Volcanic ash hazard climatology for an eruption of Hekla Volcano,Iceland

Ash produced by a volcanic eruption on Iceland can be hazardous for both the transatlantic flight paths and European airports and airspace. In order to begin to quantify the risk to aircraft, this study explored the probability of ash from a short explosive eruption of Hekla Volcano (63.98°N, 19.7°W) reaching European airspace. Transport, dispersion and deposition of the ash cloud from a three hour ‘explosive’ eruption with an initial plume height of 12 km was simulated using the Met Office's Numerical Atmospheric-dispersion Modelling Environment, NAME, the model used operationally by the London Volcanic Ash Advisory Centre. Eruptions were simulated over a six year period, from 2003 until 2008, and ash clouds were tracked for four days following each eruption.Results showed that a rapid spread of volcanic ash is possible, with all countries in Europe facing the possibility of an airborne ash concentration exceeding International Civil Aviation Organization (ICAO) limits within 24 h of an eruption. An additional high impact, low probability event which could occur is the southward spread of the ash cloud which would block transatlantic flights approaching and leaving Europe. Probabilities of significant concentrations of ash are highest to the east of Iceland, with probabilities exceeding 20% in most countries north of 50°N. Deposition probabilities were highest at Scottish and Scandinavian airports. There is some seasonal variability in the probabilities; ash is more likely to reach southern Europe in winter when the mean winds across the continent are northerly. Ash concentrations usually remain higher for longer during summer when the mean wind speeds are lower.     

Volcanic risk ranking for Auckland, New Zealand. I: Methodology and hazard investigation

Volcanic eruptions typically produce a number of hazards, and many regions are at risk from more than one volcano or volcanic field. So that detailed risk assessments can be carried out, it is necessary to rank potential volcanic hazards and events in terms of risk. As it is often difficult to make accurate predictions regarding the characteristics of future eruptions, a method for ranking hazards and events has been developed that does not rely on precise values. Risk is calculated individually for each hazard from each source as the product of likelihood, extent and effect, based on the parameters order of magnitude. So that multiple events and outcomes can be considered, risk is further multiplied by the relative probability of the event occurring (probability_e) and the relative importance of the outcome (importance_o). By adding the values obtained, total risk is calculated and a ranking can be carried out.This method was used to rank volcanic hazards and events that may impact the Auckland Region, New Zealand. Auckland is at risk from the Auckland volcanic field, Okataina volcanic centre, Taupo volcano, Tuhua volcano, Tongariro volcanic centre, and Mt. Taranaki volcano. Relative probabilities were determined for each event, with the highest given to Mt. Taranaki. Hazards considered were, for local events: tephra fall, scoria fall and ballistic impacts, lava flow, base surge and associated shock waves, tsunami, volcanic gases and acid rain, earthquakes and ground deformation, mudflows and mudfills, lightning and flooding; and for distal events: tephra fall, pyroclastic flows, poisonous gases and acid rain, mudflows and mudfills, climate variations and earthquakes. Hazards from each source were assigned values for likelihood, with the largest for tephra fall from all sources, earthquakes and ground deformation, lava flows, scoria fall and base surge for an Auckland eruption on land, and earthquakes and ground deformation from an Auckland eruption in the ocean. The largest values for extent were for tephra fall and climate variation from each of the distal centres. However, these parameters do not give a true indication of risk. In a companion paper the effect of each hazard is fully investigated and the risk ranking completed.     

Volcanic hazard at Vesuvius: An analysis for the revision of the current emergency plan

Mt Somma-Vesuvius is a composite volcano on the southern margin of the Campanian Plain which has been active since 39 ka BP and which poses a hazard and risk for the people living around its base. The volcano last erupted in 1944, and since this date has been in repose. As the level of volcanic risk perception is very high in the scientific community, in 1995 a hazard and risk evaluation, and evacuation plan, was published by the Italian Department of Civil Protection (Dipartimento della Protezione Civile). The plan considered the response to a worst-case scenario, taken to be a subplinian eruption on the scale of the 1631 AD eruption, and based on a volcanological reconstruction of this eruption, assumes that a future eruption will be preceded by about two weeks of ground uplift at the volcano's summit, and about one week of locally perceptible seismic activity. Moreover, by analogy with the 1631 events, the plan assumes that ash fall and pyroclastic flow should be recognized as the primary volcanic hazard. To design the response to this subplinian eruption, the emergency plan divided the Somma-Vesuvius region into three hazard zones affected by pyroclastic flows (Red Zone), tephra fall (Yellow and Green Zone), and floods (Blue Zone). The plan at present is the subject of much controversy, and, in our opinion, several assumptions need to be modified according to the following arguments: a) For the precursory unrest problem, recent scientific studies show that at present neither forecast capability is realistic, so that the assumption that a future eruption will be preceded by about two weeks of forecasts need to be modified; b) Regarding the exposure of the Vesuvius region to flow phenomena, the Red Zone presents much inconsistency near the outer border as it has been defined by the administrative limits of the eighteen municipality area lying on the volcano. As this outer limit shows no uniformity, a pressing need exists to define appropriately the flow hazard zone, since there are some important public structures not considered in the current Red Zone that could be exposed to flow risk; c) Modern wind records clearly indicate that at the time of a future eruption winds could blow not only from the west, but also from the east, so that the Yellow Zone (the area with the potential to be affected by significant tephra fall deposits) must be redefined. As a result the relationship between the Yellow Zone and Green Zone (the area within and beyond which the impact of tephra fall is expected to be insignificant) must be reconsidered mainly in the Naples area; d) The May 1998 landslide, caused in the Apennine region east of the volcano by continuous rain fall, led to the definition of a zone affected by re-mobilisation of tephra (Blue Zone), confined in the Nola valley. However, as described in the 1631 chronicles of the eruption, if generation of debris flows occurs during and after a future eruption, a much wider region east of the Somma-Vesuvius must be affected by events of this type.     

Intraglacial volcanism in the Western Volcanic Zone, Iceland

The Western Volcanic Zone in Iceland (64.19° to 65.22° N) has the morphological characteristics of a distinct Mid-Atlantic ridge segment. This volcanic zone was mapped at a scale of 1:36.000, and 258 intraglacial monogenetic volcanoes from the Late Pleistocene (0.01–0.78?Ma) were identified and investigated. The zone is characterized by infrequent comparatively large volcanic eruptions and the overall volcanic activity appears to have been low throughout the Late Pleistocene. Tholeiitic basaltic rocks dominate in the Western Volcanic Zone with about 0.5?vol.?% of intermediate and silicic rocks. The basalts divide into picrites, olivine tholeiites, and tholeiites. Three main eruptive phases can be distinguished in the intraglacial volcanoes: an effusive deep-water lava phase producing basal pillow lavas, an explosive shallow-water phase producing hyaloclastites and an effusive subaerial capping lava phase. Three evolutionary stages therefore charcterize these volcanoes; late dykes and irregular minor intrusions could be added as the fourth main stage. These intrusions are potential heat sources for short-lived hydrothermal systems and may play an important role in the final shaping of the volcanoes. Substantial parts of the hyaloclastites of each unit are proximal sedimentary deposits. The intraglacial volcanoes divide into two main morphological groups, ridge-shaped volcanoes, i.e., tindars (including pillow lava ridges) and subrectangular volcanoes, i.e., tuyas and hyaloclastite or pillow lava mounds. The volume of the tuyas is generally much larger than that of the tindars. The largest tuya, Eiríksj?kull, is about 48?km³ and therefore the largest known monogenetic volcano in Iceland. Many of the large volcanoes, both tuyas and tindars, show a similar, systematic range in geochemistry. The most primitive compositions were erupted first and the magmas then changed to more differentiated compositions. The ridge-shaped tindars clearly erupted from volcanic fissures and the more equi-dimensional tuyas mainly from a single crater. It is suggested that the morphology and structure of the intraglacial volcanos mainly depends on two factors, (a) tectonic control and (b) availability of magma at the time of eruption.     

The Murdjadjo, Western Algeria, fault-related fold: Implications for seismic hazard

The murdjadjo (Oran) geological structure which consists of an asymmetricfold has been studied. The anticline has a length of about 32 km and isN050 trending. Its relationship with the relatively high historical seismicityof the region is analysed. New critical investigations of contemporary documents enabled us to re-evaluate the December, 12, 1959(M_s = 4.7) and the May 12, 1889 (M_s = 4.6) earthquakes. Fieldobservations reveal the existence of a fault which affect the south-easternflank of the Murdjadjo anticline. The fault dips 60^° to the NW andcut the tilted Neogene deposits which juxtaposes the Quaternary tilteddeposits. A NE-SW-trending direction of stream pattern underlies thefaulted flank of the anticline. Furthermore, offset of stream patternindicate a strike lateral slip component of the fault. Marine terracesmapped along the Oran coast indicates a uniform uplift rate of0.18 mm/yr which may be compared to the coseismic rate obtained inthe chelif region. Also, development of secondary small plain on theuplifted flank, the high subsidence in the Mleta quaternary plain whichjuxtaposes the faulted flank constitute evidence of recent tectonicmovements. The Murdjadjo fault, composed by two segments, mayproduce in the future strong earthquakes of magnitude equal or greaterthan 6.5. This fact suggests that the Oran earthquake of October 9, 1790(M = 7.5) which produced sea waves along the Spanish coast is likelygenerated by the Murdjadjo fault- related fold. Recurrence of earthquakedetermined on the basis of historical seismicity suggests a return period ofabout 1000 years for an earthquake of M = 7.3 which seem underestimatedcompared to the paleoseismic data available in The Tell atlas of Algeria.     

Current seismic quiescence in Greece: Implications for seismic hazard

Based on previous observations of the phenomenon of precursory seismic quiescence before crustal main shocks and recent results that indicate an increase in the occurrence of main shocks in the next years, we focus this study on the detection of the seismic quiescence situation in Greece in the beginning of 1999. We use the declustered seismicity catalogue of the Institute of Geodynamics, National Observatory of Athens (NOA) from 1968–1998, to investigate the significance of seismic quiescence for the region 19^°–29^°E and 34^°–42^°N. We searched for seismicity rate changes at every node of the grid by a moving time window and we present the results for the beginning of 1999. The results map four (4) areas having a quiescence which duration ranges from 3.8 to6 years in the beginning of 1999. Three of these areas have been devestated by catastrophic earthquakes 17–21 years ago and significant quiescence also preceded those main shocks. Based on these results, an estimate of the future seismic hazard of these areas is made.     

Volcanic hazard assessment for Ruapehu composite volcano,taupo volcanic zone,New Zealand

Ruapehu is a very active andesitic composite volcano which has erupted five times in the past 10 years. Historical events have included phreatomagmatic eruptions through a hot crater lake and two dome-building episodes. Ski-field facilities, road and rail bridges, alpine huts and portions of a major hydroelectrical power scheme have been damaged or destroyed by these eruptions. Destruction of a rail bridge by a lahar in 1953 caused the loss of 151 lives. Other potential hazards, with Holocene analogues, include Strombolian and sub-Plinian explosive eruptions, lava extrusion from summit or flank vents and collapse of portions of the volcano. The greatest hazards would result from renewed phreatomagmatic activity in Crater Lake or collapse of its weak southeastern wall. Three types of hazard zones can be defined for the phreatomagmatic events: inner zones of extreme risk from ballistic blocks and surges, outer zones of disruption to services from fall deposits and zones of risk from lahars, which consist of tongues down major river valleys. Ruapehu is prone to destructive lahars because of the presence of 10⁷ m³ of hot acid water in Crater Lake and because of the surrounding summit glaciers and ice fields. The greatest risks at Ruapehu are to thousands of skiers on the ski field which crosses a northern lahar path. Three early warning schemes have been established to deal with the lahar problems. Collapse of the southeastern confining wall would release much of the lake into an eastern lahar path causing widespread damage. This is a long-term risk which could only be mitigated by drainage of the lake.     

Volcanic risk ranking for Auckland, New Zealand. II: Hazard consequences and risk calculation

In a companion paper, a methodology for ranking volcanic hazards and events in terms of risk was presented, and the likelihood and extent of potential hazards in the Auckland Region, New Zealand investigated. In this paper, the effects of each hazard are considered and the risk ranking completed. Values for effect are proportions of total loss and, as with likelihood and extent, are based on order of magnitude.Two outcomes were considered – building damage and loss of human life. In terms of building damage, tephra produces the highest risk by an order of magnitude, followed by lava flows and base surge. For loss of human life, risk from base surge is highest. The risks from pyroclastic flows and tsunami are an order of magnitude smaller. When combined, tephra fall followed by base surge produces the highest risk. The risks from lava flows and pyroclastic flows are an order of magnitude smaller. For building damage, the risk from Mt. Taranaki volcano, 280 km from the Auckland CBD, is largest, followed by Okataina volcanic centre, an Auckland volcanic field eruption centred on land, then Tongariro volcanic centre. In terms of human loss, the greatest risk is from an Auckland eruption centred on land. The risks from an Auckland eruption centred in the ocean, Okataina volcanic centre, and Taupo volcano are more than an order of magnitude smaller. When combined, the risk from Mt. Taranaki remains highest, followed by an Auckland eruption centred on land. The next largest risks are from the Okataina and Tongariro volcanic centres, followed by Taupo volcano.Three alternative situations were investigated. As multiple eruptions may occur from the Auckland volcanic field, it was assumed that a local event would involve two eruptions. This increased risk of a local eruption occurring on land so that it was equal to that of an eruption from Mt. Taranaki. It is possible that a future eruption may be of a similar, or larger size, to the previous Rangitoto eruption. Risk was re-calculated for local eruptions based on the extent of hazards from Rangitoto. This increased the risk of lava flow to greater than that of base surge, and the risk from an Auckland land eruption became greatest. The relative probabilities used for Mt. Taranaki volcano and the Auckland volcanic field may only be minimum values. When the probability of these occurring was increased by 50%, there was no change in either ranking.Editorial responsibility: J. S. Gilbert     

京津唐地区地震灾害和危险性评估

利用我国京津唐地区500年以来记录较完整的历史地震烈度资料,尝试进行了地震灾害与危险性分析,以提供制定抗震设防基本参数或烈度的参考.首先,我们用ArcGIS把这些历史烈度资料进行了数字化,并把研究区分成 0.1°×0.1°的小方格.然后,我们对烈度资料进行了统计分析,得到每个小方格的地震烈度-频度关系（即灾害曲线）.最后,基于地震发生遵从泊松分布的假定,利用灾害曲线估算了京津唐地区的地震风险,即在未来一段时间内(如 50年)该地区遭受某一地震烈度(如Ⅶ,Ⅷ,或Ⅸ度)的超越概率.同时,我们还估算了50年超越概率10%所对应的地震烈度,如：北京为Ⅸ,天津为Ⅸ,唐山为≥Ⅸ,保定为Ⅷ,廊坊为Ⅸ.研究结果表明,京津唐地区有较高的地震危险性,现行的抗震设防要求可能偏低.     

earthquake disaster rapid assessment for emergency response supported by high-precision data of hazard bearing body

The earthquake disaster rapid assessment(EDRA)is the core technical support for the post-earthquake emergency response. At present, with the popularization of high-precision population, social and economic data, most of the subordinate units of China Earthquake Administration(CEA)have heightened the precision of hazard bearing body data used in EDRA from the original county-level precision to the 30″×30″ precision. However, while the precision of fundamental data has been heightened, no efforts have been made to improve the main algorithms and the technical process of EDRA. It turns out that the assessment has become more accurate, but the problems of the time-consuming process(10-20 minutes, probably 20 minutes or more in great earthquakes)and the low-precision losses distributions that exposed in EDRA supported by county-level precision data remain unresolved.This paper introduces the high-precision(30″×30″)hazard bearing body data, and describes the principle of EDRA and its implementation under the support of county-level precision data at first. Then the paper elaborates the principle of improving EDRA's data foundation using high-precision hazard bearing body data, the principle of improving the computation efficiency and persisting the data precision in the assessment process by means of the cell-to-cell grid algebraic operation, and the method for improving the assessment speed through the segmentation and reorganization of the technical process of EDRA.It is validated that through the improvements, the EDRA has become more accurate and much less time-consuming(less than 1 minute), and is able to output high-precision(30″×30″)distributions of seismic losses. The high-precision hazard bearing body data of wide range are the simulated data but not the survey data. Though the data have been simulated based on the census data, there is still a gap between their accuracy and the real situation. Further research and optimization on the data are needed.     

Hydrothermal alteration of plagioclase and growth of secondary feldspar in the Hengill Volcanic Centre, SW Iceland

Dissolution of igneous feldspar and the formation and occurrence of secondary feldspar in tholeiitic basalts from the Hengill volcanic centre, in SW Iceland was studied by microprobe analysis of cuttings from two ca. 2000 m deep geothermal wells. Well NG-7 in Nesjavellir represents a geothermal system in a rift zone where the intensity of young, insignificantly altered intrusions increases with depth. Well KhG-1 in Kolviðarhóll represents the margin of a rift zone where the intensity of intrusives is lower and the intensity of alteration higher. This marginal well represents altered basaltic crust in an early retrograde state. The secondary plagioclase in both wells is mainly oligoclase, occurring in association with K-feldspar and chlorite±actinolite. The texture of this assemblage depends on the lithology and intensity of alteration. In Nesjavellir (NG-7) the composition of secondary albite-oligoclase is correlated with the host-rock composition. This connection is not apparent in more intensely altered samples from Kolviðarhóll (KhG-1). The influence of temperature on composition of secondary Na-feldspar is unclear in both wells although Ca is expected to increase with temperature. Any temperature dependence may be suppressed by the influence of rock composition in Nesjavellir and by retrograde conditions at Kolviðarhóll. The absence of clear compositional gradients between igneous plagioclase and secondary feldspar and between Na-feldspar and K-feldspar suggests that secondary feldspars formed by dissolution precipitation reactions.     

Seismic hazard assessment for Iceland in terms of macroseismic intensity using a site approach

We present the results of probabilistic seismic hazard assessment for Iceland in the framework of the EU project UPStrat-MAFA using the so-called site approach implemented in the SASHA computational code. This approach estimates seismic hazard in terms of macroseismic intensity by basically relying on local information about documented effects of past seismic events in the framework of a formally coherent and complete treatment of intensity data. In the case of Iceland, due to the lack of observed intensities for past earthquakes, local seismic histories were built using indirect macroseismic estimates deduced from epicentral information through an empirical attenuation relationship in probabilistic form. Seismic hazard was computed for four exceedance probabilities for an exposure time of 50 years, equivalent to average return periods of 50, 200, 475 and 975 years. For some localities, further return periods were examined and deaggregation analysis was performed. Results appear significantly different from previous seismic hazard maps, though just a semi-qualitative comparison is possible because of the different shaking measure considered (peak ground acceleration versus intensity), and the different computational methodology and input data used in these studies.     

Volcanic systems and calderas in the Vatnajökull region,central Iceland: Constraints on crustal structure from gravity data

A Bouguer anomaly map is presented of southern central Iceland, including the western part of Vatnajökull and adjacent areas. A complete Bouguer reduction for both ice surface and bedrock topography is carried out for the glaciated regions. Parts of the volcanic systems of Vonarskarð-Hágöngur, Bárðarbunga-Veiðivötn, Grímsvötn-Laki, and to a lesser extent Kverkfjöll, show up as distinct features on the gravity map. The large central volcanoes with calderas: Vonarskarð, Bárðarbunga, Kverkfjöll and Grímsvötn, are associated with 15–20 mGal gravity highs caused by high density bodies in the uppermost 5 km of the crust. Each of these bodies is thought to be composed of several hundred km³ of gabbros that have probably accumulated over the lifetime of the volcano. The Skaftárkatlar subglacial geothermal areas are not associated with major anomalous bodies in the upper crust. The central volcanoes of Vonarskarð and Hágöngur belong to the same volcanic system; this also applies to Bárðarbunga and Hamarinn, and Grímsvötn and Þórðarhyrna. None of the smaller of the two volcanoes sharing a system (Hágöngur, Hamarinn and Þórðarhyrna) is associated with distinct gravity anomalies and clear caldera structures have not been identified. However, ridges in the gravity field extend between each pair of central volcanoes, indicating that they are connected by dense dyke swarms. This suggests that when two central volcanoes share the same system, one becomes the main pathway for magma, forming a long-lived crustal magma chamber, a caldera and large volume basic intrusive bodies in the upper crust. Short residence times of magma in the crust beneath these centres favour essentially basaltic volcanism. In the case of the second, auxillary central volcano, magma supply is limited and occurs only sporadically. This setting may lead to longer residence times of magma in the smaller central volcanoes, favouring evolution of the magma and occasional eruption of rhyolites. The eastern margin of the Eastern Volcanic Zone is marked by a NE–SW lineation in the gravity field, probably caused by accumulation of low density, subglacially erupted volcanics within the volcanic zone. This lineation lies 5–10 km to the east of Grímsvötn.     

Spatio-temporal hazard estimation in the Auckland Volcanic Field,New Zealand,with a new event-order model

The Auckland Volcanic Field (AVF) with 49 eruptive centres in the last c. 250 ka presents many challenges to our understanding of distributed volcanic field construction and evolution. We re-examine the age constraints within the AVF and perform a correlation exercise matching the well-dated record of tephras from cores distributed throughout the field to the most likely source volcanoes, using thickness and location information and a simple attenuation model. Combining this augmented age information with known stratigraphic constraints, we produce a new age-order algorithm for the field, with errors incorporated using a Monte Carlo procedure. Analysis of the new age model discounts earlier appreciations of spatio-temporal clustering in the AVF. Instead the spatial and temporal aspects appear independent; hence the location of the last eruption provides no information about the next location. The temporal hazard intensity in the field has been highly variable, with over 63% of its centres formed in a high-intensity period between 40 and 20 ka. Another, smaller, high-intensity period may have occurred at the field onset, while the latest event, at 504 ± 5 years B.P., erupted 50% of the entire field’s volume. This emphasises the lack of steady-state behaviour that characterises the AVF, which may also be the case in longer-lived fields with a lower dating resolution. Spatial hazard intensity in the AVF under the new age model shows a strong NE-SW structural control of volcanism that may reflect deep-seated crustal or subduction zone processes and matches the orientation of the Taupo Volcanic Zone to the south.     

Volcanic hazard assessment in the Phlegraean Fields: a contribution based on stratigraphic and historical data

Phenomena occurring since 1982 in the Phlegraean Fields, interpreted as precursors of a potential renewal of volcanic activity, have forced us to anticipate some conclusions of a volcanic-hazard study based on the reconstruction of past eruptions in the area, to serve as basis for civil defense preparedness plans. The eruptive history of the Phlegraean Fields suggests a progressive decrease with time in the strength of eruptive phenomena paralleling a migration of vents towards the center of the Phlegraean caldera. Studies concerning the volcanic risk zonation were therefore concentrated on activities during the last 4,500 years and two eruptions (Monte Nuovo and Agnano Monte Spina), that occurred in 1538 and 4,400 years B.P., respectively were selected as the «reference eruptions» from which possible eruption scenarios were drawn.     

Stress field around the Coloumbo magma chamber,southern Aegean: Its significance for assessing volcanic and seismic hazard in Santorini

Coloumbo submarine volcano lies 6.5 km offshore the NE part of the Santorini island complex and exhibits high seismicity along with vigorous hydrothermal activity. This study models the local stress field around Coloumbo's magma chamber and investigates its influence on intrusion emplacement and geometry. The two components of the stress field, hoop and radial stress, are calculated using analytical formulas that take into account the depth and radius of the magma chamber as these are determined from seismological and other observations. These calculations indicate that hoop stress at the chamber walls is maximum at an angle of 74° thus favouring flank intrusions, while the radial stress switches from tensile to compressive at a critical distance of 5.7 km from the center of the magma chamber. Such estimates agree well with neotectonic and seismological observations that describe the local/regional stress field in the area. We analyse in detail the case where a flank intrusion reaches the surface very near the NE coast of Thera as this is the worst-case eruption scenario. The geometrical features of such a feeder dyke point to an average volumetric flow rate of 9.93 m³ s⁻¹ which corresponds to a Volcanic Explosivity Index of 3 if a future eruption lasts about 70 days. Hazards associated with such an eruption include ashfall, ballistic ejecta and base surges due to explosive mixing of magma with seawater. Previous studies have shown that areas near erupting vents are also foci of moderate to large earthquakes that precede or accompany an eruption. Our calculations show that a shallow event (3–5 km) of moment magnitude 5.9 near the eruptive vent may cause Peak Ground Acceleration in the range 122–177 cm s⁻² at different locations around Santorini. These values indicate that seismic hazard even due to a moderate earthquake near Coloumbo, is not trivial and may have a significant impact especially on older buildings at Thera island.     

Paleocene deep-water sediments and radiolarian faunas: Implications for evolution of Yarlung-Zangbo foreland basin, southern Tibet

Only a few Paleocene radiolarian assemblages have been reported, while the Early Paleocene zonal schemes remain poorly delineated. The Early Paleocene on-land radiolarians were described in the Hidaka melange belt of Japan and the North Island of New Zeal…