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Browsing by Author "Jaffe, BE"

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The 2011 Tohoku-oki tsunami — three years on
(Elsevier, 2014-12) Goto, K; Ikehara, K; Goff, JR; Chagué-Goff, C; Jaffe, BE
The 2011 Tohoku-oki tsunami that devastated the Pacific coast of Tohoku, Japan was a turning point for modern research. As a result of this event it was recognized that paleotsunami research is vital to help understand the size and recurrence interval of low-frequency large tsunamis. This paper reviews the progress of geological research on the 2011 Tohoku-oki tsunami and summarizes new questions that are arising out of this work. For example, recent work suggests that the landward extent and thickness of the sandy deposit, as well as the presence or absence of marine microfossils in the sediment are most likely to be mainly controlled by the initial wave properties, sediment source, offshore bathymetry and onshore topography. This in turn implies that there are certain relationships between the characteristics of a tsunami deposit and the wave properties and it may be possible to reconstruct the latter from the deposits. Offshore tsunami deposits related to the 2011 Tohoku-oki tsunami have also been well described. This recent research indicates that sedimentation and erosion in inner bay and open ocean (~ 20 m water depth) locations can be in the order of several meters, suggesting that the tsunami shear force was strong in the nearshore zone. On the other hand, sandy to muddy deposits a few centimeters thick were observed at about 100 to 6000 m water depth. It is likely that the tsunami resulted in resuspension of sea bottom sediments and that suspended material flowed downslope as a turbidity current or suspended flow, although many authors recognize the possibility that strong earthquake groundshaking might have also generated turbidity currents. Studies of the 2011 Tohoku-oki event have led researchers back to two of the fundamental issues of tsunami geology: understanding the linkage between onshore and offshore sedimentation and erosion, and establishing identification criteria for tsunami deposits. Moreover though, beyond the issue of simple tsunami geology, it is important for all researchers to communicate with governments and the general public in order to reduce future casualties by using risk assessments based on our understanding of infrequent large tsunamis.© 2014, Elsevier B.V.
Erosion, deposition and landscape change on the Sendai coastal plain, Japan, resulting from the March 11, 2011 Tohoku-oki tsunami
(Elsevier B.V., 2020-12-12) Richmond, B; Szczuciński, W; Chagué-Goff, C; Goto, K; Sugawara, D; Witter, R; Tappin, DR; Jaffe, BE; Fujino, S; Nishimura, Y; Goff, JR
Case studies of recent tsunami impacts have proven to be extremely useful in understanding the geologic processes involved during inundation and return flow, and refining the criteria used to identify paleotsunami deposits in the geologic record. Here, we report on erosion, deposition and associated landscape change resulting from the March 11, 2011 Tohoku-oki tsunami along a nearly 4.5 km shore-normal transect on the coastal plain near Sendai, Japan. The study area on the broad, low-relief prograding coastal Sendai plain comprised a sand beach backed by ~ 3 m high sand dunes and a forest, a wetland, the Teizan canal, agricultural rice fields, buildings and roads. Field observations focused on measurements of tsunami flow characteristics (height and direction), mapping of erosion features and assessing sediment deposition based on shallow trenches at 50–100 m spacing. Recorded tsunami inundation heights reached up to about 11 m above mean sea level within the first 500 m from the shoreline and then ranged between 3 and 5 m for the next 2 km, gradually decreasing to about 3 m close to the inundation limit. The tsunami deposit generally thinned landward from an average maximum ~ 30 cm thick sand deposit in the coastal forest to a thin mud drape several mm thick near the inundation limit. A discontinuous sand-dominated sheet was prevalent to about 2800 m from the shoreline where mud content then gradually increased further landward eventually resulting in a mud-dominated deposit ranging from 3.5 cm to a few mm thickness. The overall thinning and fining of the deposit was often interrupted by localized features that led to complex sedimentological relationships over short distances. Satellite imagery taken on 14 March 2011, 3 days after the Tohoku-oki Tsunami shows prominent foreshore incisions with 100 s + meters spacing alongshore, a foredune ridge that underwent severe erosion and development of a prominent shore-parallel elongated scour depression. Our field survey in early May 2011 revealed that the foreshore recovered quickly with rapid post-tsunami sediment deposition from incident waves, whereas the dune–ridge complex had undergone only minor re-working from eolian processes. © 2020 Elsevier B.V
Field observations of erosion, deposition, and tsunami flow characteristics on the Sendai Coastal Plain after the March 2011, Tohoku-oki Tsunami, Japan
(American Geophysical Union, 2011-11-05) Richmond, BM; Goto, K; Fujino, S; Nishimura, Y; Sugawara, D; Tappin, DR; Witter, RC; Jaffe, BE; Chagué-Goff, C; Szczuciński, W; Yulianto, E; Goff, JR
Historical and instrumental data show that the Pacific coast of Mexico has been exposed to destructive tsunamis over at least the past 500 years. This coast is also affected by hurricanes generated in the eastern Pacific. The great 1985 Mexico earthquake and its aftershock generated tsunamis that affected the Ixtapa-Zihuatanejo and Michoacán coast. The purpose of our study was two-fold, a) to determine whether we could distinguish storm from tsunami deposits, and b) whether tsunami deposits from historical events are preserved in the tropical environments of the Ixtapa-Zihuatanejo coast. Two anomalous sand units in the Ixtapa estuary are interpreted as the result of high-energy marine inundation events that occurred in the last century. Several lines of evidence using a multi-proxy approach (historical studies, interviews with local witnesses, geomorphological and geological surveys, coring and trenching, and laboratory analyses including grain size, micropaleontology, geochemistry, magnetic susceptibility and radiometric dating) indicate the occurrence of two tsunamis that we link to local events: the 1985 Mexico and possibly the 1979 Petatlan earthquakes. We thereby provide the first onshore geological evidence of historical tsunamis on the Pacific coast of Mexico. © American Geophysical Union
The future of tsunami research following the 2011 Tohoku-oki event
(Elsevier B.V., 2012-12-20) Goto, K; Chagué-Goff, C; Goff, JR; Jaffe, BE
In this paper we summarize the regional setting, our previous understanding of historical and pre-historical tsunamis on the Pacific coast of Tohoku, Japan, prior to the 2011 Tohoku-oki tsunami, and our current understanding of the sedimentological, geochemical and paleontological features of the onshore and offshore deposits of the event. Post-tsunami surveys revealed many new insights, such as; (1) the maximum extent of the sand deposit is sometimes only 60% of the inundation distance, (2) the inundation limit can be estimated by geochemical analysis even a few months after the event, (3) a minor amount of marine sediment was transported inland by the tsunami on the Sendai and adjacent plains with the major sediment sources being from beach and dune erosion or vented sediments from liquefaction, although nearshore and offshore surveys revealed that there was a significant amount of sediment transport on the seafloor, (4) coarse gravel deposits (~ 1 m in thickness) were usually thicker than the sand ones (~ 30 cm in thickness), and (5) beach erosion was minimal in some places while severe in others. Another important aspect of this event is that it was a large, infrequent, tsunami that took place where possible predecessors (e.g., AD869 Jōgan) were already known to have occurred based on historical and geological evidence. The AD869 Jōgan tsunami deposits are noticeably similar to the 2011 Tohoku-oki sands, therefore suggesting that the Jōgan and its source mechanism may have been larger than previously thought. While we have learned many lessons from the 2011 Tohoku-oki event, more research is needed to provide reliable tsunami risk assessments around the world. © 2020 Elsevier B.V.
Geological and geochemical field survey on the Sendai Plain following the 11 March 2011 Tohoku-Oki Tsunami
(American Geophysical Union, 2011-12-05) Chagué-Goff, C; Goto, K; Fujino, S; Nishimura, D; Szczuciński, W; Rishmond, B; Tappin, D; Jaffe, BE; Witter, R; Yulianto, K; Goff, JR
A post-tsunami survey was carried out in May 2011 by members of a UNESCO-IOC International Tsunami Survey Team. The geological and geochemical survey was carried out along a transect extending 4.5 km inland north of Sendai airport, and focused on tsunami flow characteristics, sedimentation and erosion, as well as assessing the impact of saltwater contamination on the paddy fields . Tsunami inundation in this area reached c. 4.5 km inland, and the limit was marked by the elevated Tobu Highway, except where underpass structures allowed inundation further inland. The tsunami deposit generally thinned and fined inland, with the sandy deposit thinning landward from about 30 cm thickness in the coastal forest to less than 0.5 cm c. 2.8 km inland. Rip-up clasts were observed mostly near the base of the sandy deposits. Further inland, the deposit was dominated by mud, although it contained thin sand laminae one to a few grain-thick up to the limit of inundation near Tobu Highway. The thickness of the tsunami deposit was found to show large variability over short distances. Erosion and liquefaction features were also commonly observed. Ponded water was reported between the coastal forest and up to 2.6 km inland, while salt crusts were observed on numerous rice paddy fields up to the limit of tsunami inundation, where the water had evaporated. Conductivity measurements of ponded water, canals, irrigation and drainage channels revealed that the water was still saline to brackish, despite >60 mm of precipitation in the two months since the tsunami. Elevated concentrations of water-leachable chloride (salt) were measured both in mud and sand deposits, where seawater had stagnated and evaporated.
Initial field survey report of the 2011 East Japan Tsunami in Sendai, Natori adn Iwanuma Cities
(UNESCO-IOC, 2011-07-10) Sugawara, D; Goto, K; Chagué-Goff, C; Fujino, S; Goff, JR; Jaffe, BE; Nishimura, Y; Richmond, B; Szczuciński, W; Tappin, DR; Witter, R; Yuliento, E
The East Japan Earthquake (Mw 9.0) and associated tsunami struck the Pacific coast of eastern Japan on March 11th, 2011 at 2:46 p.m. (Japan Standard Time). Maximum run-up heights reached about 40 m along the Sanriku region’s coast and around 10 m on the Sendai coastline. The coasts of Iwate, Miyagi and Fukushima Prefectures in particular were badly damaged, and a considerable amount of time and money will be required to restore these areas. Tsunami inundation up to 5 km inland occurred across the Sendai Plain, which remained partly flooded for several weeks after the event. Some areas were still under water 2 months after the earthquake, and are likely to remain flooded for some time as a result of subsidence. The Disaster Control Research Center at Tohoku University conducted scientific research of the inundated coastal plains of Sendai, Natori and Iwanuma Cities in collaboration with other research institutes from Japan and overseas with the support of UNESCO-IOC (Intergovernmental Oceanographic Commission). Data and samples collected during the field survey are now being analyzed by various institutes around the World. This report is a summary of our field survey that focused on an area to the north of Sendai Airport. Radioactivity data recorded at the time of survey are also provided.
Modern and possible paleotsunami deposits in Samenoura, Sanriku Coast, and their relation to tsunami source mechanisms
(Japan Geoscience Union Meeting, 2014-05-02) Sugawara, D; Nishimura, Y; Goto, K; Goff, JR; Jaffe, BE; Richmond, B; Chagué-Goff, C; Szczuciński, W; Yokoyama, Y; Miyairi, Y; Sawada, C
Samenoura is situated in the bay head of a small inlet on the Pacific coast of Oshika Peninsula, one of the nearest places to the epicenter of the 2011 Tohoku-oki Earthquake. According to the Joint Survey Group, wave heights were measured at more than 20 m near the coastline. This area was severely damaged as a result of both co-seismic subsidence and tsunami inundation. We carried out field surveys of the Tohoku-oki and paleotsunami deposits at Samenoura in March, May and October 2013. Sandy deposits laid down by the Tohoku-oki tsunami were up to 20 cm thick at locations with an elevation greater than 10 m, and were several cm thick within the forest higher up. The tsunami deposit also contained numerous shell fragments and foraminifera. Although some possible sources of the tsunami deposits can be attributed to narrow sandy beaches near the study area, the deposition of such a thick sandy deposit is more or less enigmatic, considering the steep Ria-type coastal topography.Using a gouge auger and geoslicer, we found at least two sand layers intercalated within muddy sediments. A volcanic ash layer, which corresponds to the AD 915 Towada-a tephra, was also identified from a horizon between these sand layers. The underlying sand layer was most probably laid down by the 869 Jogan earthquake tsunami, one of the large-scale events known to have affected the region. Previous studies of the Jogan tsunami have proposed several possible source models that involve an interplate thrust earthquake. Given that the local bathymetry and topography of Samenoura Bay may be sensitive to the waveform of a large-scale tsunami, paleotsunami deposits found from this area may be the key to determining the source mechanisms of events on the Sanriku Coast.In this presentation, the possible correlation of the sandy deposits with known paleotsunami events based on detailed radiocarbon dating is discussed. The hydrodynamic character and processes of tsunami sediment erosion and deposition in Samenoura Bay are analyzed using numerical modeling of both interplate and outer-rise earthquake scenarios. © Japan Geoscience Union Meeting, 2014.
New insights of tsunami hazard from the 2011 Tohoku-oki event
(Elsevier, 2011-12-01) Goto, K; Chagué-Goff, C; Fujino, S; Goff, JR; Jaffe, BE; Nishimura, Y; Richmond, B; Sugawara, D; Szczuciński, W; Tappin, DR; Witter, R; Yulianto, E
We report initial results from our recent field survey documenting the inundation and resultant deposits of the 2011 Tohoku-oki tsunami from Sendai Plain, Japan. The tsunami inundated up to 4.5 km inland but the >0.5 cm-thick sand deposit extended only 2.8 km (62% of the inundation distance). The deposit however continued as a mud layer to the inundation limit. The mud deposit contained high concentrations of water-leachable chloride and we conclude that geochemical markers and microfossil data may prove to be useful in identifying the maximum inundation limit of paleotsunamis that could extend well beyond any preserved sand layer. Our newly acquired data on the 2011 event suggest that previous estimates of paleotsunamis (e.g. 869 AD Jogan earthquake and tsunami) in this area have probably been underestimated. If the 2011 and 869 AD events are indeed comparable, the risk from these natural hazards in Japan is much greater than previously recognized. (c) 2011 Elsevier
Palaeotsunamis in the Pacific Islands
(Elsevier, 2011-07-01) Goff, JR; Chagué-Goff, C; Dominey-Howes, D; McAdoo, B; Cronin, S; Bonté-Grapetin, M; Nichol, SL; Horrocks, M; Cisternas, M; Lamarche, G; Pelletier, B; Jaffe, BE; Dudley, W
The recent 29 September 2009 South Pacific and 27 February 2010 Chilean events are a graphic reminder that the tsunami hazard and risk for the Pacific Ocean region should not be forgotten. Pacific Islands Countries (PICs) generally have short ( < 150 years) historic records, which means that to understand their tsunami hazard and risk researchers must study evidence for prehistoric events. However, our current state of knowledge of palaeotsunamis in PICs as opposed to their circum-Pacific counterparts is minimal at best. We briefly outline the limited extent of our current knowledge and propose an innovative methodology for future research in the Pacific. Each PLC represents a point source of information in the Pacific Ocean and this would allow their palaeotsunami records to be treated akin to palaeo-DART (R) (Deep-ocean Assessment and Reporting of Tsunamis) buoys. Contemporaneous palaeotsunamis from local, regional and distant sources could be identified by using the spatial distribution of island records throughout the Pacific Ocean in conjunction with robust event chronologies. This would be highly innovative and, more importantly, would help provide the building blocks necessary to achieve more meaningful disaster risk reduction for PICs. (C) 2010 Elsevier B.V.
Preface for special issue of marine geology: in the wake of the 2011 Tohoku-oki tsunami – three years on
(Elsevier, 2014-12) Goto, K; Chagué-Goff, C; Goff, JR; Ikehara, K; Jaffe, BE
The 2011 Tohoku-oki event that devastated the northeast coast of Japan gives us a rare opportunity to improve our knowledge about tsunami deposits. Before this event the geological evidence of historical and prehistoric tsunamis was generally not included in tsunami mitigation plans. The 2011 event clearly forces all those working on tsunami disaster mitigation to rethink the importance of geological data as a key line of evidence for understanding magnitudes intervals and magnitudes. The geological work related to this tsunami is of global interest. It is the appropriate time to produce a special issue that includes papers presenting a more in-depth analysis of the deposits, more highly developed numerical modeling, and analysis of high-resolution pre- and post-tsunami DEM data for the 2011 Tohoku-oki tsunami. The papers in this special issue provide many new insights to help us better understand the nature of the tsunami deposits, both onshore and offshore. This special issue includes 11 original papers and 1 review paper related to the 2011 Tohoku-oki tsunami event. The papers comprising this special issue of Marine Geology are focused on four primary topics: 1) Onshore sedimentation and erosion (Nandasena et al., 2013 (reprinted); Fujiwara and Tanigawa, 2014, Goto et al., 2014a, Koiwa et al., 2014, Schneider et al., 2014 and Yamada et al., 2014) 2) Offshore sedimentation and erosion (Ikehara et al., 2014--this issue and Kitahashi et al., 2014) 3) Linkage of offshore and onshore sedimentation by modeling (Sugawara et al., 2014) 4) Reinterpretation of beach ridge formation (Goff and Sugawara, 2014) 5) Terminology and social relevance 5) Terminology and social relevance (Goff et al., 2014, Goto et al., 2014b). © 2014 Published by Elsevier B.V.
Progress in palaeotsunami research
(Elsevier, 2012-01-01) Goff, JR; Chagué-Goff, C; Nichol, SL; Jaffe, BE; Dominey-Howes, D
The study of palaeotsunamis preserved in the sedimentary record has developed over the past three decades to a point where the criteria used to identify these events range from well-tested and accepted to new methods yet to receive wide application. In this paper we review progress with the development of these criteria and identify opportunities for refinements and for extending their application to new settings. The emphasis here is on promoting the use of multiple proxies, selected to best match the context of the site or region of interest. Ultimately, this requires that palaeotsunami research must be a multidisciplinary endeavour and indeed, extend beyond the geological sciences of sedimentology and stratigraphy and, to include knowledge and approaches from field such as archaeology, anthropology and sociology. We also argue that in some instances, despite the use of multiple proxies, the evidence for tsunami inundation of a coast simply may not be preserved. (C) 2011 Elsevier B.V.
The search for geologic evidence of distant-source tsunamis using new field data in California
(U.S. Geological Survey, 2014) Wilson, R; Hemphill-Haley, E; Jaffe, BE; Richmond, B; Peters, R; Graehl, N; Kelsey, H; Leeper, R; Watt, S; McGann, M; Hoirup, DF; Chagué-Goff, C; Goff, JR; Caldwell, D; Loofbourrow, C
A statewide assessment for geological evidence of tsunamis, primarily from distant-source events, found tsunami deposits at several locations, though evidence was absent at most locations evaluated. Several historical distant-source tsunamis, including the 1946 Aleutian, 1960 Chile, and 1964 Alaska events, caused inundation along portions of the northern and central California coast. Recent numerical tsunami modeling results identify the eastern Aleutian Islands subduction zone as the “worstcase” distant-source region, with the potential for causing tsunami runups of 7–10 m in northern and central California and 3–4 m in southern California. These model results, along with a review of historical topographic maps and past geotechnical evaluations, guided site selection for tsunami deposit surveys. A reconnaissance of 20 coastal marshlands was performed through site visits and coring of shallow surface sediments to determine if evidence for past tsunamis existed. Although conclusive evidence of tsunami deposits was not found at most of the sites evaluated, geologic evidence consistent with tsunami inundation was found at two locations: Three marshes in the Crescent City area and Pillar Point marsh near Half Moon Bay. Potential tsunami deposits were also evaluated at the Carpinteria Salt Marsh Reserve in Santa Barbara County. In Crescent City, deposits were ascribed to tsunamis on the basis of stratigraphic architecture, particle size, and microfossil content, and they were further assigned to the 1964 Alaska and 1700 Cascadia tsunamis on the basis of dating by cesium-137 and radiocarbon methods, respectively. The 1946 tsunami sand deposit was clearly identified throughout Pillar Point marsh, and one to two other similar but highly discontinuous sand layers were present within 0.5 m of the surface. A tsunami-origin interpretation for sand layers at Carpinteria is merely consistent with graded bedding and unsupported by diatom or foraminiferal assemblages. Additional studies, including age dating, grain-size, and microfossil analyses are underway for the deposits at Crescent City, Pillar Point marsh, and Carpinteria, which may help further identify if other tsunami deposits exist at those sites. The absence of evidence for tsunamis at other sites examined should not preclude further work beyond the reconnaissance-level investigations at those locations.
Using magnetic fabric to reconstruct the dynamics of tsunami deposition on the Sendai Plain, Japan — the 2011 Tohoku-oki tsunami
(Elsevier B.V., 2014-12-01) Schneider, JL; Chagué-Goff, C; Bouchez, JL; Goff, JR; Sugawara, D; Goto, K; Jaffe, BE; Richmond, B
The magnetic fabric and grain size of sand deposits emplaced during the 2011 Tohoku-oki tsunami were studied in five trenches along a 1800 m long shore normal transect on the Sendai plain as well as in a near shore sedimentary infill of a scour depression. The magnetic susceptibility in all deposits is due to ferromagnetic minerals (mainly magnetite) making the anisotropy of magnetic susceptibility (magnetic fabric) suitable for fabric analyses. The dominant magnetic fabric is planar in all trenches and stronger in finer-grained inland deposits than in the coarser sediments. This planar fabric is related to tractive shearing of the bedload basal portion of the tsunami flow that led to the deposition of traction carpet layers. Among the various fabric parameters used for this study, the vertical evolution of the shape factor (q) of the magnetic ellipsoid in each trench follows the evolution of the magnetic lineation (L) and foliation (F). These parameters provide information on the hydrodynamic energy (flow speed) fluctuations during the emplacement of the tsunami deposit. For the most proximal deposits, characterized by well-sorted reworked beach sand with minor fluctuations in grain-size distribution, the magnetic fabric is sensitive to hydrodynamic energy variations during sedimentation. Reconstruction of tsunami flow orientation in the sediments, based on the orientation of the mean Kmax calculated for each trench, appears to be unambiguous only for the sandy infills of small topographic depressions. The variations in flow direction indicators elsewhere could be related to local variation of the flow and to micro-topographic effects. These findings are encouraging for the use of the magnetic fabric proxy in the study of paleotsunami deposits. © 2014 Elsevier B.V.

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