is used for volcanoes with possible Holocene activity, but with sufficiently questionable documentation that we wanted to draw attention to that uncertainty. These entries include mariner's equivocal reports of submarine volcanism and volcanoes known only by uncertain reports of historical activity (with no other evidence of Holocene eruptions).
Finally, we should comment on the "youthful" volcanoes that we have not included in the file. A volcano mapped as "Quaternary" would not be entered unless more specific Holocene age data were available. When a group of volcanoes is listed in a region of "Pleistocene-Holocene volcanism", we have entered only those for which Holocene evidence is available. Volcanoes listed as Holocene, or "active", in previous compilations, but later found to be Pleistocene or older, have also been excluded, as have a few "volcanoes", well established in the literature, but later found to be misidentifications.
In summary, the Status category conveys the following hierarchical progression from high to low certainty of Holocene volcanism: (1) "Historical," (2) dated eruptions based on a spectrum of techniques from "Hydrophonic" through "Radiocarbon" to "Anthropology", which is transitional to (3) "Holocene," (4) thermal features such as "Fumarolic", and (5) "Uncertain." Any entry can (and probably does) carry evidence to be found under lower levels of this hierarchy, but we have entered the highest Status category indicated by the data known to us. Furthermore, the Status listed is that of the most recent eruptive activity. A major Pleistocene center with only a single Holocene flank vent, for example, would have a "Holocene" status.
D1 = Last known eruption 2000 or later
D2 = Last known eruption 1900-1999
D3 = Last known eruption 1800-1899
D4 = Last known eruption 1700-1799
D5 = Last known eruption 1500-1699
D6 = Last known eruption A.D. 1-1499
D7 = Last known eruption B.C. (Holocene)
U = Undated, but probable Holocene eruption
? = Uncertain Holocene eruption
This code enables mapmakers to identify volcanoes in groups of increasing recency (and certainty) of eruptions. For example, for all volcanoes that have erupted in this century, choose D1, and for all with eruptions since 1 A.D. choose D1 through D6. Remember, however, that many volcanoes designated by a U (Undated) in regions with a short historical record have had unrecorded eruptions in the past few thousand years (perhaps even few hundred years). Volcanoes designated by D6 or D7 include: (1) volcanoes with reasonably complete records yet no known eruptions for hundreds or thousands of years; and (2) poorly studied volcanoes with undocumented younger eruptions.
One of the most difficult problems of standardization has been the varying usage of the word "volcano." Definitions of "volcano" range from individual vents, measured in meters, through volcanic edifices measured in kilometers or tens of kilometers, to volcanic fields measured in hundreds of kilometers. In a compilation such as this one, the disadvantage of the narrowest definition is not so much the multiplicity of names introduced, as the dismembering of a single volcanic plumbing system's history into apparently unrelated separate records. The interiors of ancient volcanoes, now eroded and exposed for geologic study, show us that most subsurface magma chambers--the suppliers of lavas to overlying volcanoes--are at least several kilometers in diameter. We also know that many contemporary volcanoes grow by additions from countless flank vents as well as activity at a central crater. Consequently, we have tended to group closely spaced "volcanoes" such as the historical vents of the Canary Islands (many listed as separate volcanoes in the CAVW) by the major volcanic edifice on which they are found. Volcanoes listed here are rarely closer than 10 km to their nearest neighbor, and are commonly separated by at least 20 km.
Another problem is simply the identification of volcanoes. Prominent, steaming cones are easy to recognize, but water, ice, erosion, collapse processes, or dense vegetation can mask very dangerous volcanoes. For example, Lake Taupo, in the center of New Zealand's North Island, is beautifully tranquil, with no obvious features alerting non-geologists to its particularly violent history. In the Alaskan summer of 1975, two volcanologists traced an ever-thickening ash layer to a vent now covered by the Hayes Glacier, and a "new" volcano was added to the NE end of the Aleutian arc. Also in Alaska, 5 decades passed before the true source of this century's largest eruption was recognized: Subsurface magma connections led to prominent collapse of Mount Katmai in 1912, and this was assumed to be the eruption's source until careful fieldwork showed it to be Katmai's inconspicuous neighbor, Novarupta. These examples illustrate why the listings below must be recognized as incomplete. Inclusion in this compilation may depend on thoroughness of mapping--quite variable through the world's volcanic regions--and the most dangerous volcanoes may be those not yet recognized by compilers.
The Catalog of Active Volcanoes of the World is a regional series of publications by the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI). The first (Indonesia) was published in 1951, and the current set of 22 volumes has been an invaluable reference source for all volcanologists as well as the initial source of information for our data file. Volumes for Alaska and Iceland will soon complete the first editions of the CAVW. Although seriously dated, the catalogs remain an valuable source for maps, photographs, early bibliographies, and the petrochemistry of eruptive products.
The Pleistocene/Holocene boundary was defined as 10,000 years BP (before present) at the 1969 INQUA Congress. More recent work with precise tree-ring chronologies has confirmed the 14C 10,000-year boundary and we use it as the time period covered by our data file.
This group includes locations for which equally reliable sources disagree over the existence of Holocene volcanism. Also included are those for which uncertainty is expressed by the original author (e.g., "perhaps Holocene age"), and line straddlers (e.g., "late Pleistocene or early Holocene").
N.H. Fisher, in the introduction to his 1957 CAVW Melanesia catalog, described difficulty in distinguishing between "fumarolic" and "solfataric" on the basis of temperature or gases, but felt that the former indicated a higher degree of activity and closer association with magma. Other workers have noted strong fluctuation in sulfur production through time. We believe that usage has been too inconsistent to merit retaining the two terms. "Solfatara" is the name of a tuff ring at Campi Flegrei that erupted in 1198.
Three deep-sea sites with this status were included in an earlier compilation. These sea-floor springs, which reached temperatures of 350°C, were on oceanic rift zones at the divergence of lithospheric plates. As marine exploration has continued, however, these hot springs are found to be common, and we now restrict our inclusion of deep-sea centers to those with dated eruptive activity.
For this sum we have excluded from the circum-Pacific area the Sunda Arc (subregions 0601-0604) resulting from subduction of Indian Ocean crust NE under the Eurasian Plate. Also excluded are inland subregions (0705, 1001-1007, 1104, 1204-1210) and oceanic groups lying within the marginal "ring" (1503, 1506, and all of region 13).
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Ballard, R.D., 1976. Window on Earth's interior. National Geographic, v. 150, p. 228-249.
Pike, R.J., 1978. Volcanoes on the inner planets: some preliminary comparisons of gross topography. Proc. 9th Lunar Planet. Sci Conf., p. 3239-3273.
Miller, T.P., and Smith, R.L., 1976. "New" volcanoes in the Aleutian arc. U.S. Geological Survey Circular 733, p. 11.
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