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1.
Sediment deposited by the Tohoku tsunami of March 11, 2011 in the Southern Kurils (Kunashir, Shikotan, Zeleniy, Yuri, Tanfiliev islands) was radically different from sedimentation during local strong storms and from tsunamis with larger runup at the same location. Sediments from the 2011 Tohoku tsunami were surveyed in the field, immediately and 6 months after the event, and analyzed in the laboratory for sediment granulometry, benthos Foraminifa assemblages, and diatom algae. Run-up elevation and inundation distance were calculated from the wrackline (accumulations of driftwood, woody debris, grass, and seaweed) marking the distal edge of tsunami inundation. Run-up of the tsunami was 5 m at maximum, and 3–4 m on average. Maximum distance of inundation was recorded in river mouths (up to 630 m), but was generally in the range of 50–80 m. Although similar to the local strong storms in runup height, the tsunami generally did not erode the coast, nor leave a deposit. However, deposits uncharacteristic of tsunami, described as brown aleuropelitic (silty and clayey) mud rich in organic matter, were found in closed bays facing the South Kuril Strait. These closed bays were covered with sea ice at the time of tsunami. As the tsunami waves broke the ice, the ice floes enhanced the bottom erosion on shoals and destruction of low-lying coastal peatland even at modest ranges of runup. In the muddy tsunami deposits, silt comprised up to 64 % and clay up to 41.5 %. The Foraminifera assemblages displayed features characteristic of benthic microfauna in the near-shore zone. Deep-sea diatoms recovered from tsunami deposits in two closely situated bays, namely Krabovaya and Otradnaya bays, had different requirements for environmental temperature, suggesting these different diatoms were brought to the bays by the tsunami wave entraining various water masses when skirting the island from the north and from the south.  相似文献   

2.
The M w = 9.0 earthquake that occurred off the coast of Japan’s Tohoku region produced a great tsunami causing catastrophic damage and loss of life. Within hours of the tsunami event, satellite data were readily available and massive media coverage immediately circulated thousands of photographs and videos of the tsunami. Satellite data allow a rapid assessment of inundated areas where access can be difficult either as a result of damaged infrastructure (e.g., roads, bridges, ports, airports) or because of safety issues (e.g., the hazard at Nuclear Power Plant at Fukushima). In this study, we assessed in a day tsunami inundation distances and runup heights using satellite data (very high-resolution satellite images from the GeoEye1 satellite and from the DigitalGlobe worldview, SRTM and ASTER GDEM) of the Tohoku region, Northeast Japan. Field survey data by Japanese and other international scientists validated our results. This study focused on three different locations. Site selection was based on coastal morphologies and the distance to the tsunami source (epicenter). Study sites are Rikuzentakata, Oyagawahama, and Yagawahama in the Oshika Peninsula, and the Sendai coastal plain (Sendai City to Yamamoto City). Maximum inundation distance (6 km along the river) and maximum runup (39 m) at Rikuzentakata estimated from satellite data agree closely with the 39.7 m inundation reported in the field. Here the ria coastal morphology and horn shaped bay enhanced the tsunami runup and effects. The Sendai coastal plain shows large inundation distances (6 km) and lower runup heights. Natori City and Wakabayashi Ward, on the Sendai plain, have similar runup values (12 and 16 m, respectively) obtained from SRTM data; these are comparable to those obtained from field surveys (12 and 9.5 m). However, at Yagawahama and Oyagawahama, Miyagi Prefecture, both SRTM and ASTER data provided maximum runup heights (41 to 45 m and 33 to 34 m, respectively), which are higher than those measured in the field (about 27 m). This difference in DEM and field data is associated with ASTER and SRTM DEM’s pixel size and vertical accuracy, the latter being dependent on ground coverage, slope, aspect and elevation. Countries with less access to technology and infrastructure can benefit from the use of satellite imagery and freely available DEMs for an initial, pre-field surveys, rapid estimate of inundated areas, distances and runup, and for assisting in hazard management and mitigation after a natural disaster.  相似文献   

3.
The tsunami generated by the 2011 Tohoku Earthquake (M w = 9.0) reached maximum heights of about 5 m along the coast of the Kuril Islands. The most essential feature of this event was sea ice about 0.5 m thick moved by the ocean water. The tsunami did not cause any essential damage on the Kuril Islands, but significantly affected coastal zones and produced interesting effects. The problem of a tsunami accompanied by marine ice is discussed and illustrated with photos.  相似文献   

4.
The 2010 Mentawai earthquake (magnitude 7.7) generated a destructive tsunami that caused more than 500 casualties in the Mentawai Islands, west of Sumatra, Indonesia. Seismological analyses indicate that this earthquake was an unusual “tsunami earthquake,” which produces much larger tsunamis than expected from the seismic magnitude. We carried out a field survey to measure tsunami heights and inundation distances, an inversion of tsunami waveforms to estimate the slip distribution on the fault, and inundation modeling to compare the measured and simulated tsunami heights. The measured tsunami heights at eight locations on the west coasts of North and South Pagai Island ranged from 2.5 to 9.3 m, but were mostly in the 4–7 m range. At three villages, the tsunami inundation extended more than 300 m. Interviews of local residents indicated that the earthquake ground shaking was less intense than during previous large earthquakes and did not cause any damage. Inversion of tsunami waveforms recorded at nine coastal tide gauges, a nearby GPS buoy, and a DART station indicated a large slip (maximum 6.1 m) on a shallower part of the fault near the trench axis, a distribution similar to other tsunami earthquakes. The total seismic moment estimated from tsunami waveform inversion was 1.0 × 1021 Nm, which corresponded to Mw 7.9. Computed coastal tsunami heights from this tsunami source model using linear equations are similar to the measured tsunami heights. The inundation heights computed by using detailed bathymetry and topography data and nonlinear equations including inundation were smaller than the measured ones. This may have been partly due to the limited resolution and accuracy of publically available bathymetry and topography data. One-dimensional run-up computations using our surveyed topography profiles showed that the computed heights were roughly similar to the measured ones.  相似文献   

5.
Modeling of the 2011 Japan Tsunami: Lessons for Near-Field Forecast   总被引：2，自引：0，他引：2  
During the devastating 11 March 2011 Japanese tsunami, data from two tsunami detectors were used to determine the tsunami source within 1.5 h of earthquake origin time. For the first time, multiple near-field tsunami measurements of the 2011 Japanese tsunami were used to demonstrate the accuracy of the National Oceanic and Atmospheric Administration (NOAA) real-time flooding forecast system in the far field. To test the accuracy of the same forecast system in the near field, a total of 11 numerical models with grids telescoped to 2 arcsec (~60 m) were developed to hindcast the propagation and coastal inundation of the 2011 Japanese tsunami along the entire east coastline of Japan. Using the NOAA tsunami source computed in near real-time, the model results of tsunami propagation are validated with tsunami time series measured at different water depths offshore and near shore along Japan’s coastline. The computed tsunami runup height and spatial distribution are highly consistent with post-tsunami survey data collected along the Japanese coastline. The computed inundation penetration also agrees well with survey data, giving a modeling accuracy of 85.5 % for the inundation areas along 800 km of coastline between Ibaraki Prefecture (north of Kashima) and Aomori Prefecture (south of Rokkasho). The inundation model results highlighted the variability of tsunami impact in response to different offshore bathymetry and flooded terrain. Comparison of tsunami sources inferred from different indirect methods shows the crucial importance of deep-ocean tsunami measurements for real-time tsunami forecasts. The agreement between model results and observations along Japan’s coastline demonstrate the ability and potential of NOAA’s methodology for real-time near-field tsunami flooding forecasts. An accurate tsunami flooding forecast within 30 min may now be possible using the NOAA forecast methodology with carefully placed tsunameters and large-scale high-resolution inundation models with powerful computing capabilities.  相似文献   

6.
Field Survey of the 27 February 2010 Chile Tsunami   总被引：1，自引：0，他引：1  
On 27 February 2010, a magnitude M w?=?8.8 earthquake occurred off the coast of Chile??s Maule region causing substantial damage and loss of life. Ancestral tsunami knowledge from the 1960 event combined with education and evacuation exercises prompted most coastal residents to spontaneously evacuate after the earthquake. Many of the tsunami victims were tourists in coastal campgrounds. The international tsunami survey team (ITST) was deployed within days of the event and surveyed 800?km of coastline from Quintero to Mehuín and the Pacific Islands of Santa María, Mocha, Juan Fernández Archipelago, and Rapa Nui (Easter). The collected survey data include more than 400 tsunami flow depth, runup and coastal uplift measurements. The tsunami peaked with a localized runup of 29?m on a coastal bluff at Constitución. The observed runup distributions exhibit significant variations on local and regional scales. Observations from the 2010 and 1960 Chile tsunamis are compared.  相似文献   

7.
This paper presents the results from an extensive field data collection effort following the December 26, 2004 earthquake and tsunami in Banda Aceh, Sumatra. The data were collected under the auspices of TSUNARISQUE, a joint French-Indonesian program dedicated to tsunami research and hazard mitigation, which has been active since before the 2004 event. In total, data from three months of field investigations are presented, which detail important aspects of the tsunami inundation dynamics in Banda Aceh. These include measurements of runup, tsunami wave heights, flow depths, flow directions, event chronology and building damage patterns. The result is a series of detailed inundation maps of the northern and western coasts of Sumatra including Banda Aceh and Lhok Nga. Among the more important findings, we obtained consistent accounts that approximately ten separate waves affected the region after the earthquake; this indicates a high-frequency component of the tsunami wave energy in the extreme near-field. The largest tsunami wave heights were on the order of 35 m with a maximum runup height of 51 m. This value is the highest runup value measured in human history for a seismically generated tsunami. In addition, our field investigations show a significant discontinuity in the tsunami wave heights and flow depths along a line approximately 3 km inland, which the authors interpret to be the location of the collapse of the main tsunami bore caused by sudden energy dissipation. The propagating bore looked like a breaking wave from the landward side although it has distinct characteristics. Patterns of building damage are related to the location of the propagating bore with overall less damage to buildings beyond the line where the bore collapsed. This data set was built to be of use to the tsunami community for the purposes of calibrating and improving existing tsunami inundation models, especially in the analysis of extreme near-field events.  相似文献   

8.
Historic‐ and prehistoric‐tsunami sand deposits are used to independently establish runup records for tsunami hazard mitigation and modeled runup verification in Crescent City, California, located in the southern Cascadia Subduction Zone. Inundation from historic (1964) farfield tsunami (~5–6 m runup height) left sand sheet deposits (100–200 m width) in wetlands located behind a low beach ridge [3–4 m elevation of the National Geodetic Vertical Datum of 1988 (NAVD88)]. The most landward flooding lines (4·5–5 m elevation) in high‐gradient alluvial wetlands exceed the 1964 sand sheet records of inundation by 1–2 m in elevation. The most landward flooding in low‐gradient alluvial wetlands exceed the corresponding sand sheet record of inundation distance by 1000 m. Nevertheless, the sand sheet record is an important proxy for high‐velocity inundation. Sand sheet deposition from the 1964 historic tsunami closely corresponds to the landward extent of large debris transport and structural damage in the Crescent City waterfront. The sand sheet deposits provide a proxy for maximum hazard or ‘kill zone’ in the study area. Six paleotsunami sand sheets (0·3–3 ka) are recorded in the back‐ridge marshes in Crescent City, yielding a ~450 year mean recurrence interval for nearfield Cascadia tsunami. Two paleotsunami sand deposit records, likely correlated to Cascadia ruptures between 1·0 and 1·5 ka, are traced to 1·2 km distance and 9–10 m elevation, as adjusted for paleo‐sea level. The paleotsunami sand deposits demonstrate at least twice the runup height, and four times the inundation distance of the farfield 1964 tsunami sand sheet in the same marsh system. The preserved paleotsunami deposits in Crescent City are compared to the most landward flooding, as modeled by other investigators from a predicted Cascadia (~ Mw 9) rupture. The short geologic record (~1·5 ka) yields slightly lower runup records than those predicted for the modeled Mw 9 rupture scenario in the same marsh, but it generally verifies predicted maximum tsunami runup for use in the planning of emergency response and rapid evacuation. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

9.
On November 15, 2006, Crescent City in Del Norte County, California was hit by a tsunami generated by a M w 8.3 earthquake in the central Kuril Islands. Strong currents that persisted over an eight-hour period damaged floating docks and several boats and caused an estimated $9.2 million in losses. Initial tsunami alert bulletins issued by the West Coast Alaska Tsunami Warning Center (WCATWC) in Palmer, Alaska were cancelled about three and a half hours after the earthquake, nearly five hours before the first surges reached Crescent City. The largest amplitude wave, 1.76-meter peak to trough, was the sixth cycle and arrived over two hours after the first wave. Strong currents estimated at over 10 knots, damaged or destroyed three docks and caused cracks in most of the remaining docks. As a result of the November 15 event, WCATWC changed the definition of Advisory from a region-wide alert bulletin meaning that a potential tsunami is 6 hours or further away to a localized alert that tsunami water heights may approach warning- level thresholds in specific, vulnerable locations like Crescent City. On January 13, 2007 a similar Kuril event occurred and hourly conferences between the warning center and regional weather forecasts were held with a considerable improvement in the flow of information to local coastal jurisdictions. The event highlighted the vulnerability of harbors from a relatively modest tsunami and underscored the need to improve public education regarding the duration of the tsunami hazards, improve dialog between tsunami warning centers and local jurisdictions, and better understand the currents produced by tsunamis in harbors.  相似文献   

10.
—The 1994 great Kuril earthquake generated an unusual tsunami that was observed at five tide gauges on the Hokkaido coast of the Okhotsk Sea. The tsunami arrived at tide gauges considerably earlier than the expected time, calculated on the assumption that the tsunami source area coincides with the aftershock area. Numerical simulation of the tsunami shows that the first wave of the tsunami in the Okhotsk Sea was generated by the significant subsidence north of the Kuril Islands. It is assumed that this subsidence is due to the earthquake. The coseismic deformation area of the ocean bottom extended over a vastly larger area than the aftershock area or the rupture area for the Kuril earthquake. The numerical simulation also shows that the tsunami observed at Utoro during the first hour after the origin time of the earthquake was mainly generated by the horizontal movement of the sloping ocean bottom near the Shiretoko Peninsula.  相似文献   

11.
We calculated tsunami runup probability (in excess of 0.5 m) at coastal sites throughout the Caribbean region. We applied a Poissonian probability model because of the variety of uncorrelated tsunami sources in the region. Coastlines were discretized into 20 km by 20 km cells, and the mean tsunami runup rate was determined for each cell. The remarkable ~500-year empirical record compiled by O’Loughlin and Lander (2003) was used to calculate an empirical tsunami probability map, the first of three constructed for this study. However, it is unclear whether the 500-year record is complete, so we conducted a seismic moment-balance exercise using a finite-element model of the Caribbean-North American plate boundaries and the earthquake catalog, and found that moment could be balanced if the seismic coupling coefficient is c = 0.32. Modeled moment release was therefore used to generate synthetic earthquake sequences to calculate 50 tsunami runup scenarios for 500-year periods. We made a second probability map from numerically-calculated runup rates in each cell. Differences between the first two probability maps based on empirical and numerical-modeled rates suggest that each captured different aspects of tsunami generation; the empirical model may be deficient in primary plate-boundary events, whereas numerical model rates lack backarc fault and landslide sources. We thus prepared a third probability map using Bayesian likelihood functions derived from the empirical and numerical rate models and their attendant uncertainty to weight a range of rates at each 20 km by 20 km coastal cell. Our best-estimate map gives a range of 30-year runup probability from 0–30% regionally.  相似文献   

12.
The importance of accurate tsunami simulation has increased since the 2004 Sumatra-Andaman earthquake and the Indian Ocean tsunami that followed it, because it is an important tool for inundation mapping and, potentially, tsunami warning. An important source of uncertainty in tsunami simulations is the source model, which is often estimated from some combination of seismic, geodetic or geological data. A magnitude 8.3 earthquake that occurred in the Kuril subduction zone on 15 November, 2006 resulted in the first teletsunami to be widely recorded by bottom pressure recorders deployed in the northern Pacific Ocean. Because these recordings were unaffected by shallow complicated bathymetry near the coast, this provides a unique opportunity to investigate whether seismic rupture models can be inferred from teleseismic waves with sufficient accuracy to be used to forecast teletsunami. In this study, we estimated the rupture model of the 2006 Kuril earthquake by inverting the teleseimic waves and used that to model the tsunami source. The tsunami propagation was then calculated by solving the linear long-wave equations. We found that the simulated 2006 Kuril tsunami compared very well to the ocean bottom recordings when simultaneously using P and long-period surface waves in the earthquake source process inversion.  相似文献   

13.
On 11 March 2011, a moment magnitude M w = 9.0 earthquake occurred off the Japan Tohoku coast causing catastrophic damage and loss of human lives. In the immediate aftermath of the earthquake, we conducted the reconnaissance survey in the city of Rikuzentakata, Japan. In comparison with three previous historical tsunamis impacting the same region, the 2011 event presented the largest values with respect to the tsunami height, the inundation area and the inundation distance. A representative tsunami height of 15 m was recorded in Rikuzentakata, with increased heights of 20 m around rocky headlands. In terms of the inundation area, the 2011 Tohoku tsunami exceeded by almost 2.6 times the area flooded by the 1960 Chilean tsunami, which ranks second among the four events compared. The maximum tsunami inundation distance was 8.1 km along the Kesen River, exceeding the 1933 Showa and 1960 Chilean tsunami inundations by factors of 6.2 and 2.7, respectively. The overland tsunami inundation distance was less than 2 km. The tsunami inundation height linearly decreased along the Kesen River at a rate of approximately 1 m/km. Nevertheless, the measured inland tsunami heights exhibit significant variations on local and regional scales. A designated “tsunami control forest” planted with a cross-shore width of about 200 m along a 2 km stretch of Rikuzentakata coastline was completely overrun and failed to protect the local community during this extreme event. Similarly, many designated tsunami shelters were too low and were overwashed by tsunami waves, thereby failing to provide shelter for evacuees—a risk that had been underestimated.  相似文献   

14.
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15.
On March 11th 2011 a M w 9.0 mega-thrust interface subduction earthquake, the Great East Japan Earthquake, occurred 130 km off the northeast coast of Japan in the Pacific Ocean at the Japan Trench, triggering tsunami which caused damage along 600 km of coastline. Observations of damage to buildings (including vertical evacuation facilities) and coastal defences in Tōhoku are presented following investigation by the Earthquake Engineering Field Investigation Team (EEFIT) at 10 locations in Iwate and Miyagi Prefectures. Observations are presented in the context of the coastal setting and tsunami characteristics experienced at each location. Damage surveys were carried out in Kamaishi City and Kesennuma City using a damage scale for reinforced concrete (RC), timber and steel frame buildings adapted from an earlier EEFIT tsunami damage scale. Observations show that many sea walls and breakwaters were overtopped, overturned, or broken up, but provided some degree of protection. We show the extreme variability of damage in a local area due to inundation depth, flow direction, velocity variations and sheltering. Survival of many RC shear wall structures shows their high potential to withstand local earthquake and significant tsunami inundation but further research is required into mitigation of scour, liquefaction, debris impact, and the prevention of overturning failure. Damage to steel and timber buildings are also discussed. These observations are intended to contribute to mitigation of future earthquake and tsunami damage by highlighting the key features which influence damage level and local variability of damage sustained by urban coastal infrastructure when subjected to extreme tsunami inundation depths.  相似文献   

16.
Tsunami Sediment Characteristics at the Thai Andaman Coast   总被引：1，自引：0，他引：1  
This paper describes and summarizes the 2004 Indian Ocean tsunami sediment characteristics at the Thai Andaman coast. Field investigations have been made approximately 3 years after the 2004 Indian Ocean tsunami event. Seven transects have been examined at five locations. Sediment samples have been collected for grain-size analyses by wet-sieve method. Tsunami sediments are compared to three deposits from coastal sub-environments. The mean grain-size and standard deviation of deposits show that shoreface deposits are fine to very fine sand, poorly to moderately well sorted; swash zone deposits are coarse to fine sand, poorly to well sorted; berm/dune deposits are medium to fine sand, poorly to well sorted; and tsunami deposits are coarse to very fine sand, poorly to moderately well sorted. A plot of deposit mean grain-size versus sorting indicates that tsunami deposits are composed of shoreface deposits, swash zone deposits and berm/dune deposits as well. The tsunami sediment is a gray sand layer deposited with an erosional base on a pre-existing soil (rooted soil). The thickness of the tsunami sediment layer is variable. The best location for observation of the recent tsunami sediment is at about 50–200 m inland from the coastline. In most cases, the sediment layer is normally graded. In some cases, the sediment contains rip-up clasts of muddy soils and/or organic matter. The vertical variation of tsunami sediment texture shows that the mean grain-size is fining upward and landward. Break points of slope in a plot of standard deviation versus depth mark a break in turbulence associated with a transition to a lower or higher Reynolds number runup. This can be used to evaluate tsunami sediment main layer and tsunami sediment sub layers. The skewness of tsunami sediment indicates a grain size distribution with prominent finer-grain or coarse-grain particles. The kurtosis of tsunami sediment indicates grain-size distributions which are flat to peak distribution (or multi-modal to uni-modal distribution) upward. Generally, the major origins of tsunami sediment are swash zone and berm/dune zone sands where coarse to medium sands are the significant material at these locations. The minor origin of tsunami sediment is the shoreface where the significant materials are fine to very fine sands. However, for a coastal area where the shoreface slope is mild, the major origin of tsunami sediment is the shoreface. The interpretation of runup number from tsunami sediment characteristics gets three runups for the 2004 Indian Ocean tsunami at the Thai Andaman coast. It corresponds to field observations from local eyewitnesses. The 1st runup transported and deposited more coarse particles than the following runups. Overall, the pattern of onshore tsunami sediment transportation indicates erosion at swash zone and berm/dune zone, followed by dynamic equilibrium at an area behind the berm/dune zone and after that deposition at inland zone until the limit of sediment inundation. The total deposition is a major pattern in onshore tsunami sediment transportation at the deposition zone which the sediment must find in the direction of transport.  相似文献   

17.
在分析3次千岛群岛大地震对应东北地区地震的基础上,讨论了在地质构造背景下千岛群岛大地震引起板块俯冲与我国东北地区地震的相关性.结果表明,千岛群岛发生7级以上地震对应东北地区地震有较强相关性;千岛群岛在大地震破裂过程中产生的俯冲作用自东向西对东北板块产生挤压作用,东北地震区相继发生了浅源地震;千岛群岛地区发生地震时,东北...  相似文献   

18.
We apply a recently developed and validated numerical model of tsunami propagation and runup to study the inundation of Resurrection Bay and the town of Seward by the 1964 Alaska tsunami. Seward was hit by both tectonic and landslide-generated tsunami waves during the $M_{\rm W}$ 9.2 1964 megathrust earthquake. The earthquake triggered a series of submarine mass failures around the fjord, which resulted in landsliding of part of the coastline into the water, along with the loss of the port facilities. These submarine mass failures generated local waves in the bay within 5?min of the beginning of strong ground motion. Recent studies estimate the total volume of underwater slide material that moved in Resurrection Bay to be about 211?million m3 (Haeussler et?al. in Submarine mass movements and their consequences, pp 269?C278, 2007). The first tectonic tsunami wave arrived in Resurrection Bay about 30?min after the main shock and was about the same height as the local landslide-generated waves. Our previous numerical study, which focused only on the local landslide-generated waves in Resurrection Bay, demonstrated that they were produced by a number of different slope failures, and estimated relative contributions of different submarine slide complexes into tsunami amplitudes (Suleimani et?al. in Pure Appl Geophys 166:131?C152, 2009). This work extends the previous study by calculating tsunami inundation in Resurrection Bay caused by the combined impact of landslide-generated waves and the tectonic tsunami, and comparing the composite inundation area with observations. To simulate landslide tsunami runup in Seward, we use a viscous slide model of Jiang and LeBlond (J Phys Oceanogr 24(3):559?C572, 1994) coupled with nonlinear shallow water equations. The input data set includes a high resolution multibeam bathymetry and LIDAR topography grid of Resurrection Bay, and an initial thickness of slide material based on pre- and post-earthquake bathymetry difference maps. For simulation of tectonic tsunami runup, we derive the 1964 coseismic deformations from detailed slip distribution in the rupture area, and use them as an initial condition for propagation of the tectonic tsunami. The numerical model employs nonlinear shallow water equations formulated for depth-averaged water fluxes, and calculates a temporal position of the shoreline using a free-surface moving boundary algorithm. We find that the calculated tsunami runup in Seward caused first by local submarine landslide-generated waves, and later by a tectonic tsunami, is in good agreement with observations of the inundation zone. The analysis of inundation caused by two different tsunami sources improves our understanding of their relative contributions, and supports tsunami risk mitigation in south-central Alaska. The record of the 1964 earthquake, tsunami, and submarine landslides, combined with the high-resolution topography and bathymetry of Resurrection Bay make it an ideal location for studying tectonic tsunamis in coastal regions susceptible to underwater landslides.  相似文献   

19.
Erosion and Sedimentation from the 17 July, 1998 Papua New Guinea Tsunami   总被引：1，自引：0，他引：1  
— This paper describes erosion and sedimentation associated with the 17 July 1998 Papua New Guinea tsunami. Observed within two months of the tsunami, distinct deposits of a layer averaging 8-cm thick of gray sand rested on a brown muddy soil. In most cases the sand is normally graded, with more coarse sand near the base and fine sand at the top. In some cases the deposit contains rip-up clasts of muddy soil and in some locations it has a mud cap. Detailed measurements of coastal topography, tsunami flow height and direction indicators, and deposit thickness were made in the field, and samples of the deposit were collected for grain-size analysis in the laboratory. Four shore-normal transects were examined in detail to assess the shore-normal and along shore distribution of the tsunami deposit. Near the shoreline, the tsunami eroded approximately 10–25 cm of sand from the beach and berm. The sandy layer deposited by the tsunami began 50–150 m inland from the shoreline and extended across the coastal plain to within about 40 m of the limit of inundation; a total distance of up to 750 m from the beach. As much as 2/3 of the sand in the deposit originated from offshore. Across most of the coastal plain the deposit thickness and mean grain size varied little. In the along-shore direction the deposit thickness varied with the tsunami wave height; both largest near the entrance to Sissano Lagoon.  相似文献   

20.
A typical model of the source of a tsunami (“macroseismic source”) is suggested for use in approximate estimation of maximum tsunami height using straightforward numerical modeling. In this paper the model is tested using three actual events: the 1952 North Kuril Is., 1971 Moneron, and 1994 Shikotan earthquakes, which excited considerable tsunamis at Russia’s Far East coasts. Comparison of the maximum tsunami runup values as obtained in numerical experiments with observations of actual tsunamis showed that the numerical model proposed here is suitable for crude estimation of tsunami runup and tsunami waiting times for coastal population centers in the near zone of a tsunami source.  相似文献   

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