Pumice eruptions of the lesser Antilles

Stratigraphic studies on the active and potentially active volcanoes of the Lesser Antilles have revealed two main types of andesitic pyroclastic deposit. One with dense clasts in a poorly vesicular ash represents nuée ardente eruptions of Pelean type and the other group of vesicular pumice and ash represent both Plinian airfall and ash-pumice flow eruptions. The pumiceous deposits can be divided into airfall lapilli, airfall ash, crystal-pumice surge, ashpumice flow and ash hurricane types. No pumice eruptions have been witnessed in the Lesser Antilles during the period of written history although the stratigraphy of archaeological sites shows they occurred in pre-Columbian times. Detailed stratigraphic studies of Mt. Pelée, Martinique, and the Quill, St. Eustatius, show that, throughout their history, pumice eruptions have alternated with nuée ardente eruptions with approximately equal frequency. The widespread occurrence of pumiceous deposits on many of the West Indian volcanoes and the frequent alternations in the stratigraphic sections suggest the high probability that they will be witnessed in the future. On Martinique, some on the late prehistoric pumiceous pyroclastic flow deposits (the ash hurricanes) have been traced 20 km from the central vent to the out-skirts of Fort de France, indicating that they are the major hazard in the Lesser Antilles. Measured stratigraphic sections show that the Pelean type nuée ardente deposits are separated from the pumiceous pyroclastic deposits by others of intermediate vesicularity and appearance. The presence of such deposits of intermediate vesicularity could provide a future warning of impending change in pyroclastic style. As no such deposits formed on Mt. Pelée this century the present «safer» episode of nuée ardente (Pelean type) activity is expected to continue.     

Erosion and aggradation on persistently active volcanoes—a case study from Semeru Volcano,Indonesia

Erosion processes on active volcanoes in humid climates result in some of the highest sediment yields on Earth. Episodic sediment yields after large eruptions have been evaluated, but not the long-term and continuous patterns on persistently active volcanoes. We have used high-spatial resolution satellite imagery and DEMs/DSMs along with field-based geologic mapping to assess accurately sediment budgets for the active Semeru Volcano in Java, Indonesia. Patterns of aggradation and degradation on Semeru differ from that of other active volcanoes because (1) both episodic pyroclastic density currents (PDC) and continuous supplies of tephra generate pulses of sediment, (2) sediment is transferred via cycles of aggradation and degradation that continue for >15 years in river channels after each PDC-producing eruption, and (3) rain-triggered lahars remove much greater material than fluvial transport during long, intense rainfall events. The geomorphic response of two of Semeru’s rivers to volcanic sediment migration indicates that (1) each river experiences alternating aggradation and degradation cycles following PDC-producing eruptions and (2) spatial patterns of sediment transfer are governed by geomorphic characteristics of the river reaches. Usually high degradation in the steep source reach is followed by a long bypassing middle reach. Aggradation predominates in the depositional reaches further down valley on the ring plain. Average sediment yields (10³–10⁵ t/km²/year) at persistently active volcanoes are two to three orders of magnitude lower than sediment yields after large and infrequent eruptions, but the continuous and steady sediment transfer in rivers removes more sediment on a mid-term (10 years) to long-term (30 years) basis. In contrast to the trend observed on composite cones after large and infrequent eruptions, decay of sediment yields is not exponential and river channels do not fully recover at steadily active volcanoes as episodic inputs from BAF eruptions, superimposed on the background remobilization of daily tephra, have a greater cumulative effect.     

On precursor of Kamchatkan volcanoes eruptions based on data from satellite monitoring

Kamchatka is one of the most active volcanic regions on the planet. Large explosive volcanic eruptions, in which the ash elevates up to 8?C15 km above sea level, occur here every 1.5 years. Study of eruptions precursors in order to reduce a volcanic risk for the population is an urgent problem of Volcanology. The available precursor of strong explosive eruptions of volcanoes, identified from satellite data (thermal anomaly), as well as examples of successful prediction of eruptions using this precursor, are represented in this paper.     

Glass compositions and tempo of post-17 ka eruptions from the Afar Triangle recorded in sediments from lakes Ashenge and Hayk,Ethiopia

Numerous volcanoes in the Afar Triangle and adjacent Ethiopian Rift Valley have erupted during the Quaternary, depositing volcanic ash (tephra) horizons that have provided crucial chronology for archaeological sites in eastern Africa. However, late Pleistocene and Holocene tephras have hitherto been largely unstudied and the more recent volcanic history of Ethiopia remains poorly constrained. Here, we use sediments from lakes Ashenge and Hayk (Ethiopian Highlands) to construct the first <17 cal ka BP tephrostratigraphy for the Afar Triangle. The tephra record reveals 21 visible and crypto-tephra layers, and our new database of major and trace element glass compositions will aid the future identification of these tephra layers from proximal to distal locations. Tephra compositions include comendites, pantellerites and minor peraluminous and metaluminous rhyolites. Variable and distinct glass compositions of the tephra layers indicate they may have been erupted from as many as seven volcanoes, most likely located in the Afar Triangle. Between 15.3−1.6 cal. ka BP, explosive eruptions occurred at a return period of <1000 years. The majority of tephras are dated at 7.5−1.6 cal. ka BP, possibly reflecting a peak in regional volcanic activity. These findings demonstrate the potential and necessity for further study to construct a comprehensive tephra framework. Such tephrostratigraphic work will support the understanding of volcanic hazards in this rapidly developing region.     

Reprint of Glass compositions and tempo of post-17 ka eruptions from the Afar Triangle recorded in sediments from lakes Ashenge and Hayk,Ethiopia

Numerous volcanoes in the Afar Triangle and adjacent Ethiopian Rift Valley have erupted during the Quaternary, depositing volcanic ash (tephra) horizons that have provided crucial chronology for archaeological sites in eastern Africa. However, late Pleistocene and Holocene tephras have hitherto been largely unstudied and the more recent volcanic history of Ethiopia remains poorly constrained. Here, we use sediments from lakes Ashenge and Hayk (Ethiopian Highlands) to construct the first <17 cal ka BP tephrostratigraphy for the Afar Triangle. The tephra record reveals 21 visible and crypto-tephra layers, and our new database of major and trace element glass compositions will aid the future identification of these tephra layers from proximal to distal locations. Tephra compositions include comendites, pantellerites and minor peraluminous and metaluminous rhyolites. Variable and distinct glass compositions of the tephra layers indicate they may have been erupted from as many as seven volcanoes, most likely located in the Afar Triangle. Between 15.3−1.6 cal. ka BP, explosive eruptions occurred at a return period of <1000 years. The majority of tephras are dated at 7.5−1.6 cal. ka BP, possibly reflecting a peak in regional volcanic activity. These findings demonstrate the potential and necessity for further study to construct a comprehensive tephra framework. Such tephrostratigraphic work will support the understanding of volcanic hazards in this rapidly developing region.     

Agrigan: An introduction to the geology of an active volcano in the Northern Mariana Island arc

Agrigan is the tallest (965 m a.s.l.) and largest (44 km²) of the volcanoes of the northern Mariana Islands. Its slopes are asymmetric to the east; a small caldera (4 km²) dominates the interior. The volcanic edifice has been disrupted along three sets of faults: 1) exterior slump faults, 2) radial faults, and 3) interior faults related to caldera-collapse. The rocks of the volcano are characterized by porphyritic clinopyroxene-olivine-plagioclase basalts and subordinate andesites. Cumulate xenoliths composed of Fo₈₁, An₉₅ and diopside are common in the basalts. Development of the volcano began with 3–4 km of submarine growth. The earliest recognizable flows are the result of fissural Hawaiian- and Strombolian-type eruptions. These were followed by the eruption of more viscous lavas from above the present summit. Flank eruptions of basalt and andesite preceded voluminous outpourings of andesitic pyroclastics contemporaneous with caldera-collapse. Subsequent magmatic resurgence is localized along a N10E rift zone. Violent ejection of lapilli and ash occurred in 1917.     

A comparison of the recent eruptions of Mt. Pelée,Martinique and Soufrière,St. Vincent

The simultaneous eruption of Mt. Pelée, Martinique and Soufrière, St. Vincent are regarded as the first recognized examples of Pelean-type and St. Vincent-type pyroclastic eruptions. Both produced nuées ardentes, the former usually laterally directed because of the presence of a dome and the latter vertically directed from an open crater. Both volcanoes have subsequently erupted for a second time this century. The 1902–05 and 1929–32 eruptions of Mt. Pelée produced andesite lava of almost identical composition and mineralogy. Both contain two generations of plagioclase, orthopyroxene, Fe-Ti oxide, corroded brown amphibole and olivine rimmed by pyroxene. In contrast, the Soufrière material is more basic in composition varying from basaltic andesite to basalt in 1902–03 and basaltic andesite in 1971–72. The Soufrière material contains two generations of plagioclase (with those of 1971–72 having additional zones of labradorite), clinopyroxene, orthopyroxene, olivine and Fe-Ti oxide. The pyroclastic deposits are strikingly different, those from the Pelean-type eruption are termed «block and ash deposits» being characterised by poorly vesicular lava blocks up to 7 m in diameter, while the St. Vincent-type eruption produced «scoria and ash deposits» containing vesicular ropey blocks or bombs no larger than 1 m in diameter. The differences in styles of eruption are attributed to differences in viscosity and mechanism of eruption of the magmas. Stratigraphic studies of Mt. Pelée reveal that the volcano has produced basaltic andesite scoria and ash deposits from St. Vincent-type eruptions. It is concluded that the recent eruptions of Pelée tapped a deep level magma during both eruptions releasing magma of similar composition, while the 1971 Soufrière magma is thought to be a remnant of the 1903 basaltic magma which remained at a high level within the volcano where it underwent enrichment in plagioclase and loss of olivine and oxide.     

The impact of moderate-scale explosive eruptions on stratospheric gas injections

Volcanic gases such as SO ₂, H ₂S, HCl and COS emitted during explosive eruptions significantly affect atmospheric chemistry and therefore the Earth's climate. We have evaluated the dependence of volcanic gas emission into the atmosphere on altitude, latitude, and tectonic setting of volcanoes and on the season in which eruptions occurred. These parameters markedly influence final stratospheric gas loading. The latitudes and altitudes of 360 active volcanoes were compared to the height of the tropopause to calculate the potential quantity of volcanic gases injected into the stratosphere. We calculated a possible stratospheric gas loading based on different volcanic plume heights (6, 10, and 15 km) generated by moderate-scale explosive eruptions to show the importance of the actual plume height and volcano location. At a plume height of 15 km for moderate-scale explosive eruptions, a volcano at sea level can cause stratospheric gas loading because the maximum distance to the tropopause is 15–16 km in the equatorial region (0–30°). Eruptions in the tropics have to be more powerful to inject gas into the stratosphere than eruptions at high latitudes because the tropopause rises from ca. 9–11 km at the poles to 15–16 km in the equatorial region (0–30°N and S). The equatorial region is important for stratospheric gas injection because it is the area with the highest frequency of eruptions. Gas injected into the stratosphere in equatorial areas may spread globally into both hemispheres.     

Explosive felsic volcanism on El Hierro (Canary Islands)

The Canary Islands consist of seven basaltic shield volcanoes whose submerged portion is much more voluminous than the subaerial part of each island. Like so many other volcanic oceanic islands, the indicative deposits of explosive felsic volcanism are not a common feature on the Canary archipelago. Hitherto, they have only been documented from the central islands of Gran Canaria and Tenerife, which are the largest volcanic complexes of the islands. On the other Canary Islands, the presence of felsic rocks is mostly restricted to intrusions and a few lava flows, generally within the succession in the oldest parts of individual islands. In this paper, we present a detailed stratigraphic, lithological and sedimentological study of a significant felsic pumice deposit on the island of El Hierro, referred here as the Malpaso Member, which represents the only explosive episode of felsic volcanism found on the Canary Islands (outside of Gran Canaria and Tenerife). The products of the eruption indicate a single eruptive event and cover an area of about 15 km². This work provides a detailed stratigraphic and chronological framework for El Hierro, and four subunits are identified within the member on the basis of lithological and granulometric characteristics. The results of this study demonstrate the importance of an explosive eruption in a setting where the activity is typified by effusive basaltic events. Given the style and the spatial distribution of the Malpaso eruption and its products, a future event with similar characteristics could have a serious impact on the population, infrastructure and economy of the island of El Hierro.     

Tyatya Volcano, southwestern Kuril arc: Recent eruptive activity inferred from widespread tephra

Abstract Tyatya Volcano, situated in Kunashir Island at the southwestern end of Kuril Islands, is a large composite stratovolcano and one of the most active volcanoes in the Kuril arc. The volcanic edifice can be divided into the old and the young ones, which are composed of rocks of distinct magma types, low‐ and medium‐K series, respectively. The young volcano has a summit caldera with a central cone. Recent eruptions have occurred at the central cone and at the flank vents of the young volcano. We found several distal ash layers at the volcano and identified their ages and sources, that is, tephras of ad 1856, ad 1739, ad 1694 and ca 1 Ka derived from three volcanoes of Hokkaido, Japan, and caad 969 from Baitoushan Volcano of China/North Korea. These could provide good time markers to reveal the eruptive history of the central cone, which had continued intermittently with Strombolian eruptions and lava flow effusions since before 1 Ka. Relatively explosive eruptions have occurred three times at the cone during the past 1000 years. We revealed that, topographically, the youngest lava flows from the cone are covered not by the tephra of ad 1739 but by that of ad 1856. This evidence, together with a report of dense smoke rising from the summit in ad 1812, suggests that the latest major eruption with lava effusion from the central cone occurred in this year. In 1973, after a long period of dormancy, short‐lived phreatomagmatic eruptions began to occur from fissure vents at the northern flank of the young volcano. This was followed by large eruptions of Strombolian to sub‐Plinian types occurring from several craters at the southern flank. The 1973 activity is evaluated as Volcanic Explosivity Index = 4 (approximately 0.2 km³), the largest eruption during the 20th century in the southwestern Kuril arc. The rocks of the central cone are strongly porphyritic basalt and basaltic andesite, whereas the 1973 scoria is aphyric basalt, suggesting that magma feeding systems are definitely different between the summit and flank eruptions.     

Volcan ceboruco: A major composite volcano of the mexican volcanic belt

Ceboruco is a major composite volcano at the western end of the Mexican Volcanic Belt, near the junction between the North American and Pacific plates. The volcano is built from successive eruptions of andesite lavas and pyroclastic rocks, and major eruptions during its history have resulted in the formation of two concentric calderas. The youngest volcanic activity has included the extrusion of dacites within the inner caldera and a voluminous flank eruption of andesite during 1870–72. Fumarolic activity persists to the present day. Chemical analyses show that the lavas are of cale-alkaline type and rangs from andesite (SiO₂=58–61%) to acid dacite (SiO₂=68%) in composition. The rate of increase of K₂O relative to SiO is greater than that in volcanic rocks from the Mexican Volcanic Belt as a whole. This indicates that simple models based on the application of such relationships may not be adequate to explain the petrogenesis of calc-alkaline lavas.     

Neutron activation analysis of the 1965 taal volcanic ash

Neutron activation analysis of the Taal volcanic ash revealed the presence of unusual amount of scandium in the volcanic ash as compared to the standard basalt BCR-1. The BCR-1 value for Fe/Sc is 2760 while that of Taal ash is about 2649. It is suggested that the eruption was probably characterized by the ejection of scandium-rich materials. Scandium may be used as supplementary evidence in evaluating an impending future Taal volcanic activity.     

Geochemistry and petrogenesis of the kilimanjaro volcanic rocks of the Amboseli area,Kenya

The paper summarizes the geochemical and petrogenetic aspects of an investigation of late Tertiary to Recent volcanic rocks in the Amboseli area of southern Kenya. A study of chemical variations in the Amboseli and Kilimanjaro lavas distinguishes a mildly alkaline series (alkali olivine basalts, trachybasalts/trachyandesites, trachytes, rhomb porphyries and phonolites) from a strongly alkaline series embracing subordinate nephelinitic, phonolitic and tephritic lavas. The two series probably evolved independently from a source in the mantle. A comparison of Kilimanjaro with other East African volcanoes shows that the focus of strongly alkaline volcanicity moved from eastern Uganda and western Kenya to northern Tanzania at the end of Miocene times. The Pliocene to Recent centres near the Kenya-Tanzania border show evidence of decreasing alkalinity from a western zone of nephelinite-phonolite volcanoes to an eastern region in which central volcanoes are characterized by the association of strongly and mildly alkaline suites.     

Seismic energy releases from volcanoes

Seismic energy release during the precursory, eruptive and declining stages of volcanic activities provides various information about the mechanisms of volcanic eruptions and the temporary developments of their activities. Hitherto the energy release patterns from precursory earthquake swarms were used to predict the eruption times, especially of andesitic or dacitic volcanoes. In this paper the discussion is expanded to quantify the total amount of seismic energy released at the threshold of volcanic eruptions, with reference to the results observed at several volcanoes. The results generally indicate that the cumulative seismic energy release from the precursory earthquake swarms exceed 10¹⁷¹⁸ergs before eruptions at any andesitic or dacitic volvanoes. This allows the seismic efficiency, or the ratio of energy radiated seismically, and the energy required for the volumetric expansion to be estimated by incorporating available deformation data with the seismic data. The dependency of seismic efficiency on the type of volcanic activity, i. e. non-explosive outbreaks, phreatic and magmatic eruptions, dome formation, etc., was evaluated from observations at a few volcanoes that provided a variety of examples.     

2017年全球活动火山时空分布以及阿贡火山喷发前后的形变特征

归纳总结2017年度全球81座活火山的活动情况,共计活动1058座次,平均每周记录20座活火山的活动信息。根据火山潜在喷发的危险性和火山活动的强弱程度对上述火山进行分级描述,火山活动主要反映了地球表层的构造活动,其中大角度俯冲带的弧后火山最为强烈,小角度的俯冲带、拉张裂谷和走滑为主的板块边界火山活动较为平静,火山活动频繁的印度尼西亚岛链是受灾最为严重的区域。预计全球火山活动将进一步加剧,印尼岛链受火山灾害威胁的程度依然较大。位于印尼岛链巴厘岛上的阿贡火山自2017年9月开始活动以来,整个喷发过程极具代表性,监测阿贡火山喷发过程可为全球典型火山喷发事件研究提供参考。     

Geology and tectonic setting of the Mule Creek caldera,New Mexico,U.S.A.

The 10-km diameter Mule Creek caldera is the youngest felsic eruptive center in the Mogollon-Datil volcanic field of southwestern New Mexico. The caldera forms a topographic basin surrounded by a raised rim. The caldera wall is well displayed on the south and west sides of the structure where it dips 20–30 degrees toward the center of the basin. Mudflow breccia fills the caldera and is banked up against the caldera wall. Post-caldera porphyritic quartz latite domes and flows crop out along the ring-fracture zone. The caldera is superimposed upon an older volcanic complex of flow-banded rhyolite and porphyritic andesite lava. The Mule Creek caldera probably originated by explosive eruption of about 10 km³ of pumice and ash, in part preserved in the matrix of the mudflow breccia. Periods of explosive volcanism during the deposition of mudflow breccia are documented by tuffaceous beds interbedded with the breccia. A thin rhyolite ash-flow sheet originated in the caldera and overlies the mudflow breccia. The youngest felsic rocks around the caldera are (1) domes and flows of crystal-rich porphyritic quartz latite of variable mineralogy, interpreted as a defluidized magma, and (2) widespread crystal-poor, flow-banded rhyolite, dated at 18.6 m.y., which is not directly related to the caldera sequence. The Mule Creek caldera and other volcanic features farther south represent the only documented overlap of felsic volcanism with early stages of Basin-Range tectonism in the Mogollon-Datil field.     

Fractal analysis of experimentally generated pyroclasts: A tool for volcanic hazard assessment

Rapid decompression experiments on natural volcanic rocks mimick explosive eruptions. Fragment size distributions (FSD) of such experimentally generated pyroclasts are investigated using fractal geometry. The fractal dimension of fragmentation, D, of FSD is measured for samples from Unzen (Japan) and Popocatépetl (Mexico) volcanoes.Results show that: (i) FSD are fractal and can be quantified by measuring D values; (ii) D increases linearly with potential energy for fragmentation (PEF) and, thus, with increasing applied pressure; (iii) the rate of increase of D with PEF depends on open porosity: the higher the open porosity, the lower the increase of D with PEF; (iv) at comparable open porosity, samples display a similar behavior for any rock composition.The method proposed here has the potential to become a standard routine to estimate eruptive energy of past and recent eruptions using values of D and open porosity, providing an important step towards volcanic hazard assessment.     

Notes on the 1965 Taal Volcanic eruptions

Neutron activation analyses were performed on samples of olivine-bearing basalt, of volcanic bomb, of volcanic ashes, of residues of water from the old crater lake, of residues of bubbling waters taken near the cinder cone, and of residue of rainwater collected at Parc, Diliman, Quezon City, all of which were volcanic products of the 1965 Taal eruption. The analysis was performed to determine the approximate ratios of important minor and trace elements in the volcanic products, in order to better understand the geochemical processes involved in the 1965 eruption of the Taal Volcano. The radionuclides of Cu, Fe, Na and Mn were positively identified in all the volcanic samples that were irradiated. Scandium was present only in the ash samples. The aproximate Cu/Na ratios for the volcanic ashes, volcanic bomb, and basalt are similar; they ranged from 0.171 to 0.200. The Cu/Na values obtained for the water samples varied from 0.253 to 2.010. The results of fast neutron activation show that the Si, Al, Fe, Mg, and O percentages of the different ash layers are similar. Based on the present work and upon past analyses, it is suggested that the solidification index for Taal is about 10. The eruptivity of Taal Volcano seems to be related to the rift in the crust, rate of migration of the magmatic volatiles, and pressure of the volatile fraction in the magma reservoir. All these factors are probably operating jointly and effectively, making it possible for the Taal Volcano to possess strongly predictable eruptivity, in the light of its past eruption history and its periodic cycle of eruption. It is suggested that the Taal and the Mayon Volcanoes are related from a regional and structural point of view. This observation is reflected in the striking similarity of their respective periodic cycle of eruptions.     

Earthquakes at depth beneath volcanoes,forerunners of their activities. Application to White Island,New Zealand

The concept of a time-depth correlation between tectonic earthquakes at depth beneath some volcanoes, and their eruptions, developed by the author since 1962, has been confirmed by new observations and successful prediction of renewed volcanic activity in New Zealand.Regular earthquake migrations are observed along the Benioff zone, and volcanic eruptions are found to be related to these seismic migrations beneath the volcanoes, as follows:

Therefore, in island arcs and continental margins, volcanic activity is the result of two processes occurring beneath the volcanoes: (1) a “tectonic process”, a migration of strain release along the downgoing lithosphere, of which the earthquakes are the manifestation; (2) a “magmatic process”, a relatively fast vertical ascent of magmatic material from the deep root of the volcano, where the observed shocks may be the starting signal from this level.The rate of migration of tectonic earthquakes increases with depth in the upper mantle.An empirical time relationship between the earthquakes occurring at depth beneath a volcano and its eruptions, has been successfully tested for renewed activity at White Island in New Zealand, over the period 1977–1978.     

Volcanism in Iceland in historical time: Volcano types,eruption styles and eruptive history

The large-scale volcanic lineaments in Iceland are an axial zone, which is delineated by the Reykjanes, West and North Volcanic Zones (RVZ, WVZ, NVZ) and the East Volcanic Zone (EVZ), which is growing in length by propagation to the southwest through pre-existing crust. These zones are connected across central Iceland by the Mid-Iceland Belt (MIB). Other volcanically active areas are the two intraplate belts of Öræfajökull (ÖVB) and Snæfellsnes (SVB). The principal structure of the volcanic zones are the 30 volcanic systems, where 12 are comprised of a fissure swarm and a central volcano, 7 of a central volcano, 9 of a fissure swarm and a central domain, and 2 are typified by a central domain alone.Volcanism in Iceland is unusually diverse for an oceanic island because of special geological and climatological circumstances. It features nearly all volcano types and eruption styles known on Earth. The first order grouping of volcanoes is in accordance with recurrence of eruptions on the same vent system and is divided into central volcanoes (polygenetic) and basalt volcanoes (monogenetic). The basalt volcanoes are categorized further in accordance with vent geometry (circular or linear), type of vent accumulation, characteristic style of eruption and volcanic environment (i.e. subaerial, subglacial, submarine).Eruptions are broadly grouped into effusive eruptions where >95% of the erupted magma is lava, explosive eruptions if >95% of the erupted magma is tephra (volume calculated as dense rock equivalent, DRE), and mixed eruptions if the ratio of lava to tephra occupy the range in between these two end-members. Although basaltic volcanism dominates, the activity in historical time (i.e. last 11 centuries) features expulsion of basalt, andesite, dacite and rhyolite magmas that have produced effusive eruptions of Hawaiian and flood lava magnitudes, mixed eruptions featuring phases of Strombolian to Plinian intensities, and explosive phreatomagmatic and magmatic eruptions spanning almost the entire intensity scale; from Surtseyan to Phreatoplinian in case of “wet” eruptions and Strombolian to Plinian in terms of “dry” eruptions. In historical time the magma volume extruded by individual eruptions ranges from ∼1 m³ to ∼20 km³ DRE, reflecting variable magma compositions, effusion rates and eruption durations.All together 205 eruptive events have been identified in historical time by detailed mapping and dating of events along with extensive research on documentation of eruptions in historical chronicles. Of these 205 events, 192 represent individual eruptions and 13 are classified as “Fires”, which include two or more eruptions defining an episode of volcanic activity that lasts for months to years. Of the 159 eruptions verified by identification of their products 124 are explosive, effusive eruptions are 14 and mixed eruptions are 21. Eruptions listed as reported-only are 33. Eight of the Fires are predominantly effusive and the remaining five include explosive activity that produced extensive tephra layers. The record indicates an average of 20–25 eruptions per century in Iceland, but eruption frequency has varied on time scale of decades. An apparent stepwise increase in eruption frequency is observed over the last 1100 years that reflects improved documentation of eruptive events with time. About 80% of the verified eruptions took place on the EVZ where the four most active volcanic systems (Grímsvötn, Bárdarbunga–Veidivötn, Hekla and Katla) are located and 9%, 5%, 1% and 0.5% on the RVZ–WVZ, NVZ, ÖVB, and SVB, respectively. Source volcano for ∼4.5% of the eruptions is not known.Magma productivity over 1100 years equals about 87 km³ DRE with basaltic magma accounting for about 79% and intermediate and acid magma accounting for 16% and 5%, respectively. Productivity is by far highest on the EVZ where 71 km³ (∼82%) were erupted, with three flood lava eruptions accounting for more than one half of that volume. RVZ–WVZ accounts for 13% of the magma and the NWZ and the intraplate belts for 2.5% each. Collectively the axial zone (RVZ, WVZ, NVZ) has only erupted 15–16% of total magma volume in the last 1130 years.