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1.
We propose a model for the seismic driving of environmental changes and illustrate it using a case study from New Zealand dated to the 15th Century AD. A “seismic staircase” shows a chronological progression of environmental outcomes that includes tsunami, rock avalanches, vegetation disturbance, rapid coastal dune building, river aggradation, and abandonment of prehistoric coastal settlements. The 15th Century event appears to be unique in the past Millenium and is most notable for its period of rapid coastal dune building.The coincidence of a catastrophic El Niño episode in the mid 15th Century AD may have served to move sediments rapidly through the terrestrial system thus delimiting clearly separate geomorphological after-effects. We contend that seismic driving is a major factor in determining paleoenvironmental change in tectonically active areas during the Holocene and provides the palaeoenvironmental context within which smaller scale events operate. 相似文献
2.
Teija Alenius Matti Saarnisto Jussi‐Pekka Taavitsainen Juha‐Pekka Lunkka 《Geoarchaeology》2011,26(1):142-163
Although the documented history of Dvina Karelia (northern Russian Karelia) does not begin until the second half of the 16th century, individual finds of prehistoric artifacts point to earlier human occupation. The present paleoecological study of the Vuonninen area is the first of its kind concerning prehistoric land use in Dvina Karelia, a large region extending from Finland to the White Sea. It is based on the pollen analysis of sediments from Lake Ylä‐Kuittijärvi near the old Karelian village of Vuonninen. In its general features, the picture of the early stages of cultivation and human activity in the village of Vuonninen is comparable to results from East Finland, the Karelian Isthmus, and the northern shores of Lake Ladoga. The first, minor indications of human influence appear in the sediments of the 4th–6th centuries A.D. in Lake Kuittijärvi. Distinct and unambiguous signs of human activity appear in the pollen record in the 12th century. This is particularly evident in the decreasing proportion of Picea, caused by the clearance of spruce forest. The beginning of cultivation is dated according to Secale pollen to the beginning of the 15th century. Intensive arable farming emerges in the early 19th century in the form of regular occurrences of Secale and Hordeum pollen. © 2010 Wiley Periodicals, Inc. 相似文献
3.
We present the results of work on the compilation of a fuller and more comprehensive historical catalogue of earthquakes and tsunamis in the basin of the Black Sea and the Sea of Azov, an area of primary importance for the Russian Federation. In the 20th century, there were no significant tsunamis in the Black Sea; therefore, its coast was not considered tsunami-prone. A systematic search for new data sources, a revision of earlier ones, and the use of new approaches to the identification of tsunamigenic events resulted in a more than doubling of the number of known tsunamigenic events in this basin, bringing it up to 50. The total length of the new tsunami catalogue reached 3000 years, which makes it the second longest after the Mediterranean tsunami catalogue (about 4000 years). Taking into account the seismotectonic features of the Black Sea region, we processed data on historical tsunamis and analyzed the geographical and temporal distributions of their sources. For all tsunamigenic events we performed a parameterization of available information about their sources and coastal manifestations, evaluated the tsunami intensity based on the Soloviev-Imamura scale, and proposed a classification of tsunami and tsunami-like water wave disturbances based on their genesis. Tsunami run-up heights, inland penetration, and damage were estimated with regard for the newly found data. Among the identified historical events, there are devastating tsunamis with run-ups of 4-5 m, sometimes up to 6-8 m, which resulted in disastrous consequences for several ancient cities (Dioscuria, Sebastopolis, Bizone, and Panticapaeum) and many coastal settlements. Expert assessments of the most tsunami-prone areas of the coasts are given. 相似文献
4.
The Hauraki Gulf is a semi-enclosed sea next to the largest population centre in New Zealand, the Auckland metropolitan region. The potential tsunami hazard is of concern to regional and local planners around the Hauraki Gulf. The Hauraki Gulf has recorded 11 tsunamis and one meteorological tsunami (rissaga) since 1840.The historical tsunami data are relatively sparse, particularly for the largest events in 1868 and 1883. Moreover, local sources may produce damaging tsunamis but none has occurred during recorded history. Therefore numerical modelling of potential tsunami events provides a powerful tool to obtain data for planning purposes. Three main scenarios have been identified for numerical modelling:1. A teletsunami event from an earthquake off the West Coast of South America. Historically this region has produced the largest teletsunamis in the Hauraki Gulf.2. A tsunami generated by a local earthquake along the Kerepehi Fault. This fault bisects the Gulf, has been active during the last century at the southern inland end, and is overlain by a considerable thickness of soft sediment that may amplify the seismic waves.3. A tsunami generated by a volcanic eruption within the Auckland Volcanic Field. This field has involved a series of mainly monogenetic basaltic eruptions over the last 140,000 years. Many of these eruptions have involved phreatomagmatic eruptions around the coastal margins, or within the shallow waters close to Auckland. 相似文献
5.
Barrier dunes on the northern side of the Tawharanui Peninsula, north of Auckland, New Zealand, appear to have been overtopped by extreme waves that have deposited two large sand washover lobes in a back beach wetland. Present-day storm surges and storm waves are incapable of overtopping the barrier dunes. However, historical data and numerical models indicate tsunamis are amplified by resonance within the adjacent bay and Hauraki Gulf. Further, the location of nearshore reefs in close proximity to the washover lobes suggests that the interaction between tsunamis and the reefs further amplified the waves at those locations. The presence of a distinctive pumice (Loisels Pumice) within the washover deposits suggests that the deposits are associated with a 15th Century eruption from the submarine Mt Healy caldera located northeast of New Zealand. 相似文献
6.
Earthquakes and tsunamis in a region of diapiric folding 总被引：1，自引：0，他引：1
G.A. Eiby 《Tectonophysics》1982,85(3-4)
New Zealand earthquakes rarely cause significant tsunamis. In 1947 two tsunamis reaching a height of about 10 m were associated with earthquakes of less than magnitude 6. Their records have the predominantly low-frequency character of the tsunami-generating shocks on the inner margin of the Japan Trench, but they originated beneath a shallow coastal platform, and not close to the Hikurangi Trench. The platform consists of weak folded sediments penetrated by diapiric intrusions from which large quantities of mud and breccia have been explosively expelled from time to time. The mechanical behaviour of this extruded material is believed to be responsible for the character of the shocks, and to provide a mechanism for the generation of tsunamis. 相似文献
7.
Kevin L. Jones 《Geoarchaeology》1990,5(3):255-273
Since the first occupation of New Zealand by Polynesians 1000 years B.P., there have been three major phases of sedimentation in river valleys. These occurred in broad periods of 700 to 600 years B.P., 450 to 300 years B.P., and from 1880 to the present. This offers a useful opportunity to develop a field procedure for rapidly setting maximum ages for pre-European settlements on river terraces. Radiocarbon dates confirm the value of the procedure. Fortified settlements on alluvium in the New Zealand North Island East Coast area date to the period after about 450 years B.P., in a chronological pattern similar to that elsewhere in New Zealand. the generalized phases of terrace age are not always easily applied to particular field situations and the real advantages of the method lie in the provision of approximate dates for surface surveys of settlement pattern. 相似文献
8.
In the seventeenth century, two tsunamis that were generated by earthquakes on the Kuril–Kamchatka subduction zone inundated the eastern coast of Hokkaido, northern Japan. Stratigraphic evidence for these two tsunamis and related land-level change in coastal Hokkaido consists of two landward-thinning sand layers in the sediments of Lake Tokotan, a coastal lagoon on the Hokkaido coast. The marine origin of these sand layers is indicated by the presence of brackish–marine diatoms. The rarity and high degree of fragmentation of diatom valves suggests that the sands were transported in a short time over a considerable distance. Tsunamis at this site were probably generated by great earthquakes along the Kuril–Kamchatka Trench. Volcanic ash deposits lying just above the sands suggest that tsunamis occurred in the late 17th century. Tsunamis during the historic period are not recorded in Lake Tokotan, which suggests that the sand layers were deposited by tsunamis substantially larger than historic tsunamis. 相似文献
9.
The coastal zone of northwest Portugal can be subdivided into two geomorphological sectors: Sector 1, between the Minho River and the town of Espinho, where the coastal segments consist of estuaries, sandy and shingle beaches with rocky outcrops, and Holocene dune systems (foredunes and some migrating dunes with blow-outs). The estuaries and the foredunes in particular are very degraded by human activities. Sector 2, between Espinho and the Mondego Cape, where coastal lagoons and Holocene dune systems (foredunes, parabolic and transverse dunes) occur. This study deals with the macroscale, i.e. 100–1000 years, forcing by sea-level changes and neotectonic activity on the one hand, and mesoscale, i.e. 1–100 years, forcing by climate fluctuations on the other hand, on these (palaeo-)environments. It is shown in particular that sea-level changes and neotectonic activity play a dominant role in the evolution of the coastal zone since the Late Pleistocene. Sediment starvation on the shoreface is postulated to be one of the major causes for coastal erosion since at least the 15th century. The mesoscale role of climate is difficult to assess at the present stage of knowledge, mainly because of overprinting by the macroscale evolution of the coast. However, data on estuarine saltmarsh evolution in sector 1 point towards discrete changes in storminess, while the development of Medieval dune systems in sectors 1 and 2 are attributed to the Little Ice Age or, alternatively, to human occupation of the dune areas. 相似文献
10.
The degree to which human modifications in the coastal zone have increased or decreased coastal erosion rates is difficult
to determine owing to the short time period for which shoreline-position data are available. This limitation is circumvented
in areas where long-term recession rates can be determined from geologic data. Three such areas from Matagorda Bay have been
examined to determine the temporal variation in recession rates over the past several thousand years. Preliminary results
indicate that recession rates over the past century may be 30% to 40% greater than those of prehistoric time. Although additional
data are needed, it is suggested that accelerated rates result from human modification of the coastal zone, and that in the
future increased recession rates can be anticipated. 相似文献
11.
George Pararas-Carayannis 《Natural Hazards》1988,1(3):285-294
The major earthquake measuring 8.1 on the Richter scale which struck the west coast of Mexico on Thursday 19 September 1985, generated a small tsunami. A major aftershock on 21 September, with a magnitude of 7.5 also produced a small tsunami. Both tsunamis propagated across the Pacific and were recorded by several tide stations in Central America, Colombia, Ecuador, French Polynesia, Samoa, and Hawaii. No reports of damage were received from any of the stations, and only minor damage due to the first tsunami was reported from the source region.A survey was made by the International Tsunami Information Center (ITIC) of the coastal area affected, from Manzanillo to Zihuatanejo. Tsunami runup measurements were taken and interviews with local residents in the coastal areas were conducted.A source mechanism study of the tsunamis was undertaken using seismic and geologic data and empirical relationships. Earthquake and tsunami energies were estimated and the tsunami genertion areas defined.The earthquake energies were estimated to be 5.61 × 1024 erg for the 19 September event and 9.9 × 1023 erg for the 21 September event. Tsunami energies were estimated to be 0.7 × 1020 erg for the first event and 0.56 × 1020 erg for the second event. The source area of the first tsunami was determined to be approximately one-half of the earthquake source area, or approximately 7500 km2, while the source area of the second tsunami was estimated to be equal to the earthquake area.The relatively small tsunamis generated by these large earthquakes are attributed to the shallow angle of subduction of the Cocos plate underneath the North American plate for this particular region, and to the small vertical component of crustal displacements. However, the angle of subduction increases further south and local earthquakes from that area have the potential of producing large tsunamis on the west coast of Mexico.This paper was presented at the 4th International Symposium on Natural and Man-made Coastal Hazards held in Ensenada, Mexico, August 1988. 相似文献
12.
13.
O. P. Mishra D. Zhao Chandan Ghosh Z. Wang O. P. Singh Biman Ghosh K. K. Mukherjee D. K. Saha G. K. Chakrabortty S. G. Gaonkar 《Natural Hazards》2011,57(1):51-64
The Andaman–Nicobar (A–N) Islands region has attracted many geo-scientists because of its unique location and complex geotectonic
settings. The recent occurrence of tsunamis due to the megathrust tsunamigenic north Sumatra earthquake (Mw 9.3) with a series
of aftershocks in the A–N region caused severe damage to the coastal regions of India and Indonesia. Several pieces of evidence
suggest that the occurrence of earthquakes in the A–N region is related to its complex geodynamical processes. In this study,
it has been inferred that deep-seated structural heterogeneities related to dehydration of the subducting Indian plate beneath
the Island could have induced the process of brittle failure through crustal weakening to contribute immensely to the coastal
hazard in the region. The present study based on 3-D P-wave tomography of the entire rupture zone of the A–N region using
the aftershocks of the 2004 Sumatra–Andaman earthquake (Mw 9.3) clearly demonstrates the role of crustal heterogeneity in
seismogenesis and in causing the strong shakings and tsunamis. The nature and extent of the imaged crustal heterogeneity beneath
the A–N region may have facilitated the degree of damage and extent of coastal hazards in the region. The 3-D velocity heterogeneities
reflect asperities that manifest what type of seismogenic layers exist beneath the region to dictate the size of earthquakes
and thereby they help to assess the extent of earthquake vulnerability in the coastal regions. The inference of this study
may be used as one of the potential inputs for assessment of seismic vulnerability to the region, which may be considered
for evolving earthquake hazard mitigation model for the coastal areas of the Andaman–Nicobar Islands region. 相似文献
14.
海啸作为五大海洋自然灾害之一,严重威胁着人类生命财产安全。近些年来,国内外学者对地震海啸进行了大量研究,主要针对海啸的生成、传播、爬高和淹没的数值模拟,以及古海啸沉积物进行研究,但是对于海啸地震震源机制的研究还比较欠缺,尤其是缺乏对震级小于6.5的海啸地震的研究。针对我国的地震海啸研究现状,强调震级小于6.5地震引发海啸的问题不容忽视。本文归纳整理了全球766次地震海啸,利用三角图分类基本法则对海啸地震震源机制解进行分类,并对其中341个发生在1976年后的海啸地震进行震源机制解分析,对其中633次海啸浪高进行统计学方法分析研究。本文认为逆冲型、正断型、走滑型和奇异型机制地震均能引发海啸,逆冲型地震引发的海啸占比最大,震级小于6.5级地震引发的海啸的浪高也有高达10 m的情况,也能产生巨大破坏性。逆冲型、正断型、奇异型地震可直接引起海底地形垂向变化,进而引发海啸,而走滑型地震引发海啸则可能有两种原因,一种是走滑型地震并非纯走滑型而是带有正断或逆冲分量从而引发海啸,另外一种是走滑型地震引发海底滑坡导致海底地形变化进而产生海啸。从海啸地震震源深度分析,能产生海啸的地震震源深度97%以上都是浅源地震,主要集中在30 km深度以内,但是也有中深源地震海啸。本文综合海啸地震的震源特点、我国地理位置以及以往海啸发生的情况,认为未来我国沿海地区威胁性的地震海啸主要集中在马尼拉海沟和台湾海峡区域,在今后海啸预警方面需要格外重视这些区域,通过建立完善海啸预警系统来减少损失。 相似文献
15.
Stefano Tinti 《Natural Hazards》1991,4(2-3):267-283
A method for the evaluation of tsunami potential in the seas surrounding Italy is presented. A major difficulty for performing reliable estimates of tsunami occurrence is that the existing tsunami catalog for Italy includes a small number of cases. This is due partly to the catalog incompleteness, strangely more pronounced in our century, and partly to the relative infrequency of tsunamis along the Italian seas. Evaluation of tsunami activity is therefore deduced by complementing the tsunami catalog data with data on seismicity that are by far more abundant and reliable. Analysis of seismicity and assessment of earthquake rate in coastal and submarine regions form the basis of the present method to perform tsunami potential estimates for Italy. One essential limitation of the method is that only tsunamis of seismic origin are taken into account, which leads to an underestimation of the tsunami potential. Since tsunamis generated by earthquakes are much more frequent than events produced by slumps or volcanic eruptions, the underestimation is not dramatic and very likely affects only a limited portion of the Italian coasts. In the present application of the method, eight separate regions have been considered that together cover all the coasts of Italy. In each region, seismicity has been independently examined and the earthquake potential has been calculated in small 20 × 20 cells. Then, on the basis of suitable assumptions, tsunami potential has been evaluated in each cell. According to this study, the Italian coasts that are the most exposed to the attacks of locally generated tsunamis are to be found in the Messina Straits, in Tyrrhenian coasts of Calabria, in the Ionian Sicilian coasts around Catania, and in the Gargano promontory in the Southern Adriatic Sea. Furthermore, this study confirms that the Northern Adriatic Sea has a low level of tsunami potential, in agreement with recent studies emphasizing that the large historical events concerning this region included in the first versions of the Italian tsunami catalog are largely overestimated and must be decreased. 相似文献
16.
Tsunamis originating in Indonesia and Papua New Guinea can be locally devastating and also occasionally threaten coastal areas of northern Australia. Tsunamis may be caused by earthquakes, volcanoes or submarine landslides. In Rabaul a unique set of records exists of tsunamis and seiches generated by tectonic earthquakes, volcanic earthquakes and a volcanic eruption. Spectral analysis of the digitised waveforms has been undertaken to compare the effects of the different sources and to estimate the characteristic natural periods of Rabaul Harbour. Seiches in Rabaul Harbourhave dominant periods of 20 to 30 min, a period band that is also typical for coastal recordings of tsunamis. 相似文献
17.
《Russian Geology and Geophysics》2015,56(10):1475-1483
Moraines studied in the Chon-Kyzylsuu River valley (southeastern Lake Issyk-Kul region, Tien Shan) were mobilized during historic and prehistoric large earthquakes. Seismic triggers of moraine mobilization included the M > 8 Kebin earthquake of 1911 and prehistoric events that produced rockslides, landslides, and multiple fault scarps. Rockslides in the Chon-Kyzylsuu basin are located in the hanging wall of the Terskey border thrust fault. The observed deformation results from at least four prehistoric earthquakes in the second half of the Holocene (early 20th century BC, early 11th century BC, middle 8th century BC, and early 2nd century BC), with local shaking intensity I > 7. 相似文献
18.
Although the upper Mississippi embayment is an area of low relief, the region has been subjected to tectonic influence throughout its history and continues to be so today. Tectonic activity can be recognized through seismicity patterns and geological indicators of activity, either those as a direct result of earthquakes, or longer term geomorphic, structural, and sedimentological signatures. The rate of seismic activity in the upper Mississippi embayment is generally lower than at the margins of tectonic plates; the embayment, however, is the most seismically active region east of the Rocky Mountains, with activity concentrated in the New Madrid seismic zone. This zone produced the very large New Madrid earthquakes of 1811 and 1812.
Geological and geophysical evidence of neotectonic activity in the upper Mississippi embayment includes faulting in the Benton Hills and Thebes Gap in Missouri, paleoliquefaction in the Western Lowlands of Missouri, subsurface faulting beneath and tilting of Crowley's Ridge in northeastern Arkansas and southeastern Missouri, subsurface faulting along the Crittenden County fault zone near Memphis, Tennessee, faulting along the east flank of the Tiptonville dome, and numerous indicators of historic and prehistoric large earthquakes in the New Madrid seismic zone.
Paleoearthquake studies in the New Madrid seismic zone have used trenching, seismic reflection, shallow coring, pedology, geomorphology, archaeology, and dendrochronology to identify and date faulting, deposits of liquefied sand, and areas of uplift and subsidence. The cause of today's relatively high rate of tectonic activity in the Mississippi embayment remains elusive. It is also not clear whether this activity rate is a short term phenomenon or has been constant over millions of years. Ongoing geodetic and geological studies should provide more insight as to the precise manner in which crustal strain is accumulating, and perhaps allow improved regional neotectonic models. 相似文献
19.
Steve C. Cole Brian F. Atwater Patrick T. McCutcheon Julie K. Stein Eileen Hemphill-Haley 《Geoarchaeology》1996,11(2):165-177
Although inhabited by thousands of people when first reached by Europeans, the Pacific coast of southern Washington has little recognized evidence of prehistoric human occupation. This apparent contradiction may be explained partly by geologic evidence for coastal submergence during prehistoric earthquakes on the Cascadia subduction zone. Recently discovered archaeological sites, exposed in the banks of two tidal streams, show evidence for earthquake-induced submergence and consequent burial by intertidal mud about A.D. 1700. We surmise that, because of prehistoric earthquakes, other archaeological sites may now lie hidden beneath the surfaces of modern tidelands. Such burial of archaeological sites raises questions about the estimation of prehistoric human population densities along coasts subject to earthquake-induced submergence. © 1996 John Wiley & Sons, Inc. 相似文献
20.
Futoshi Nanayama Ryuta Furukawa Kiyoyuki Shigeno Akito Makino Yuji Soeda Yaeko Igarashi 《Sedimentary Geology》2007,200(3-4):275-294
Large earthquakes along the Kuril subduction zone in northern Japan are known to have caused damaging tsunami, although there is a little information on historical earthquakes and tsunami in this area because no documents exist before the 19th century that might refer to tsunami events. To determine the likely timing and size of future events we need information on their recurrence intervals and to do this for the prehistoric past we have investigated sediments located in the Kiritappu marsh in eastern Hokaido that we interpret as laid down by tsunami. Using reliable multiple lines of evidence from sedimentological, geomorphological, micropaleontological, and chronological results, we identify 13 tsunami sands. Two of these lie within a peat bed above a historical tephra, Ta-a (AD 1739); the upper one probably corresponds to the AD 1843 Tempo Tokachi-oki earthquake (M 8.2) tsunami, and the lower to either the AD 1952 Tokachi-oki earthquake (M 8.2) tsunami or the AD 1960 Chilean earthquake (M 9.5) tsunami. Underlying are 11 prehistoric tsunami sand beds (nine large sand beds and two smaller sand beds) deposited during the past 4000 years. Because of the wide spatial distribution of the large sand beds, and inundation distances inland of between 1200 to 3000 m, we suggest that they record unusually large tsunamis along the Kuril subduction zone. According to our analyses, these tsunami sands were derived from the coastal area and, although they do not show clear graded bedding, they commonly have gradational upper boundaries and erosional bases and include internal sedimentary structures such as plane beds, dunes, and current ripples, reflecting bedload transportation. Based on our results we calculate the recurrence interval of unusually large earthquakes (probably M 8.6) along the Kuril subduction zone as about 365–553 years and estimate the youngest large event to have occurred in the 17th century. 相似文献