Mechanism of the 2015 volcanic tsunami earthquake near Torishima, Japan

PubMed Central

Satake, Kenji

2018-01-01

Tsunami earthquakes are a group of enigmatic earthquakes generating disproportionally large tsunamis relative to seismic magnitude. These events occur most typically near deep-sea trenches. Tsunami earthquakes occurring approximately every 10 years near Torishima on the Izu-Bonin arc are another example. Seismic and tsunami waves from the 2015 event [Mw (moment magnitude) = 5.7] were recorded by an offshore seafloor array of 10 pressure gauges, ~100 km away from the epicenter. We made an array analysis of dispersive tsunamis to locate the tsunami source within the submarine Smith Caldera. The tsunami simulation from a large caldera-floor uplift of ~1.5 m with a small peripheral depression yielded waveforms remarkably similar to the observations. The estimated central uplift, 1.5 m, is ~20 times larger than that inferred from the seismologically determined non–double-couple source. Thus, the tsunami observation is not compatible with the published seismic source model taken at face value. However, given the indeterminacy of Mzx, Mzy, and M{tensile} of a shallow moment tensor source, it may be possible to find a source mechanism with efficient tsunami but inefficient seismic radiation that can satisfactorily explain both the tsunami and seismic observations, but this question remains unresolved. PMID:29740604

Mechanism of the 2015 volcanic tsunami earthquake near Torishima, Japan.

PubMed

Fukao, Yoshio; Sandanbata, Osamu; Sugioka, Hiroko; Ito, Aki; Shiobara, Hajime; Watada, Shingo; Satake, Kenji

2018-04-01

Tsunami earthquakes are a group of enigmatic earthquakes generating disproportionally large tsunamis relative to seismic magnitude. These events occur most typically near deep-sea trenches. Tsunami earthquakes occurring approximately every 10 years near Torishima on the Izu-Bonin arc are another example. Seismic and tsunami waves from the 2015 event [ M w (moment magnitude) = 5.7] were recorded by an offshore seafloor array of 10 pressure gauges, ~100 km away from the epicenter. We made an array analysis of dispersive tsunamis to locate the tsunami source within the submarine Smith Caldera. The tsunami simulation from a large caldera-floor uplift of ~1.5 m with a small peripheral depression yielded waveforms remarkably similar to the observations. The estimated central uplift, 1.5 m, is ~20 times larger than that inferred from the seismologically determined non-double-couple source. Thus, the tsunami observation is not compatible with the published seismic source model taken at face value. However, given the indeterminacy of M zx , M zy , and M {tensile} of a shallow moment tensor source, it may be possible to find a source mechanism with efficient tsunami but inefficient seismic radiation that can satisfactorily explain both the tsunami and seismic observations, but this question remains unresolved.

The tsunami source area of the 2003 Tokachi-oki earthquake estimated from tsunami travel times and its relationship to the 1952 Tokachi-oki earthquake

USGS Publications Warehouse

Hirata, K.; Tanioka, Y.; Satake, K.; Yamaki, S.; Geist, E.L.

2004-01-01

We estimate the tsunami source area of the 2003 Tokachi-oki earthquake (Mw 8.0) from observed tsunami travel times at 17 Japanese tide gauge stations. The estimated tsunami source area (???1.4 ?? 104 km2) coincides with the western-half of the ocean-bottom deformation area (???2.52 ?? 104 km2) of the 1952 Tokachi-oki earthquake (Mw 8.1), previously inferred from tsunami waveform inversion. This suggests that the 2003 event ruptured only the western-half of the 1952 rupture extent. Geographical distribution of the maximum tsunami heights in 2003 differs significantly from that of the 1952 tsunami, supporting this hypothesis. Analysis of first-peak tsunami travel times indicates that a major uplift of the ocean-bottom occurred approximately 30 km to the NNW of the mainshock epicenter, just above a major asperity inferred from seismic waveform inversion. Copyright ?? The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences.

Geological evidence for Holocene earthquakes and tsunamis along the Nankai-Suruga Trough, Japan

NASA Astrophysics Data System (ADS)

Garrett, Ed; Fujiwara, Osamu; Garrett, Philip; Heyvaert, Vanessa M. A.; Shishikura, Masanobu; Yokoyama, Yusuke; Hubert-Ferrari, Aurélia; Brückner, Helmut; Nakamura, Atsunori; De Batist, Marc

2016-04-01

The Nankai-Suruga Trough, lying immediately south of Japan's densely populated and highly industrialised southern coastline, generates devastating great earthquakes (magnitude > 8). Intense shaking, crustal deformation and tsunami generation accompany these ruptures. Forecasting the hazards associated with future earthquakes along this >700 km long fault requires a comprehensive understanding of past fault behaviour. While the region benefits from a long and detailed historical record, palaeoseismology has the potential to provide a longer-term perspective and additional insights. Here, we summarise the current state of knowledge regarding geological evidence for past earthquakes and tsunamis, incorporating literature originally published in both Japanese and English. This evidence comes from a wide variety of sources, including uplifted marine terraces and biota, marine and lacustrine turbidites, liquefaction features, subsided marshes and tsunami deposits in coastal lakes and lowlands. We enhance available results with new age modelling approaches. While publications describe proposed evidence from > 70 sites, only a limited number provide compelling, well-dated evidence. The best available records allow us to map the most likely rupture zones of eleven earthquakes occurring during the historical period. Our spatiotemporal compilation suggests the AD 1707 earthquake ruptured almost the full length of the subduction zone and that earthquakes in AD 1361 and 684 were predecessors of similar magnitude. Intervening earthquakes were of lesser magnitude, highlighting variability in rupture mode. Recurrence intervals for ruptures of the a single seismic segment range from less than 100 to more than 450 years during the historical period. Over longer timescales, palaeoseismic evidence suggests intervals ranging from 100 to 700 years. However, these figures reflect thresholds of evidence creation and preservation as well as genuine recurrence intervals. At present, we have

Tsunami Source Modeling of the 2015 Volcanic Tsunami Earthquake near Torishima, South of Japan

NASA Astrophysics Data System (ADS)

Sandanbata, O.; Watada, S.; Satake, K.; Fukao, Y.; Sugioka, H.; Ito, A.; Shiobara, H.

2017-12-01

An abnormal earthquake occurred at a submarine volcano named Smith Caldera, near Torishima Island on the Izu-Bonin arc, on May 2, 2015. The earthquake, which hereafter we call "the 2015 Torishima earthquake," has a CLVD-type focal mechanism with a moderate seismic magnitude (M5.7) but generated larger tsunami waves with an observed maximum height of 50 cm at Hachijo Island [JMA, 2015], so that the earthquake can be regarded as a "tsunami earthquake." In the region, similar tsunami earthquakes were observed in 1984, 1996 and 2006, but their physical mechanisms are still not well understood. Tsunami waves generated by the 2015 earthquake were recorded by an array of ocean bottom pressure (OBP) gauges, 100 km northeastern away from the epicenter. The waves initiated with a small downward signal of 0.1 cm and reached peak amplitude (1.5-2.0 cm) of leading upward signals followed by continuous oscillations [Fukao et al., 2016]. For modeling its tsunami source, or sea-surface displacement, we perform tsunami waveform simulations, and compare synthetic and observed waveforms at the OBP gauges. The linear Boussinesq equations are adapted with the tsunami simulation code, JAGURS [Baba et al., 2015]. We first assume a Gaussian-shaped sea-surface uplift of 1.0 m with a source size comparable to Smith Caldera, 6-7 km in diameter. By shifting source location around the caldera, we found the uplift is probably located within the caldera rim, as suggested by Sandanbata et al. [2016]. However, synthetic waves show no initial downward signal that was observed at the OBP gauges. Hence, we add a ring of subsidence surrounding the main uplift, and examine sizes and amplitudes of the main uplift and the subsidence ring. As a result, the model of a main uplift of around 1.0 m with a radius of 4 km surrounded by a ring of small subsidence shows good agreement of synthetic and observed waveforms. The results yield two implications for the deformation process that help us to understanding

Characteristics of pneumonia deaths after an earthquake and tsunami: an ecological study of 5.7 million participants in 131 municipalities, Japan

PubMed Central

Shibata, Yosuke; Ojima, Toshiyuki; Tomata, Yasutake; Okada, Eisaku; Nakamura, Mieko; Kawado, Miyuki; Hashimoto, Shuji

2016-01-01

Objective On 11 March 2011, the Great East Japan Earthquake struck off Japan. Although some studies showed that the earthquake increased the risk of pneumonia death, no study reported whether and how much a tsunami increased the risk. We examined the risk for pneumonia death after the earthquake/tsunami. Design This is an ecological study. Setting Data on population and pneumonia deaths obtained from the Vital Statistics 2010 and 2012, National Census 2010 and Basic Resident Register 2010 and 2012 in Japan. Participants About 5.7 million participants residing in Miyagi, Iwate and Fukushima Prefectures during 1 year after the disaster were targeted. All municipalities (n=131) were categorised into inland (n=93), that is, the earthquake-impacted area, and coastal types (n=38), that is, the earthquake-impacted and tsunami-impacted area. Outcome measures The number of pneumonia deaths per week was totalled from 12 March 2010 to 9 March 2012. The number of observed pneumonia deaths (O) and the sum of the sex and age classes in the observed population multiplied by the sex and age classes of expected pneumonia mortality (E) were calculated. Expected pneumonia mortality was the pneumonia mortality during the year before. Standardised mortality ratios (SMRs) were calculated for pneumonia deaths (O/E), adjusting for sex and age using the indirect method. SMRs were then calculated by coastal and inland municipalities. Results 6603 participants died of pneumonia during 1 year after the earthquake. SMRs increased significantly during the 1st–12th weeks. In the 2nd week, SMRs in coastal and inland municipalities were 2.49 (95% CI 2.02 to 7.64) and 1.48 (95% CI 1.24 to 2.61), respectively. SMRs of coastal municipalities were higher than those of inland municipalities. Conclusions An earthquake increased the risk of pneumonia death and tsunamis additionally increased the risk. PMID:26908515

The Japan Medical Association's disaster preparedness: lessons from the Great East Japan Earthquake and Tsunami.

PubMed

Ishii, Masami; Nagata, Takashi

2013-10-01

A complex disaster, the Great East Japan Earthquake of March 11, 2011, consisted of a large-scale earthquake, tsunami, and nuclear accident, resulting in more than 15 000 fatalities, injuries, and missing persons and damage over a 500-km area. The entire Japanese public was profoundly affected by "3/11." The risk of radiation exposure initially delayed the medical response, prolonging the recovery efforts. Japan's representative medical organization, the Japan Medical Association (JMA), began dispatching Japan Medical Association Teams (JMATs) to affected areas beginning March 15, 2011. About 1400 JMATs comprising nearly 5500 health workers were launched. The JMA coordinated JMAT operations and cooperated in conducting postmortem examination, transporting large quantities of medical supplies, and establishing a multiorganizational council to provide health assistance to disaster survivors. Importantly, these response efforts contributed to the complete recovery of the health care system in affected areas within 3 months, and by July 15, 2011, JMATs were withdrawn. Subsequently, JMATs II have been providing long-term continuing medical support to disaster-affected areas. However, Japan is at great risk for future natural disasters because of its Pacific Rim location. Also, its rapidly aging population, uneven distribution of and shortage of medical resources in regional communities, and an overburdened public health insurance system highlight the need for a highly prepared and effective disaster response system.

S-net project: Construction of large scale seafloor observatory network for tsunamis and earthquakes in Japan

NASA Astrophysics Data System (ADS)

Mochizuki, M.; Kanazawa, T.; Uehira, K.; Shimbo, T.; Shiomi, K.; Kunugi, T.; Aoi, S.; Matsumoto, T.; Sekiguchi, S.; Yamamoto, N.; Takahashi, N.; Shinohara, M.; Yamada, T.

2016-12-01

National Research Institute for Earth Science and Disaster Resilience ( NIED ) has launched the project of constructing an observatory network for tsunamis and earthquakes on the seafloor. The observatory network was named "S-net, Seafloor Observation Network for Earthquakes and Tsunamis along the Japan Trench". The S-net consists of 150 seafloor observatories which are connected in line with submarine optical cables. The total length of submarine optical cable is about 5,700 km. The S-net system extends along Kuril and Japan trenches around Japan islands from north to south covering the area between southeast off island of Hokkaido and off the Boso Peninsula, Chiba Prefecture. The project has been financially supported by MEXT Japan. An observatory package is 34cm in diameter and 226cm long. Each observatory equips two units of a high sensitive water-depth sensor as a tsunami meter and four sets of three-component seismometers. The water-depth sensor has measurement resolution of sub-centimeter level. Combination of multiple seismometers secures wide dynamic range and robustness of the observation that are needed for early earthquake warning. The S-net is composed of six segment networks that consists of about 25 observatories and 800-1,600km length submarine optical cable. Five of six segment networks except the one covering the outer rise area of the Japan Trench has been already installed. The data from the observatories on those five segment networks are being transferred to the data center at NIED on a real-time basis, and then verification of data integrity are being carried out at the present moment. Installation of the last segment network of the S-net, that is, the outer rise one is scheduled to be finished within FY2016. Full-scale operation of the S-net will start at FY2017. We will report construction and operation of the S-net submarine cable system as well as the outline of the obtained data in this presentation.

Two Cases of Tsunami Dust Pneumonia: Organizing Pneumonia Caused by the Inhalation of Dried Tsunami Sludge after the 2011 Great East Japan Earthquake.

PubMed

Yamanda, Shinsuke; Kobayashi, Seiichi; Hanagama, Masakazu; Sato, Hikari; Suzuki, Satoshi; Ueda, Shinsaku; Takahashi, Toru; Yanai, Masaru

We report two cases of organizing pneumonia (OP) secondary to the inhalation of the dried tsunami sludge which formed during the 2011 Great East Japan Earthquake and the consequent tsunami. After the disaster, both of these patients had been engaged in the restoration work. About half a month later, they developed shortness of breath and pulmonary infiltrates. These patients were diagnosed with interstitial pneumonia. Their biopsy specimens revealed multifocal peribronchiolitis and OP. An electron probe microanalysis of these specimens demonstrated the presence of elements from the earth's crust in the inflammatory lesions. These two cases indicate that exposure to dried tsunami sludge can cause OP.

Characteristics of pneumonia deaths after an earthquake and tsunami: an ecological study of 5.7 million participants in 131 municipalities, Japan.

PubMed

Shibata, Yosuke; Ojima, Toshiyuki; Tomata, Yasutake; Okada, Eisaku; Nakamura, Mieko; Kawado, Miyuki; Hashimoto, Shuji

2016-02-23

On 11 March 2011, the Great East Japan Earthquake struck off Japan. Although some studies showed that the earthquake increased the risk of pneumonia death, no study reported whether and how much a tsunami increased the risk. We examined the risk for pneumonia death after the earthquake/tsunami. This is an ecological study. Data on population and pneumonia deaths obtained from the Vital Statistics 2010 and 2012, National Census 2010 and Basic Resident Register 2010 and 2012 in Japan. About 5.7 million participants residing in Miyagi, Iwate and Fukushima Prefectures during 1 year after the disaster were targeted. All municipalities (n=131) were categorised into inland (n=93), that is, the earthquake-impacted area, and coastal types (n=38), that is, the earthquake-impacted and tsunami-impacted area. The number of pneumonia deaths per week was totalled from 12 March 2010 to 9 March 2012. The number of observed pneumonia deaths (O) and the sum of the sex and age classes in the observed population multiplied by the sex and age classes of expected pneumonia mortality (E) were calculated. Expected pneumonia mortality was the pneumonia mortality during the year before. Standardised mortality ratios (SMRs) were calculated for pneumonia deaths (O/E), adjusting for sex and age using the indirect method. SMRs were then calculated by coastal and inland municipalities. 6603 participants died of pneumonia during 1 year after the earthquake. SMRs increased significantly during the 1st-12th weeks. In the 2nd week, SMRs in coastal and inland municipalities were 2.49 (95% CI 2.02 to 7.64) and 1.48 (95% CI 1.24 to 2.61), respectively. SMRs of coastal municipalities were higher than those of inland municipalities. An earthquake increased the risk of pneumonia death and tsunamis additionally increased the risk. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Real Time Earthquake Information System in Japan

NASA Astrophysics Data System (ADS)

Doi, K.; Kato, T.

2003-12-01

An early earthquake notification system in Japan had been developed by the Japan Meteorological Agency (JMA) as a governmental organization responsible for issuing earthquake information and tsunami forecasts. The system was primarily developed for prompt provision of a tsunami forecast to the public with locating an earthquake and estimating its magnitude as quickly as possible. Years after, a system for a prompt provision of seismic intensity information as indices of degrees of disasters caused by strong ground motion was also developed so that concerned governmental organizations can decide whether it was necessary for them to launch emergency response or not. At present, JMA issues the following kinds of information successively when a large earthquake occurs. 1) Prompt report of occurrence of a large earthquake and major seismic intensities caused by the earthquake in about two minutes after the earthquake occurrence. 2) Tsunami forecast in around three minutes. 3) Information on expected arrival times and maximum heights of tsunami waves in around five minutes. 4) Information on a hypocenter and a magnitude of the earthquake, the seismic intensity at each observation station, the times of high tides in addition to the expected tsunami arrival times in 5-7 minutes. To issue information above, JMA has established; - An advanced nationwide seismic network with about 180 stations for seismic wave observation and about 3,400 stations for instrumental seismic intensity observation including about 2,800 seismic intensity stations maintained by local governments, - Data telemetry networks via landlines and partly via a satellite communication link, - Real-time data processing techniques, for example, the automatic calculation of earthquake location and magnitude, the database driven method for quantitative tsunami estimation, and - Dissemination networks, via computer-to-computer communications and facsimile through dedicated telephone lines. JMA operationally

Influence of the great East Japan earthquake and tsunami 2011 on occurrence of cerebrovascular diseases in Iwate, Japan.

PubMed

Omama, Shinichi; Yoshida, Yuki; Ogasawara, Kuniaki; Ogawa, Akira; Ishibashi, Yasuhiro; Nakamura, Motoyuki; Tanno, Kozo; Ohsawa, Masaki; Onoda, Toshiyuki; Itai, Kazuyoshi; Sakata, Kiyomi

2013-06-01

Little information is available regarding the occurrence of cerebrovascular diseases after tsunamis. This study was performed to determine the influence of the tsunami damage caused by the Great East Japan earthquake on occurrence of cerebrovascular diseases. Subjects from the coastline and inland areas of Iwate Prefecture who developed cerebrovascular diseases before and after the disaster were included in the analysis. Standardized incidence ratios of 2011 against the previous 3 years were calculated in two 4-week periods before and four 4-week periods after the disaster, according to stroke subtype, sex, age group, and flood damage. The standard incidence ratio for cerebrovascular diseases was 1.20 (1.00-1.40) in the first 4-week period after the disaster and was not significant in other periods. The standard incidence ratios in the first 4-week period for cerebral infarction, intracerebral hemorrhage, and subarachnoid hemorrhage were 1.22 (0.98-1.46), 1.15 (0.76-1.55), and 1.20 (0.52-1.88), respectively. These values were 1.51 (1.19-1.88) for men, 1.35 (1.06-1.64) for subjects aged ≥ 75 years, and 1.35 (1.06-1.64) for the high flooding areas. The standard incidence ratio of cerebral infarction in the first 4-week period for men aged ≥ 75 years in the high flooding areas was 2.34 (1.34-3.34). In the areas highly flooded by the tsunami caused by the Great East Japan earthquake, the occurrence of cerebral infarction among elderly men more than doubled in the first 4 weeks after the disaster.

Advanced Simulation of Coupled Earthquake and Tsunami Events

NASA Astrophysics Data System (ADS)

Behrens, Joern

2013-04-01

Tsunami-Earthquakes represent natural catastrophes threatening lives and well-being of societies in a solitary and unexpected extreme event as tragically demonstrated in Sumatra (2004), Samoa (2009), Chile (2010), or Japan (2011). Both phenomena are consequences of the complex system of interactions of tectonic stress, fracture mechanics, rock friction, rupture dynamics, fault geometry, ocean bathymetry, and coastline geometry. The ASCETE project forms an interdisciplinary research consortium that couples the most advanced simulation technologies for earthquake rupture dynamics and tsunami propagation to understand the fundamental conditions of tsunami generation. We report on the latest research results in physics-based dynamic rupture and tsunami wave propagation simulation, using unstructured and adaptive meshes with continuous and discontinuous Galerkin discretization approaches. Coupling both simulation tools - the physics-based dynamic rupture simulation and the hydrodynamic tsunami wave propagation - will give us the possibility to conduct highly realistic studies of the interaction of rupture dynamics and tsunami impact characteristics.

Tsunami hazards to U.S. coasts from giant earthquakes in Alaska

USGS Publications Warehouse

Ryan, Holly F.; von Huene, Roland E.; Scholl, Dave; Kirby, Stephen

2012-01-01

In the aftermath of Japan's devastating 11 March 2011Mw 9.0 Tohoku earthquake and tsunami, scientists are considering whether and how a similar tsunami could be generated along the Alaskan-Aleutian subduction zone (AASZ). A tsunami triggered by an earthquake along the AASZ would cross the Pacific Ocean and cause extensive damage along highly populated U.S. coasts, with ports being particularly vulnerable. For example, a tsunami in 1946 generated by a Mw 8.6 earthquake near Unimak Pass, Alaska (Figure 1a), caused significant damage along the U.S. West Coast, took 150 lives in Hawaii, and inundated shorelines of South Pacific islands and Antarctica [Fryer et al., 2004; Lopez and Okal, 2006]. The 1946 tsunami occurred before modern broadband seismometers were in place, and the mechanisms that created it remain poorly understood.

Long-term perspectives on giant earthquakes and tsunamis at subduction zones

USGS Publications Warehouse

Satake, K.; Atwater, B.F.; ,

2007-01-01

Histories of earthquakes and tsunamis, inferred from geological evidence, aid in anticipating future catastrophes. This natural warning system now influences building codes and tsunami planning in the United States, Canada, and Japan, particularly where geology demonstrates the past occurrence of earthquakes and tsunamis larger than those known from written and instrumental records. Under favorable circumstances, paleoseismology can thus provide long-term advisories of unusually large tsunamis. The extraordinary Indian Ocean tsunami of 2004 resulted from a fault rupture more than 1000 km in length that included and dwarfed fault patches that had broken historically during lesser shocks. Such variation in rupture mode, known from written history at a few subduction zones, is also characteristic of earthquake histories inferred from geology on the Pacific Rim. Copyright ?? 2007 by Annual Reviews. All rights reserved.

Geologic Evidence of Tsunamigenic Earthquakes from the Southern Part of the Japan Trench

NASA Astrophysics Data System (ADS)

Pilarczyk, J.; Sawai, Y.; Namegaya, Y.; Tamura, T.; Tanigawa, K.; Matsumoto, D.; Shinozaki, T.; Fujiwara, O.; Shishikura, M.; Shimada, Y.; Dura, T.; Horton, B.

2017-12-01

The northern and southern parts of the Japan Trench have generated earthquakes with moment magnitudes up to 8.0. Similarly, the middle part of the Japan Trench has historically generated tsunamigenic-earthquakes up to M 7.0. However, in 2011, the Tohoku-oki (M 9.0) event ruptured 500 km along the middle part of the Japan Trench and generated the largest known tsunami to have originated from this part of the subduction zone. Seismic models indicate that the Tohoku-oki earthquake may have transferred stress southwards down the fault to the potentially locked southern part of the Japan Trench. It is unknown if this transfer of stress could produce an earthquake and tsunami that would impact the metropolitan areas of east-central Japan in the near future that may be comparable in magnitude to the Tohoku-oki event. Here, we reconstruct the history of individual great earthquakes and accompanying tsunamis using geological records from the coastal zone adjacent to the southern part of the Japan Trench, providing an assessment of the seismic hazard for metropolitan areas in east-central Japan. In the Kujukuri strand plain, we found three anomalous marine sand layers intercalated within muddy peat, which can be traced 3.8 km inland and 50 km along the present Kujukuri coastline. Each sand layer has features consistent with tsunami deposits, such as a distinct erosional base, rip-up clasts, normal grading, and a mud drape. Preliminary radiocarbon dating suggests three tsunamis inundated the Kujukuri coastline over the last millennium.

Probabilistic tsunami hazard assessment based on the long-term evaluation of subduction-zone earthquakes along the Sagami Trough, Japan

NASA Astrophysics Data System (ADS)

Hirata, K.; Fujiwara, H.; Nakamura, H.; Osada, M.; Ohsumi, T.; Morikawa, N.; Kawai, S.; Maeda, T.; Matsuyama, H.; Toyama, N.; Kito, T.; Murata, Y.; Saito, R.; Takayama, J.; Akiyama, S.; Korenaga, M.; Abe, Y.; Hashimoto, N.; Hakamata, T.

2017-12-01

For the forthcoming large earthquakes along the Sagami Trough where the Philippine Sea Plate is subducting beneath the northeast Japan arc, the Earthquake Research Committee(ERC) /Headquarters for Earthquake Research Promotion, Japanese government (2014a) assessed that M7 and M8 class earthquakes will occur there and defined the possible extent of the earthquake source areas. They assessed 70% and 0% 5% of the occurrence probability within the next 30 years (from Jan. 1, 2014), respectively, for the M7 and M8 class earthquakes. First, we set possible 10 earthquake source areas(ESAs) and 920 ESAs, respectively, for M8 and M7 class earthquakes. Next, we constructed 125 characterized earthquake fault models (CEFMs) and 938 CEFMs, respectively, for M8 and M7 class earthquakes, based on "tsunami receipt" of ERC (2017) (Kitoh et al., 2016, JpGU). All the CEFMs are allowed to have a large slip area for expression of fault slip heterogeneity. For all the CEFMs, we calculate tsunamis by solving a nonlinear long wave equation, using FDM, including runup calculation, over a nesting grid system with a minimum grid size of 50 meters. Finally, we re-distributed the occurrence probability to all CEFMs (Abe et al., 2014, JpGU) and gathered excess probabilities for variable tsunami heights, calculated from all the CEFMs, at every observation point along Pacific coast to get PTHA. We incorporated aleatory uncertainties inherent in tsunami calculation and earthquake fault slip heterogeneity. We considered two kinds of probabilistic hazard models; one is "Present-time hazard model" under an assumption that the earthquake occurrence basically follows a renewal process based on BPT distribution if the latest faulting time was known. The other is "Long-time averaged hazard model" under an assumption that earthquake occurrence follows a stationary Poisson process. We fixed our viewpoint, for example, on the probability that the tsunami height will exceed 3 meters at coastal points in next

Towards coupled earthquake dynamic rupture and tsunami simulations: The 2011 Tohoku earthquake.

NASA Astrophysics Data System (ADS)

Galvez, Percy; van Dinther, Ylona

2016-04-01

The 2011 Mw9 Tohoku earthquake has been recorded with a vast GPS and seismic network given an unprecedented chance to seismologists to unveil complex rupture processes in a mega-thrust event. The seismic stations surrounding the Miyagi regions (MYGH013) show two clear distinct waveforms separated by 40 seconds suggesting two rupture fronts, possibly due to slip reactivation caused by frictional melting and thermal fluid pressurization effects. We created a 3D dynamic rupture model to reproduce this rupture reactivation pattern using SPECFEM3D (Galvez et al, 2014) based on a slip-weakening friction with sudden two sequential stress drops (Galvez et al, 2015) . Our model starts like a M7-8 earthquake breaking dimly the trench, then after 40 seconds a second rupture emerges close to the trench producing additional slip capable to fully break the trench and transforming the earthquake into a megathrust event. The seismograms agree roughly with seismic records along the coast of Japan. The resulting sea floor displacements are in agreement with 1Hz GPS displacements (GEONET). The simulated sea floor displacement reaches 8-10 meters of uplift close to the trench, which may be the cause of such a devastating tsunami followed by the Tohoku earthquake. To investigate the impact of such a huge uplift, we ran tsunami simulations with the slip reactivation model and plug the sea floor displacements into GeoClaw (Finite element code for tsunami simulations, George and LeVeque, 2006). Our recent results compare well with the water height at the tsunami DART buoys 21401, 21413, 21418 and 21419 and show the potential using fully dynamic rupture results for tsunami studies for earthquake-tsunami scenarios.

Analysis of changes in traumatic symptoms and daily life activity of children affected by the 2011 Japan earthquake and tsunami over time.

PubMed

Usami, Masahide; Iwadare, Yoshitaka; Watanabe, Kyota; Kodaira, Masaki; Ushijima, Hirokage; Tanaka, Tetsuya; Harada, Maiko; Tanaka, Hiromi; Sasaki, Yoshinori; Saito, Kazuhiko

2014-01-01

On March 11, 2011, Japan was struck by a massive earthquake and tsunami. The tsunami caused tremendous damage and traumatized a number of people, including children. This study aimed to compare traumatic symptoms and daily life activity among children 20 months after the 2011 Great East Japan Earthquake and Tsunami with those observed after 8 months. The study comprised two groups. The first comprised 12,524 kindergarten, elementary school, and junior high school children in Ishinomaki City, Miyagi Prefecture, Japan, who were evaluated 8 months after the disaster. The second comprised 10,597 children from the same place who were evaluated 20 months after the disaster. The Post Traumatic Stress Symptoms for Children 15 items (PTSSC-15), a self-completion questionnaire on traumatic symptoms, and a questionnaire on children's daily life were distributed to the children. An effective response was obtained from 11,639 (92.9%, 8 months after) and 10,597 (86.9%, 20 months after) children. The PTSSC-15 score was significantly higher in junior high school girls than in boys. The PTSSC-15 score was significantly higher in 4th-6th grade girls than in boys after 8 months. Elementary and junior high school children evaluated after 20 months had a significantly lower PTSSC-15 score than those evaluated after 8 months. The number of children having breakfast was significantly higher after 8 months than that after 20 months. In both the groups, children of all grades who had breakfast had a significantly lower PTSSC-15 score than those who did not have breakfast. We conclude that traumatic symptoms and daily life activity of children who survived the earthquake and tsunami improved over time.

Unusually large earthquakes inferred from tsunami deposits along the Kuril trench

USGS Publications Warehouse

Nanayama, F.; Satake, K.; Furukawa, R.; Shimokawa, K.; Atwater, B.F.; Shigeno, K.; Yamaki, S.

2003-01-01

The Pacific plate converges with northeastern Eurasia at a rate of 8-9 m per century along the Kamchatka, Kuril and Japan trenches. Along the southern Kuril trench, which faces the Japanese island of Hokkaido, this fast subduction has recurrently generated earthquakes with magnitudes of up to ???8 over the past two centuries. These historical events, on rupture segments 100-200 km long, have been considered characteristic of Hokkaido's plate-boundary earthquakes. But here we use deposits of prehistoric tsunamis to infer the infrequent occurrence of larger earthquakes generated from longer ruptures. Many of these tsunami deposits form sheets of sand that extend kilometres inland from the deposits of historical tsunamis. Stratigraphic series of extensive sand sheets, intercalated with dated volcanic-ash layers, show that such unusually large tsunamis occurred about every 500 years on average over the past 2,000-7,000 years, most recently ???350 years ago. Numerical simulations of these tsunamis are best explained by earthquakes that individually rupture multiple segments along the southern Kuril trench. We infer that such multi-segment earthquakes persistently recur among a larger number of single-segment events.

2011 Tohoku Earthquake and Japan's Nuclear Disaster - Implications for Indian Ocean Rim countries

NASA Astrophysics Data System (ADS)

Chadha, R. K.

2011-12-01

The Nuclear disaster in Japan after the M9.0 Tohoku earthquake on March 11, 2011 has elicited global response to have a relook at the safety aspects of the nuclear power plants from all angles including natural hazards like earthquakes and tsunami. Several countries have gone into safety audits of their nuclear programs in view of the experience in Japan. Tectonically speaking, countries located close to subduction zones or in direct line of impact of the subduction zones are the most vulnerable to earthquake or tsunami hazard, as these regions are the locale of great tsunamigenic earthquakes. The Japan disaster has also cautioned to the possibility of great impact to the critical structures along the coasts due to other ocean processes caused by ocean-atmosphere interactions and also due to global warming and sea level rise phenomena in future. This is particular true for island countries. The 2011 Tohoku earthquake in Japan will be remembered more because of its nuclear tragedy and tsunami rather than the earthquake itself. The disaster happened as a direct impact of a tsunami generated by the earthquake 130 km off the coast of Sendai in the Honshu region of Japan. The depth of the earthquake was about 25 km below the ocean floor and it occurred on a thrust fault causing a displacement of more than 20 meters. At few places, water is reported to have inundated areas up to 8-10 km inland. The height of the tsunami varied between 10 and 3 meters along the coast. Generally, during an earthquake damage to buildings or other structures occur due to strong shaking which is expressed in the form of ground accelerations 'g'. Although, Peak Ground Accelerations (PGA) consistently exceeded 2g at several places from Sendai down south, structures at the Fukushima Daiichi Nuclear Power Plant did not collapse due to the earthquake. In the Indian Ocean Rim countries, Indian, Pakistan and South Africa are the three countries where Nuclear power plants are operational, few of them

Earthquake and Tsunami Disaster Mitigation in the Marmara Region and Disaster Education in Turkey Part3

NASA Astrophysics Data System (ADS)

Kaneda, Yoshiyuki; Ozener, Haluk; Meral Ozel, Nurcan; Kalafat, Dogan; Ozgur Citak, Seckin; Takahashi, Narumi; Hori, Takane; Hori, Muneo; Sakamoto, Mayumi; Pinar, Ali; Oguz Ozel, Asim; Cevdet Yalciner, Ahmet; Tanircan, Gulum; Demirtas, Ahmet

2017-04-01

There have been many destructive earthquakes and tsunamis in the world.The recent events are, 2011 East Japan Earthquake/Tsunami in Japan, 2015 Nepal Earthquake and 2016 Kumamoto Earthquake in Japan, and so on. And very recently a destructive earthquake occurred in Central Italy. In Turkey, the 1999 Izmit Earthquake as the destructive earthquake occurred along the North Anatolian Fault (NAF). The NAF crosses the Sea of Marmara and the only "seismic gap" remains beneath the Sea of Marmara. Istanbul with high population similar to Tokyo in Japan, is located around the Sea of Marmara where fatal damages expected to be generated as compound damages including Tsunami and liquefaction, when the next destructive Marmara Earthquake occurs. The seismic risk of Istanbul seems to be under the similar risk condition as Tokyo in case of Nankai Trough earthquake and metropolitan earthquake. It was considered that Japanese and Turkish researchers can share their own experiences during past damaging earthquakes and can prepare for the future large earthquakes in cooperation with each other. Therefore, in 2013 the two countries, Japan and Turkey made an agreement to start a multidisciplinary research project, MarDiM SATREPS. The Project runs researches to aim to raise the preparedness for possible large-scale earthquake and Tsunami disasters in Marmara Region and it has four research groups with the following goals. 1) The first one is Marmara Earthquake Source region observational research group. This group has 4 sub-groups such as Seismicity, Geodesy, Electromagnetics and Trench analyses. Preliminary results such as seismicity and crustal deformation on the sea floor in Sea of Marmara have already achieved. 2) The second group focuses on scenario researches of earthquake occurrence along the North Anatolia Fault and precise tsunami simulation in the Marmara region. Research results from this group are to be the model of earthquake occurrence scenario in Sea of Marmara and the

Tsunami on Sanriku Coast in 1586: Orphan or Ghost Tsunami ?

NASA Astrophysics Data System (ADS)

Satake, K.

2017-12-01

The Peruvian earthquake on July 9, 1586 was the oldest earthquake that damaged Lima. The tsunami height was assigned as 24 m in Callao and 1-2 m in Miyagi prefecture in Japan by Soloviev and Go (1975). Dorbath et al. (1990) studied historical earthquakes in Peru and estimated that the 1586 earthquake was similar to the 1974 event (Mw 8.1) with source length of 175 km. They referred two different tsunami heights, 3. 7m and 24 m, in Callao, and judged that the latter was exaggerated. Okal et al. (2006) could not make a source model to explain both tsunami heights in Callao and Japan. More recently, Butler et al. (2017) estimated the age of coral boulders in Hawaii as AD 1572 +/- 21, speculated the tsunami source in Aleutians, and attributed it to the source of the 1586 tsunami in Japan. Historical tsunamis, both near-field and far-field, have been documented along the Sanriku coast since 1586 (e.g., Watanabe, 1998). However, there is no written document for the 1586 tsunami (Tsuji et al., 2013). Ninomiya (1960) compiled the historical tsunami records on the Sanriku coast soon after the 1960 Chilean tsunami, and correlated the legend of tsunami in Tokura with the 1586 Peruvian earthquake, although he noted that the dates were different. About the legend, he referred to Kunitomi(1933) who compiled historical tsunami data after the 1933 Showa Sanriku tsunami. Kunitomi referred to "Tsunami history of Miyagi prefecture" published after the 1896 Meiji Sanriku tsunami. "Tsunami history" described the earthquake and tsunami damage of Tensho earthquake on January 18 (Gregorian),1586 in central Japan, and correlated the tsunami legend in Tokura on June 30, 1586 (G). Following the 2011 Tohoku tsunami, tsunami legend in Tokura was studied again (Ebina, 2015). A local person published a story he heard from his grandfather that many small valleys were named following the 1611 tsunami, which inundated further inland than the 2011 tsunami. Ebina (2015), based on historical documents

A short history of tsunami research and countermeasures in Japan.

PubMed

Shuto, Nobuo; Fujima, Koji

2009-01-01

The tsunami science and engineering began in Japan, the country the most frequently hit by local and distant tsunamis. The gate to the tsunami science was opened in 1896 by a giant local tsunami of the highest run-up height of 38 m that claimed 22,000 lives. The crucial key was a tide record to conclude that this tsunami was generated by a "tsunami earthquake". In 1933, the same area was hit again by another giant tsunami. A total system of tsunami disaster mitigation including 10 "hard" and "soft" countermeasures was proposed. Relocation of dwelling houses to high ground was the major countermeasures. The tsunami forecasting began in 1941. In 1960, the Chilean Tsunami damaged the whole Japanese Pacific coast. The height of this tsunami was 5-6 m at most. The countermeasures were the construction of structures including the tsunami breakwater which was the first one in the world. Since the late 1970s, tsunami numerical simulation was developed in Japan and refined to become the UNESCO standard scheme that was transformed to 22 different countries. In 1983, photos and videos of a tsunami in the Japan Sea revealed many faces of tsunami such as soliton fission and edge bores. The 1993 tsunami devastated a town protected by seawalls 4.5 m high. This experience introduced again the idea of comprehensive countermeasures, consisted of defense structure, tsunami-resistant town development and evacuation based on warning.

Paleo-tsunami history along the northern Japan Trench: evidence from Noda Village, northern Sanriku coast, Japan

NASA Astrophysics Data System (ADS)

Inoue, Taiga; Goto, Kazuhisa; Nishimura, Yuichi; Watanabe, Masashi; Iijima, Yasutaka; Sugawara, Daisuke

2017-12-01

Throughout history, large tsunamis have frequently affected the Sanriku area of the Pacific coast of the Tohoku region, Japan, which faces the Japan Trench. Although a few studies have examined paleo-tsunami deposits along the Sanriku coast, additional studies of paleo-earthquakes and tsunamis are needed to improve our knowledge of the timing, recurrence interval, and size of historical and pre-historic tsunamis. At Noda Village, in Iwate Prefecture on the northern Sanriku coast, we found at least four distinct gravelly sand layers based on correlation and chronological data. Sedimentary features such as grain size and thickness suggest that extreme waves from the sea formed these layers. Numerical modeling of storm waves further confirmed that even extremely large storm waves cannot account for the distribution of the gravelly sand layers, suggesting that these deposits are highly likely to have formed by tsunami waves. The numerical method of storm waves can be useful to identify sand layers as tsunami deposits if the deposits are observed far inland or at high elevations. The depositional age of the youngest tsunami deposit is consistent with the AD 869 Jogan earthquake tsunami, a possible predecessor of the AD 2011 Tohoku-oki tsunami. If this is the case, then the study site currently defines the possible northern extent of the AD 869 Jogan tsunami deposit, which is an important step in improving the tsunami source model of the AD 869 Jogan tsunami. Our results suggest that four large tsunamis struck the Noda site between 1100 and 2700 cal BP. The local tsunami sizes are comparable to the AD 2011 and AD 1896 Meiji Sanriku tsunamis, considering the landward extent of each tsunami deposit.

Geological and historical evidence of irregular recurrent earthquakes in Japan.

PubMed

Satake, Kenji

2015-10-28

Great (M∼8) earthquakes repeatedly occur along the subduction zones around Japan and cause fault slip of a few to several metres releasing strains accumulated from decades to centuries of plate motions. Assuming a simple 'characteristic earthquake' model that similar earthquakes repeat at regular intervals, probabilities of future earthquake occurrence have been calculated by a government committee. However, recent studies on past earthquakes including geological traces from giant (M∼9) earthquakes indicate a variety of size and recurrence interval of interplate earthquakes. Along the Kuril Trench off Hokkaido, limited historical records indicate that average recurrence interval of great earthquakes is approximately 100 years, but the tsunami deposits show that giant earthquakes occurred at a much longer interval of approximately 400 years. Along the Japan Trench off northern Honshu, recurrence of giant earthquakes similar to the 2011 Tohoku earthquake with an interval of approximately 600 years is inferred from historical records and tsunami deposits. Along the Sagami Trough near Tokyo, two types of Kanto earthquakes with recurrence interval of a few hundred years and a few thousand years had been recognized, but studies show that the recent three Kanto earthquakes had different source extents. Along the Nankai Trough off western Japan, recurrence of great earthquakes with an interval of approximately 100 years has been identified from historical literature, but tsunami deposits indicate that the sizes of the recurrent earthquakes are variable. Such variability makes it difficult to apply a simple 'characteristic earthquake' model for the long-term forecast, and several attempts such as use of geological data for the evaluation of future earthquake probabilities or the estimation of maximum earthquake size in each subduction zone are being conducted by government committees. © 2015 The Author(s).

Earthquake and Tsunami booklet based on two Indonesia earthquakes

NASA Astrophysics Data System (ADS)

Hayashi, Y.; Aci, M.

2014-12-01

Many destructive earthquakes occurred during the last decade in Indonesia. These experiences are very important precepts for the world people who live in earthquake and tsunami countries. We are collecting the testimonies of tsunami survivors to clarify successful evacuation process and to make clear the characteristic physical behaviors of tsunami near coast. We research 2 tsunami events, 2004 Indian Ocean tsunami and 2010 Mentawai slow earthquake tsunami. Many video and photographs were taken by people at some places in 2004 Indian ocean tsunami disaster; nevertheless these were few restricted points. We didn't know the tsunami behavior in another place. In this study, we tried to collect extensive information about tsunami behavior not only in many places but also wide time range after the strong shake. In Mentawai case, the earthquake occurred in night, so there are no impressive photos. To collect detail information about evacuation process from tsunamis, we contrived the interview method. This method contains making pictures of tsunami experience from the scene of victims' stories. In 2004 Aceh case, all survivors didn't know tsunami phenomena. Because there were no big earthquakes with tsunami for one hundred years in Sumatra region, public people had no knowledge about tsunami. This situation was highly improved in 2010 Mentawai case. TV programs and NGO or governmental public education programs about tsunami evacuation are widespread in Indonesia. Many people know about fundamental knowledge of earthquake and tsunami disasters. We made drill book based on victim's stories and painted impressive scene of 2 events. We used the drill book in disaster education event in school committee of west Java. About 80 % students and teachers evaluated that the contents of the drill book are useful for correct understanding.

A Coupled Earthquake-Tsunami Simulation Framework Applied to the Sumatra 2004 Event

NASA Astrophysics Data System (ADS)

Vater, Stefan; Bader, Michael; Behrens, Jörn; van Dinther, Ylona; Gabriel, Alice-Agnes; Madden, Elizabeth H.; Ulrich, Thomas; Uphoff, Carsten; Wollherr, Stephanie; van Zelst, Iris

2017-04-01

Large earthquakes along subduction zone interfaces have generated destructive tsunamis near Chile in 1960, Sumatra in 2004, and northeast Japan in 2011. In order to better understand these extreme events, we have developed tools for physics-based, coupled earthquake-tsunami simulations. This simulation framework is applied to the 2004 Indian Ocean M 9.1-9.3 earthquake and tsunami, a devastating event that resulted in the loss of more than 230,000 lives. The earthquake rupture simulation is performed using an ADER discontinuous Galerkin discretization on an unstructured tetrahedral mesh with the software SeisSol. Advantages of this approach include accurate representation of complex fault and sea floor geometries and a parallelized and efficient workflow in high-performance computing environments. Accurate and efficient representation of the tsunami evolution and inundation at the coast is achieved with an adaptive mesh discretizing the shallow water equations with a second-order Runge-Kutta discontinuous Galerkin (RKDG) scheme. With the application of the framework to this historic event, we aim to better understand the involved mechanisms between the dynamic earthquake within the earth's crust, the resulting tsunami wave within the ocean, and the final coastal inundation process. Earthquake model results are constrained by GPS surface displacements and tsunami model results are compared with buoy and inundation data. This research is part of the ASCETE Project, "Advanced Simulation of Coupled Earthquake and Tsunami Events", funded by the Volkswagen Foundation.

Concerns over modeling and warning capabilities in wake of Tohoku Earthquake and Tsunami

NASA Astrophysics Data System (ADS)

Showstack, Randy

2011-04-01

Improved earthquake models, better tsunami modeling and warning capabilities, and a review of nuclear power plant safety are all greatly needed following the 11 March Tohoku earthquake and tsunami, according to scientists at the European Geosciences Union's (EGU) General Assembly, held 3-8 April in Vienna, Austria. EGU quickly organized a morning session of oral presentations and an afternoon panel discussion less than 1 month after the earthquake and the tsunami and the resulting crisis at Japan's Fukushima nuclear power plant, which has now been identified as having reached the same level of severity as the 1986 Chernobyl disaster. Many of the scientists at the EGU sessions expressed concern about the inability to have anticipated the size of the earthquake and the resulting tsunami, which appears likely to have caused most of the fatalities and damage, including damage to the nuclear plant.

Analysis of Changes in Traumatic Symptoms and Daily Life Activity of Children Affected by the 2011 Japan Earthquake and Tsunami over Time

PubMed Central

Usami, Masahide; Iwadare, Yoshitaka; Watanabe, Kyota; Kodaira, Masaki; Ushijima, Hirokage; Tanaka, Tetsuya; Harada, Maiko; Tanaka, Hiromi; Sasaki, Yoshinori; Saito, Kazuhiko

2014-01-01

Background On March 11, 2011, Japan was struck by a massive earthquake and tsunami. The tsunami caused tremendous damage and traumatized a number of people, including children. This study aimed to compare traumatic symptoms and daily life activity among children 20 months after the 2011 Great East Japan Earthquake and Tsunami with those observed after 8 months. Methods The study comprised two groups. The first comprised 12,524 kindergarten, elementary school, and junior high school children in Ishinomaki City, Miyagi Prefecture, Japan, who were evaluated 8 months after the disaster. The second comprised 10,597 children from the same place who were evaluated 20 months after the disaster. The Post Traumatic Stress Symptoms for Children 15 items (PTSSC-15), a self-completion questionnaire on traumatic symptoms, and a questionnaire on children's daily life were distributed to the children. An effective response was obtained from 11,639 (92.9%, 8 months after) and 10,597 (86.9%, 20 months after) children. Results The PTSSC-15 score was significantly higher in junior high school girls than in boys. The PTSSC-15 score was significantly higher in 4th–6th grade girls than in boys after 8 months. Elementary and junior high school children evaluated after 20 months had a significantly lower PTSSC-15 score than those evaluated after 8 months. The number of children having breakfast was significantly higher after 8 months than that after 20 months. In both the groups, children of all grades who had breakfast had a significantly lower PTSSC-15 score than those who did not have breakfast. Conclusions We conclude that traumatic symptoms and daily life activity of children who survived the earthquake and tsunami improved over time. PMID:24586427

NASA MISR Images Tsunami Inundation Along Japan Eastern Coast

NASA Image and Video Library

2011-03-12

The extent of inundation from the destructive and deadly tsunami triggered by the March 11, 2011, magnitude 8.9 earthquake centered off Japan northeastern coast east of the city of Sendai is revealed in this image pair from NASA Terra spacecraft.

Tsunami Numerical Simulation for Hypothetical Giant or Great Earthquakes along the Izu-Bonin Trench

NASA Astrophysics Data System (ADS)

Harada, T.; Ishibashi, K.; Satake, K.

2013-12-01

We performed tsunami numerical simulations from various giant/great fault models along the Izu-Bonin trench in order to see the behavior of tsunamis originated in this region and to examine the recurrence pattern of great interplate earthquakes along the Nankai trough off southwest Japan. As a result, large tsunami heights are expected in the Ryukyu Islands and on the Pacific coasts of Kyushu, Shikoku and western Honshu. The computed large tsunami heights support the hypothesis that the 1605 Keicho Nankai earthquake was not a tsunami earthquake along the Nankai trough but a giant or great earthquake along the Izu-Bonin trench (Ishibashi and Harada, 2013, SSJ Fall Meeting abstract). The Izu-Bonin subduction zone has been regarded as so-called 'Mariana-type subduction zone' where M>7 interplate earthquakes do not occur inherently. However, since several M>7 outer-rise earthquakes have occurred in this region and the largest slip of the 2011 Tohoku earthquake (M9.0) took place on the shallow plate interface where the strain accumulation had considered to be a little, a possibility of M>8.5 earthquakes in this region may not be negligible. The latest M 7.4 outer-rise earthquake off the Bonin Islands on Dec. 22, 2010 produced small tsunamis on the Pacific coast of Japan except for the Tohoku and Hokkaido districts and a zone of abnormal seismic intensity in the Kanto and Tohoku districts. Ishibashi and Harada (2013) proposed a working hypothesis that the 1605 Keicho earthquake which is considered a great tsunami earthquake along the Nankai trough was a giant/great earthquake along the Izu-Bonin trench based on the similarity of the distributions of ground shaking and tsunami of this event and the 2010 Bonin earthquake. In this study, in order to examine the behavior of tsunamis from giant/great earthquakes along the Izu-Bonin trench and check the Ishibashi and Harada's hypothesis, we performed tsunami numerical simulations from fault models along the Izu-Bonin trench

Sleep duration among children 8 months after the 2011 Japan earthquake and tsunami.

PubMed

Usami, Masahide; Iwadare, Yoshitaka; Kodaira, Masaki; Watanabe, Kyota; Aoki, Momoko; Katsumi, Chiaki; Matsuda, Kumi; Makino, Kazunori; Iijima, Sonoko; Harada, Maiko; Tanaka, Hiromi; Sasaki, Yoshinori; Tanaka, Tetsuya; Ushijima, Hirokage; Saito, Kazuhiko

2013-01-01

To elucidate relationships between disaster damage conditions and sleep duration among children who survived the 2011 Japan earthquake and tsunami. The subjects comprised 12,524 children in kindergartens, elementary schools, and junior high schools in Ishinomaki City, Miyagi Prefecture, Japan. The Post Traumatic Stress Symptoms for Children 15 items (PTSSC-15), a self-completion questionnaire on traumatic symptoms, and a sleep questionnaire were distributed to them. A questionnaire regarding disaster damage conditions of the children's homes was distributed to their teachers. Of 12,524, an effective response was obtained from 11,692 (93.3%). Relationships between sleep duration and traumatic symptoms were displayed low correlations. Children with house damage and/or evacuation experiences slept for a significantly shorter time than children without these experiences. It is critical not only to examine traumatic symptoms in children but also to collect sleep duration and disaster damage conditions following natural disasters.

Alaska earthquake source for the SAFRR tsunami scenario: Chapter B in The SAFRR (Science Application for Risk Reduction) Tsunami Scenario

USGS Publications Warehouse

Kirby, Stephen; Scholl, David; von Huene, Roland E.; Wells, Ray

2013-01-01

Tsunami modeling has shown that tsunami sources located along the Alaska Peninsula segment of the Aleutian-Alaska subduction zone have the greatest impacts on southern California shorelines by raising the highest tsunami waves for a given source seismic moment. The most probable sector for a Mw ~ 9 source within this subduction segment is between Kodiak Island and the Shumagin Islands in what we call the Semidi subduction sector; these bounds represent the southwestern limit of the 1964 Mw 9.2 Alaska earthquake rupture and the northeastern edge of the Shumagin sector that recent Global Positioning System (GPS) observations indicate is currently creeping. Geological and geophysical features in the Semidi sector that are thought to be relevant to the potential for large magnitude, long-rupture-runout interplate thrust earthquakes are remarkably similar to those in northeastern Japan, where the destructive Mw 9.1 tsunamigenic earthquake of 11 March 2011 occurred. In this report we propose and justify the selection of a tsunami source seaward of the Alaska Peninsula for use in the Tsunami Scenario that is part of the U.S. Geological Survey (USGS) Science Application for Risk Reduction (SAFRR) Project. This tsunami source should have the potential to raise damaging tsunami waves on the California coast, especially at the ports of Los Angeles and Long Beach. Accordingly, we have summarized and abstracted slip distribution from the source literature on the 2011 event, the best characterized for any subduction earthquake, and applied this synoptic slip distribution to the similar megathrust geometry of the Semidi sector. The resulting slip model has an average slip of 18.6 m and a moment magnitude of Mw = 9.1. The 2011 Tohoku earthquake was not anticipated, despite Japan having the best seismic and geodetic networks in the world and the best historical record in the world over the past 1,500 years. What was lacking was adequate paleogeologic data on prehistoric earthquakes

Reexamination of the magnitudes for the 1906 and 1922 Chilean earthquakes using Japanese tsunami amplitudes: Implications for source depth constraints

USGS Publications Warehouse

Carvajal, M.; Cisternas, M.; Gubler, A.; Catalan, P. A.; Winckler, P.; Wesson, Robert L.

2017-01-01

Far-field tsunami records from the Japanese tide gauge network allow the reexamination of the moment magnitudes (Mw) for the 1906 and 1922 Chilean earthquakes, which to date rely on limited information mainly from seismological observations alone. Tide gauges along the Japanese coast provide extensive records of tsunamis triggered by six great (Mw >8) Chilean earthquakes with instrumentally determined moment magnitudes. These tsunami records are used to explore the dependence of tsunami amplitudes in Japan on the parent earthquake magnitude of Chilean origin. Using the resulting regression parameters together with tide gauge amplitudes measured in Japan we estimate apparent moment magnitudes of Mw 8.0–8.2 and Mw8.5–8.6 for the 1906 central and 1922 north-central Chile earthquakes. The large discrepancy of the 1906 magnitude estimated from the tsunami observed in Japan as compared with those previously determined from seismic waves (Ms 8.4) suggests a deeper than average source with reduced tsunami excitation. A deep dislocation along the Chilean megathrust would favor uplift of the coast rather than beneath the sea, giving rise to a smaller tsunami and producing effects consistent with those observed in 1906. The 1922 magnitude inferred from far-field tsunami amplitudes appear to better explain the large extent of damage and the destructive tsunami that were locally observed following the earthquake than the lower seismic magnitudes (Ms 8.3) that were likely affected by the well-known saturation effects. Thus, a repeat of the large 1922 earthquake poses seismic and tsunami hazards in a region identified as a mature seismic gap.

Numerical experiment on tsunami deposit distribution process by using tsunami sediment transport model in historical tsunami event of megathrust Nankai trough earthquake

NASA Astrophysics Data System (ADS)

Imai, K.; Sugawara, D.; Takahashi, T.

2017-12-01

A large flow caused by tsunami transports sediments from beach and forms tsunami deposits in land and coastal lakes. A tsunami deposit has been found in their undisturbed on coastal lakes especially. Okamura & Matsuoka (2012) found some tsunami deposits in the field survey of coastal lakes facing to the Nankai trough, and tsunami deposits due to the past eight Nankai Trough megathrust earthquakes they identified. The environment in coastal lakes is stably calm and suitable for tsunami deposits preservation compared to other topographical conditions such as plains. Therefore, there is a possibility that the recurrence interval of megathrust earthquakes and tsunamis will be discussed with high resolution. In addition, it has been pointed out that small events that cannot be detected in plains could be separated finely (Sawai, 2012). Various aspects of past tsunami is expected to be elucidated, in consideration of topographical conditions of coastal lakes by using the relationship between the erosion-and-sedimentation process of the lake bottom and the external force of tsunami. In this research, numerical examination based on tsunami sediment transport model (Takahashi et al., 1999) was carried out on the site Ryujin-ike pond of Ohita, Japan where tsunami deposit was identified, and deposit migration analysis was conducted on the tsunami deposit distribution process of historical Nankai Trough earthquakes. Furthermore, examination of tsunami source conditions is possibly investigated by comparison studies of the observed data and the computation of tsunami deposit distribution. It is difficult to clarify details of tsunami source from indistinct information of paleogeographical conditions. However, this result shows that it can be used as a constraint condition of the tsunami source scale by combining tsunami deposit distribution in lakes with computation data.

Statistical Modeling of Fire Occurrence Using Data from the Tōhoku, Japan Earthquake and Tsunami.

PubMed

Anderson, Dana; Davidson, Rachel A; Himoto, Keisuke; Scawthorn, Charles

2016-02-01

In this article, we develop statistical models to predict the number and geographic distribution of fires caused by earthquake ground motion and tsunami inundation in Japan. Using new, uniquely large, and consistent data sets from the 2011 Tōhoku earthquake and tsunami, we fitted three types of models-generalized linear models (GLMs), generalized additive models (GAMs), and boosted regression trees (BRTs). This is the first time the latter two have been used in this application. A simple conceptual framework guided identification of candidate covariates. Models were then compared based on their out-of-sample predictive power, goodness of fit to the data, ease of implementation, and relative importance of the framework concepts. For the ground motion data set, we recommend a Poisson GAM; for the tsunami data set, a negative binomial (NB) GLM or NB GAM. The best models generate out-of-sample predictions of the total number of ignitions in the region within one or two. Prefecture-level prediction errors average approximately three. All models demonstrate predictive power far superior to four from the literature that were also tested. A nonlinear relationship is apparent between ignitions and ground motion, so for GLMs, which assume a linear response-covariate relationship, instrumental intensity was the preferred ground motion covariate because it captures part of that nonlinearity. Measures of commercial exposure were preferred over measures of residential exposure for both ground motion and tsunami ignition models. This may vary in other regions, but nevertheless highlights the value of testing alternative measures for each concept. Models with the best predictive power included two or three covariates. © 2015 Society for Risk Analysis.

Impact of earthquake-induced tsunamis on public health

NASA Astrophysics Data System (ADS)

Mavroulis, Spyridon; Mavrouli, Maria; Lekkas, Efthymios; Tsakris, Athanassios

2017-04-01

Tsunamis are caused by rapid sea floor displacement during earthquakes, landslides and large explosive eruptions in marine environment setting. Massive amounts of sea water in the form of devastating surface waves travelling hundreds of kilometers per hour have the potential to cause extensive damage to coastal infrastructures, considerable loss of life and injury and emergence of infectious diseases (ID). This study involved an extensive and systematic literature review of 50 research publications related to public health impact of the three most devastating tsunamis of the last 12 years induced by great earthquakes, namely the 2004 Sumatra-Andaman earthquake (moment magnitude Mw 9.2), the 2009 Samoa earthquake (Mw 8.1) and the 2011 Tōhoku (Japan) earthquake (Mw 9.0) in the Indian, Western Pacific and South Pacific Oceans respectively. The inclusion criteria were literature type comprising journal articles and official reports, natural disaster type including tsunamis induced only by earthquakes, population type including humans, and outcome measure characterized by disease incidence increase. The potential post-tsunami ID are classified into 11 groups including respiratory, pulmonary, wound-related, water-borne, skin, vector-borne, eye, fecal-oral, food-borne, fungal and mite-borne ID. Respiratory infections were detected after all the above mentioned tsunamis. Wound-related, skin and water-borne ID were observed after the 2004 and 2011 tsunamis, while vector-borne, fecal-oral and eye ID were observed only after the 2004 tsunami and pulmonary, food-borne and mite-borne ID were diagnosed only after the 2011 tsunami. Based on available age and genre data, it is concluded that the most vulnerable population groups are males, children (age ≤ 15 years) and adults (age ≥ 65 years). Tetanus and pneumonia are the deadliest post-tsunami ID. The detected risk factors include (1) lowest socioeconomic conditions, poorly constructed buildings and lack of prevention

Sleep Duration among Children 8 Months after the 2011 Japan Earthquake and Tsunami

PubMed Central

Usami, Masahide; Iwadare, Yoshitaka; Kodaira, Masaki; Watanabe, Kyota; Aoki, Momoko; Katsumi, Chiaki; Matsuda, Kumi; Makino, Kazunori; Iijima, Sonoko; Harada, Maiko; Tanaka, Hiromi; Sasaki, Yoshinori; Tanaka, Tetsuya; Ushijima, Hirokage; Saito, Kazuhiko

2013-01-01

Background To elucidate relationships between disaster damage conditions and sleep duration among children who survived the 2011 Japan earthquake and tsunami. Methods The subjects comprised 12,524 children in kindergartens, elementary schools, and junior high schools in Ishinomaki City, Miyagi Prefecture, Japan. The Post Traumatic Stress Symptoms for Children 15 items (PTSSC-15), a self-completion questionnaire on traumatic symptoms, and a sleep questionnaire were distributed to them. A questionnaire regarding disaster damage conditions of the children’s homes was distributed to their teachers. Of 12,524, an effective response was obtained from 11,692 (93.3%). Results Relationships between sleep duration and traumatic symptoms were displayed low correlations. Children with house damage and/or evacuation experiences slept for a significantly shorter time than children without these experiences. Conclusion It is critical not only to examine traumatic symptoms in children but also to collect sleep duration and disaster damage conditions following natural disasters. PMID:23738015

Impacts of tides on tsunami propagation due to potential Nankai Trough earthquakes in the Seto Inland Sea, Japan

NASA Astrophysics Data System (ADS)

Lee, Han Soo; Shimoyama, Tomohisa; Popinet, Stéphane

2015-10-01

The impacts of tides on extreme tsunami propagation due to potential Nankai Trough earthquakes in the Seto Inland Sea (SIS), Japan, are investigated through numerical experiments. Tsunami experiments are conducted based on five scenarios that consider tides at four different phases, such as flood, high, ebb, and low tides. The probes that were selected arbitrarily in the Bungo and Kii Channels show less significant effects of tides on tsunami heights and the arrival times of the first waves than those that experience large tidal ranges in inner basins and bays of the SIS. For instance, the maximum tsunami height and the arrival time at Toyomaesi differ by more than 0.5 m and nearly 1 h, respectively, depending on the tidal phase. The uncertainties defined in terms of calculated maximum tsunami heights due to tides illustrate that the calculated maximum tsunami heights in the inner SIS with standing tides have much larger uncertainties than those of two channels with propagating tides. Particularly in Harima Nada, the uncertainties due to the impacts of tides are greater than 50% of the tsunami heights without tidal interaction. The results recommend simulate tsunamis together with tides in shallow water environments to reduce the uncertainties involved with tsunami modeling and predictions for tsunami hazards preparedness. This article was corrected on 26 OCT 2015. See the end of the full text for details.

Hazard Assessment and Early Warning of Tsunamis: Lessons from the 2011 Tohoku earthquake

NASA Astrophysics Data System (ADS)

Satake, K.

2012-12-01

The March 11, 2011 Tohoku earthquake (M 9.0) was the largest earthquake in Japanese history, and was the best recorded subduction-zone earthquakes in the world. In particular, various offshore geophysical observations revealed large horizontal and vertical seafloor movements, and the tsunami was recorded on high-quality, high-sampling gauges. Analysis of such tsunami waveforms shows a temporal and spatial slip distribution during the 2011 Tohoku earthquake. The fault rupture started near the hypocenter and propagated into both deep and shallow parts of the plate interface. Very large, ~25 m, slip off Miyagi on the deep part of plate interface corresponds to an interplate earthquake of M 8.8, the location and size similar to 869 Jogan earthquake model, and was responsible for the large tsunami inundation in Sendai and Ishinomaki plains. Huge slip, more than 50 m, occurred on the shallow part near the trench axis ~3 min after the earthquake origin time. This delayed shallow rupture (M 8.8) was similar to the 1896 "tsunami earthquake," and was responsible for the large tsunami on the northern Sanriku coast, measured at ~100 km north of the largest slip. Thus the Tohoku earthquake can be decomposed into an interplate earthquake and the triggered "tsunami earthquake." The Japan Meteorological Agency issued tsunami warning 3 minutes after the earthquake, and saved many lives. However, their initial estimation of tsunami height was underestimated, because the earthquake magnitude was initially estimated as M 7.9, hence the computed tsunami heights were lower. The JMA attempts to improve the tsunami warning system, including technical developments to estimate the earthquake size in a few minutes by using various and redundant information, to deploy and utilize the offshore tsunami observations, and to issue a warning based on the worst case scenario if a possibility of giant earthquake exists. Predicting a trigger of another large earthquake would still be a challenge

Listening to the 2011 magnitude 9.0 Tohoku-Oki, Japan, earthquake

USGS Publications Warehouse

Peng, Zhigang; Aiken, Chastity; Kilb, Debi; Shelly, David R.; Enescu, Bogdan

2012-01-01

The magnitude 9.0 Tohoku-Oki, Japan, earthquake on 11 March 2011 is the largest earthquake to date in Japan’s modern history and is ranked as the fourth largest earthquake in the world since 1900. This earthquake occurred within the northeast Japan subduction zone (Figure 1), where the Pacific plate is subducting beneath the Okhotsk plate at rate of ∼8–9 cm/yr (DeMets et al. 2010). This type of extremely large earthquake within a subduction zone is generally termed a “megathrust” earthquake. Strong shaking from this magnitude 9 earthquake engulfed the entire Japanese Islands, reaching a maximum acceleration ∼3 times that of gravity (3 g). Two days prior to the main event, a foreshock sequence occurred, including one earthquake of magnitude 7.2. Following the main event, numerous aftershocks occurred around the main slip region; the largest of these was magnitude 7.9. The entire foreshocks-mainshock-aftershocks sequence was well recorded by thousands of sensitive seismometers and geodetic instruments across Japan, resulting in the best-recorded megathrust earthquake in history. This devastating earthquake resulted in significant damage and high death tolls caused primarily by the associated large tsunami. This tsunami reached heights of more than 30 m, and inundation propagated inland more than 5 km from the Pacific coast, which also caused a nuclear crisis that is still affecting people’s lives in certain regions of Japan.

Patient trends in orthopedic traumas and related disorders after tsunami caused by the Great East Japan Earthquake: An experience in the primary referral medical center.

PubMed

Matsuzawa, Gaku; Sano, Hirotaka; Ohnuma, Hideji; Tomiya, Akihito; Kuwahara, Yoshiyuki; Hashimoto, Chihiro; Imamura, Itaru; Ishibashi, Satoru; Kobayashi, Michio; Kobayashi, Masakazu; Ishii, Tadashi; Kaneda, Iwao; Itoi, Eiji

2016-07-01

In the Great East Japan Earthquake, the Japanese Red Cross Ishinomaki Hospital played an important role as a principal referral center within the Ishinomaki region, one of the most severely affected areas in eastern Japan. The present study describes the patient population, clinical characteristics, and time courses of the medical problems observed at this hospital. A retrospective survey of medical logs and records was conducted on the first 2 weeks after the earthquake to characterize orthopedic traumas and related disorders treated during this catastrophe. Patient number, severity of injuries, number of patients secondarily transported to the referral medical centers in the inland area, and the number of surgeries performed during the study period were investigated. Totally, 7686 patients visited the hospital. Of which, 1807 patients suffered from exogenous diseases, such as trauma, burns, crush syndrome, deep venous thrombosis, and infectious diseases. Patients who suffered from hypothermia were the most frequently seen within the first 2 weeks after the earthquake. Interestingly, most patients' conditions were not severe and required only simple treatments. Four patients (0.2% of patients with exogenous diseases) were secondarily transported to the referral medical centers in the inland area and only four patients were surgically treated because of a lack of available implants, surgical devices, and electric power supply. The Great East Japan Earthquake and subsequent tsunami, which occurred during an early spring afternoon, resulted in a unique orthopedic patient population, which included few severely injured patients compared with numerous deaths. We believe that each coastal region hospital should develop its own emergency medical care system to address future tsunami events while considering their surrounding environment. The information described in the present study should be important for preparation toward future events involving massive earthquakes

Impact of the 11 March, 2011, Tohoku earthquake and tsunami on the chemical industry

NASA Astrophysics Data System (ADS)

Krausmann, E.; Cruz, A. M.

2012-04-01

An earthquake of magnitude 9.0 occurred off the Pacific coast of Tohoku, Japan, on March 11, 2011, at 14:46:23 Japan Standard Time (5:46:23 UTC). It generated a tsunami 130 km off the coast of Miyagi Prefecture in northeast Japan, which inundated over 400 km2 of land. The death toll has reached >15,800 according to the Japan National Policy Agency with over 3,700 still missing as of 26 October 2011. Significant damage to or complete collapse of houses also resulted. The earthquake generated strong ground motion; nevertheless most damage was caused by the tsunami, which is a tribute to the effectiveness of Japan's earthquake damage reduction measures in saving lives and property. Nonetheless, the direct losses amount to more than 200 billion US dollars (not counting the costs of the accident at the Fukushima nuclear power plant). The earthquake and tsunami had a significant impact on all types of industry, and in particular on the petrochemical and chemical industry in the affected areas, resulting in hazardous-materials releases, fires and explosions and forcing businesses to interrupt production. These so-called Natech accidents pose an immediate or even long-term threat to the population and the environment, and can also interrupt the supply chain. Overall, the earthquake and tsunami took over 30% of Japan's oil production offline, and two refineries are still not or only partially in operation to repair the damage caused by the fires and explosions. The fire-fighting efforts could only be started 4 days after the disaster due to the absence of personnel that had been evacuated and because of the continuing tsunami alerts. In one of the affected refineries the fires could only be extinguished 10 days after the disasters. Many petrochemical and chemical companies reported problems either due to damage to facilities or because of power outages. In fact, in facilities that suffered no or only minor damage the resuming of operations was hampered by continuous

Ray Tracing for Dispersive Tsunamis and Source Amplitude Estimation Based on Green's Law: Application to the 2015 Volcanic Tsunami Earthquake Near Torishima, South of Japan

NASA Astrophysics Data System (ADS)

Sandanbata, Osamu; Watada, Shingo; Satake, Kenji; Fukao, Yoshio; Sugioka, Hiroko; Ito, Aki; Shiobara, Hajime

2018-04-01

Ray tracing, which has been widely used for seismic waves, was also applied to tsunamis to examine the bathymetry effects during propagation, but it was limited to linear shallow-water waves. Green's law, which is based on the conservation of energy flux, has been used to estimate tsunami amplitude on ray paths. In this study, we first propose a new ray tracing method extended to dispersive tsunamis. By using an iterative algorithm to map two-dimensional tsunami velocity fields at different frequencies, ray paths at each frequency can be traced. We then show that Green's law is valid only outside the source region and that extension of Green's law is needed for source amplitude estimation. As an application example, we analyzed tsunami waves generated by an earthquake that occurred at a submarine volcano, Smith Caldera, near Torishima, Japan, in 2015. The ray-tracing results reveal that the ray paths are very dependent on its frequency, particularly at deep oceans. The validity of our frequency-dependent ray tracing is confirmed by the comparison of arrival angles and travel times with those of observed tsunami waveforms at an array of ocean bottom pressure gauges. The tsunami amplitude at the source is nearly twice or more of that just outside the source estimated from the array tsunami data by Green's law.

Far-field tsunami magnitude determined from ocean-bottom pressure gauge data around Japan

NASA Astrophysics Data System (ADS)

Baba, T.; Hirata, K.; Kaneda, Y.

2003-12-01

\\hspace*{3mm}Tsunami magnitude is the most fundamental parameter to scale tsunamigenic earthquakes. According to Abe (1979), the tsunami magnitude, Mt, is empirically related to the crest to trough amplitude, H, of the far-field tsunami wave in meters (Mt = logH + 9.1). Here we investigate the far-field tsunami magnitude using ocean-bottom pressure gauge data. The recent ocean-bottom pressure measurements provide more precise tsunami data with a high signal-to-noise ratio. \\hspace*{3mm}Japan Marine Science and Technology Center is monitoring ocean bottom pressure fluctuations using two submarine cables of depths of 1500 - 2400 m. These geophysical observatory systems are located off Cape Muroto, Southwest Japan, and off Hokkaido, Northern Japan. The ocean-bottom pressure data recorded with the Muroto and Hokkaido systems have been collected continuously since March, 1997 and October, 1999, respectively. \\hspace*{3mm}Over the period from March 1997 to June 2003, we have observed four far-field tsunami signals, generated by earthquakes, on ocean-bottom pressure records. These far-field tsunamis were generated by the 1998 Papua New Guinea eq. (Mw 7.0), 1999 Vanuatu eq. (Mw 7.2), 2001 Peru eq. (Mw 8.4) and 2002 Papua New Guinea eq. (Mw 7.6). Maximum amplitude of about 30 mm was recorded by the tsunami from the 2001 Peru earthquake. \\hspace*{3mm}Direct application of the Abe's empirical relation to ocean-bottom pressure gauge data underestimates tsunami magnitudes by about an order of magnitude. This is because the Abe's empirical relation was derived only from tsunami amplitudes with coastal tide gauges where tsunami is amplified by the shoaling of topography and the reflection at the coastline. However, these effects do not work for offshore tsunami in deep oceans. In general, amplification due to shoaling near the coastline is governed by the Green's Law, in which the tsunami amplitude is proportional to h-1/4, where h is the water depth. Wave amplitude also is

Sedimentary Signatures of Submarine Earthquakes: Deciphering the Extent of Sediment Remobilization from the 2011 Tohoku Earthquake and Tsunami and 2010 Haiti Earthquake

NASA Astrophysics Data System (ADS)

McHugh, C. M.; Seeber, L.; Moernaut, J.; Strasser, M.; Kanamatsu, T.; Ikehara, K.; Bopp, R.; Mustaque, S.; Usami, K.; Schwestermann, T.; Kioka, A.; Moore, L. M.

2017-12-01

The 2004 Sumatra-Andaman Mw9.3 and the 2011 Tohoku (Japan) Mw9.0 earthquakes and tsunamis were huge geological events with major societal consequences. Both were along subduction boundaries and ruptured portions of these boundaries that had been deemed incapable of such events. Submarine strike-slip earthquakes, such as the 2010 Mw7.0 in Haiti, are smaller but may be closer to population centers and can be similarly catastrophic. Both classes of earthquakes remobilize sediment and leave distinct signatures in the geologic record by a wide range of processes that depends on both environment and earthquake characteristics. Understanding them has the potential of greatly expanding the record of past earthquakes, which is critical for geohazard analysis. Recent events offer precious ground truth about the earthquakes and short-lived radioisotopes offer invaluable tools to identify sediments they remobilized. In the 2011 Mw9 Japan earthquake they document the spatial extent of remobilized sediment from water depths of 626m in the forearc slope to trench depths of 8000m. Subbottom profiles, multibeam bathymetry and 40 piston cores collected by the R/V Natsushima and R/V Sonne expeditions to the Japan Trench document multiple turbidites and high-density flows. Core tops enriched in xs210Pb,137Cs and 134Cs reveal sediment deposited by the 2011 Tohoku earthquake and tsunami. The thickest deposits (2m) were documented on a mid-slope terrace and trench (4000-8000m). Sediment was deposited on some terraces (600-3000m), but shed from the steep forearc slope (3000-4000m). The 2010 Haiti mainshock ruptured along the southern flank of Canal du Sud and triggered multiple nearshore sediment failures, generated turbidity currents and stirred fine sediment into suspension throughout this basin. A tsunami was modeled to stem from both sediment failures and tectonics. Remobilized sediment was tracked with short-lived radioisotopes from the nearshore, slope, in fault basins including the

Local tsunamis and earthquake source parameters

USGS Publications Warehouse

Geist, Eric L.; Dmowska, Renata; Saltzman, Barry

1999-01-01

This chapter establishes the relationship among earthquake source parameters and the generation, propagation, and run-up of local tsunamis. In general terms, displacement of the seafloor during the earthquake rupture is modeled using the elastic dislocation theory for which the displacement field is dependent on the slip distribution, fault geometry, and the elastic response and properties of the medium. Specifically, nonlinear long-wave theory governs the propagation and run-up of tsunamis. A parametric study is devised to examine the relative importance of individual earthquake source parameters on local tsunamis, because the physics that describes tsunamis from generation through run-up is complex. Analysis of the source parameters of various tsunamigenic earthquakes have indicated that the details of the earthquake source, namely, nonuniform distribution of slip along the fault plane, have a significant effect on the local tsunami run-up. Numerical methods have been developed to address the realistic bathymetric and shoreline conditions. The accuracy of determining the run-up on shore is directly dependent on the source parameters of the earthquake, which provide the initial conditions used for the hydrodynamic models.

Tohoku-Oki Earthquake Tsunami Runup and Inundation Data for Sites Around the Island of Hawaiʻi

USGS Publications Warehouse

Trusdell, Frank A.; Chadderton, Amy; Hinchliffe, Graham; Hara, Andrew; Patenge, Brent; Weber, Tom

2012-01-01

At 0546 U.t.c. March 11, 2011, a Mw 9.0 ("great") earthquake occurred near the northeast coast of Honshu Island, Japan, generating a large tsunami that devastated the east coast of Japan and impacted many far-flung coastal sites around the Pacific Basin. After the earthquake, the Pacific Tsunami Warning Center issued a tsunami alert for the State of Hawaii, followed by a tsunami-warning notice from the local State Civil Defense on March 10, 2011 (Japan is 19 hours ahead of Hawaii). After the waves passed the islands, U.S. Geological Survey (USGS) scientists from the Hawaiian Volcano Observatory (HVO) measured inundation (maximum inland distance of flooding), runup (elevation at maximum extent of inundation) and took photographs in coastal areas around the Island of Hawaiʻi. Although the damage in West Hawaiʻi is well documented, HVO's mapping revealed that East Hawaiʻi coastlines were also impacted by the tsunami. The intent of this report is to provide runup and inundation data for sites around the Island of Hawaiʻi.

Source of the 1730 Chilean earthquake from historical records: Implications for the future tsunami hazard on the coast of Metropolitan Chile

NASA Astrophysics Data System (ADS)

Carvajal, M.; Cisternas, M.; Catalán, P. A.

2017-05-01

Historical records of an earthquake that occurred in 1730 affecting Metropolitan Chile provide essential clues on the source characteristics for the future earthquakes in the region. The earthquake and tsunami of 1730 have been recognized as the largest to occur in Metropolitan Chile since the beginning of written history. The earthquake destroyed buildings along >1000 km of the coast and produced a large tsunami that caused damage as far as Japan. Here its source characteristics are inferred by comparing local tsunami inundations computed from hypothetical earthquakes with varying magnitude and depth, with those inferred from historical observations. It is found that a 600-800 km long rupture involving average slip amounts of 10-14 m (Mw 9.1-9.3) best explains the observed tsunami heights and inundations. This large earthquake magnitude is supported by the 1730 tsunami heights inferred in Japan. The inundation results combined with local uplift reports suggest a southward increase of the slip depth along the rupture zone of the 1730 earthquake. While shallow slip on the area to the north of the 2010 earthquake rupture zone is required to explain the reported inundation, only deeper slip at this area can explain the coastal uplift reports. Since the later earthquakes of the region involved little or no slip at shallow depths, the near-future earthquakes on Metropolitan Chile could release the shallow slip accumulated since 1730 and thus lead to strong tsunami excitation. Moderate shaking from a shallow earthquake could delay tsunami evacuation for the most populated coastal region of Chile.

Method to Determine Appropriate Source Models of Large Earthquakes Including Tsunami Earthquakes for Tsunami Early Warning in Central America

NASA Astrophysics Data System (ADS)

Tanioka, Yuichiro; Miranda, Greyving Jose Arguello; Gusman, Aditya Riadi; Fujii, Yushiro

2017-08-01

Large earthquakes, such as the Mw 7.7 1992 Nicaragua earthquake, have occurred off the Pacific coasts of El Salvador and Nicaragua in Central America and have generated distractive tsunamis along these coasts. It is necessary to determine appropriate fault models before large tsunamis hit the coast. In this study, first, fault parameters were estimated from the W-phase inversion, and then an appropriate fault model was determined from the fault parameters and scaling relationships with a depth dependent rigidity. The method was tested for four large earthquakes, the 1992 Nicaragua tsunami earthquake (Mw7.7), the 2001 El Salvador earthquake (Mw7.7), the 2004 El Astillero earthquake (Mw7.0), and the 2012 El Salvador-Nicaragua earthquake (Mw7.3), which occurred off El Salvador and Nicaragua in Central America. The tsunami numerical simulations were carried out from the determined fault models. We found that the observed tsunami heights, run-up heights, and inundation areas were reasonably well explained by the computed ones. Therefore, our method for tsunami early warning purpose should work to estimate a fault model which reproduces tsunami heights near the coast of El Salvador and Nicaragua due to large earthquakes in the subduction zone.

Mental Health and Related Factors after the Great East Japan Earthquake and Tsunami

PubMed Central

Yokoyama, Yukari; Otsuka, Kotaro; Kawakami, Norito; Kobayashi, Seiichiro; Ogawa, Akira; Tannno, Kozo; Onoda, Toshiyuki; Yaegashi, Yumi; Sakata, Kiyomi

2014-01-01

Mental health is one of the most important issues facing disaster survivors. The purpose of this study is to determine the prevalence and correlates of mental health problems in survivors of the Great East Japan Earthquake and Tsunami at 6–11 months after the disaster. The questionnaire and notification were sent to the survivors in three municipalities in the Tohoku area of the Northern part of Honshu, Japan’s largest island, between September 2011 and February 2012. Questionnaires were sent to 12,772, 11,411, and 18,648 residents in the Yamada, Otsuchi, and Rikuzentakata municipalities, respectively. Residents were asked to bring the completed questionnaires to their health check-ups. A total of 11,124 or (26.0%) of them underwent health check-ups, and 10,198 were enrolled. We excluded 179 for whom a K6 score was missing and two who were both 17 years of age, which left 10,025 study participants (3,934 male and 6,091 female, mean age 61.0 years). K6 was used to measure mental health problems. The respondents were classified into moderate (5–12 of K6) and serious mental health problems (13+). A total of 42.6% of the respondents had moderate or serious mental health problems. Multivariate analysis showed that women were significantly associated with mental health problems. Other variables associated with mental health problems were: younger male, health complaints, severe economic status, relocations, and lack of a social network. An interaction effect of sex and economic status on severe mental health problems was statistically significant. Our findings suggest that mental health problems were prevalent in survivors of the Great East Japan Earthquake and Tsunami. For men and women, health complaints, severe economic status, relocations, and lack of social network may be important risk factors of poor mental health. For men, interventions focusing on economic support may be particularly useful in reducing mental health problems after the disaster. PMID

Disaster waste characteristics and radiation distribution as a result of the Great East Japan Earthquake.

PubMed

Shibata, Tomoyuki; Solo-Gabriele, Helena; Hata, Toshimitsu

2012-04-03

The compounded impacts of the catastrophes that resulted from the Great East Japan Earthquake have emphasized the need to develop strategies to respond to multiple types and sources of contamination. In Japan, earthquake and tsunami-generated waste were found to have elevated levels of metals/metalloids (e.g., mercury, arsenic, and lead) with separation and sorting more difficult for tsunami-generated waste as opposed to earthquake-generated waste. Radiation contamination superimposed on these disaster wastes has made it particularly difficult to manage the ultimate disposal resulting in delays in waste management. Work is needed to develop policies a priori for handling wastes from combined catastrophes such as those recently observed in Japan.

Sustained Increase in the Incidence of Acute Decompensated Heart Failure After the 2011 Japan Earthquake and Tsunami.

PubMed

Nakamura, Motoyuki; Tanaka, Fumitaka; Komi, Ryousuke; Tanaka, Kentarou; Onodera, Masayuki; Kawakami, Mikio; Koeda, Yorihiko; Sakai, Toshiaki; Tanno, Kozo; Onoda, Toshiyuki; Matsura, Yuki; Komatsu, Takashi

2016-11-01

This study investigated the long-term impact of the 2011 Japan earthquake and tsunami on the incidence of acute decompensated heart failure (HF) in the disaster area. This was a population-based study using comprehensive registration for all hospitals within the study area. The standardized incidence ratio (SIR) and 95% confidence interval (CI) for new onset of HF during the disaster year (2011) and postdisaster years (2012 to 2014) were determined. When SIR were compared between the low- and high-impact areas, as defined by the extent of tsunami inundation in residential areas, SIR showed a significant increase in high-impact areas in 2011 (1.67, 95% CI 1.45 to 1.88) and tended to return to baseline in 2012, the first postdisaster year (1.25, 95% CI 1.06 to 1.43). The rate again increased in 2013 (1.38, 95% CI 1.18 to 1.57) and 2014 (1.55, 95% CI 1.35 to 1.75). In low-impact areas, no such increase was apparent during either the disaster year or the postdisaster years. Mean postdisaster period SIR for municipalities significantly correlated with the percentage of tsunami flooding in residential areas (r = 0.52, p <0.05) and with the percentage of refugees within the population (r = 0.74, p <0.01). There was no significant relation between maximum seismic intensity and mean SIR in these municipalities. In conclusion, these results suggest that the catastrophic tsunami but not the earthquake per se resulted in a prolonged increase in the incidence of HF among the general population living in tsunami-stricken areas. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Complex earthquake rupture and local tsunamis

USGS Publications Warehouse

Geist, E.L.

2002-01-01

In contrast to far-field tsunami amplitudes that are fairly well predicted by the seismic moment of subduction zone earthquakes, there exists significant variation in the scaling of local tsunami amplitude with respect to seismic moment. From a global catalog of tsunami runup observations this variability is greatest for the most frequently occuring tsunamigenic subduction zone earthquakes in the magnitude range of 7 < Mw < 8.5. Variability in local tsunami runup scaling can be ascribed to tsunami source parameters that are independent of seismic moment: variations in the water depth in the source region, the combination of higher slip and lower shear modulus at shallow depth, and rupture complexity in the form of heterogeneous slip distribution patterns. The focus of this study is on the effect that rupture complexity has on the local tsunami wave field. A wide range of slip distribution patterns are generated using a stochastic, self-affine source model that is consistent with the falloff of far-field seismic displacement spectra at high frequencies. The synthetic slip distributions generated by the stochastic source model are discretized and the vertical displacement fields from point source elastic dislocation expressions are superimposed to compute the coseismic vertical displacement field. For shallow subduction zone earthquakes it is demonstrated that self-affine irregularities of the slip distribution result in significant variations in local tsunami amplitude. The effects of rupture complexity are less pronounced for earthquakes at greater depth or along faults with steep dip angles. For a test region along the Pacific coast of central Mexico, peak nearshore tsunami amplitude is calculated for a large number (N = 100) of synthetic slip distribution patterns, all with identical seismic moment (Mw = 8.1). Analysis of the results indicates that for earthquakes of a fixed location, geometry, and seismic moment, peak nearshore tsunami amplitude can vary by a

The Great Tohoku-Oki Earthquake and Tsunami of March 11, 2011 in Japan: A Critical Review and Evaluation of the Tsunami Source Mechanism

NASA Astrophysics Data System (ADS)

Pararas-Carayannis, George

2014-12-01

The great Tohoku-Oki earthquake of March 11, 2011 generated a very destructive and anomalously high tsunami. To understand its source mechanism, an examination was undertaken of the seismotectonics of the region and of the earthquake's focal mechanism, energy release, rupture patterns and spatial and temporal sequencing and clustering of major aftershocks. It was determined that the great tsunami resulted from a combination of crustal deformations of the ocean floor due to up-thrust tectonic motions, augmented by additional uplift due to the quake's slow and long rupturing process, as well as to large coseismic lateral movements which compressed and deformed the compacted sediments along the accretionary prism of the overriding plane. The deformation occurred randomly and non-uniformly along parallel normal faults and along oblique, en-echelon faults to the earthquake's overall rupture direction—the latter failing in a sequential bookshelf manner with variable slip angles. As the 1992 Nicaragua and the 2004 Sumatra earthquakes demonstrated, such bookshelf failures of sedimentary layers could contribute to anomalously high tsunamis. As with the 1896 tsunami, additional ocean floor deformation and uplift of the sediments was responsible for the higher waves generated by the 2011 earthquake. The efficiency of tsunami generation was greater along the shallow eastern segment of the fault off the Miyagi Prefecture where most of the energy release of the earthquake and the deformations occurred, while the segment off the Ibaraki Prefecture—where the rupture process was rapid—released less seismic energy, resulted in less compaction and deformation of sedimentary layers and thus to a tsunami of lesser offshore height. The greater tsunamigenic efficiency of the 2011 earthquake and high degree of the tsunami's destructiveness along Honshu's coastlines resulted from vertical crustal displacements of more than 10 m due to up-thrust faulting and from lateral compression

Disaster mitigation science for Earthquakes and Tsunamis -For resilience society against natural disasters-

NASA Astrophysics Data System (ADS)

Kaneda, Y.; Takahashi, N.; Hori, T.; Kawaguchi, K.; Isouchi, C.; Fujisawa, K.

2017-12-01

Destructive natural disasters such as earthquakes and tsunamis have occurred frequently in the world. For instance, 2004 Sumatra Earthquake in Indonesia, 2008 Wenchuan Earthquake in China, 2010 Chile Earthquake and 2011 Tohoku Earthquake in Japan etc., these earthquakes generated very severe damages. For the reduction and mitigation of damages by destructive natural disasters, early detection of natural disasters and speedy and proper evacuations are indispensable. And hardware and software developments/preparations for reduction and mitigation of natural disasters are quite important. In Japan, DONET as the real time monitoring system on the ocean floor is developed and deployed around the Nankai trough seismogenic zone southwestern Japan. So, the early detection of earthquakes and tsunamis around the Nankai trough seismogenic zone will be expected by DONET. The integration of the real time data and advanced simulation researches will lead to reduce damages, however, in the resilience society, the resilience methods will be required after disasters. Actually, methods on restorations and revivals are necessary after natural disasters. We would like to propose natural disaster mitigation science for early detections, evacuations and restorations against destructive natural disasters. This means the resilience society. In natural disaster mitigation science, there are lots of research fields such as natural science, engineering, medical treatment, social science and literature/art etc. Especially, natural science, engineering and medical treatment are fundamental research fields for natural disaster mitigation, but social sciences such as sociology, geography and psychology etc. are very important research fields for restorations after natural disasters. Finally, to realize and progress disaster mitigation science, human resource cultivation is indispensable. We already carried out disaster mitigation science under `new disaster mitigation research project on Mega

The tsunami's impact on mortality in a town severely damaged by the 2011 Great East Japan Earthquake.

PubMed

Nagata, Satoko; Teramoto, Chie; Okamoto, Reiko; Koide, Keiko; Nishida, Masumi; Suzuki, Ruriko; Nomura, Michie; Tada, Toshiko; Kishi, Emiko; Sakai, Yoko; Jojima, Noriko; Kusano, Emiko; Iwamoto, Saori; Saito, Miki; Murashima, Sachiyo

2014-07-01

This study identifies the relationship between tsunami damage and mortality through a demographic pyramid of a town severely damaged by the tsunami following the Great East Japan Earthquake of 11 March 2011. It uses cross-sectional data collection. Volunteers visited all households, including shelters, and asked residents about the whereabouts of family members and neighbours. The information was collated with lists of evacuees and the dead to confirm the whereabouts of all residents about 50 days after the disaster. Demographic pyramids for the whole population based on pre- and post-disaster data were drawn. In all, 1,412 (8.8 per cent) were dead or missing, 60.2 per cent of whom were aged 65 and over and 37.5 per cent aged 75 and over, suggesting that the very old should be located beyond the reach of tsunamis. The mortality rate of children was lower than that in other studies, which may indicate the efficacy of disaster evacuation drills. © 2014 The Author(s). Disasters © Overseas Development Institute, 2014.

Simultaneous Sea-Level Oscillations in Japanese Bays Induced by the Tsunami of Nankai-Trough Earthquake

NASA Astrophysics Data System (ADS)

Oishi, Y.; Furumura, T.; Imamura, F.; Yamashita, K.; Sugawara, D.

2016-12-01

In this study, we investigate the response of bays to the tsunami of Nankai-trough earthquake based on tsunami simulations and demonstrate the possibility that sea-level oscillation of each bay, which is induced by an incident tsunami, interacts with those of other bays. Several major cities in Japan, including the capital, are located in the bays near the Nankai trough and it is assumed that these cities will be largely affected by the tsunamis caused by recurring large earthquakes at the trough. Therefore, it is very important for these populated cities to understand the mechanism and properties of the tsunami-induced oscillations that continue for a long time in bays to draw up evacuation plans. To investigate the response of bays for various tsunamis that may occur in the Nankai trough area, we distributed the tsunami sources that have the form of a 2-D Gaussian function around the Nankai trough. From simulations with these sources, it was found that strong oscillations of bay water occur when the source is located in the bay itself or when strong oscillations occur in other bays. For example, when the Tosa bay oscillates, the Tokyo bay that is 600 km away from the Tosa bay also oscillates. Among the bays around the Nankai trough, the Suruga bay, the deepest bay in Japan with a 2500-km depth, oscillates more strongly than other bays for most cases. To check the influence of the strong oscillations in the Suruga bay on other bays, we conducted tsunami simulations using a modified topography model in which the Suruga bay is artificially landfilled. As a consequence, the strength of oscillations in the adjacent bays are reduced by 20-30%, suggesting the large influence of the distinguished oscillation of the Suruga bay on these bays. We finally conducted tsunami simulations using the eleven Nankai-trough earthquake scenarios of the Central Disaster Prevention Council (CDPC) of Japan as tsunami sources, and the mutual relation regarding the strengths of

Impact of the Japan earthquake disaster with massive Tsunami on emergency coronary intervention and in-hospital mortality in patients with acute ST-elevation myocardial infarction.

PubMed

Itoh, Tomonori; Nakajima, Satoshi; Tanaka, Fumitaka; Nishiyama, Osamu; Matsumoto, Tatsuya; Endo, Hiroshi; Sakai, Toshiaki; Nakamura, Motoyuki; Morino, Yoshihiro

2014-09-01

The aims of this study were to evaluate reperfusion rate, therapeutic time course and in-hospital mortality pre- and post-Japan earthquake disaster, comparing patients with ST-elevation myocardial infarction (STEMI) treated in the inland area or the Tsunami-stricken area of Iwate prefecture. Subjects were 386 consecutive STEMI patients admitted to the four percutaneous coronary intervention (PCI) centers in Iwate prefecture in 2010 and 2011. Patients were divided into two groups: those treated in the inland or Tsunami-stricken area. We compared clinical characteristics, time course and in-hospital mortality in both years in the two groups. PCI was performed in 310 patients (80.3%). Door-to-balloon (D2B) time in the Tsunami-stricken area in 2011 was significantly shorter than in 2010 in patients treated with PCI. However, the rate of PCI performed in the Tsunami-stricken area in March-April 2011 was significantly lower than that in March-April 2010 (41.2% vs 85.7%; p=0.03). In-hospital mortality increased three-fold from 7.1% in March-April 2010 to 23.5% in March-April 2011 in the Tsunami-stricken area. Standardized mortality ratio (SMR) in March-April 2011 in the Tsunami-stricken area was significantly higher than the control SMR (SMR 4.72: 95% confidence interval (CI): 1.77-12.6: p=0.007). The rate of PCI decreased and in-hospital mortality increased immediately after the Japan earthquake disaster in the Tsunami-stricken area. Disorder in hospitals and in the distribution systems after the disaster impacted the clinical care and outcome of STEMI patients. © The European Society of Cardiology 2014.

Disaster Victim Identification using Orthopedic Implants in the 2011 East-Japan Earthquake and Tsunami.

PubMed

Numata, Norio; Makinae, Haruka; Yoshida, Wataru; Daimon, Masao; Murakami, Hideki

2017-03-01

On March 11, 2011, an earthquake (magnitude 9.0) devastated Japan's east coast, and the associated tsunami resulted in social and mechanical destruction. Search for the missing people is still ongoing. Surgical implants are common in the general population. Medical implants usually have lot numbers, and their forensic use is common for victim identification. This investigation was conducted mainly in the cities of Kamaishi and Otsuchi, both of which were affected by the tsunami disaster in 2011. We visited 6 mortuaries with the police between March 20 (9 days after the tsunami) and April 20 (40 days after the tsunami) to examine the presence of surgical scars and related information. Unidentified human remains were investigated by visual and tactile examination. We also visited temples where the ashes were preserved. If implants were found, their lot numbers and estimated surgical procedures were recorded to determine positive identification. Ten of 233 sets of unidentified human remains before cremation displayed characteristics of a potential past surgical history. However, only 2 of these 233 sets had orthopedic implants. Instead, non-combustible orthopedic implants were found and recognized in 8 of the 331 sets of unidentified human ashes in the temples after cremation; the lot numbers were fully legible in 2 of the 8 sets. We estimated the surgical procedures, which led to positive identification. In conclusion, lot numbers and the surgical knowledge of orthopedic surgeons could assist with the positive identification of disaster victims. However, the relevant information can be erased after cremation.

Genomic and metagenomic analysis of microbes in a soil environment affected by the 2011 Great East Japan Earthquake tsunami.

PubMed

Hiraoka, Satoshi; Machiyama, Asako; Ijichi, Minoru; Inoue, Kentaro; Oshima, Kenshiro; Hattori, Masahira; Yoshizawa, Susumu; Kogure, Kazuhiro; Iwasaki, Wataru

2016-01-14

The Great East Japan Earthquake of 2011 triggered large tsunami waves, which flooded broad areas of land along the Pacific coast of eastern Japan and changed the soil environment drastically. However, the microbial characteristics of tsunami-affected soil at the genomic level remain largely unknown. In this study, we isolated microbes from a soil sample using general low-nutrient and seawater-based media to investigate microbial characteristics in tsunami-affected soil. As expected, a greater proportion of strains isolated from the tsunami-affected soil than the unaffected soil grew in the seawater-based medium. Cultivable strains in both the general low-nutrient and seawater-based media were distributed in the genus Arthrobacter. Most importantly, whole-genome sequencing of four of the isolated Arthrobacter strains revealed independent losses of siderophore-synthesis genes from their genomes. Siderophores are low-molecular-weight, iron-chelating compounds that are secreted for iron uptake; thus, the loss of siderophore-synthesis genes indicates that these strains have adapted to environments with high-iron concentrations. Indeed, chemical analysis confirmed the investigated soil samples to be rich in iron, and culture experiments confirmed weak cultivability of some of these strains in iron-limited media. Furthermore, metagenomic analyses demonstrated over-representation of denitrification-related genes in the tsunami-affected soil sample, as well as the presence of pathogenic and marine-living genera and genes related to salt-tolerance. Collectively, the present results would provide an example of microbial characteristics of soil disturbed by the tsunami, which may give an insight into microbial adaptation to drastic environmental changes. Further analyses on microbial ecology after a tsunami are envisioned to develop a deeper understanding of the recovery processes of terrestrial microbial ecosystems.

Development of Real-time Tsunami Inundation Forecast Using Ocean Bottom Tsunami Networks along the Japan Trench

NASA Astrophysics Data System (ADS)

Aoi, S.; Yamamoto, N.; Suzuki, W.; Hirata, K.; Nakamura, H.; Kunugi, T.; Kubo, T.; Maeda, T.

2015-12-01

In the 2011 Tohoku earthquake, in which huge tsunami claimed a great deal of lives, the initial tsunami forecast based on hypocenter information estimated using seismic data on land were greatly underestimated. From this lesson, NIED is now constructing S-net (Seafloor Observation Network for Earthquakes and Tsunamis along the Japan Trench) which consists of 150 ocean bottom observatories with seismometers and pressure gauges (tsunamimeters) linked by fiber optic cables. To take full advantage of S-net, we develop a new methodology of real-time tsunami inundation forecast using ocean bottom observation data and construct a prototype system that implements the developed forecasting method for the Pacific coast of Chiba prefecture (Sotobo area). We employ a database-based approach because inundation is a strongly non-linear phenomenon and its calculation costs are rather heavy. We prepare tsunami scenario bank in advance, by constructing the possible tsunami sources, and calculating the tsunami waveforms at S-net stations, coastal tsunami heights and tsunami inundation on land. To calculate the inundation for target Sotobo area, we construct the 10-m-mesh precise elevation model with coastal structures. Based on the sensitivities analyses, we construct the tsunami scenario bank that efficiently covers possible tsunami scenarios affecting the Sotobo area. A real-time forecast is carried out by selecting several possible scenarios which can well explain real-time tsunami data observed at S-net from tsunami scenario bank. An advantage of our method is that tsunami inundations are estimated directly from the actual tsunami data without any source information, which may have large estimation errors. In addition to the forecast system, we develop Web services, APIs, and smartphone applications and brush them up through social experiments to provide the real-time tsunami observation and forecast information in easy way to understand toward urging people to evacuate.

Characterizing Mega-Earthquake Related Tsunami on Subduction Zones without Large Historical Events

NASA Astrophysics Data System (ADS)

Williams, C. R.; Lee, R.; Astill, S.; Farahani, R.; Wilson, P. S.; Mohammed, F.

2014-12-01

Due to recent large tsunami events (e.g., Chile 2010 and Japan 2011), the insurance industry is very aware of the importance of managing its exposure to tsunami risk. There are currently few tools available to help establish policies for managing and pricing tsunami risk globally. As a starting point and to help address this issue, Risk Management Solutions Inc. (RMS) is developing a global suite of tsunami inundation footprints. This dataset will include both representations of historical events as well as a series of M9 scenarios on subductions zones that have not historical generated mega earthquakes. The latter set is included to address concerns about the completeness of the historical record for mega earthquakes. This concern stems from the fact that the Tohoku Japan earthquake was considerably larger than had been observed in the historical record. Characterizing the source and rupture pattern for the subduction zones without historical events is a poorly constrained process. In many case, the subduction zones can be segmented based on changes in the characteristics of the subducting slab or major ridge systems. For this project, the unit sources from the NOAA propagation database are utilized to leverage the basin wide modeling included in this dataset. The length of the rupture is characterized based on subduction zone segmentation and the slip per unit source can be determined based on the event magnitude (i.e., M9) and moment balancing. As these events have not occurred historically, there is little to constrain the slip distribution. Sensitivity tests on the potential rupture pattern have been undertaken comparing uniform slip to higher shallow slip and tapered slip models. Subduction zones examined include the Makran Trench, the Lesser Antilles and the Hikurangi Trench. The ultimate goal is to create a series of tsunami footprints to help insurers understand their exposures at risk to tsunami inundation around the world.

History of earthquakes and tsunamis along the eastern Aleutian-Alaska megathrust, with implications for tsunami hazards in the California Continental Borderland

USGS Publications Warehouse

Ryan, Holly F.; von Huene, Roland E.; Wells, Ray E.; Scholl, David W.; Kirby, Stephen; Draut, Amy E.; Dumoulin, Julie A.; Dusel-Bacon, C.

2012-01-01

During the past several years, devastating tsunamis were generated along subduction zones in Indonesia, Chile, and most recently Japan. Both the Chile and Japan tsunamis traveled across the Pacific Ocean and caused localized damage at several coastal areas in California. The question remains as to whether coastal California, in particular the California Continental Borderland, is vulnerable to more extensive damage from a far-field tsunami sourced along a Pacific subduction zone. Assuming that the coast of California is at risk from a far-field tsunami, its coastline is most exposed to a trans-Pacific tsunami generated along the eastern Aleutian-Alaska subduction zone. We present the background geologic constraints that could control a possible giant (Mw ~9) earthquake sourced along the eastern Aleutian-Alaska megathrust. Previous great earthquakes (Mw ~8) in 1788, 1938, and 1946 ruptured single segments of the eastern Aleutian-Alaska megathrust. However, in order to generate a giant earthquake, it is necessary to rupture through multiple segments of the megathrust. Potential barriers to a throughgoing rupture, such as high-relief fracture zones or ridges, are absent on the subducting Pacific Plate between the Fox and Semidi Islands. Possible asperities (areas on the megathrust that are locked and therefore subject to infrequent but large slip) are identified by patches of high moment release observed in the historical earthquake record, geodetic studies, and the location of forearc basin gravity lows. Global Positioning System (GPS) data indicate that some areas of the eastern Aleutian-Alaska megathrust, such as that beneath Sanak Island, are weakly coupled. We suggest that although these areas will have reduced slip during a giant earthquake, they are not really large enough to form a barrier to rupture. A key aspect in defining an earthquake source for tsunami generation is determining the possibility of significant slip on the updip end of the megathrust near

Infectious disease frequency among evacuees at shelters after the great eastern Japan earthquake and tsunami: a retrospective study.

PubMed

Kawano, Takahisa; Hasegawa, Kohei; Watase, Hiroko; Morita, Hiroshi; Yamamura, Osamu

2014-02-01

After the Great Eastern Japan Earthquake and tsunami, the World Health Organization cautioned that evacuees at shelters would be at increased risk of infectious disease transmission; however, the frequency that occurred in this population was not known. We reviewed medical charts of evacuees who visited medical clinics at 6 shelters from March 19, to April 8, 2011. Excluded were patients who did not reside within the shelters or whose medical records lacked a name or date. We investigated the frequency of and cumulative incidences of acute respiratory infection [ARI], acute gastroenteritis, acute jaundice syndrome, scabies, measles, pertussis, and tetanus. Of 1364 patients who visited 6 shelter clinics, 1167 patients (86.1%) were eligible for the study. The median total number of evacuees was 2545 (interquartile range [IQR], 2277-3009). ARI was the most common infectious disease; the median number of patients with ARI was 168.8 per week per 1000 evacuees (IQR, 64.5-186.1). Acute gastroenteritis was the second most common; the median number of patients was 23.7 per week per 1000 evacuees (IQR, 5.1-24.3). No other infectious diseases were observed. The median cumulative incidence of ARI per 1000 evacuees in each shelter was 13.1 person-days (IQR, 8.5-18.8). The median cumulative incidence of gastroenteritis was 1.6 person-days (IQR, 0.3-3.4). After the Great Eastern Japan Earthquake and tsunami, outbreaks of ARI and acute gastroenteritis occurred in evacuation shelters.

Unrevealing the History of Earthquakes and Tsunamis of the Mexican Subduction Zone

NASA Astrophysics Data System (ADS)

Ramirez-Herrera, M. T.; Castillo-Aja, M. D. R.; Cruz, S.; Corona, N.; Rangel Velarde, V.; Lagos, M.

2014-12-01

The great earthquakes and tsunamis of the last decades in Sumatra, Chile, and Japan remind us of the need for expanding the record of history of such catastrophic events. It can't be argued that even countries with extensive historical documents and tsunami sand deposits still have unsolved questions on the frequency of them, and the variables that control them along subduction zones. We present here preliminary results of a combined approach using historical archives and multiple proxies of the sedimentary record to unrevealing the history of possible great earthquakes and their tsunamis on the Mexican Subduction zone. The Mexican subduction zone extends over 1000 km long and little is known if the entire subduction zone along the Middle American Trench behaves as one enormous unit rather than in segments that rupture at different frequencies and with different strengths (as the short instrumental record shows). We searched on historical archives and earthquake databases to distinguish tsunamigenic events registered from the 16th century to now along the Jalisco-Colima and Guerrero-Oaxaca coastal stretches. The historical data referred are mostly from the 19th century on since the population on the coast was scarce before. We found 21 earthquakes with tsunamigenic potential, and of those 16 with doubtful to definitive accompanying tsunami on the Jalisco-Colima coast, and 31 tsunamigenic earthquakes on the Oaxaca-Guerrero coast. Evidence of great earthquakes and their tsunamis from the sedimentary record are scarce, perhaps due poor preservation of tsunami deposits in this tropical environment. Nevertheless, we have found evidence for a number of tsunamigenic events, both historical and prehistorical, 1932 and 1400 AD on Jalisco, and 3400 BP, 1789 AD, 1979 ad, and 1985 AD on Guerrero-Oaxaca. We continue working and a number of events are still to be dated. This work would aid in elucidating the history of earthquakes and tsunamis on the Mexican subduction zone.

Immediate ecological impacts of the 2011 Tohoku earthquake tsunami on intertidal flat communities.

PubMed

Urabe, Jotaro; Suzuki, Takao; Nishita, Tatsuki; Makino, Wataru

2013-01-01

Following the Great East Japan Earthquake in 2011, a large tsunami developed and struck the Pacific coast of eastern Japan. To assess the immediate impacts of the tsunami on coastal communities, changes in taxon composition and richness of macrobenthic animals before and after the tsunami were examined at nine intertidal flats in Sendai Bay and the Sanriku Ria coast. The results showed that 30-80% of taxa indigenously inhabiting intertidal flats disappeared after the tsunami. Among animal types, endobenthic and sessile epibenthic animals were more vulnerable to the tsunami than mobile epibenthic animals like shore crabs and snails. For all the intertidal flats examined, animals that were originally dwellers in lower tidal zones and not recorded before the tsunami were also found right after the tsunami, indicating that the tsunami not only took away many benthic taxa from the intertidal flats but also brought in some taxa from elsewhere. However, overall changes in taxon community composition were greater for intertidal flats that experienced larger inundation heights. These results showed that the ecological impacts of the tsunami were proportional to the physical impacts as gauged by wave height and that mobile epibenthic animals were less vulnerable to the tsunami.

Source depth dependence of micro-tsunamis recorded with ocean-bottom pressure gauges: The January 28, 2000 Mw 6.8 earthquake off Nemuro Peninsula, Japan

USGS Publications Warehouse

Hirata, K.; Takahashi, H.; Geist, E.; Satake, K.; Tanioka, Y.; Sugioka, H.; Mikada, H.

2003-01-01

Micro-tsunami waves with a maximum amplitude of 4-6 mm were detected with the ocean-bottom pressure gauges on a cabled deep seafloor observatory south of Hokkaido, Japan, following the January 28, 2000 earthquake (Mw 6.8) in the southern Kuril subduction zone. We model the observed micro-tsunami and estimate the focal depth and other source parameters such as fault length and amount of slip using grid searching with the least-squares method. The source depth and stress drop for the January 2000 earthquake are estimated to be 50 km and 7 MPa, respectively, with possible ranges of 45-55 km and 4-13 MPa. Focal depth of typical inter-plate earthquakes in this region ranges from 10 to 20 km and stress drop of inter-plate earthquakes generally is around 3 MPa. The source depth and stress drop estimates suggest that the earthquake was an intra-slab event in the subducting Pacific plate, rather than an inter-plate event. In addition, for a prescribed fault width of 30 km, the fault length is estimated to be 15 km, with possible ranges of 10-20 km, which is the same as the previously determined aftershock distribution. The corresponding estimate for seismic moment is 2.7x1019 Nm with possible ranges of 2.3x1019-3.2x1019Nm. Standard tide gauges along the nearby coast did not record any tsunami signal. High-precision ocean-bottom pressure measurements offshore thus make it possible to determine fault parameters of moderate-sized earthquakes in subduction zones using open-ocean tsunami waveforms. Published by Elsevier Science B. V.

Earthquake mechanism and seafloor deformation for tsunami generation

USGS Publications Warehouse

Geist, Eric L.; Oglesby, David D.; Beer, Michael; Kougioumtzoglou, Ioannis A.; Patelli, Edoardo; Siu-Kui Au, Ivan

2014-01-01

Tsunamis are generated in the ocean by rapidly displacing the entire water column over a significant area. The potential energy resulting from this disturbance is balanced with the kinetic energy of the waves during propagation. Only a handful of submarine geologic phenomena can generate tsunamis: large-magnitude earthquakes, large landslides, and volcanic processes. Asteroid and subaerial landslide impacts can generate tsunami waves from above the water. Earthquakes are by far the most common generator of tsunamis. Generally, earthquakes greater than magnitude (M) 6.5–7 can generate tsunamis if they occur beneath an ocean and if they result in predominantly vertical displacement. One of the greatest uncertainties in both deterministic and probabilistic hazard assessments of tsunamis is computing seafloor deformation for earthquakes of a given magnitude.

Tsunami Hazard Assessment of Coastal South Africa Based on Mega-Earthquakes of Remote Subduction Zones

NASA Astrophysics Data System (ADS)

Kijko, Andrzej; Smit, Ansie; Papadopoulos, Gerassimos A.; Novikova, Tatyana

2018-04-01

After the mega-earthquakes and concomitant devastating tsunamis in Sumatra (2004) and Japan (2011), we launched an investigation into the potential risk of tsunami hazard to the coastal cities of South Africa. This paper presents the analysis of the seismic hazard of seismogenic sources that could potentially generate tsunamis, as well as the analysis of the tsunami hazard to coastal areas of South Africa. The subduction zones of Makran, South Sandwich Island, Sumatra, and the Andaman Islands were identified as possible sources of mega-earthquakes and tsunamis that could affect the African coast. Numerical tsunami simulations were used to investigate the realistic and worst-case scenarios that could be generated by these subduction zones. The simulated tsunami amplitudes and run-up heights calculated for the coastal cities of Cape Town, Durban, and Port Elizabeth are relatively small and therefore pose no real risk to the South African coast. However, only distant tsunamigenic sources were considered and the results should therefore be viewed as preliminary.

Tsunami Hazard Assessment of Coastal South Africa Based on Mega-Earthquakes of Remote Subduction Zones

NASA Astrophysics Data System (ADS)

Kijko, Andrzej; Smit, Ansie; Papadopoulos, Gerassimos A.; Novikova, Tatyana

2017-11-01

After the mega-earthquakes and concomitant devastating tsunamis in Sumatra (2004) and Japan (2011), we launched an investigation into the potential risk of tsunami hazard to the coastal cities of South Africa. This paper presents the analysis of the seismic hazard of seismogenic sources that could potentially generate tsunamis, as well as the analysis of the tsunami hazard to coastal areas of South Africa. The subduction zones of Makran, South Sandwich Island, Sumatra, and the Andaman Islands were identified as possible sources of mega-earthquakes and tsunamis that could affect the African coast. Numerical tsunami simulations were used to investigate the realistic and worst-case scenarios that could be generated by these subduction zones. The simulated tsunami amplitudes and run-up heights calculated for the coastal cities of Cape Town, Durban, and Port Elizabeth are relatively small and therefore pose no real risk to the South African coast. However, only distant tsunamigenic sources were considered and the results should therefore be viewed as preliminary.

Posttraumatic symptoms in elementary and junior high school children after the 2011 Japan earthquake and tsunami: symptom severity and recovery vary by age and sex.

PubMed

Iwadare, Yoshitaka; Usami, Masahide; Suzuki, Yuriko; Ushijima, Hirokage; Tanaka, Tetsuya; Watanabe, Kyota; Kodaira, Masaki; Saito, Kazuhiko

2014-04-01

To measure psychiatric symptoms exhibited by children in Ishinomaki City, Japan, an area severely damaged by the 2011 earthquake and tsunami, at 8 and 20 months post-tsunami to investigate differences in symptom severity and recovery rate by age, sex, and degree of trauma experienced. Prospective data were collected from children in elementary school (5th and 6th grades) and junior high school (8th and 9th grades). Students completed the Post-Traumatic Stress Symptoms for Children-15 (PTSSC-15) survey. Trauma severity was scored according to experiences of bereavement, home damage, and evacuation. In total, 3795 PTSSC-15 surveys were analyzed, yielding total scores, post-traumatic stress disorder (PTSD) factor subscores, and depression factor subscores, which were analyzed according to grade group, sex, and degree of trauma (trauma dose). In the elementary school children, mean total PTSSC-15 score, PTSD factor score, and depression factor score were significantly improved at 20 months post-tsunami compared with 8 months (P < .0001 for all), whereas there were no significant improvements in the junior high school children. In females of the older group, the depression factor score at 20 months post-tsunami was significantly higher than at 8 months (P < .01). Elementary school and junior high school children living near the epicenter of the 2011 Japan earthquake and tsunami exhibited marked differences in PTSD and depressive symptoms. The mental health status of elementary school children improved, whereas that of junior high school children did not. Crown Copyright © 2014. Published by Mosby, Inc. All rights reserved.

Facts about the Eastern Japan Great Earthquake of March 2011

NASA Astrophysics Data System (ADS)

Moriyama, T.

2011-12-01

The 2011 great earthquake was a magnitude 9.0 Mw undersea megathrust earthquake off the coast of Japan that occurred early morning UTC on Friday, 11 March 2011, with the epicenter approximately 70 kilometres east of the Oshika Peninsula of Tohoku and the hypocenter at an underwater depth of approximately 32 km. It was the most powerful known earthquake to have hit Japan, and one of the five most powerful earthquakes in the world overall since modern record keeping began in 1900. The earthquake triggered extremely destructive tsunami waves of up to 38.9 metres that struck Tohoku Japan, in some cases traveling up to 10 km inland. In addition to loss of life and destruction of infrastructure, the tsunami caused a number of nuclear accidents, primarily the ongoing level 7 meltdowns at three reactors in the Fukushima I Nuclear Power Plant complex, and the associated evacuation zones affecting hundreds of thousands of residents. The Japanese National Police Agency has confirmed 1,5457 deaths, 5,389 injured, and 7,676 people missing across eighteen prefectures, as well as over 125,000 buildings damaged or destroyed. JAXA carried out ALOS emergency observation just after the earthquake occured, and acquired more than 400 scenes over the disaster area. The coseismic interferogram by InSAR analysis cleary showing the epicenter of the earthquake and land surface deformation over Tohoku area. By comparison of before and after satellite images, the large scale damaged area by tunami are extracted. These images and data can access via JAXA website and also GEO Tohoku oki event supersite website.

Nutrition in the Great East Japan Earthquake Disaster.

PubMed

Amagai, Teruyoshi; Ichimaru, Satomi; Tai, Mayumi; Ejiri, Yutaka; Muto, Atsushi

2014-10-01

The Great East Japan Earthquake Disaster (GEJED) struck the northeast region of Honshu, the main island of Japan, on March 11, 2011. This mega-disaster claimed more than 15,000 lives, with approximately 3000 later deaths being disaster related. The GEJED consisted of a mega-earthquake, tsunami, and nuclear accident. Survivors living in temporary shelters might have received insufficient levels of vitamins, with the exception of vitamin B1, which appeared to be overestimated, and excess levels of sodium. However, scientific data collection and surveys following the GEJED were extremely limited. This experience highlights the need to prepare an “emergency nutrition assessment” system for optimal nutrition in future disasters.

Signals in the ionosphere generated by tsunami earthquakes: observations and modeling suppor

NASA Astrophysics Data System (ADS)

Rolland, L.; Sladen, A.; Mikesell, D.; Larmat, C. S.; Rakoto, V.; Remillieux, M.; Lee, R.; Khelfi, K.; Lognonne, P. H.; Astafyeva, E.

2017-12-01

Forecasting systems failed to predict the magnitude of the 2011 great tsunami in Japan due to the difficulty and cost of instrumenting the ocean with high-quality and dense networks. Melgar et al. (2013) show that using all of the conventional data (inland seismic, geodetic, and tsunami gauges) with the best inversion method still fails to predict the correct height of the tsunami before it breaks onto a coast near the epicenter (< 500 km). On the other hand, in the last decade, scientists have gathered convincing evidence of transient signals in the ionosphere Total Electron Content (TEC) observations that are associated to open ocean tsunami waves. Even though typical tsunami waves are only a few centimeters high, they are powerful enough to create atmospheric vibrations extending all the way to the ionosphere, 300 kilometers up in the atmosphere. Therefore, we are proposing to incorporate the ionospheric signals into tsunami early-warning systems. We anticipate that the method could be decisive for mitigating "tsunami earthquakes" which trigger tsunamis larger than expected from their short-period magnitude. These events are challenging to characterize as they rupture the near-trench subduction interface, in a distant region less constrained by onshore data. As a couple of devastating tsunami earthquakes happens per decade, they represent a real threat for onshore populations and a challenge for tsunami early-warning systems. We will present the TEC observations of the recent Java 2006 and Mentawaii 2010 tsunami earthquakes and base our analysis on acoustic ray tracing, normal modes summation and the simulation code SPECFEM, which solves the wave equation in coupled acoustic (ocean, atmosphere) and elastic (solid earth) domains. Rupture histories are entered as finite source models, which will allow us to evaluate the effect of a relatively slow rupture on the surrounding ocean and atmosphere.

Numerical tsunami simulations in the western Pacific Ocean and East China Sea from hypothetical M 9 earthquakes along the Nankai trough

NASA Astrophysics Data System (ADS)

Harada, Tomoya; Satake, Kenji; Furumura, Takashi

2017-04-01

We carried out tsunami numerical simulations in the western Pacific Ocean and East China Sea in order to examine the behavior of massive tsunami outside Japan from the hypothetical M 9 tsunami source models along the Nankai Trough proposed by the Cabinet Office of Japanese government (2012). The distribution of MTHs (maximum tsunami heights for 24 h after the earthquakes) on the east coast of China, the east coast of the Philippine Islands, and north coast of the New Guinea Island show peaks with approximately 1.0-1.7 m，4.0-7.0 m，4.0-5.0 m, respectively. They are significantly higher than that from the 1707 Ho'ei earthquake (M 8.7), the largest earthquake along the Nankai trough in recent Japanese history. Moreover, the MTH distributions vary with the location of the huge slip(s) in the tsunami source models although the three coasts are far from the Nankai trough. Huge slip(s) in the Nankai segment mainly contributes to the MTHs, while huge slip(s) or splay faulting in the Tokai segment hardly affects the MTHs. The tsunami source model was developed for responding to the unexpected occurrence of the 2011 Tohoku Earthquake, with 11 models along the Nanakai trough, and simulated MTHs along the Pacific coasts of the western Japan from these models exceed 10 m, with a maximum height of 34.4 m. Tsunami propagation was computed by the finite-difference method of the non-liner long-wave equations with the Corioli's force and bottom friction (Satake, 1995) in the area of 115-155 ° E and 8° S-40° N. Because water depth of the East China Sea is shallower than 200 m, the tsunami propagation is likely to be affected by the ocean bottom fiction. The 30 arc-seconds gridded bathymetry data provided by the General Bathymetric Chart of the Oceans (GEBCO-2014) are used. For long propagation of tsunami we simulated tsunamis for 24 hours after the earthquakes. This study was supported by the"New disaster mitigation research project on Mega thrust earthquakes around Nankai

Immediate Ecological Impacts of the 2011 Tohoku Earthquake Tsunami on Intertidal Flat Communities

PubMed Central

Urabe, Jotaro; Suzuki, Takao; Nishita, Tatsuki; Makino, Wataru

2013-01-01

Following the Great East Japan Earthquake in 2011, a large tsunami developed and struck the Pacific coast of eastern Japan. To assess the immediate impacts of the tsunami on coastal communities, changes in taxon composition and richness of macrobenthic animals before and after the tsunami were examined at nine intertidal flats in Sendai Bay and the Sanriku Ria coast. The results showed that 30–80% of taxa indigenously inhabiting intertidal flats disappeared after the tsunami. Among animal types, endobenthic and sessile epibenthic animals were more vulnerable to the tsunami than mobile epibenthic animals like shore crabs and snails. For all the intertidal flats examined, animals that were originally dwellers in lower tidal zones and not recorded before the tsunami were also found right after the tsunami, indicating that the tsunami not only took away many benthic taxa from the intertidal flats but also brought in some taxa from elsewhere. However, overall changes in taxon community composition were greater for intertidal flats that experienced larger inundation heights. These results showed that the ecological impacts of the tsunami were proportional to the physical impacts as gauged by wave height and that mobile epibenthic animals were less vulnerable to the tsunami. PMID:23650529

Mexican Earthquakes and Tsunamis Catalog Reviewed

NASA Astrophysics Data System (ADS)

Ramirez-Herrera, M. T.; Castillo-Aja, R.

2015-12-01

Today the availability of information on the internet makes online catalogs very easy to access by both scholars and the public in general. The catalog in the "Significant Earthquake Database", managed by the National Center for Environmental Information (NCEI formerly NCDC), NOAA, allows access by deploying tabular and cartographic data related to earthquakes and tsunamis contained in the database. The NCEI catalog is the product of compiling previously existing catalogs, historical sources, newspapers, and scientific articles. Because NCEI catalog has a global coverage the information is not homogeneous. Existence of historical information depends on the presence of people in places where the disaster occurred, and that the permanence of the description is preserved in documents and oral tradition. In the case of instrumental data, their availability depends on the distribution and quality of seismic stations. Therefore, the availability of information for the first half of 20th century can be improved by careful analysis of the available information and by searching and resolving inconsistencies. This study shows the advances we made in upgrading and refining data for the earthquake and tsunami catalog of Mexico since 1500 CE until today, presented in the format of table and map. Data analysis allowed us to identify the following sources of error in the location of the epicenters in existing catalogs: • Incorrect coordinate entry • Place name erroneous or mistaken • Too general data that makes difficult to locate the epicenter, mainly for older earthquakes • Inconsistency of earthquakes and the tsunami occurrence: earthquake's epicenter located too far inland reported as tsunamigenic. The process of completing the catalogs directly depends on the availability of information; as new archives are opened for inspection, there are more opportunities to complete the history of large earthquakes and tsunamis in Mexico. Here, we also present new earthquake and

Tsunami inundation after the Great East Japan Earthquake and mortality of affected communities.

PubMed

Ishiguro, A; Yano, E

2015-10-01

To examine the relationship between mortality rate and tsunami inundation after the Great East Japan Earthquake (GEJE) in 2011. Cross-sectional study. One hundred and fifty-five town or village sections in Ishinomaki, Myagi Prefecture, were included in this study. Three areas in the city were classified by characteristic landforms: plains area (n = 114), ria coastal area (n = 27) and Kitakami riverside (n = 14). The correlation coefficient between tsunami inundation depth and mortality rate was calculated for each area, and the differences between the areas were examined. Furthermore, multivariate analyses adjusted for the characteristics of the sections were conducted using census data taken before the GEJE. An association was found between inundation depth and mortality rate for Ishinomaki as a whole (r = 0.65, P < 0.001), Kitakami riverside (r = 0.85, P < 0.001) and the plains area (r = 0.75, P < 0.001) in separate analyses. However, no association was detected between inundation depth and mortality rate for the ria coastal area (r = 0.14, P = 0.47). The ria coastal area has good accessibility to the hills and tight bonding between members of the community. These factors seemed to play crucial roles in the lower mortality rate in this area despite the deep inundation. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Trauma, depression, and resilience of earthquake/tsunami/nuclear disaster survivors of Hirono, Fukushima, Japan.

PubMed

Kukihara, Hiroko; Yamawaki, Niwako; Uchiyama, Kumi; Arai, Shoichi; Horikawa, Etsuo

2014-07-01

A mega-earthquake and tsunami struck the northeastern coast of Japan, and many survivors were forced to evacuate to temporary housing due to rising radiation levels. The aims of this study were to investigate the prevalence of symptoms of post-traumatic stress disorder (PTSD), depression, and poor general health among survivors, to test the predictive roles of resilience on mental and physical health, and to examine the predictive sociodemographic factors on resilience. Two hundred and forty-one evacuees (men/women: 116/125) from Hirono, Fukushima participated in the study. They were asked to complete the Connor-Davidson Resilience Scale, the Zung Self-Rating Depression Scale, the Impact of Events Scale-Revised, and a demographic questionnaire. Among all participants, 53.5% exhibited the clinically concerning symptoms of PTSD, and among them 33.2% indicated clinical PTSD symptoms. Additionally, 66.8% reported symptoms of depression, and among them 33.2% showed mildly depressive symptoms, while 19.1% and 14.5% demonstrated moderate and severe depressive symptoms, respectively. Resilience was a significant buffer for depression, PTSD, and general health. Additionally, employment status, eating/exercise habits, and drinking habits predicted resilience. The results indicated that depression and PTSD are prevalent among the survivors of massive earthquakes, tsunamis, and accidents from nuclear power plants. However, the results also showed that some survivors managed to endure the traumatic events relatively well, and resilience was a significant protective factor in dealing with such events. Therefore, it is crucial to assist survivors in improving their resilience by providing job opportunities and encouraging a healthy lifestyle. © 2014 The Authors. Psychiatry and Clinical Neurosciences © 2014 Japanese Society of Psychiatry and Neurology.

Deep venous thrombosis among disaster shelter inhabitants following the March 2011 earthquake and tsunami in Japan: a descriptive study.

PubMed

Shibata, M; Hanzawa, K; Ueda, S; Yambe, T

2014-05-01

A retrospective analysis of data collected during subject screening following Japan's March 2011 earthquake and tsunami was performed. We aimed to determine the incidence of deep venous thrombosis (DVT) among screened subjects and to identify risk factors associated with the development of DVT as independent variables. Calf ultrasonography was undertaken in 269 subjects living in 21 shelters in Miyagi prefecture during the one-month period immediately following the March 2011 disaster. Information regarding the health and risk factors of subjects was collected by questionnaire and assessment of physical signs. Of the 269 evacuees screened, 65 (24%) met the criteria for calf DVT. We found lower limb trauma, reduced frequency of urination and sleeping in a vehicle to be independent positive predictors of DVT. Evacuees had an increased risk of developing DVT, associated with tsunami-related lower limb injury, immobility and dehydration.

The great Lisbon earthquake and tsunami of 1755: lessons from the recent Sumatra earthquakes and possible link to Plato's Atlantis

NASA Astrophysics Data System (ADS)

Gutscher, M.-A.

2006-05-01

Great earthquakes and tsunami can have a tremendous societal impact. The Lisbon earthquake and tsunami of 1755 caused tens of thousands of deaths in Portugal, Spain and NW Morocco. Felt as far as Hamburg and the Azores islands, its magnitude is estimated to be 8.5 9. However, because of the complex tectonics in Southern Iberia, the fault that produced the earthquake has not yet been clearly identified. Recently acquired data from the Gulf of Cadiz area (tomography, seismic profiles, high-resolution bathymetry, sampled active mud volcanoes) provide strong evidence for an active east dipping subduction zone beneath Gibraltar. Eleven out of 12 of the strongest earthquakes (M>8.5) of the past 100 years occurred along subduction zone megathrusts (including the December 2004 and March 2005 Sumatra earthquakes). Thus, it appears likely that the 1755 earthquake and tsunami were generated in a similar fashion, along the shallow east-dipping subduction fault plane. This implies that the Cadiz subduction zone is locked (like the Cascadia and Nankai/Japan subduction zones), with great earthquakes occurring over long return periods. Indeed, the regional paleoseismic record (contained in deep-water turbidites and shallow lagoon deposits) suggests great earthquakes off South West Iberia every 1500 2000 years. Tsunami deposits indicate an earlier great earthquake struck SW Iberia around 200 BC, as noted by Roman records from Cadiz. A written record of even older events may also exist. According to Plato's dialogues The Critias and The Timaeus, Atlantis was destroyed by ‘strong earthquakes and floods … in a single day and night’ at a date given as 11,600 BP. A 1 m thick turbidite deposit, containing coarse grained sediments from underwater avalanches, has been dated at 12,000 BP and may correspond to the destructive earthquake and tsunami described by Plato. The effects on a paleo-island (Spartel) in the straits of Gibraltar would have been devastating, if inhabited, and may

Tsunami evacuation plans for future megathrust earthquakes in Padang, Indonesia, considering stochastic earthquake scenarios

NASA Astrophysics Data System (ADS)

Muhammad, Ario; Goda, Katsuichiro; Alexander, Nicholas A.; Kongko, Widjo; Muhari, Abdul

2017-12-01

This study develops tsunami evacuation plans in Padang, Indonesia, using a stochastic tsunami simulation method. The stochastic results are based on multiple earthquake scenarios for different magnitudes (Mw 8.5, 8.75, and 9.0) that reflect asperity characteristics of the 1797 historical event in the same region. The generation of the earthquake scenarios involves probabilistic models of earthquake source parameters and stochastic synthesis of earthquake slip distributions. In total, 300 source models are generated to produce comprehensive tsunami evacuation plans in Padang. The tsunami hazard assessment results show that Padang may face significant tsunamis causing the maximum tsunami inundation height and depth of 15 and 10 m, respectively. A comprehensive tsunami evacuation plan - including horizontal evacuation area maps, assessment of temporary shelters considering the impact due to ground shaking and tsunami, and integrated horizontal-vertical evacuation time maps - has been developed based on the stochastic tsunami simulation results. The developed evacuation plans highlight that comprehensive mitigation policies can be produced from the stochastic tsunami simulation for future tsunamigenic events.

Interviewing insights regarding the fatalities inflicted by the 2011 Great East Japan Earthquake

NASA Astrophysics Data System (ADS)

Ando, M.; Ishida, M.; Hayashi, Y.; Mizuki, C.; Nishikawa, Y.; Tu, Y.

2013-09-01

One hundred fifty survivors of the 11 March 2011 Great East Japan Earthquake (Tohoku-oki earthquake) (Mw = 9.0) were interviewed to study the causes of deaths from the associated tsunami in coastal areas of Tohoku. The first official tsunami warning underestimated the height of the tsunami and 40% of the interviewees did not obtain this warning due to immediate blackouts and a lack of communication after the earthquake. Many chose to remain in dangerous locations based on the underestimated warning and their experiences with previous smaller tsunamis and/or due to misunderstanding the mitigating effects of nearby breakwaters in blocking incoming tsunamis. Some delayed their evacuation to perform family safety checks, and in many situations, the people affected misunderstood the risks involved in tsunamis. In this area, three large tsunamis have struck in the 115 yr preceding the 2011 tsunami. These tsunamis remained in the collective memory of communities, and numerous measures against future tsunami damage, such as breakwaters and tsunami evacuation drills, had been implemented. Despite these preparedness efforts, approximately 18 500 deaths and cases of missing persons occurred. The death rate with the age of 65 and above was particularly high, four times higher than that with other age groups. These interviews indicate that deaths resulted from a variety of reasons, but if residents had taken immediate action after the major ground motion stopped, most residents might have been saved. Education about the science behind earthquakes and tsunamis could help save more lives in the future.

A long source area of the 1906 Colombia-Ecuador earthquake estimated from observed tsunami waveforms

NASA Astrophysics Data System (ADS)

Yamanaka, Yusuke; Tanioka, Yuichiro; Shiina, Takahiro

2017-12-01

The 1906 Colombia-Ecuador earthquake induced both strong seismic motions and a tsunami, the most destructive earthquake in the history of the Colombia-Ecuador subduction zone. The tsunami propagated across the Pacific Ocean, and its waveforms were observed at tide gauge stations in countries including Panama, Japan, and the USA. This study conducted slip inverse analysis for the 1906 earthquake using these waveforms. A digital dataset of observed tsunami waveforms at the Naos Island (Panama) and Honolulu (USA) tide gauge stations, where the tsunami was clearly observed, was first produced by consulting documents. Next, the two waveforms were applied in an inverse analysis as the target waveform. The results of this analysis indicated that the moment magnitude of the 1906 earthquake ranged from 8.3 to 8.6. Moreover, the dominant slip occurred in the northern part of the assumed source region near the coast of Colombia, where little significant seismicity has occurred, rather than in the southern part. The results also indicated that the source area, with significant slip, covered a long distance, including the southern, central, and northern parts of the region.[Figure not available: see fulltext.

Near-field hazard assessment of March 11, 2011 Japan Tsunami sources inferred from different methods

USGS Publications Warehouse

Wei, Y.; Titov, V.V.; Newman, A.; Hayes, G.; Tang, L.; Chamberlin, C.

2011-01-01

Tsunami source is the origin of the subsequent transoceanic water waves, and thus the most critical component in modern tsunami forecast methodology. Although impractical to be quantified directly, a tsunami source can be estimated by different methods based on a variety of measurements provided by deep-ocean tsunameters, seismometers, GPS, and other advanced instruments, some in real time, some in post real-time. Here we assess these different sources of the devastating March 11, 2011 Japan tsunami by model-data comparison for generation, propagation and inundation in the near field of Japan. This study provides a comparative study to further understand the advantages and shortcomings of different methods that may be potentially used in real-time warning and forecast of tsunami hazards, especially in the near field. The model study also highlights the critical role of deep-ocean tsunami measurements for high-quality tsunami forecast, and its combination with land GPS measurements may lead to better understanding of both the earthquake mechanisms and tsunami generation process. ?? 2011 MTS.

Transfusion under triple threat: Lessons from Japan's 2011 earthquake, tsunami, and nuclear crisis.

PubMed

Nollet, Kenneth E; Komazawa, Tomoko; Ohto, Hitoshi

2016-10-01

The Great East Japan Earthquake of March 11, 2011 provoked tsunami waves with inland penetration up to 5 km and run-up heights to 40 m. More than 400 km 2 were flooded, mainly along the northeast coast of Japan's largest island, Honshu. Nearly 20,000 human lives were abruptly taken by this natural disaster. Four coastal nuclear facilities went into automatic shutdown; at one, Fukushima Daiichi, cooling system failures resulted in the meltdown of three reactor cores, accompanied by explosive release of radioisotopes. Essentials of modern blood banking and transfusion medicine were lost: roads, vehicles, blood collection venues, and facilities for blood testing and processing. Normal channels of communication were interrupted, not only by physical damage but also due to circuit overload as mobile phone users sought information and tried to exchange messages about their own and others' health, welfare, and whereabouts. The Japanese Red Cross, as a monopoly supplier of allogeneic blood, responded with a nationally coordinated effort that met the transfusion demands of a disaster characterized by immediate mass fatality rather than mass injury. Japan's routine transfusion demands are also met by hospital-based autologous blood programs, which could be pressed into service for emergency allogeneic collections. Herein we report institutional and personal experience in anticipation of future disasters, in which transfusion needs might differ from routine demand. Copyright © 2016 Elsevier Ltd. All rights reserved.

2011 Great East Japan tsunami in Okhotsk Sea region: numerical modelings and observation data

NASA Astrophysics Data System (ADS)

Kostenko, Irina; Zaytsev, Andrey; Yalciner, Ahmet; Pelinovsky, Efim

2013-04-01

The 11 March, 2011 Great East Japan Earthquake with Mw: 9.0 occurred at 05:46:23 UTC with its epicenter estimated at 38.322_N, 142.369_E, and focal depth of 32 km (USGS, 2011). Tsunami waves propagated in Pacific Ocean to all directions. At Russian coast the highest waves were observed in the Kuril Islands (Malokurilskoye, Kunashir Island) which located in between Pacific ocean and the Okhotsk Sea. Kuril island provides limited transmission of tsunami waves from Pacific ocean. tsunami In 2011 Great East Japan Earthquake and Tsunami event, the maximum amplitude of the tsunami was observed as 3 m in Kuril islands. However, tsunami arrived Okhotsk Sea losing a significant amount of energy. Therefore the tsunami amplitudes at the coast of the Okhotsk Sea were smaller. In order to estimate the level of energy loss while passing through the narrow straits of the Kuril Islands, a series of numerical simulations was done by using tsunami numerical code NAMI DANCE. Ten largest earthquake shocks capable of generating tsunami were used as inputs of tsunami sources in the modeling. Hence the relation between the transmission of tsunami and the dimensions of the straits are compared and discussed. Finally the characteristics of tsunami propagation (arrival time and coastal amplification) at the coast in the Okhotsk Sea. The varying grid structure is used in numerical modeling in order to make finer analysis of tsunami passing through narrow straits of the Kuril Islands. This allows to combine exactly the installation locations of stationary and computational gauges. The simulation results are compared with the observations. The linear form of shallow water equations are used in the deep ocean region offshore part of the Sea of Okhotsk. Boussinesq type equations were also used at the near shore area in simulations. Since the Okhotsk Sea Results are a semi enclosed basin, the reflection characteristics at the coastal boundaries may be important. The numerical experiments are also

Preliminary Observations of the Tsunami's Impact on U.S. Trade and Transportation With Japan

DOT National Transportation Integrated Search

2011-05-01

The United States faces potential ramifications from the damage to Japan's freight transportation system caused by the March 2011 earthquake and tsunami. During that time, the United States may face lower levels of both air and maritime imports in au...

The Redwood Coast Tsunami Work Group: Promoting Earthquake and Tsunami Resilience on California's North Coast

NASA Astrophysics Data System (ADS)

Dengler, L. A.; Henderson, C.; Larkin, D.; Nicolini, T.; Ozaki, V.

2014-12-01

In historic times, Northern California has suffered the greatest losses from tsunamis in the U.S. contiguous 48 states. 39 tsunamis have been recorded in the region since 1933, including five that caused damage. This paper describes the Redwood Coast Tsunami Work Group (RCTWG), an organization formed in 1996 to address the tsunami threat from both near and far sources. It includes representatives from government agencies, public, private and volunteer organizations, academic institutions, and individuals interested in working to reduce tsunami risk. The geographic isolation and absence of scientific agencies such as the USGS and CGS in the region, and relatively frequent occurrence of both earthquakes and tsunami events has created a unique role for the RCTWG, with activities ranging from basic research to policy and education and outreach programs. Regional interest in tsunami issues began in the early 1990s when there was relatively little interest in tsunamis elsewhere in the state. As a result, the group pioneered tsunami messaging and outreach programs. Beginning in 2008, the RCTWG has partnered with the National Weather Service and the California Office of Emergency Services in conducting the annual "live code" tsunami communications tests, the only area outside of Alaska to do so. In 2009, the RCTWG joined with the Southern California Earthquake Alliance and the Bay Area Earthquake Alliance to form the Earthquake Country Alliance to promote a coordinated and consistent approach to both earthquake and tsunami preparedness throughout the state. The RCTWG has produced and promoted a variety of preparedness projects including hazard mapping and sign placement, an annual "Earthquake - Tsunami Room" at County Fairs, public service announcements and print material, assisting in TsunamiReady community recognition, and facilitating numerous multi-agency, multidiscipline coordinated exercises, and community evacuation drills. Nine assessment surveys from 1993 to 2013

Holocene Tsunami Deposits From Large Tsunamis Along the Kuril Subduction Zone, Northeast Japan

NASA Astrophysics Data System (ADS)

Nanayama, F.; Furukawa, R.; Satake, K.; Soeda, Y.; Shigeno, K.

2003-12-01

Holocene tsunami deposits in eastern Hokkaido between Nemuro and Tokachi show that the Kuril subduction zone repeatedly produced earthquakes and tsunamis larger than those recorded in this region since AD 1804 (Nanayama et al., Nature, 424, 660-663, 2003). Twenty-two postulated tsunami sand layers from the past 9500 years are preserved on lake bottom near Kushiro City, and about ten postulated tsunami sand layers from the past 3000 years are preserved in peat layers on the coastal marsh of Kiritappu. We dated these ten tsunami deposits (named Ts1 to Ts10 from shallower to deeper) in peat layers by radiocarbon and tephrochronology, correlated them with historical earthquakes and tsunamis, and surveyed their spatial distribution to estimate the tsunamisO inland inundation limits. Ts10 and Ts9 are under regional tephra Ta-c2 (ca. 2.5 ka) and represent prehistorical events. Ts8 to Ts5 are between two regional tephra layers Ta-c2 and B-Tm (ca. 9th century). In particular, Ts5 is found just below B-Tm, so it is dated 9th century (Heian era). Ts4 is dated ca 13th century (Kamakura era), while Ts3, found just below Us-b and Ta-b (AD 1667-1663), is dated 17th century (Edo era). Ts2 is dated 19th century (Edo era) and may correspond to the AD 1843 Tempo Tokachi-oki earthquake (Mt 8.0) recorded in a historical document Nikkanki of Kokutai-ji temple at Akkeshi. Ts1 is inferred 20th century and may correspond to the tsunami from the AD 1960 Chilean earthquake (M 9.5) or the AD 1952 Tokachi-oki earthquake (Mt 8.2). Our detailed surveys indicate that Ts3 and Ts4 can be traced more than 3 km from the present coast line in Kirittapu marsh, much longer than the limits (< 1 km) of recent deposits Ts1 and Ts2 or documented inundation of the 19th and 20th century tsunamis. The recurrence intervals of great tsunami inundation are about 400 to 500 years, longer than that of typical interplate earthquakes along the Kuril subduction zone. The longer interval and the apparent large tsunami

ROAD BRIDGES IN MINAMI-SANRIKU WASHED AWAY IN THE MARCH 11th 2011 GREAT EAST JAPAN EARTHQUAKE AND TSUNAMI

NASA Astrophysics Data System (ADS)

Aglipay, Mary Roxanne I.; Konagai, Kazuo; Kyokawa, Hiroyuki; Keshab, Sharma

On March 11th, 2011, Minami-Sanriku, located in the northeastern coast of Japan was severely inundated by the tsunami that followed the Great East Japan Earthquake on March 11, 2011. Road bridges near the coastlines in this area have been extensively damaged with their decks being overturned or carried over long distances. An attempt was made to deduce as rational scenarios as possible before remaining debris was cleaned up. Though the reasons for the washout of bridges can be many and complex, it is to be noted that bridge decks have hollows for the optimum light-weight solution, which fact eventually allowed the bridge decks to be carried over remarkable distances. Poor connection details and cavities, hollows between deck beams, are considered to have facilitated overturning due to uplift forces.

Seismogeodesy for rapid earthquake and tsunami characterization

NASA Astrophysics Data System (ADS)

Bock, Y.

2016-12-01

Rapid estimation of earthquake magnitude and fault mechanism is critical for earthquake and tsunami warning systems. Traditionally, the monitoring of earthquakes and tsunamis has been based on seismic networks for estimating earthquake magnitude and slip, and tide gauges and deep-ocean buoys for direct measurement of tsunami waves. These methods are well developed for ocean basin-wide warnings but are not timely enough to protect vulnerable populations and infrastructure from the effects of local tsunamis, where waves may arrive within 15-30 minutes of earthquake onset time. Direct measurements of displacements by GPS networks at subduction zones allow for rapid magnitude and slip estimation in the near-source region, that are not affected by instrumental limitations and magnitude saturation experienced by local seismic networks. However, GPS displacements by themselves are too noisy for strict earthquake early warning (P-wave detection). Optimally combining high-rate GPS and seismic data (in particular, accelerometers that do not clip), referred to as seismogeodesy, provides a broadband instrument that does not clip in the near field, is impervious to magnitude saturation, and provides accurate real-time static and dynamic displacements and velocities in real time. Here we describe a NASA-funded effort to integrate GPS and seismogeodetic observations as part of NOAA's Tsunami Warning Centers in Alaska and Hawaii. It consists of a series of plug-in modules that allow for a hierarchy of rapid seismogeodetic products, including automatic P-wave picking, hypocenter estimation, S-wave prediction, magnitude scaling relationships based on P-wave amplitude (Pd) and peak ground displacement (PGD), finite-source CMT solutions and fault slip models as input for tsunami warnings and models. For the NOAA/NASA project, the modules are being integrated into an existing USGS Earthworm environment, currently limited to traditional seismic data. We are focused on a network of

Tsunami simulation method initiated from waveforms observed by ocean bottom pressure sensors for real-time tsunami forecast; Applied for 2011 Tohoku Tsunami

NASA Astrophysics Data System (ADS)

Tanioka, Yuichiro

2017-04-01

After tsunami disaster due to the 2011 Tohoku-oki great earthquake, improvement of the tsunami forecast has been an urgent issue in Japan. National Institute of Disaster Prevention is installing a cable network system of earthquake and tsunami observation (S-NET) at the ocean bottom along the Japan and Kurile trench. This cable system includes 125 pressure sensors (tsunami meters) which are separated by 30 km. Along the Nankai trough, JAMSTEC already installed and operated the cable network system of seismometers and pressure sensors (DONET and DONET2). Those systems are the most dense observation network systems on top of source areas of great underthrust earthquakes in the world. Real-time tsunami forecast has depended on estimation of earthquake parameters, such as epicenter, depth, and magnitude of earthquakes. Recently, tsunami forecast method has been developed using the estimation of tsunami source from tsunami waveforms observed at the ocean bottom pressure sensors. However, when we have many pressure sensors separated by 30km on top of the source area, we do not need to estimate the tsunami source or earthquake source to compute tsunami. Instead, we can initiate a tsunami simulation from those dense tsunami observed data. Observed tsunami height differences with a time interval at the ocean bottom pressure sensors separated by 30 km were used to estimate tsunami height distribution at a particular time. In our new method, tsunami numerical simulation was initiated from those estimated tsunami height distribution. In this paper, the above method is improved and applied for the tsunami generated by the 2011 Tohoku-oki great earthquake. Tsunami source model of the 2011 Tohoku-oki great earthquake estimated using observed tsunami waveforms, coseimic deformation observed by GPS and ocean bottom sensors by Gusman et al. (2012) is used in this study. The ocean surface deformation is computed from the source model and used as an initial condition of tsunami

Prioritizing earthquake and tsunami alerting efforts

NASA Astrophysics Data System (ADS)

Allen, R. M.; Allen, S.; Aranha, M. A.; Chung, A. I.; Hellweg, M.; Henson, I. H.; Melgar, D.; Neuhauser, D. S.; Nof, R. N.; Strauss, J. A.

2015-12-01

The timeline of hazards associated with earthquakes ranges from seconds for the strong shaking at the epicenter, to minutes for strong shaking at more distant locations in big quakes, to tens of minutes for a local tsunami. Earthquake and tsunami warning systems must therefore include very fast initial alerts, while also taking advantage of available time in bigger and tsunami-generating quakes. At the UC Berkeley Seismological Laboratory we are developing a suite of algorithms to provide the fullest possible information about earthquake shaking and tsunami inundation from seconds to minutes after a quake. The E-larmS algorithm uses the P-wave to rapidly detect an earthquake and issue a warning. It is currently issuing alerts to test users in as little as 3 sec after the origin time. Development of a new waveform detector may lead to even faster alerts. G-larmS uses permanent deformation estimates from GNSS stations to estimate the geometry and extent of rupture underway providing more accurate ground shaking estimates in big (M>~7) earthquakes. It performed well in the M6.0 2014 Napa earthquake. T-larmS is a new algorithm designed to extend alert capabilities to tsunami inundation. Rapid estimates of source characteristics for subduction zones event can not only be used to warn of the shaking hazard, but also the local tsunami inundation hazard. These algorithms are being developed, implemented and tested with a focus on the western US, but are also now being tested in other parts of the world including Israel, Turkey, Korea and Chile. Beta users in the Bay Area are receiving the alerts and beginning to implement automated actions. They also provide feedback on users needs, which has led to the development of the MyEEW smartphone app. This app allows beta users to receive the alerts on their cell phones. All these efforts feed into our ongoing assessment of directions and priorities for future development and implementation efforts.

The 1946 Unimak Tsunami Earthquake Area: revised tectonic structure in reprocessed seismic images and a suspect near field tsunami source

USGS Publications Warehouse

Miller, John J.; von Huene, Roland E.; Ryan, Holly F.

2014-01-01

In 1946 at Unimak Pass, Alaska, a tsunami destroyed the lighthouse at Scotch Cap, Unimak Island, took 159 lives on the Hawaiian Islands, damaged island coastal facilities across the south Pacific, and destroyed a hut in Antarctica. The tsunami magnitude of 9.3 is comparable to the magnitude 9.1 tsunami that devastated the Tohoku coast of Japan in 2011. Both causative earthquake epicenters occurred in shallow reaches of the subduction zone. Contractile tectonism along the Alaska margin presumably generated the far-field tsunami by producing a seafloor elevation change. However, the Scotch Cap lighthouse was destroyed by a near-field tsunami that was probably generated by a coeval large undersea landslide, yet bathymetric surveys showed no fresh large landslide scar. We investigated this problem by reprocessing five seismic lines, presented here as high-resolution graphic images, both uninterpreted and interpreted, and available for the reader to download. In addition, the processed seismic data for each line are available for download as seismic industry-standard SEG-Y files. One line, processed through prestack depth migration, crosses a 10 × 15 kilometer and 800-meter-high hill presumed previously to be basement, but that instead is composed of stratified rock superimposed on the slope sediment. This image and multibeam bathymetry illustrate a slide block that could have sourced the 1946 near-field tsunami because it is positioned within a distance determined by the time between earthquake shaking and the tsunami arrival at Scotch Cap and is consistent with the local extent of high runup of 42 meters along the adjacent Alaskan coast. The Unimak/Scotch Cap margin is structurally similar to the 2011 Tohoku tsunamigenic margin where a large landslide at the trench, coeval with the Tohoku earthquake, has been documented. Further study can improve our understanding of tsunami sources along Alaska’s erosional margins.

Tsunami hazard assessments with consideration of uncertain earthquakes characteristics

NASA Astrophysics Data System (ADS)

Sepulveda, I.; Liu, P. L. F.; Grigoriu, M. D.; Pritchard, M. E.

2017-12-01

The uncertainty quantification of tsunami assessments due to uncertain earthquake characteristics faces important challenges. First, the generated earthquake samples must be consistent with the properties observed in past events. Second, it must adopt an uncertainty propagation method to determine tsunami uncertainties with a feasible computational cost. In this study we propose a new methodology, which improves the existing tsunami uncertainty assessment methods. The methodology considers two uncertain earthquake characteristics, the slip distribution and location. First, the methodology considers the generation of consistent earthquake slip samples by means of a Karhunen Loeve (K-L) expansion and a translation process (Grigoriu, 2012), applicable to any non-rectangular rupture area and marginal probability distribution. The K-L expansion was recently applied by Le Veque et al. (2016). We have extended the methodology by analyzing accuracy criteria in terms of the tsunami initial conditions. Furthermore, and unlike this reference, we preserve the original probability properties of the slip distribution, by avoiding post sampling treatments such as earthquake slip scaling. Our approach is analyzed and justified in the framework of the present study. Second, the methodology uses a Stochastic Reduced Order model (SROM) (Grigoriu, 2009) instead of a classic Monte Carlo simulation, which reduces the computational cost of the uncertainty propagation. The methodology is applied on a real case. We study tsunamis generated at the site of the 2014 Chilean earthquake. We generate earthquake samples with expected magnitude Mw 8. We first demonstrate that the stochastic approach of our study generates consistent earthquake samples with respect to the target probability laws. We also show that the results obtained from SROM are more accurate than classic Monte Carlo simulations. We finally validate the methodology by comparing the simulated tsunamis and the tsunami records for

Decline in intertidal biota after the 2011 Great East Japan Earthquake and Tsunami and the Fukushima nuclear disaster: field observations

NASA Astrophysics Data System (ADS)

Horiguchi, Toshihiro; Yoshii, Hiroshi; Mizuno, Satoshi; Shiraishi, Hiroaki

2016-02-01

In 2011, 2012, and 2013, in the intertidal zones of eastern Japan, we investigated the ecological effects of the severe accident at the Fukushima Daiichi Nuclear Power Plant that accompanied the 2011 Great East Japan Earthquake and Tsunami. The number of intertidal species decreased significantly with decreasing distance from the power plant, and no rock shell (Thais clavigera) specimens were collected near the plant, from Hirono to Futaba Beach (a distance of approximately 30 km) in 2012. The collection of rock shell specimens at many other sites hit by the tsunami suggests that the absence of rock shells around the plant in 2012 might have been caused by the nuclear accident in 2011. Quantitative surveys in 2013 showed that the number of species and population densities in the intertidal zones were much lower at sites near, or within several kilometers south of, the plant than at other sites and lower than in 1995, especially in the case of Arthropoda. There is no clear explanation for these findings, but it is evident that the intertidal biota around the power plant has been affected since the nuclear accident.

Decline in intertidal biota after the 2011 Great East Japan Earthquake and Tsunami and the Fukushima nuclear disaster: field observations.

PubMed

Horiguchi, Toshihiro; Yoshii, Hiroshi; Mizuno, Satoshi; Shiraishi, Hiroaki

2016-02-04

In 2011, 2012, and 2013, in the intertidal zones of eastern Japan, we investigated the ecological effects of the severe accident at the Fukushima Daiichi Nuclear Power Plant that accompanied the 2011 Great East Japan Earthquake and Tsunami. The number of intertidal species decreased significantly with decreasing distance from the power plant, and no rock shell (Thais clavigera) specimens were collected near the plant, from Hirono to Futaba Beach (a distance of approximately 30 km) in 2012. The collection of rock shell specimens at many other sites hit by the tsunami suggests that the absence of rock shells around the plant in 2012 might have been caused by the nuclear accident in 2011. Quantitative surveys in 2013 showed that the number of species and population densities in the intertidal zones were much lower at sites near, or within several kilometers south of, the plant than at other sites and lower than in 1995, especially in the case of Arthropoda. There is no clear explanation for these findings, but it is evident that the intertidal biota around the power plant has been affected since the nuclear accident.

Decline in intertidal biota after the 2011 Great East Japan Earthquake and Tsunami and the Fukushima nuclear disaster: field observations

PubMed Central

Horiguchi, Toshihiro; Yoshii, Hiroshi; Mizuno, Satoshi; Shiraishi, Hiroaki

2016-01-01

In 2011, 2012, and 2013, in the intertidal zones of eastern Japan, we investigated the ecological effects of the severe accident at the Fukushima Daiichi Nuclear Power Plant that accompanied the 2011 Great East Japan Earthquake and Tsunami. The number of intertidal species decreased significantly with decreasing distance from the power plant, and no rock shell (Thais clavigera) specimens were collected near the plant, from Hirono to Futaba Beach (a distance of approximately 30 km) in 2012. The collection of rock shell specimens at many other sites hit by the tsunami suggests that the absence of rock shells around the plant in 2012 might have been caused by the nuclear accident in 2011. Quantitative surveys in 2013 showed that the number of species and population densities in the intertidal zones were much lower at sites near, or within several kilometers south of, the plant than at other sites and lower than in 1995, especially in the case of Arthropoda. There is no clear explanation for these findings, but it is evident that the intertidal biota around the power plant has been affected since the nuclear accident. PMID:26842814

Delayed increase in male suicide rates in tsunami disaster-stricken areas following the great east japan earthquake: a three-year follow-up study in Miyagi Prefecture.

PubMed

Orui, Masatsugu; Sato, Yasuhiro; Tazaki, Kanako; Kawamura, Ikuko; Harada, Shuichiro; Hayashi, Mizuho

2015-03-01

Devastating natural disasters and their aftermath are known to cause psychological distress. However, little information is available regarding suicide rates following tsunami disasters that destroy regional social services and networks. The aim of the present study was to determine whether the tsunami disaster following the Great East Japan Earthquake in March 2011 has influenced suicide rates. The study period was from March 2009 to February 2014. Tsunami disaster-stricken areas were defined as the 16 municipalities facing the Pacific Ocean in Miyagi Prefecture. Inland areas were defined as other municipalities in Miyagi that were damaged by the earthquake. Suicide rates in the tsunami disaster-stricken areas were compared to national averages, using a time-series analysis and the Poisson distribution test. In tsunami disaster-stricken areas, male suicide rates were significantly lower than the national average during the initial post-disaster period and began to increase after two years. Likewise, male suicide rates in the inland areas decreased for seven months, and then increased to exceed the national average. In contrast, female post-disaster suicide rates did not change in both areas compared to the national average. Importantly, the male suicide rates in the inland areas started to increase earlier compared to the tsunami-stricken areas, which may reflect the relative deficiency of mental healthcare services in the inland areas. Considering the present status that many survivors from the tsunami disaster still live in temporary housing and face various challenges to rebuild their lives, we should continue intensive, long-term mental healthcare services in the tsunami-stricken areas.

Scedosporium aurantiacum brain abscess after near-drowning in a survivor of a tsunami in Japan.

PubMed

Nakamura, Yutaka; Suzuki, Naomi; Nakajima, Yoshio; Utsumi, Yu; Murata, Okinori; Nagashima, Hiromi; Saito, Heisuke; Sasaki, Nobuhito; Fujimura, Itaru; Ogino, Yoshinobu; Kato, Kanako; Terayama, Yasuo; Miyamoto, Shinya; Yarita, Kyoko; Kamei, Katsuhiko; Nakadate, Toshihide; Endo, Shigeatsu; Shibuya, Kazutoshi; Yamauchi, Kohei

2013-12-01

Many victims of the tsunami that occurred following the Great East Japan Earthquake on March 11, 2011 developed systemic disorders owing to aspiration pneumonia. Herein, we report a case of tsunami lung wherein Scedosporium aurantiacum was detected in the respiratory tract. A magnetic resonance image of the patient's head confirmed multiple brain abscesses and lateral right ventricle enlargement. In this case report, we describe a potential refractory multidrug-resistant infection following a tsunami disaster. Copyright © 2013 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.

The public health impact of tsunami disasters.

PubMed

Keim, Mark E

2011-01-01

Tsunamis have the potential to cause an enormous impact on the health of millions of people. During the last half of the twentieth century, more people were killed by tsunamis than by earthquakes. Most recently, a major emergency response operation has been underway in northeast Japan following a devastating tsunami triggered by the biggest earthquake on record in Japan. This natural disaster has been described as the most expensive in world history. There are few resources in the public health literature that describe the characteristics and epidemiology of tsunami-related disasters, as a whole. This article reviews the phenomenology and impact of tsunamis as a significant public health hazard.

Psychological trauma after the Great East Japan Earthquake.

PubMed

Matsumoto, Kazunori; Sakuma, Atsushi; Ueda, Ikki; Nagao, Ayami; Takahashi, Yoko

2016-08-01

The Great East Japan Earthquake (GEJE) struck the northeastern part of Japan on 11 March 2011 and triggered a devastating tsunami, causing widespread destruction along the coast of northeastern Japan. The tsunami also led to an accident at the Fukushima Daiichi nuclear power plant. Incidents occurring in such major disasters are known to lead to psychological trauma. This paper has summarized English-language documentation regarding GEJE-related psychological trauma or post-traumatic stress disorder (PTSD). Research thus far has reported the possibility of higher probable PTSD prevalence among residents of the GEJE areas than in the average Japanese population during normal times. At the very least, many people have experienced trauma symptoms at self-recognition levels 1 year or longer after the disaster. It appears that the percentage of persons with high PTSD risk was higher in regions with radiation-related impacts than in regions where the main damage was caused by the earthquake and tsunami. Results have not been limited to showing relations between severe exposure to a traumatic event and PTSD symptoms but also show that a variety of factors, including social factors, has been shown to interact with PTSD symptoms. The fact that Japanese society as a whole united against the trauma of the GEJE may have worked to minimize the effects of trauma. To grasp a full picture of the effects of psychological trauma due to the GEJE, further surveys and research are necessary. It will be necessary to continue engagements related to these problems and issues into the future. © 2016 The Authors. Psychiatry and Clinical Neurosciences © 2016 Japanese Society of Psychiatry and Neurology.

Preparation of Synthetic Earthquake Catalogue and Tsunami Hazard Curves in Marmara Sea using Monte Carlo Simulations

NASA Astrophysics Data System (ADS)

Bayraktar, Başak; Özer Sözdinler, Ceren; Necmioǧlu, Öcal; Meral Özel, Nurcan

2017-04-01

The Marmara Sea and its surrounding is one of the most populated areas in Turkey. Many densely populated cities, such as megacity Istanbul with a population of more than 14 million, a great number of industrial facilities in largest capacity and potential, refineries, ports and harbors are located along the coasts of Marmara Sea. The region is highly seismically active. There has been a wide range of studies in this region regarding the fault mechanisms, seismic activities, earthquakes and triggered tsunamis in the Sea of Marmara. The historical documents reveal that the region has been experienced many earthquakes and tsunamis in the past. According to Altinok et al. (2011), 35 tsunami events happened in Marmara Sea between BC 330 and 1999. As earthquakes are expected in Marmara Sea with the break of segments of North Anatolian Fault (NAF) in the future, the region should be investigated in terms of the possibility of tsunamis by the occurrence of earthquakes in specific return periods. This study aims to make probabilistic tsunami hazard analysis in Marmara Sea. For this purpose, the possible sources of tsunami scenarios are specified by compiling the earthquake catalogues, historical records and scientific studies conducted in the region. After compiling all this data, a synthetic earthquake and tsunami catalogue are prepared using Monte Carlo simulations. For specific return periods, the possible epicenters, rupture lengths, widths and displacements are determined with Monte Carlo simulations assuming the angles of fault segments as deterministic. For each earthquake of synthetic catalogue, the tsunami wave heights will be calculated at specific locations along Marmara Sea. As a further objective, this study will determine the tsunami hazard curves for specific locations in Marmara Sea including the tsunami wave heights and their probability of exceedance. This work is supported by SATREPS-MarDim Project (Earthquake and Tsunami Disaster Mitigation in the

The Great East Japan Earthquake, tsunami, and Fukushima Daiichi nuclear power plant accident: a triple disaster affecting the mental health of the country.

PubMed

Yamashita, Jun; Shigemura, Jun

2013-09-01

The Great East Japan Earthquake in 2011 caused 2 other serious disasters: a tsunami and a nuclear power plant accident. A chronic shortage of mental health resources had been previously reported in the Tohoku region, and the triple disaster worsened the situation. Eventually a public health approach was implemented by providing a common room in temporary housing developments to build a sense of community and to approach evacuees so that they could be triaged and referred to mental health teams. Japan now advocates using psychological first aid to educate first responders. This article extracts key lessons from relevant literature. Copyright © 2013 Elsevier Inc. All rights reserved.

Have the tsunami and nuclear accident following the Great East Japan Earthquake affected the local distribution of hospital physicians?

PubMed

Kashima, Saori; Inoue, Kazuo; Matsumoto, Masatoshi

2017-01-01

The Great East Japan Earthquake occurred on 11 March 2011 near the northeast coast of the main island, 'Honshu', of Japan. It wreaked enormous damage in two main ways: a giant tsunami and an accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP). This disaster may have affected the distribution of physicians in the region. Here, we evaluate the effect of the disaster on the distribution of hospital physicians in the three most severely affected prefectures (Iwate, Miyagi, and Fukushima). We obtained individual information about physicians from the Physician Census in 2010 (pre-disaster) and 2012 (post-disaster). We examined geographical distributions of physicians in two ways: (1) municipality-based analysis for demographic evaluation; and (2) hospital-based analysis for geographic evaluation. In each analysis, we calculated the rate of change in physician distributions between pre- and post-disaster years at various distances from the tsunami-affected coast, and from the restricted area due to the FDNPP accident. The change in all, hospital, and clinic physicians were 0.2%, 0.7%, and -0.7%, respectively. In the municipality-based analysis, after taking account of the decreased population, physician numbers only decreased within the restricted area. In the hospital-based analysis, hospital physician numbers did not decrease at any distance from the tsunami-affected coast. In contrast, there was a 3.3% and 2.3% decrease in hospital physicians 0-25 km and 25-50 km from the restricted area surrounding the FDNPP, respectively. Additionally, decreases were larger and increases were smaller in areas close to the FDNPP than in areas further away. Our results suggest that the tsunami did not affect the distribution of physicians in the affected regions. However, the FDNPP accident changed physician distribution in areas close to the power plant.

Have the tsunami and nuclear accident following the Great East Japan Earthquake affected the local distribution of hospital physicians?

PubMed Central

Inoue, Kazuo; Matsumoto, Masatoshi

2017-01-01

Objective The Great East Japan Earthquake occurred on 11 March 2011 near the northeast coast of the main island, ‘Honshu’, of Japan. It wreaked enormous damage in two main ways: a giant tsunami and an accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP). This disaster may have affected the distribution of physicians in the region. Here, we evaluate the effect of the disaster on the distribution of hospital physicians in the three most severely affected prefectures (Iwate, Miyagi, and Fukushima). Methods We obtained individual information about physicians from the Physician Census in 2010 (pre-disaster) and 2012 (post-disaster). We examined geographical distributions of physicians in two ways: (1) municipality-based analysis for demographic evaluation; and (2) hospital-based analysis for geographic evaluation. In each analysis, we calculated the rate of change in physician distributions between pre- and post-disaster years at various distances from the tsunami-affected coast, and from the restricted area due to the FDNPP accident. Results The change in all, hospital, and clinic physicians were 0.2%, 0.7%, and −0.7%, respectively. In the municipality-based analysis, after taking account of the decreased population, physician numbers only decreased within the restricted area. In the hospital-based analysis, hospital physician numbers did not decrease at any distance from the tsunami-affected coast. In contrast, there was a 3.3% and 2.3% decrease in hospital physicians 0–25 km and 25–50 km from the restricted area surrounding the FDNPP, respectively. Additionally, decreases were larger and increases were smaller in areas close to the FDNPP than in areas further away. Conclusions Our results suggest that the tsunami did not affect the distribution of physicians in the affected regions. However, the FDNPP accident changed physician distribution in areas close to the power plant. PMID:28542461

Increase in avoidable hospital admissions after the Great East Japan Earthquake.

PubMed

Sasabuchi, Yusuke; Matsui, Hiroki; Yasunaga, Hideo; Fushimi, Kiyohide

2017-03-01

The Great East Japan Earthquake and subsequent tsunami and nuclear disaster on 11 March 2011 had a short-term influence on the increase in emergency department visits and hospital admissions due to various diseases. However, it remains unclear whether the earthquake and tsunami disaster affected the long-term health conditions of people in the affected areas. Using a national inpatient database in Japan, we investigated people's ambulatory care sensitive conditions (ACSCs), which are defined as conditions for which effective management and treatment should prevent admission to a hospital. We compared the number of admissions for ACSCs before-quake (July 2010 to February 2011) with after-quake (July 2012 to February 2013) periods in the disaster area compared with other areas using a difference-in-differences design. Linear regression models with the interaction between periods and areas were used to estimate the impact of the earthquake on admissions for ACSCs. No significant difference in difference was seen in preventable ACSCs (where immunisation and other interventions can prevent illness) or chronic ACSCs (where effective care can prevent flare-ups), while acute ACSCs (where early intervention can prevent more serious progression) increased significantly (3.3 admissions per 100 000 population; 95% CI 0.4 to 6.3; p=0.028). Preventable and chronic ACSCs may have increased just after the earthquake and then immediately decreased. However, avoidable admissions due to acute ACSCs remained high in the long term after the earthquake and tsunami disaster. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Prevalence and Risk Factors for Depressive Reaction among Resident Survivors after the Tsunami following the Great East Japan Earthquake, March 11, 2011

PubMed Central

Matsubara, Chieko; Murakami, Hitoshi; Imai, Koubun; Mizoue, Tetsuya; Akashi, Hidechika; Miyoshi, Chiaki; Nakasa, Tamotsu

2014-01-01

Objectives The Great East Japan Earthquake caused a gigantic tsunami which devastated coastal areas of northern Japan on 11 March 2011. Despite the large number of ‘resident survivors’ who continued to reside in their damaged houses on the second or upper floors, research on the mental health of these individuals has been limited. This study explored the prevalence of depressive reaction and risk factors for depressive reaction among these resident survivors. Methods A cross-sectional household health support needs screening was conducted for resident survivors in Higashi-Matsushima city, Miyagi prefecture, two to four months after the tsunami. The health interview that was conducted including mental status, assessed by the Patient Health Questionnaire-2 (PHQ-2). Results Of 5,454 respondents, 8.1% had depressive reaction. After adjustment by the number of weeks from the tsunami and the mortality rate at each respondent's place of residence, depressive reaction was significantly associated with house flooding below or above the ground floor (odds ratios of 1.92, 2.36, respectively), the unavailability of gas supply (odds ratio, 1.67), being female (odds ratio, 1.47), middle aged or elderly (odds ratios of 2.41, 2.42, respectively), regular intake of psychotropic medicine(s) since before the tsunami (odds ratio, 2.53) and the presence of one to five or more than six cohabiters (odds ratios of 0.61, 0.52, respectively). Conclusions The results suggest a considerable psychological burden (depressive reaction) following the tsunami among resident survivors. Special supports for families with psychiatric problems need to be considered among resident survivors. Restoration of lifeline utilities and the strengthening of social ties of persons living alone may help prevent depressive reaction among resident survivors after a tsunami. PMID:25279563

Prevalence and risk factors for depressive reaction among resident survivors after the tsunami following the Great East Japan Earthquake, March 11, 2011.

PubMed

Matsubara, Chieko; Murakami, Hitoshi; Imai, Koubun; Mizoue, Tetsuya; Akashi, Hidechika; Miyoshi, Chiaki; Nakasa, Tamotsu

2014-01-01

The Great East Japan Earthquake caused a gigantic tsunami which devastated coastal areas of northern Japan on 11 March 2011. Despite the large number of 'resident survivors' who continued to reside in their damaged houses on the second or upper floors, research on the mental health of these individuals has been limited. This study explored the prevalence of depressive reaction and risk factors for depressive reaction among these resident survivors. A cross-sectional household health support needs screening was conducted for resident survivors in Higashi-Matsushima city, Miyagi prefecture, two to four months after the tsunami. The health interview that was conducted including mental status, assessed by the Patient Health Questionnaire-2 (PHQ-2). Of 5,454 respondents, 8.1% had depressive reaction. After adjustment by the number of weeks from the tsunami and the mortality rate at each respondent's place of residence, depressive reaction was significantly associated with house flooding below or above the ground floor (odds ratios of 1.92, 2.36, respectively), the unavailability of gas supply (odds ratio, 1.67), being female (odds ratio, 1.47), middle aged or elderly (odds ratios of 2.41, 2.42, respectively), regular intake of psychotropic medicine(s) since before the tsunami (odds ratio, 2.53) and the presence of one to five or more than six cohabiters (odds ratios of 0.61, 0.52, respectively). The results suggest a considerable psychological burden (depressive reaction) following the tsunami among resident survivors. Special supports for families with psychiatric problems need to be considered among resident survivors. Restoration of lifeline utilities and the strengthening of social ties of persons living alone may help prevent depressive reaction among resident survivors after a tsunami.

Fault slip and seismic moment of the 1700 Cascadia earthquake inferred from Japanese tsunami descriptions

USGS Publications Warehouse

Satake, K.; Wang, K.; Atwater, B.F.

2003-01-01

The 1700 Cascadia earthquake attained moment magnitude 9 according to new estimates based on effects of its tsunami in Japan, computed coseismic seafloor deformation for hypothetical ruptures in Cascadia, and tsunami modeling in the Pacific Ocean. Reports of damage and flooding show that the 1700 Casscadia tsunami reached 1-5 m heights at seven shoreline sites in Japan. Three sets of estimated heights express uncertainty about location and depth of reported flooding, landward decline in tsunami heights from shorelines, and post-1700 land-level changes. We compare each set with tsunami heights computed from six Cascadia sources. Each source is vertical seafloor displacement calculated with a three-dimensional elastic dislocation model, for three sources the rupture extends the 1100 km length of the subduction zone and differs in width and shallow dip; for the other sources, ruptures of ordinary width extend 360-670 km. To compute tsunami waveforms, we use a linear long-wave approximation with a finite difference method, and we employ modern bathymetry with nearshore grid spacing as small as 0.4 km. The various combinations of Japanese tsunami heights and Cascadia sources give seismic moment of 1-9 ?? 1022 N m, equivalent to moment magnitude 8.7-9.2. This range excludes several unquantified uncertainties. The most likely earthquake, of moment magnitude 9.0, has 19 m of coseismic slip on an offshore, full-slip zone 1100 km long with linearly decreasing slip on a downdip partial-slip zone. The shorter rupture models require up to 40 m offshore slip and predict land-level changes inconsistent with coastal paleoseismological evidence. Copyright 2003 by the American Geophysical Union.

Magnitude scale for the Central American tsunamis

NASA Astrophysics Data System (ADS)

Hatori, Tokutaro

1995-09-01

Based on the tsunami data in the Central American region, the regional characteristic of tsunami magnitude scales is discussed in relation to earthquake magnitudes during the period from 1900 to 1993. Tsunami magnitudes on the Imamura-Iida scale of the 1985 Mexico and 1992 Nicaragua tsunamis are determined to be m=2.5, judging from the tsunami height-distance diagram. The magnitude values of the Central American tsunamis are relatively small compared to earthquakes with similar size in other regions. However, there are a few large tsunamis generated by low-frequency earthquakes such as the 1992 Nicaragua earthquake. Inundation heights of these unusual tsunamis are about 10 times higher than those of normal tsunamis for the same earthquake magnitude ( M s =6.9 7.2). The Central American tsunamis having magnitude m>1 have been observed by the Japanese tide stations, but the effect of directivity toward Japan is very small compared to that of the South American tsunamis.

What kind of disturbances did March 11, 2011 Tohoku Earthquake and Tsunamis leave continental margin ecosystems? : Lessons from five years monitoring research

NASA Astrophysics Data System (ADS)

Kitazato, Hiroshi; Kijima, Akihiro; Kogure, Kazuhiro; Hara, Motoyuki; Nagata, Toshi; Fujikura, Kasunori; Sonoda, Akira

2016-04-01

On March 11, 2011, huge earthquake with M9.0 took place at Japan Trench area off Northeast Japan. Vigorous disturbances of marine environments and ecosystems have taken place at coastal areas where huge tsunamis swept sediments and organisms away from the coastal areas to deeper oceans. Distributional pattern of sediments and organisms in coves and bays have strongly changed after tsunamis. Marine ecosystems at Northeast Japan have totally disturbed and damaged. Scientists from Tohoku University, the University of Tokyo and JAMSTEC have started to monitor how much marine ecosystem disturbed and how it may recover. A research team, named Tohoku Ecosystem-Associated Marine Sciences, continually makes research on marine ecosystems as ten years monitoring project funded by MEXT, Japan since 2011. On 2016, it takes five years from the Earthquake and Tsunami occurred. What happens marine ecosystems at Tohoku area during these years. Water column ecosystems are rather easy to recover from disturbances. Seaweed communities have strongly damaged, but, they gradually recover. Sediment communities have not recovered yet as sediment distribution is different from before earthquake and tsunamis. Most difficulties are scars in human minds. We, scientists, try to share scientific activities and results with local peoples including fishermen and local governments for better understanding of both oceanic conditions and fishery resources. Disaster risk reduction should accelerate with resilience of community structure. But, mental resilience is the most effective way to recover human activities at the damaged areas.

Verification of Reproduction Simulation of the 2011 Great East Japan Tsunami Using Time-Stamp Data

NASA Astrophysics Data System (ADS)

Honma, Motohiro; Ushiyama, Motoyuki

2014-05-01

In the 2011 off the pacific coast of Tohoku earthquake tsunami, the significant damage and loss of lives were caused by large tsunami in the pacific coastal areas of the northern Japan. It is important to understand the situation of tsunami inundation in detail in order to establish the effective measures of disaster prevention. In this study, we calculated the detailed tsunami inundation simulation of Rikuzentakata city and verified the simulation results using not only the static observed data such as inundation area and tsunami height estimated by traces but also time stamp data which were recorded to digital camera etc. We calculated the tsunami simulation by non-linear long-wave theory using the staggered grid and leap flog scheme. We used Fujii and Satake (2011)'s model ver.4.2 as the tsunami source. The inundation model of Rikuzentakata city was constructed by fine ground level data of 10m mesh. In this simulation, the shore and river banks were set in boundary of calculation mesh. At that time, we have calculated two patterns of simulation, one condition is that a bank doesn't collapse even if tsunami overflows on it, another condition is that a bank collapses if tsunami overflows on it and its discharge exceeds the threshold. We can use the inundation area data, which was obtained by Geospatial Information Authority of Japan (GSI), and height data of tsunami trace, which were obtained by the 2011 Tohoku Earthquake Joint Survey (TTJS) group, as "static" verification data. Comparing the inundation area of simulation result with its observation by GSI, both areas are matched very well. And then, correlation coefficient between tsunami height data resulted from simulation and observed by TTJS is 0.756. In order to verify tsunami arrival time, we used the time stamp data which were recorded to digital camera etc. by citizens. Ushiyama and Yokomaku (2012) collected these tsunami stamp data and estimated the arrival time in Rikuzentakata city. We compared the

Source of 1629 Banda Mega-Thrust Earthquake and Tsunami: Implications for Tsunami Hazard Evaluation in Eastern Indonesia

NASA Astrophysics Data System (ADS)

Major, J. R.; Liu, Z.; Harris, R. A.; Fisher, T. L.

2011-12-01

Using Dutch records of geophysical events in Indonesia over the past 400 years, and tsunami modeling, we identify tsunami sources that have caused severe devastation in the past and are likely to reoccur in the near future. The earthquake history of Western Indonesia has received much attention since the 2004 Sumatra earthquakes and subsequent events. However, strain rates along a variety of plate boundary segments are just as high in eastern Indonesia where the earthquake history has not been investigated. Due to the rapid population growth in this region it is essential and urgent to evaluate its earthquake and tsunami hazards. Arthur Wichmann's 'Earthquakes of the Indian Archipelago' shows that there were 30 significant earthquakes and 29 tsunami between 1629 to 1877. One of the largest and best documented is the great earthquake and tsunami effecting the Banda islands on 1 August, 1629. It caused severe damage from a 15 m tsunami that arrived at the Banda Islands about a half hour after the earthquake. The earthquake was also recorded 230 km away in Ambon, but no tsunami is mentioned. This event was followed by at least 9 years of aftershocks. The combination of these observations indicates that the earthquake was most likely a mega-thrust event. We use a numerical simulation of the tsunami to locate the potential sources of the 1629 mega-thrust event and evaluate the tsunami hazard in Eastern Indonesia. The numerical simulation was tested to establish the tsunami run-up amplification factor for this region by tsunami simulations of the 1992 Flores Island (Hidayat et al., 1995) and 2006 Java (Katoet al., 2007) earthquake events. The results yield a tsunami run-up amplification factor of 1.5 and 3, respectively. However, the Java earthquake is a unique case of slow rupture that was hardly felt. The fault parameters of recent earthquakes in the Banda region are used for the models. The modeling narrows the possibilities of mega-thrust events the size of the one

Rapid Tsunami Inundation Forecast from Near-field or Far-field Earthquakes using Pre-computed Tsunami Database: Pelabuhan Ratu, Indonesia

NASA Astrophysics Data System (ADS)

Gusman, A. R.; Setiyono, U.; Satake, K.; Fujii, Y.

2017-12-01

We built pre-computed tsunami inundation database in Pelabuhan Ratu, one of tsunami-prone areas on the southern coast of Java, Indonesia. The tsunami database can be employed for a rapid estimation of tsunami inundation during an event. The pre-computed tsunami waveforms and inundations are from a total of 340 scenarios ranging from 7.5 to 9.2 in moment magnitude scale (Mw), including simple fault models of 208 thrust faults and 44 tsunami earthquakes on the plate interface, as well as 44 normal faults and 44 reverse faults in the outer-rise region. Using our tsunami inundation forecasting algorithm (NearTIF), we could rapidly estimate the tsunami inundation in Pelabuhan Ratu for three different hypothetical earthquakes. The first hypothetical earthquake is a megathrust earthquake type (Mw 9.0) offshore Sumatra which is about 600 km from Pelabuhan Ratu to represent a worst-case event in the far-field. The second hypothetical earthquake (Mw 8.5) is based on a slip deficit rate estimation from geodetic measurements and represents a most likely large event near Pelabuhan Ratu. The third hypothetical earthquake is a tsunami earthquake type (Mw 8.1) which often occur south off Java. We compared the tsunami inundation maps produced by the NearTIF algorithm with results of direct forward inundation modeling for the hypothetical earthquakes. The tsunami inundation maps produced from both methods are similar for the three cases. However, the tsunami inundation map from the inundation database can be obtained in much shorter time (1 min) than the one from a forward inundation modeling (40 min). These indicate that the NearTIF algorithm based on pre-computed inundation database is reliable and useful for tsunami warning purposes. This study also demonstrates that the NearTIF algorithm can work well even though the earthquake source is located outside the area of fault model database because it uses a time shifting procedure for the best-fit scenario searching.

Dense Ocean Floor Network for Earthquakes and Tsunamis; DONET/ DONET2, Part2 -Development and data application for the mega thrust earthquakes around the Nankai trough-

NASA Astrophysics Data System (ADS)

Kaneda, Y.; Kawaguchi, K.; Araki, E.; Matsumoto, H.; Nakamura, T.; Nakano, M.; Kamiya, S.; Ariyoshi, K.; Baba, T.; Ohori, M.; Hori, T.; Takahashi, N.; Kaneko, S.; Donet Research; Development Group

2010-12-01

Yoshiyuki Kaneda Katsuyoshi Kawaguchi*, Eiichiro Araki*, Shou Kaneko*, Hiroyuki Matsumoto*, Takeshi Nakamura*, Masaru Nakano*, Shinichirou Kamiya*, Keisuke Ariyoshi*, Toshitaka Baba*, Michihiro Ohori*, Narumi Takakahashi*, and Takane Hori** * Earthquake and Tsunami Research Project for Disaster Prevention, Leading Project , Japan Agency for Marine-Earth Science and Technology (JAMSTEC) **Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology (JAMSTEC) DONET (Dense Ocean Floor Network for Earthquakes and Tsunamis) is the real time monitoring system of the Tonankai seismogenic zones around the Nankai trough southwestern Japan. We were starting to develop DONET to perform real time monitoring of crustal activities over there and the advanced early warning system. DONET will provide important and useful data to understand the Nankai trough maga thrust earthquake seismogenic zones and to improve the accuracy of the earthquake recurrence cycle simulation. Details of DONET concept are as follows. 1) Redundancy, Extendable function and advanced maintenance system using the looped cable system, junction boxes and the ROV/AUV. DONET has 20 observatories and incorporated in a double land stations concept. Also, we are developed ROV for the 10km cable extensions and heavy weight operations. 2) Multi kinds of sensors to observe broad band phenomena such as long period tremors, very low frequency earthquakes and strong motions of mega thrust earthquakes over M8: Therefore, sensors such as a broadband seismometer, an accelerometer, a hydrophone, a precise pressure gauge, a differential pressure gauge and a thermometer are equipped with each observatory in DONET. 3) For speedy detections, evaluations and notifications of earthquakes and tsunamis: DONET system will be deployed around the Tonankai seismogenic zone. 4) Provide data of ocean floor crustal deformations derived from pressure sensors: Simultaneously, the development of data

New study on the 1941 Gloria Fault earthquake and tsunami

NASA Astrophysics Data System (ADS)

Baptista, Maria Ana; Miranda, Jorge Miguel; Batlló, Josep; Lisboa, Filipe; Luis, Joaquim; Maciá, Ramon

2016-08-01

The M ˜ 8.3-8.4 25 November 1941 was one of the largest submarine strike-slip earthquakes ever recorded in the Northeast (NE) Atlantic basin. This event occurred along the Eurasia-Nubia plate boundary between the Azores and the Strait of Gibraltar. After the earthquake, the tide stations in the NE Atlantic recorded a small tsunami with maximum amplitudes of 40 cm peak to through in the Azores and Madeira islands. In this study, we present a re-evaluation of the earthquake epicentre location using seismological data not included in previous studies. We invert the tsunami travel times to obtain a preliminary tsunami source location using the backward ray tracing (BRT) technique. We invert the tsunami waveforms to infer the initial sea surface displacement using empirical Green's functions, without prior assumptions about the geometry of the source. The results of the BRT simulation locate the tsunami source quite close to the new epicentre. This fact suggests that the co-seismic deformation of the earthquake induced the tsunami. The waveform inversion of tsunami data favours the conclusion that the earthquake ruptured an approximately 160 km segment of the plate boundary, in the eastern section of the Gloria Fault between -20.249 and -18.630° E. The results presented here contribute to the evaluation of tsunami hazard in the Northeast Atlantic basin.

Complexity in Size, Recurrence and Source of Historical Earthquakes and Tsunamis in Central Chile

NASA Astrophysics Data System (ADS)

Cisternas, M.

2013-05-01

Central Chile has a 470-year-long written earthquake history, the longest of any part of the country. Thanks to the early and continuous Spanish settlement of this part of Chile (32°- 35° S), records document destructive earthquakes and tsunamis in 1575, 1647, 1730, 1822, 1906 and 1985. This sequence has promoted the idea that central Chile's large subduction inter-plate earthquakes recur at regular intervals of about 80 years. The last of these earthquakes, in 1985, was even forecast as filling a seismic gap on the thrust boundary between the subducting Nazca Plate and the overriding South America Plate. Following this logic, the next large earthquake in metropolitan Chile will not occur until late in the 21st century. However, here I challenge this conclusion by reporting recently discovered historical evidence in Spain, Japan, Peru, and Chile. This new evidence augments the historical catalog in central Chile, strongly suggests that one of these earthquakes previously assumed to occur on the inter-plate interface in fact occurred elsewhere, and forces the conclusion that another of these earthquakes (and its accompanying tsunami) dwarfed the others. These findings complicate the task of assessing the hazard of future earthquakes in Chile's most populated region.

Modelling Psychological Responses to the Great East Japan Earthquake and Nuclear Incident

PubMed Central

Goodwin, Robin; Takahashi, Masahito; Sun, Shaojing; Gaines, Stanley O.

2012-01-01

The Great East Japan (Tōhoku/Kanto) earthquake of March 2011was followed by a major tsunami and nuclear incident. Several previous studies have suggested a number of psychological responses to such disasters. However, few previous studies have modelled individual differences in the risk perceptions of major events, or the implications of these perceptions for relevant behaviours. We conducted a survey specifically examining responses to the Great Japan earthquake and nuclear incident, with data collected 11–13 weeks following these events. 844 young respondents completed a questionnaire in three regions of Japan; Miyagi (close to the earthquake and leaking nuclear plants), Tokyo/Chiba (approximately 220 km from the nuclear plants), and Western Japan (Yamaguchi and Nagasaki, some 1000 km from the plants). Results indicated significant regional differences in risk perception, with greater concern over earthquake risks in Tokyo than in Miyagi or Western Japan. Structural equation analyses showed that shared normative concerns about earthquake and nuclear risks, conservation values, lack of trust in governmental advice about the nuclear hazard, and poor personal control over the nuclear incident were positively correlated with perceived earthquake and nuclear risks. These risk perceptions further predicted specific outcomes (e.g. modifying homes, avoiding going outside, contemplating leaving Japan). The strength and significance of these pathways varied by region. Mental health and practical implications of these findings are discussed in the light of the continuing uncertainties in Japan following the March 2011 events. PMID:22666380

Experiences of municipal public health nurses following Japan's earthquake, tsunami, and nuclear disaster.

PubMed

Kayama, Mami; Akiyama, Tsuyoshi; Ohashi, Akiko; Horikoshi, Naoko; Kido, Yoshifumi; Murakata, Tazuko; Kawakami, Norito

2014-01-01

The purpose of this study was to explore the experiences of municipal public health nurses in the wake of the March 2011 massive earthquake and tsunami and resulting nuclear accident in Fukushima, Japan, from the time of the disaster until December 2013. Thirty-two public health nurses working in three cities in Fukushima prefecture were divided into four focus groups and took part in interviews, which were analyzed using a qualitative descriptive method. Two major themes were extracted: (1) experiences of difficulties and dilemmas, and (2) professional challenges and the meaning of excellence as a public health nurse. Subjects recounted their experiences based on the timeline of events. The process of overcoming various dilemmas--between prescribed roles and actual needs on the ground, being both civil servants and private citizens with families, and having to be publicly accountable while lacking adequate information--caused participants to reexamine the meaning of excellence in the practice of public health. The strenuous and complex demands of extended disaster management caused subjects to grow professionally. Helping them process their emotions should also help these nurses give focus to their posttraumatic growth, and strengthen their sense of professionalism. © 2014 Wiley Periodicals, Inc.

Cascadia Earthquake and Tsunami Scenario for California's North Coast

NASA Astrophysics Data System (ADS)

Dengler, L.

2006-12-01

In 1995 the California Division of Mines and Geology (now the California Geological Survey) released a planning scenario for an earthquake on the southern portion of the Cascadia subduction zone (CSZ). This scenario was the 8th and last of the Earthquake Planning Scenarios published by CDMG. It was the largest magnitude CDMG scenario, an 8.4 earthquake rupturing the southern 200 km of the CSZ, and it was the only scenario to include tsunami impacts. This scenario event has not occurred in historic times and depicts impacts far more severe than any recent earthquake. The local tsunami hazard is new; there is no written record of significant local tsunami impact in the region. The north coast scenario received considerable attention in Humboldt and Del Norte Counties and contributed to a number of mitigation efforts. The Redwood Coast Tsunami Work Group (RCTWG), an organization of scientists, emergency managers, government agencies, and businesses from Humboldt, Mendocino, and Del Norte Counties, was formed in 1996 to assist local jurisdictions in understanding the implications of the scenario and to promote a coordinated, consistent mitigation program. The group has produced print and video materials and promoted response and evacuation planning. Since 1997 the RCTWG has sponsored an Earthquake Tsunami Education Room at county fairs featuring preparedness information, hands-on exhibits and regional tsunami hazard maps. Since the development of the TsunamiReady Program in 2001, the RCTWG facilitates community TsunamiReady certification. To assess the effectiveness of mitigation efforts, five telephone surveys between 1993 and 2001 were conducted by the Humboldt Earthquake Education Center. A sixth survey is planned for this fall. Each survey includes between 400 and 600 respondents. Over the nine year period covered by the surveys, the percent with houses secured to foundations has increased from 58 to 80 percent, respondents aware of a local tsunami hazard increased

Recent damaging earthquakes in Japan, 2003-2008

USGS Publications Warehouse

Kayen, Robert E

2008-01-01

During the last six years, from 2003-2008, Japan has been struck by three significant and damaging earthquakes: The most recent M6.6 Niigata Chuetsu Oki earthquake of July 16, 2007 off the coast of Kashiwazaki City, Japan; The M6.6 Niigata Chuetsu earthquake of October 23, 2004, located in Niigata Prefecture in the central Uonuma Hills; and the M8.0 Tokachi Oki Earthquake of September 26, 2003 effecting southeastern Hokkaido Prefecture. These earthquakes stand out among many in a very active period of seismicity in Japan. Within the upper 100 km of the crust during this period, Japan experienced 472 earthquakes of magnitude 6, or greater. Both Niigata events affected the south-central region of Tohoku Japan, and the Tokachi-Oki earthquake affected a broad region of the continental shelf and slope southeast of the Island of Hokkaido. This report is synthesized from the work of scores of Japanese and US researchers who led and participated in post-earthquake reconnaissance of these earthquakes: their noteworthy and valuable contributions are listed in an extended acknowledgements section at the end of the paper. During the Niigata Chuetsu Oki event of 2007, damage to the Kashiwazaki-Kariwa nuclear power plant, structures, infrastructure, and ground were primarily the product of two factors: (1) high intensity motions from this moderate-sized shallow event, and (2) soft, poor performing, or liquefiable soils in the coastal region of southwestern Niigata Prefecture. Structural and geotechnical damage along the slopes of dunes was ubiquitous in the Kashiwazaki-Kariwa region. The 2004 Niigata Chuetsu Earthquake was the most significant to affect Japan since the 1995 Kobe earthquake. Forty people were killed, almost 3,000 were injured, and many hundreds of landslides destroyed entire upland villages. Landslides were of all types; some dammed streams, temporarily creating lakes threatening to overtop their new embankments and cause flash floods and mudslides. The numerous

Tsunami damage in the southern Kanto region from the 1703 Genroku Kanto earthquake

NASA Astrophysics Data System (ADS)

Muragishi, J.; Satake, K.

2014-12-01

The Genroku Kanto earthquake occurred on Dec. 31th, 1703 along the Sagami Trough where the Philippine Sea plate subducts beneath the continental plate. Hatori (1976) reported significant tsunami damage with estimated tsunami heights of 5 m along Kujukuri coast on the Pacific Ocean, and estimated the tsunami heights in the inner Tokyo Bay as approximately 2 m. In Tokyo Bay, there are no records that indicate the tsunami inundated residential areas, while some descriptions of tsunami are recorded in Edo, the former Tokyo. The notice from Edo City Commissioners to residences in Edo described that the tsunami came up to the upper-limit of Sumida River in Tokyo, where four major arrivals of tsunamis were reported. According to Saihen-onkoroku, tsunami came to Fukagawa, where one person was killed by throwing away from a boat affected by the tsunami. In Ichikawa along the coast of Chiba Prefecture in Tokyo Bay, there are historical records about the salt farm. The embankments were collapsed and the salt farm was ruined, while the tsunami damage is not described. At this location, the damage due to storm surge in 1680 is recorded in the same document. Although storm surge damage is recorded in detail, there are no records about the Genroku tsunami, suggesting that the tsunami damage, if any, is slighter than the storm surge. Along the Kujukui coast outside the Tokyo bay, the descriptions are not only damage to buildings or deaths but also an influx of sand brought by the tsunami which damaged the agricultural land. In summary, it became certain that the Genroku tsunami caused some damage in the inner Tokyo Bay area. In addition, we found that a wide range of farmland was suffered by influx of sand and crops could not grow well. Such a description may be able to contribute to the tsunami deposits in future research. This study was supported by the Special Project for Reducing Vulnerability for Urban Mega Earthquake Disasters from the MEXT of Japan.

Irian Jaya earthquake and tsunami cause serious damage

NASA Astrophysics Data System (ADS)

Imamura, Fumihiko; Subandono, D.; Watson, G.; Moore, A.; Takahashi, T.; Matsutomi, H.; Hidayat, R.

On February 17,1996, at 0559 UT, a major earthquake with moment magnitude (Mw) 7.9 killed 107 people and caused major damage at Biak Island, 30-40 km southwest of the earthquake's epicenter (Figures 1 and 2). A devastating tsunami washed away all of the houses at Korim, a small village located in a narrow bay facing directly towards the incoming wave, and it left behind clear evidence of sand erosion and deposition that indicated how far the tsunami advanced. An unexpectedly large tsunami run-up of 7.7 m was measured at Wardo in western Biak, which faces away from the primary tsunami source. This high run-up may have been caused by a local submarine landslide.

Applying the natural disasters vulnerability evaluation model to the March 2011 north-east Japan earthquake and tsunami.

PubMed

Ruiz Estrada, Mario Arturo; Yap, Su Fei; Park, Donghyun

2014-07-01

Natural hazards have a potentially large impact on economic growth, but measuring their economic impact is subject to a great deal of uncertainty. The central objective of this paper is to demonstrate a model--the natural disasters vulnerability evaluation (NDVE) model--that can be used to evaluate the impact of natural hazards on gross national product growth. The model is based on five basic indicators-natural hazards growth rates (αi), the national natural hazards vulnerability rate (ΩT), the natural disaster devastation magnitude rate (Π), the economic desgrowth rate (i.e. shrinkage of the economy) (δ), and the NHV surface. In addition, we apply the NDVE model to the north-east Japan earthquake and tsunami of March 2011 to evaluate its impact on the Japanese economy. © 2014 The Author(s). Disasters © Overseas Development Institute, 2014.

Rapid estimate of earthquake source duration: application to tsunami warning.

NASA Astrophysics Data System (ADS)

Reymond, Dominique; Jamelot, Anthony; Hyvernaud, Olivier

2016-04-01

We present a method for estimating the source duration of the fault rupture, based on the high-frequency envelop of teleseismic P-Waves, inspired from the original work of (Ni et al., 2005). The main interest of the knowledge of this seismic parameter is to detect abnormal low velocity ruptures that are the characteristic of the so called 'tsunami-earthquake' (Kanamori, 1972). The validation of the results of source duration estimated by this method are compared with two other independent methods : the estimated duration obtained by the Wphase inversion (Kanamori and Rivera, 2008, Duputel et al., 2012) and the duration calculated by the SCARDEC process that determines the source time function (M. Vallée et al., 2011). The estimated source duration is also confronted to the slowness discriminant defined by Newman and Okal, 1998), that is calculated routinely for all earthquakes detected by our tsunami warning process (named PDFM2, Preliminary Determination of Focal Mechanism, (Clément and Reymond, 2014)). Concerning the point of view of operational tsunami warning, the numerical simulations of tsunami are deeply dependent on the source estimation: better is the source estimation, better will be the tsunami forecast. The source duration is not directly injected in the numerical simulations of tsunami, because the cinematic of the source is presently totally ignored (Jamelot and Reymond, 2015). But in the case of a tsunami-earthquake that occurs in the shallower part of the subduction zone, we have to consider a source in a medium of low rigidity modulus; consequently, for a given seismic moment, the source dimensions will be decreased while the slip distribution increased, like a 'compact' source (Okal, Hébert, 2007). Inversely, a rapid 'snappy' earthquake that has a poor tsunami excitation power, will be characterized by higher rigidity modulus, and will produce weaker displacement and lesser source dimensions than 'normal' earthquake. References: CLément, J

New approach to analysis of strongest earthquakes with upper-value magnitude in subduction zones and induced by them catastrophic tsunamis on examples of catastrophic events in 21 century

NASA Astrophysics Data System (ADS)

Garagash, I. A.; Lobkovsky, L. I.; Mazova, R. Kh.

2012-04-01

The study of generation of strongest earthquakes with upper-value magnitude (near above 9) and induced by them catastrophic tsunamis, is performed by authors on the basis of new approach to the generation process, occurring in subduction zones under earthquake. The necessity of performing of such studies is connected with recent 11 March 2011 catastrophic underwater earthquake close to north-east Japan coastline and following it catastrophic tsunami which had led to vast victims and colossal damage for Japan. The essential importance in this study is determined by unexpected for all specialists the strength of earthquake occurred (determined by magnitude M = 9), inducing strongest tsunami with wave height runup on the beach up to 10 meters. The elaborated by us model of interaction of ocean lithosphere with island-arc blocks in subduction zones, with taking into account of incomplete stress discharge at realization of seismic process and further accumulation of elastic energy, permits to explain arising of strongest mega-earthquakes, such as catastrophic earthquake with source in Japan deep-sea trench in March, 2011. In our model, the wide possibility for numerical simulation of dynamical behaviour of underwater seismic source is provided by kinematical model of seismic source as well as by elaborated by authors numerical program for calculation of tsunami wave generation by dynamical and kinematical seismic sources. The method obtained permits take into account the contribution of residual tectonic stress in lithosphere plates, leading to increase of earthquake energy, which is usually not taken into account up to date.

Probabilistic Tsunami Hazard Assessment along Nankai Trough (1) An assessment based on the information of the forthcoming earthquake that Earthquake Research Committee(2013) evaluated

NASA Astrophysics Data System (ADS)

Hirata, K.; Fujiwara, H.; Nakamura, H.; Osada, M.; Morikawa, N.; Kawai, S.; Ohsumi, T.; Aoi, S.; Yamamoto, N.; Matsuyama, H.; Toyama, N.; Kito, T.; Murashima, Y.; Murata, Y.; Inoue, T.; Saito, R.; Takayama, J.; Akiyama, S.; Korenaga, M.; Abe, Y.; Hashimoto, N.

2015-12-01

The Earthquake Research Committee(ERC)/HERP, Government of Japan (2013) revised their long-term evaluation of the forthcoming large earthquake along the Nankai Trough; the next earthquake is estimated M8 to 9 class, and the probability (P30) that the next earthquake will occur within the next 30 years (from Jan. 1, 2013) is 60% to 70%. In this study, we assess tsunami hazards (maximum coastal tsunami heights) in the near future, in terms of a probabilistic approach, from the next earthquake along Nankai Trough, on the basis of ERC(2013)'s report. The probabilistic tsunami hazard assessment that we applied is as follows; (1) Characterized earthquake fault models (CEFMs) are constructed on each of the 15 hypothetical source areas (HSA) that ERC(2013) showed. The characterization rule follows Toyama et al.(2015, JpGU). As results, we obtained total of 1441 CEFMs. (2) We calculate tsunamis due to CEFMs by solving nonlinear, finite-amplitude, long-wave equations with advection and bottom friction terms by finite-difference method. Run-up computation on land is included. (3) A time predictable model predicts the recurrent interval of the present seismic cycle is T=88.2 years (ERC,2013). We fix P30 = 67% by applying the renewal process based on BPT distribution with T and alpha=0.24 as its aperiodicity. (4) We divide the probability P30 into P30(i) for i-th subgroup consisting of the earthquakes occurring in each of 15 HSA by following a probability re-distribution concept (ERC,2014). Then each earthquake (CEFM) in i-th subgroup is assigned a probability P30(i)/N where N is the number of CEFMs in each sub-group. Note that such re-distribution concept of the probability is nothing but tentative because the present seismology cannot give deep knowledge enough to do it. Epistemic logic-tree approach may be required in future. (5) We synthesize a number of tsunami hazard curves at every evaluation points on coasts by integrating the information about 30 years occurrence

Ionospheric detection of tsunami earthquakes: observation, modeling and ideas for future early warning

NASA Astrophysics Data System (ADS)

Occhipinti, G.; Manta, F.; Rolland, L.; Watada, S.; Makela, J. J.; Hill, E.; Astafieva, E.; Lognonne, P. H.

2017-12-01

Detection of ionospheric anomalies following the Sumatra and Tohoku earthquakes (e.g., Occhipinti 2015) demonstrated that ionosphere is sensitive to earthquake and tsunami propagation: ground and oceanic vertical displacement induces acoustic-gravity waves propagating within the neutral atmosphere and detectable in the ionosphere. Observations supported by modelling proved that ionospheric anomalies related to tsunamis are deterministic and reproducible by numerical modeling via the ocean/neutral-atmosphere/ionosphere coupling mechanism (Occhipinti et al., 2008). To prove that the tsunami signature in the ionosphere is routinely detected we show here perturbations of total electron content (TEC) measured by GPS and following tsunamigenic earthquakes from 2004 to 2011 (Rolland et al. 2010, Occhipinti et al., 2013), nominally, Sumatra (26 December, 2004 and 12 September, 2007), Chile (14 November, 2007), Samoa (29 September, 2009) and the recent Tohoku-Oki (11 Mars, 2011). Based on the observations close to the epicenter, mainly performed by GPS networks located in Sumatra, Chile and Japan, we highlight the TEC perturbation observed within the first 8 min after the seismic rupture. This perturbation contains information about the ground displacement, as well as the consequent sea surface displacement resulting in the tsunami. In addition to GNSS-TEC observations close to the epicenter, new exciting measurements in the far-field were performed by airglow measurement in Hawaii show the propagation of the internal gravity waves induced by the Tohoku tsunami (Occhipinti et al., 2011). This revolutionary imaging technique is today supported by two new observations of moderate tsunamis: Queen Charlotte (M: 7.7, 27 October, 2013) and Chile (M: 8.2, 16 September 2015). We finally detail here our recent work (Manta et al., 2017) on the case of tsunami alert failure following the Mw7.8 Mentawai event (25 October, 2010), and its twin tsunami alert response following the Mw7

Decrease in the traumatic symptoms observed in child survivors within three years of the 2011 Japan earthquake and tsunami.

PubMed

Usami, Masahide; Iwadare, Yoshitaka; Watanabe, Kyota; Kodaira, Masaki; Ushijima, Hirokage; Tanaka, Tetsuya; Harada, Maiko; Tanaka, Hiromi; Sasaki, Yoshinori; Saito, Kazuhiko

2014-01-01

On March 11, 2011, Japan was struck by a massive earthquake and tsunami. The tsunami caused tremendous damage and traumatized several people, including children. The aim of this study was to assess changes in traumatic symptoms 8, 20, and 30 months of the 2011 tsunami. The study comprised three groups. Copies of the Post-Traumatic Stress Symptoms for Children 15 items (PTSSC-15), a self-rating questionnaire on traumatic symptoms, were distributed to 12,524 children (8-month period), 12,193 children (20-month period), and 11,819 children (30-month period). An effective response of children 8 months, 20 months, and 30 month after the disaster was obtained in 11,639 (92.9%), 10,597 (86.9%), and 10,812 children (91.4%), respectively. We calculated the total score, PTSD subscale, and Depression subscale of PTSSC-15. We calculated the total score, PTSD subscale, and Depression subscale of PTSSC-15. The PTSSC-15 total score and PTSD subscale of children belonging to 1st-9th grade groups who were tested 30 and 20 months after the tsunami significantly decreased compared with those of children tested 8 months after the tsunami. The PTSSC-15 total score and PTSD subscale of children in 1st-9th grade groups tested after 30 months did not decrease significantly compared with those of children tested after 20 months. The PTSSC-15 Depression subscale and PTSD subscale of children in 1st-9th grade groups tested after 30 months significantly decreased compared with those of children tested 8 months after the tsunami. The PTSSC-15 Depression subscale of children in 1st-9th grade groups evaluated after 30 months significantly decreased compared with those of children evaluated after 20 months. This study demonstrates that the traumatic symptoms of children who survived the massive tsunami improved with time. Nonetheless, the traumatic symptoms, which in some cases did not improve with time.

Decrease in the Traumatic Symptoms Observed in Child Survivors within Three Years of the 2011 Japan Earthquake and Tsunami

PubMed Central

Usami, Masahide; Iwadare, Yoshitaka; Watanabe, Kyota; Kodaira, Masaki; Ushijima, Hirokage; Tanaka, Tetsuya; Harada, Maiko; Tanaka, Hiromi; Sasaki, Yoshinori; Saito, Kazuhiko

2014-01-01

Background On March 11, 2011, Japan was struck by a massive earthquake and tsunami. The tsunami caused tremendous damage and traumatized several people, including children. The aim of this study was to assess changes in traumatic symptoms 8, 20, and 30 months of the 2011 tsunami. Methods The study comprised three groups. Copies of the Post-Traumatic Stress Symptoms for Children 15 items (PTSSC-15), a self-rating questionnaire on traumatic symptoms, were distributed to 12,524 children (8-month period), 12,193 children (20-month period), and 11,819 children (30-month period). An effective response of children 8 months, 20 months, and 30 month after the disaster was obtained in 11,639 (92.9%), 10,597 (86.9%), and 10,812 children (91.4%), respectively. We calculated the total score, PTSD subscale, and Depression subscale of PTSSC-15. We calculated the total score, PTSD subscale, and Depression subscale of PTSSC-15. Results The PTSSC-15 total score and PTSD subscale of children belonging to 1st–9th grade groups who were tested 30 and 20 months after the tsunami significantly decreased compared with those of children tested 8 months after the tsunami. The PTSSC-15 total score and PTSD subscale of children in 1st–9th grade groups tested after 30 months did not decrease significantly compared with those of children tested after 20 months. The PTSSC-15 Depression subscale and PTSD subscale of children in 1st–9th grade groups tested after 30 months significantly decreased compared with those of children tested 8 months after the tsunami. The PTSSC-15 Depression subscale of children in 1st–9th grade groups evaluated after 30 months significantly decreased compared with those of children evaluated after 20 months. Conclusions This study demonstrates that the traumatic symptoms of children who survived the massive tsunami improved with time. Nonetheless, the traumatic symptoms, which in some cases did not improve with time. PMID:25340759

An unified numerical simulation of seismic ground motion, ocean acoustics, coseismic deformations and tsunamis of 2011 Tohoku earthquake

NASA Astrophysics Data System (ADS)

Maeda, T.; Furumura, T.; Noguchi, S.; Takemura, S.; Iwai, K.; Lee, S.; Sakai, S.; Shinohara, M.

2011-12-01

The fault rupture of the 2011 Tohoku (Mw9.0) earthquake spread approximately 550 km by 260 km with a long source rupture duration of ~200 s. For such large earthquake with a complicated source rupture process the radiation of seismic wave from the source rupture and initiation of tsunami due to the coseismic deformation is considered to be very complicated. In order to understand such a complicated process of seismic wave, coseismic deformation and tsunami, we proposed a unified approach for total modeling of earthquake induced phenomena in a single numerical scheme based on a finite-difference method simulation (Maeda and Furumura, 2011). This simulation model solves the equation of motion of based on the linear elastic theory with equilibrium between quasi-static pressure and gravity in the water column. The height of tsunami is obtained from this simulation as a vertical displacement of ocean surface. In order to simulate seismic waves, ocean acoustics, coseismic deformations, and tsunami from the 2011 Tohoku earthquake, we assembled a high-resolution 3D heterogeneous subsurface structural model of northern Japan. The area of simulation is 1200 km x 800 km and 120 km in depth, which have been discretized with grid interval of 1 km in horizontal directions and 0.25 km in vertical direction, respectively. We adopt a source-rupture model proposed by Lee et al. (2011) which is obtained by the joint inversion of teleseismic, near-field strong motion, and coseismic deformation. For conducting such a large-scale simulation, we fully parallelized our simulation code based on a domain-partitioning procedure which achieved a good speed-up by parallel computing up to 8192 core processors with parallel efficiency of 99.839%. The simulation result demonstrates clearly the process in which the seismic wave radiates from the complicated source rupture over the fault plane and propagating in heterogeneous structure of northern Japan. Then, generation of tsunami from coseismic

Real-time correction of tsunami site effect by frequency-dependent tsunami-amplification factor

NASA Astrophysics Data System (ADS)

Tsushima, H.

2017-12-01

For tsunami early warning, I developed frequency-dependent tsunami-amplification factor and used it to design a recursive digital filter that can be applicable for real-time correction of tsunami site response. In this study, I assumed that a tsunami waveform at an observing point could be modeled by convolution of source, path and site effects in time domain. Under this assumption, spectral ratio between offshore and the nearby coast can be regarded as site response (i.e. frequency-dependent amplification factor). If the amplification factor can be prepared before tsunamigenic earthquakes, its temporal convolution to offshore tsunami waveform provides tsunami prediction at coast in real time. In this study, tsunami waveforms calculated by tsunami numerical simulations were used to develop frequency-dependent tsunami-amplification factor. Firstly, I performed numerical tsunami simulations based on nonlinear shallow-water theory from many tsuanmigenic earthquake scenarios by varying the seismic magnitudes and locations. The resultant tsunami waveforms at offshore and the nearby coastal observing points were then used in spectral-ratio analysis. An average of the resulted spectral ratios from the tsunamigenic-earthquake scenarios is regarded as frequency-dependent amplification factor. Finally, the estimated amplification factor is used in design of a recursive digital filter that can be applicable in time domain. The above procedure is applied to Miyako bay at the Pacific coast of northeastern Japan. The averaged tsunami-height spectral ratio (i.e. amplification factor) between the location at the center of the bay and the outside show a peak at wave-period of 20 min. A recursive digital filter based on the estimated amplification factor shows good performance in real-time correction of tsunami-height amplification due to the site effect. This study is supported by Japan Society for the Promotion of Science (JSPS) KAKENHI grant 15K16309.

The 17 July 2006 Tsunami earthquake in West Java, Indonesia

USGS Publications Warehouse

Mori, J.; Mooney, W.D.; Afnimar,; Kurniawan, S.; Anaya, A.I.; Widiyantoro, S.

2007-01-01

A tsunami earthquake (Mw = 7.7) occurred south of Java on 17 July 2006. The event produced relatively low levels of high-frequency radiation, and local felt reports indicated only weak shaking in Java. There was no ground motion damage from the earthquake, but there was extensive damage and loss of life from the tsunami along 250 km of the southern coasts of West Java and Central Java. An inspection of the area a few days after the earthquake showed extensive damage to wooden and unreinforced masonry buildings that were located within several hundred meters of the coast. Since there was no tsunami warning system in place, efforts to escape the large waves depended on how people reacted to the earthquake shaking, which was only weakly felt in the coastal areas. This experience emphasizes the need for adequate tsunami warning systems for the Indian Ocean region.

Assessing the Mental Health Impact of the 2011 Great Japan Earthquake, Tsunami, and Radiation Disaster on Elementary and Middle School Children in the Fukushima Prefecture of Japan.

PubMed

Lieber, Mark

2017-01-01

On March 11, 2011, a magnitude 9.0 earthquake occurred off of Japan's Pacific coast, which was followed by huge tsunamis that destroyed many coastal cities in the area. Due to the earthquake and subsequent tsunami, malfunctions occurred at the Fukushima Daiichi (Fukushima I) nuclear power plant, resulting in the release of radioactive material in the region. While recent studies have investigated the effects of these events on the mental health of adults in the region, no studies have yet been performed investigating similar effects among children. This study aims to fill that gap by: 1) assessing the mental health of elementary and middle school children living within the Fukushima prefecture of Japan, and 2) identifying risk and protective factors that are associated with the children's mental health scores. These factors were quantified using an original demographics survey, the Strengths and Difficulties Questionnaire (SDQ), and the Impact of Event Scale-Revised (IES-R), the latter two of which have been previously validated in a Japanese setting. The surveys were distributed to approximately 3,650 elementary and middle school students during the months of February and March, 2012. The data suggests that those children who had been relocated to the city of Koriyama had significantly higher SDQ scores than those children who were native to Koriyama (p < .05) as well as a control group that lived outside of the Fukushima prefecture (p < .01). Using a multivariate regression, we also found that younger age and parental trauma were significantly correlated with higher SDQ scores (p < .001), while gender, displacement from one's home, and exposure to violence were not. These results suggest that, among children affected by natural disasters, younger children and those with parents suffering from trauma-related distress are particularly vulnerable to the onset of pediatric mental disturbances.

Impact of the Tohoku earthquake and tsunami on pneumonia hospitalisations and mortality among adults in northern Miyagi, Japan: a multicentre observational study.

PubMed

Daito, Hisayoshi; Suzuki, Motoi; Shiihara, Jun; Kilgore, Paul E; Ohtomo, Hitoshi; Morimoto, Konosuke; Ishida, Masayuki; Kamigaki, Taro; Oshitani, Hitoshi; Hashizume, Masahiro; Endo, Wataru; Hagiwara, Koichi; Ariyoshi, Koya; Okinaga, Shoji

2013-06-01

On 11 March 2011, the Tohoku earthquake and tsunami struck off the coast of northeastern Japan. Within 3 weeks, an increased number of pneumonia admissions and deaths occurred in local hospitals. A multicentre survey was conducted at three hospitals in Kesennuma City (population 74 000), northern Miyagi Prefecture. All adults aged ≥18 years hospitalised between March 2010 and June 2011 with community-acquired pneumonia were identified using hospital databases and medical records. Segmented regression analyses were used to quantify changes in the incidence of pneumonia. A total of 550 pneumonia hospitalisations were identified, including 325 during the pre-disaster period and 225 cases during the post-disaster period. The majority (90%) of the post-disaster pneumonia patients were aged ≥65 years, and only eight cases (3.6%) were associated with near-drowning in the tsunami waters. The clinical pattern and causative pathogens were almost identical among the pre-disaster and post-disaster pneumonia patients. A marked increase in the incidence of pneumonia was observed during the 3-month period following the disaster; the weekly incidence rates of pneumonia hospitalisations and pneumonia-associated deaths increased by 5.7 times (95% CI 3.9 to 8.4) and 8.9 times (95% CI 4.4 to 17.8), respectively. The increases were largest among residents in nursing homes followed by those in evacuation shelters. A substantial increase in the pneumonia burden was observed among adults after the Tohoku earthquake and tsunami. Although the exact cause remains unresolved, multiple factors including population aging and stressful living conditions likely contributed to this pneumonia outbreak.

Earthquake and Tsunami planning, outreach and awareness in Humboldt County, California

NASA Astrophysics Data System (ADS)

Ozaki, V.; Nicolini, T.; Larkin, D.; Dengler, L.

2008-12-01

Humboldt County has the longest coastline in California and is one of the most seismically active areas of the state. It is at risk from earthquakes located on and offshore and from tsunamis generated locally from faults associated with the Cascadia subduction zone (CSZ), other regional fault systems, and from distant sources elsewhere in the Pacific. In 1995 the California Division of Mines and Geology published the first earthquake scenario to include both strong ground shaking effects and a tsunami. As a result of the scenario, the Redwood Coast Tsunami Work Group (RCTWG), an organization of representatives from government agencies, tribes, service groups, academia and the private sector from the three northern coastal California counties, was formed in 1996 to coordinate and promote earthquake and tsunami hazard awareness and mitigation. The RCTWG and its member agencies have sponsored a variety of projects including education/outreach products and programs, tsunami hazard mapping, signage and siren planning, and has sponsored an Earthquake - Tsunami Education Room at the Humboldt County fair for the past eleven years. Three editions of Living on Shaky Ground an earthquake-tsunami preparedness magazine for California's North Coast, have been published since 1993 and a fourth is due to be published in fall 2008. In 2007, Humboldt County was the first region in the country to participate in a tsunami training exercise at FEMA's Emergency Management Institute in Emmitsburg, MD and the first area in California to conduct a full-scale tsunami evacuation drill. The County has conducted numerous multi-agency, multi-discipline coordinated exercises using county-wide tsunami response plan. Two Humboldt County communities were recognized as TsunamiReady by the National Weather Service in 2007. Over 300 tsunami hazard zone signs have been posted in Humboldt County since March 2008. Six assessment surveys from 1993 to 2006 have tracked preparedness actions and personal

Rapid tsunami models and earthquake source parameters: Far-field and local applications

USGS Publications Warehouse

Geist, E.L.

2005-01-01

Rapid tsunami models have recently been developed to forecast far-field tsunami amplitudes from initial earthquake information (magnitude and hypocenter). Earthquake source parameters that directly affect tsunami generation as used in rapid tsunami models are examined, with particular attention to local versus far-field application of those models. First, validity of the assumption that the focal mechanism and type of faulting for tsunamigenic earthquakes is similar in a given region can be evaluated by measuring the seismic consistency of past events. Second, the assumption that slip occurs uniformly over an area of rupture will most often underestimate the amplitude and leading-wave steepness of the local tsunami. Third, sometimes large magnitude earthquakes will exhibit a high degree of spatial heterogeneity such that tsunami sources will be composed of distinct sub-events that can cause constructive and destructive interference in the wavefield away from the source. Using a stochastic source model, it is demonstrated that local tsunami amplitudes vary by as much as a factor of two or more, depending on the local bathymetry. If other earthquake source parameters such as focal depth or shear modulus are varied in addition to the slip distribution patterns, even greater uncertainty in local tsunami amplitude is expected for earthquakes of similar magnitude. Because of the short amount of time available to issue local warnings and because of the high degree of uncertainty associated with local, model-based forecasts as suggested by this study, direct wave height observations and a strong public education and preparedness program are critical for those regions near suspected tsunami sources.

Weight Gain in Survivors Living in Temporary Housing in the Tsunami-Stricken Area during the Recovery Phase following the Great East Japan Earthquake and Tsunami.

PubMed

Takahashi, Shuko; Yonekura, Yuki; Sasaki, Ryohei; Yokoyama, Yukari; Tanno, Kozo; Sakata, Kiyomi; Ogawa, Akira; Kobayashi, Seichiro; Yamamoto, Taro

2016-01-01

Survivors who lost their homes in the Great East Japan Earthquake and Tsunami were forced to live in difficult conditions in temporary housing several months after the disaster. Body weights of survivors living in temporary housing for a long period might increase due to changes in their life style and psychosocial state during the medium-term and long-term recovery phases. The aim of this study was to determine whether there were differences between body weight changes of people living in temporary housing and those not living in temporary housing in a tsunami-stricken area during the medium-term and long-term recovery phases. Health check-ups were performed about 7 months after the disaster (in 2011) and about 18 months after the disaster (in 2012) for people living in a tsunami-stricken area (n = 6,601, mean age = 62.3 y). We compared the changes in body weight in people living in temporary housing (TH group, n = 2,002) and those not living in temporary housing (NTH group, n = 4,599) using a multiple linear regression model. While there was no significant difference between body weights in the TH and NTH groups in the 2011 survey, there was a significant difference between the mean changes in body weight in both sexes. We found that the changes in body weight were significantly greater in the TH group than in the NTH group in both sexes. The partial regression coefficients of mean change in body weight were +0.52 kg (P-value < 0.001) in males in the TH group and +0.56 kg (P-value < 0.001) in females in the TH group (reference: NTH group). Analysis after adjustment for life style, psychosocial factors and cardiovascular risk factors found that people living in temporary housing in the tsunami- stricken area had a significant increase in body weight.

Long-Term Effects of the 2011 Japan Earthquake and Tsunami on Incidence of Fatal and Nonfatal Myocardial Infarction.

PubMed

Nakamura, Motoyuki; Tanaka, Kentarou; Tanaka, Fumitaka; Matsuura, Yuuki; Komi, Ryousuke; Niiyama, Masanobu; Kawakami, Mikio; Koeda, Yorihiko; Sakai, Toshiaki; Onoda, Toshiyuki; Itoh, Tomonori

2017-08-01

This study aimed to examine the long-term effects of the 2011 Japan earthquake and tsunami on the incidence of fatal and nonfatal myocardial infarction (MI). In the present study, the incidence of 2 types of cardiac events was comprehensively recorded. The study area was divided into 2 zones based on the severity of tsunami damage, which was determined by the percentage of the inundated area within the residential area (<10%, low-impact zone and ≥10%, high-impact zone). The standardized incidence ratio (SIR) and 95% CI for both types of cardiac events during the disaster year and the postdisaster years were determined in each zone. During the 4-year period after the disaster, the SIRs for nonfatal MI did not change to a statistically significant extent in either zones. For fatal MI, the SIR was stable during the study period in the low-impact zone. However, in the high-impact zone, the SIR was significantly elevated in the disaster year of 2011 (1.80 [95% CI 1.32 to 2.28]), and this increase was sustained for the following 3 years (2012, 2.06 [1.55 to 2.57]; 2013, 1.99 [1.49 to 2.48]; 2014, 2.12 [1.62 to 2.63]). The SIRs for fatal MI for the 4 postdisaster years in the municipal areas were significantly correlated with the percentage of the inundated area (r = 0.83; p <0.001) and the number of deaths due to the tsunami (r = 0.77; p <0.005) but not with the maximum seismic intensity (r = 0.43; p = 0.12). In conclusion, these results suggest that the devastating tsunami was associated with a continual increase in the incidence of fatal MI among disaster survivors. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

A global probabilistic tsunami hazard assessment from earthquake sources

USGS Publications Warehouse

Davies, Gareth; Griffin, Jonathan; Lovholt, Finn; Glimsdal, Sylfest; Harbitz, Carl; Thio, Hong Kie; Lorito, Stefano; Basili, Roberto; Selva, Jacopo; Geist, Eric L.; Baptista, Maria Ana

2017-01-01

Large tsunamis occur infrequently but have the capacity to cause enormous numbers of casualties, damage to the built environment and critical infrastructure, and economic losses. A sound understanding of tsunami hazard is required to underpin management of these risks, and while tsunami hazard assessments are typically conducted at regional or local scales, globally consistent assessments are required to support international disaster risk reduction efforts, and can serve as a reference for local and regional studies. This study presents a global-scale probabilistic tsunami hazard assessment (PTHA), extending previous global-scale assessments based largely on scenario analysis. Only earthquake sources are considered, as they represent about 80% of the recorded damaging tsunami events. Globally extensive estimates of tsunami run-up height are derived at various exceedance rates, and the associated uncertainties are quantified. Epistemic uncertainties in the exceedance rates of large earthquakes often lead to large uncertainties in tsunami run-up. Deviations between modelled tsunami run-up and event observations are quantified, and found to be larger than suggested in previous studies. Accounting for these deviations in PTHA is important, as it leads to a pronounced increase in predicted tsunami run-up for a given exceedance rate.

Earthquake and Tsunami History and Hazards of Eastern Indonesia

NASA Astrophysics Data System (ADS)

Major, J. R.; Robinson, J. S.; Harris, R. A.

2008-12-01

Western Indonesia (i.e. Java and Sumatra) has received much attention by geoscientists, especially in recent years due to events such as the Sumatra-Andaman event of 2004. However, the seismic history of eastern Indonesia is not widely known, notwithstanding the high rate of seismic activity in the area and high convergence rates. Not only do geologic hazards (i.e. strong earthquakes, tsunami, and explosive volcanoes) comparable to those in western part of the country exist, but population has increased nearly 10 fold in the last century. Our historical research of earthquakes and tsunami in eastern Indonesia based primarily on records of Dutch Colonists has uncovered a violent history of earthquakes and tsunami from 1608 to 1877. During this time eastern Indonesia experienced over 30 significant earthquakes and 35 tsunamis. Most of these events are much larger than any recorded in the last century. Due to this marked quiescence over the past century, and recent events in the Sunda arc over the past several years, we have initiated a new investigation of the region that integrates these historic events, field investigations, and, in the future, tsunami modeling. A more complete and comprehensive seismic history of eastern Indonesia is necessary for effective risk assessment. This information, along with renewed efforts by scientists and government will be crucial for disaster mitigation and to save lives.

Mortality in the 2011 Tsunami in Japan

PubMed Central

Nakahara, Shinji; Ichikawa, Masao

2013-01-01

Introduction On 11 March 2011, a magnitude 9.0 earthquake caused a huge tsunami that struck Northeast Japan, resulting in nearly 20 000 deaths. We investigated mortality patterns by age, sex, and region in the 3 most severely affected prefectures. Methods Using police data on earthquake victims in Iwate, Miyagi, and Fukushima prefectures, mortality rates by sex, age group, and region were calculated, and regional variability in mortality rates across age groups was compared using rate ratios (RRs), with the rates in Iwate as the reference. Results In all regions, age-specific mortality showed a tendency to increase with age; there were no sex differences. Among residents of Iwate, mortality was markedly lower among school-aged children as compared with other age groups. In northern Miyagi and the southern part of the study area, RRs were higher among school-aged children than among other age groups. Conclusions The present study could not address the reasons for the observed mortality patterns and regional differences. To improve preparedness policies, future research should investigate the reasons for regional differences. PMID:23089585

Paleographical, Bathymetric and Numerical Investigations for a Tsunami Possibly Caused by Submarine Mass Failure in the Nankai Trough, Japan

NASA Astrophysics Data System (ADS)

Baba, T.; Ashi, J.; Kanamatsu, T.; Imai, K.; Yamashita, K.

2017-12-01

"SHINCHO-KI" is an ancient document that records tsunami damages caused by the 1512 Eisho earthquake, the 1605 Keicho earthquake, the 1707 Hoei earthquake and the 1854 Ansei-Nankai earthquake in Shishikui, where is located along the coast of the southeastern part of Shikoku, facing to the Nankai trough. According to SHINCHO-KI, 3700 people were dead in Shishikui by the tsunami during the 1512 Eisho earthquake. However, no evidence was found for the occurrence of the 1512 Eisho earthquake except for SHINCHO-KI, while the other earthquakes were recorded in many ancient documents in the southwestern Japan. To investigate the source mechanism of the 1512 Eisho earthquake, we carefully read a bathymetric chart and found a scarp with a height of about 400 m and a width of about 6000 m at a position about 24 km offshore in the southeastern direction from Shishikui. We also carried out a survey by using a deep-towed sub-bottom profiler (SBP) on ROV NSS during the R/V Hakuho-maru KH-16-5 cruise. The result shows detailed structures possibly caused by a recent landslide. The vertical displacement of the strata was measured to be about 50 m. By considering these results, we simulated the 1512 Eisho tsunami generated by a submarine mass failure. The topographic data in Shishikui which is needed in the calculation was made from the present data. But we removed the artificial structures such as wave breakers and altered coastlines by referring to old map images. In the numerical simulation, the initial sea surface deformation was obtained by the method proposed by Watts et al. (2005), and the tsunami propagation was calculated by solving the nonlinear shallow water equations with dispersive (Boussinesq) term on a finite difference scheme. We solved the advection terms by using the third-order upwind difference to avoid artificial viscosity. The numerical simulation estimated the maximum tsunami height of about 6m and moderate inundation on land in Shishikui by the 1512 Eisho

Earthquake and Tsunami: a movie and a book for seismic and tsunami risk reduction in Italy.

NASA Astrophysics Data System (ADS)

Nostro, C.; Baroux, E.; Maramai, A.; Graziani, L.; Tertulliani, A.; Castellano, C.; Arcoraci, L.; Casale, P.; Ciaccio, M. G.; Frepoli, A.

2009-04-01

Italy is a country well known for the seismic and volcanic hazard. However, a similarly great hazard, although not well recognized, is posed by the occurrence of tsunami waves along the Italian coastline. This is testified by a rich catalogue and by field evidence of deposits left over by pre- and historical tsunamis, even in places today considered safe. This observation is of great importance since many of the areas affected by tsunamis in the past are today touristic places. The Italian tsunamis can be caused by different sources: 1- off-shore or near coast in-land earthquakes; 2- very large earthquakes on distant sources in the Mediterranean; 3- submarine volcanic explosion in the Tyrrhenian sea; 4- submarine landslides triggered by earthquakes and volcanic activity. The consequence of such a wide spectrum of sources is that an important part of the more than 7000 km long Italian coast line is exposed to the tsunami risk, and thousands of inhabitants (with numbers increasing during summer) live near hazardous coasts. The main historical tsunamis are the 1783 and 1908 events that hit Calabrian and Sicilian coasts. The recent tsunami is that caused by the 2002 Stromboli landslide. In order to reduce this risk and following the emotional impact of the December 2004 Sumatra earthquake and tsunami, we developed an outreach program consisting in talks given by scientists and in a movie and a book, both exploring the causes of the tsunami waves, how do they propagate in deep and shallow waters, and what are the effects on the coasts. Hints are also given on the most dangerous Italian coasts (as deduced by scientific studies), and how to behave in the case of a tsunami approaching the coast. These seminars are open to the general public, but special programs are developed with schools of all grades. In this talk we want to present the book and the movie used during the seminars and scientific expositions, that was realized from a previous 3D version originally

Voluntary Health Registry of French Nationals after the Great East Japan Earthquake, Tsunami, and Fukushima Daiichi Nuclear Power Plant Accident: Methods, Results, Implications, and Feedback.

PubMed

Motreff, Yvon; Pirard, Philippe; Lagrée, Céline; Roudier, Candice; Empereur-Bissonnet, Pascal

2016-06-01

Introduction The 11th of March 2011, a magnitude 9.0 earthquake struck alongside the north-east coast of Honshu Island, Japan, causing a tsunami and a major nuclear accident. The French Institute for Public Health Surveillance (InVS) set up, within one week after the triple catastrophe, an Internet-based registry for French nationals who were in Japan at the time of the disasters. In this string of disasters, in this context of uncertainties about the nuclear risks, the aim of this registry was to facilitate the: (1) realization of further epidemiologic studies, if needed; and (2) contact of people if a medical follow-up was needed. The purpose of this report was to describe how the health registry was set up, what it was used for, and to discuss further utilization and improvements to health registries after disasters. The conception of the questionnaire to register French nationals was based on a form developed as part of the Steering Committee for the management of the post-accident phase in the event of nuclear accident or a radiological emergency situation (CODIRPA) work. The questionnaire was available online. The main objective was achieved since it was theoretically possible to contact again the 1,089 persons who completed the form. According to the data collected on their space-time budget, to the result of internal contamination measured by the French Institute for Radiological Protection and Nuclear Safety (IRSN) and dosimetric expertise published by the World Health Organization (WHO), it was not suitable to conduct an epidemiologic follow-up of adverse effects of exposure to ionizing radiations among them. However, this registry was used to launch a qualitative study on exposure to stress and psychosocial impact of the Great East Japan Earthquake on French nationals who were in Japan in March 2011. Setting a registry after a disaster is a very important step in managing the various consequences of a disaster. This experience showed that it is quickly

A short history of tsunami research and countermeasures in Japan

PubMed Central

Shuto, Nobuo; Fujima, Koji

2009-01-01

The tsunami science and engineering began in Japan, the country the most frequently hit by local and distant tsunamis. The gate to the tsunami science was opened in 1896 by a giant local tsunami of the highest run-up height of 38 m that claimed 22,000 lives. The crucial key was a tide record to conclude that this tsunami was generated by a “tsunami earthquake”. In 1933, the same area was hit again by another giant tsunami. A total system of tsunami disaster mitigation including 10 “hard” and “soft” countermeasures was proposed. Relocation of dwelling houses to high ground was the major countermeasures. The tsunami forecasting began in 1941. In 1960, the Chilean Tsunami damaged the whole Japanese Pacific coast. The height of this tsunami was 5–6 m at most. The countermeasures were the construction of structures including the tsunami breakwater which was the first one in the world. Since the late 1970s, tsunami numerical simulation was developed in Japan and refined to become the UNESCO standard scheme that was transformed to 22 different countries. In 1983, photos and videos of a tsunami in the Japan Sea revealed many faces of tsunami such as soliton fission and edge bores. The 1993 tsunami devastated a town protected by seawalls 4.5 m high. This experience introduced again the idea of comprehensive countermeasures, consisted of defense structure, tsunami-resistant town development and evacuation based on warning. PMID:19838008

Impact of the Tohoku earthquake and tsunami on pneumonia hospitalisations and mortality among adults in northern Miyagi, Japan: a multicentre observational study

PubMed Central

Daito, Hisayoshi; Suzuki, Motoi; Shiihara, Jun; Kilgore, Paul E; Ohtomo, Hitoshi; Morimoto, Konosuke; Ishida, Masayuki; Kamigaki, Taro; Oshitani, Hitoshi; Hashizume, Masahiro; Endo, Wataru; Hagiwara, Koichi; Ariyoshi, Koya; Okinaga, Shoji

2013-01-01

Background On 11 March 2011, the Tohoku earthquake and tsunami struck off the coast of northeastern Japan. Within 3 weeks, an increased number of pneumonia admissions and deaths occurred in local hospitals. Methods A multicentre survey was conducted at three hospitals in Kesennuma City (population 74 000), northern Miyagi Prefecture. All adults aged ≥18 years hospitalised between March 2010 and June 2011 with community-acquired pneumonia were identified using hospital databases and medical records. Segmented regression analyses were used to quantify changes in the incidence of pneumonia. Results A total of 550 pneumonia hospitalisations were identified, including 325 during the pre-disaster period and 225 cases during the post-disaster period. The majority (90%) of the post-disaster pneumonia patients were aged ≥65 years, and only eight cases (3.6%) were associated with near-drowning in the tsunami waters. The clinical pattern and causative pathogens were almost identical among the pre-disaster and post-disaster pneumonia patients. A marked increase in the incidence of pneumonia was observed during the 3-month period following the disaster; the weekly incidence rates of pneumonia hospitalisations and pneumonia-associated deaths increased by 5.7 times (95% CI 3.9 to 8.4) and 8.9 times (95% CI 4.4 to 17.8), respectively. The increases were largest among residents in nursing homes followed by those in evacuation shelters. Conclusions A substantial increase in the pneumonia burden was observed among adults after the Tohoku earthquake and tsunami. Although the exact cause remains unresolved, multiple factors including population aging and stressful living conditions likely contributed to this pneumonia outbreak. PMID:23422213

Psychological distress during pregnancy in Miyagi after the Great East Japan Earthquake: The Japan Environment and Children's Study.

PubMed

Watanabe, Zen; Iwama, Noriyuki; Nishigori, Hidekazu; Nishigori, Toshie; Mizuno, Satoshi; Sakurai, Kasumi; Ishikuro, Mami; Obara, Taku; Tatsuta, Nozomi; Nishijima, Ichiko; Fujiwara, Ikuma; Nakai, Kunihiko; Arima, Takahiro; Takeda, Takashi; Sugawara, Junichi; Kuriyama, Shinichi; Metoki, Hirohito; Yaegashi, Nobuo

2016-01-15

To examine psychological distress among pregnant women in Miyagi prefecture which was directly affected by the Great East Japan Earthquake and tsunami and compare other areas of Japan that were less damaged. This study was conducted in conjunction with the Japan Environment and Children's Study (JECS). We examined 10,129 Japanese women using the primary fixed data of the JECS. The Kessler 6-item psychological distress scale (K6) was administered to 7473 eligible women including 998 in Miyagi unit center ('Miyagi UC') and 6475 in the other unit centers ('13UCs'). We compared the prevalence and the risk of distress (K6 ≥ 13) during pregnancy in 'Miyagi UC' and '13UCs'. More women in 'Miyagi UC' (4.9%) suffered psychological distress, compared with '13UCs' (3.1%) (p<0.001). A significantly higher prevalence of women in 'Miyagi UC' (55.5%) had experienced negative life events, whereas '13UCs' showed 42.7% (p<0.0001). In multivariable logistic analyses adjusted for baseline characteristics, there was a significant regional difference of psychological distress (adjusted odds ratio; aOR in Miyagi UC=1.488; 95%CI, 1.059-2.090). After further adjusting for negative life events, the association was diminished (aOR=1.338; 95%CI, 0.949-1.884). The JECS had no data before the earthquake and the extent of damage was not investigated. Possible regional representativeness is also a limitation. After the Great East Japan Earthquake, the prevalence of pregnant women with psychological distress (K6 ≥ 13) were high in Miyagi prefecture. Especially in the coastal area directly affected by tsunami, it is high with or without negative life events experienced. Copyright © 2015 Elsevier B.V. All rights reserved.

The 25 October 2010 Mentawai tsunami earthquake, from real-time discriminants, finite-fault rupture, and tsunami excitation

USGS Publications Warehouse

Newman, Andrew V.; Hayes, Gavin P.; Wei, Yong; Convers, Jaime

2011-01-01

The moment magnitude 7.8 earthquake that struck offshore the Mentawai islands in western Indonesia on 25 October 2010 created a locally large tsunami that caused more than 400 human causalities. We identify this earthquake as a rare slow-source tsunami earthquake based on: 1) disproportionately large tsunami waves; 2) excessive rupture duration near 125 s; 3) predominantly shallow, near-trench slip determined through finite-fault modeling; and 4) deficiencies in energy-to-moment and energy-to-duration-cubed ratios, the latter in near-real time. We detail the real-time solutions that identified the slow-nature of this event, and evaluate how regional reductions in crustal rigidity along the shallow trench as determined by reduced rupture velocity contributed to increased slip, causing the 5–9 m local tsunami runup and observed transoceanic wave heights observed 1600 km to the southeast.

Tsunami Field Survey for the Solomon Islands Earthquake of April 1, 2007

NASA Astrophysics Data System (ADS)

Nishimura, Y.; Tanioka, Y.; Nakamura, Y.; Tsuji, Y.; Namegaya, Y.; Murata, M.; Woodward, S.

2007-12-01

Two weeks after the 2007 off-Solomon earthquake, an international tsunami survey team (ITST) of Japanese and US researchers performed a post tsunami survey in Ghizo and adjacent islands. Main purpose of the team was to provide information on the earthquake and tsunami to the national disaster council of the Solomon Islands, who was responsible for the disaster management at that time. The ITST had interview with the affected people and conducted reconnaissance mapping of the tsunami heights and flow directions. Tsunami flow heights at beach and inland were evaluated from watermarks on buildings and the position of broken branches and stuck materials on trees. These tsunami heights along the southern to western coasts of Ghizo Island were ca. 5m (a.s.l.). Tsunami run-up was traced by distribution of floating debris that carried up by the tsunami and deposited at their inundation limit. The maximum run-up was measured at Tapurai of Simbo Island to be ca. 9 m. Most of the inundation area was covered by 0-10 cm thick tsunami deposit that consists of beach sand, coral peaces and eroded soil. Coseismic uplift and subsidence were clearly identified by changes of the sea level before and after the earthquake, that were inferred by eyewitness accounts and evidences such as dried up coral reeves. These deformation patterns, as well as the tsunami height distribution, could constrain the earthquake fault geometry and motion. It is worthy of mention that the tsunami damage in villages in Ranongga Island has significantly reduced by 2-3 m uplift before the tsunami attack.

Land cover changes induced by the great east Japan earthquake in 2011.

PubMed

Ishihara, Mitsunori; Tadono, Takeo

2017-03-31

The east Japan earthquake that occurred on March 11, 2011 was a big natural disaster, comprising the large earthquake shock, tsunami, and Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. These disasters caused changes in the land use and land cover (LULC) in Japan's Tohoku district. While the LULC map created before the disaster is available, as yet there is no precise LULC map of the district after the disaster. In this study, we created a precise LULC map for the years 2013-2015 post-disaster with 30-m spatial resolution using the Landsat-8 with the Operational Land Imager (OLI) to evaluate the changes in LULC induced by the disaster. Our results indicate many changes in areas categorized as rice paddies primarily into grass categories along the coast damaged by the tsunami and in the evacuation zone around the FDNPP. Since there is a possibility of future LULC changes according to the change of the evacuation zone and implementation of reconstruction and revitalization efforts, we recommend continual monitoring of the changes in LULC by the use of satellite data in order to evaluate the long-term effects of the disaster.

Tsunami forecast by joint inversion of real-time tsunami waveforms and seismic of GPS data: application to the Tohoku 2011 tsunami

USGS Publications Warehouse

Yong, Wei; Newman, Andrew V.; Hayes, Gavin P.; Titov, Vasily V.; Tang, Liujuan

2014-01-01

Correctly characterizing tsunami source generation is the most critical component of modern tsunami forecasting. Although difficult to quantify directly, a tsunami source can be modeled via different methods using a variety of measurements from deep-ocean tsunameters, seismometers, GPS, and other advanced instruments, some of which in or near real time. Here we assess the performance of different source models for the destructive 11 March 2011 Japan tsunami using model–data comparison for the generation, propagation, and inundation in the near field of Japan. This comparative study of tsunami source models addresses the advantages and limitations of different real-time measurements with potential use in early tsunami warning in the near and far field. The study highlights the critical role of deep-ocean tsunami measurements and rapid validation of the approximate tsunami source for high-quality forecasting. We show that these tsunami measurements are compatible with other real-time geodetic data, and may provide more insightful understanding of tsunami generation from earthquakes, as well as from nonseismic processes such as submarine landslide failures.

Introduction to "Tsunamis in the Pacific Ocean: 2011-2012"

NASA Astrophysics Data System (ADS)

Rabinovich, Alexander B.; Borrero, Jose C.; Fritz, Hermann M.

2014-12-01

With this volume of the Pure and Applied Geophysics (PAGEOPH) topical issue "Tsunamis in the Pacific Ocean: 2011-2012", we are pleased to present 21 new papers discussing tsunami events occurring in this two-year span. Owing to the profound impact resulting from the unique crossover of a natural and nuclear disaster, research into the 11 March 2011 Tohoku, Japan earthquake and tsunami continues; here we present 12 papers related to this event. Three papers report on detailed field survey results and updated analyses of the wave dynamics based on these surveys. Two papers explore the effects of the Tohoku tsunami on the coast of Russia. Three papers discuss the tsunami source mechanism, and four papers deal with tsunami hydrodynamics in the far field or over the wider Pacific basin. In addition, a series of five papers presents studies of four new tsunami and earthquake events occurring over this time period. This includes tsunamis in El Salvador, the Philippines, Japan and the west coast of British Columbia, Canada. Finally, we present four new papers on tsunami science, including discussions on tsunami event duration, tsunami wave amplitude, tsunami energy and tsunami recurrence.

How can we transfer scientific knowledge to citizens? : Case studies from huge earthquake and tsunami researches

NASA Astrophysics Data System (ADS)

Kitazato, Hiroshi; Kijima, Akihiro; Kogure, Kazuhiro; Fujikura, Katsunori

2017-04-01

On March 11, 2011, huge earthquake and tsunamis took place coastal regions of Northeast Japan. Coastal infrastructure collapsed due to high waves of tsunamis. Marine ecosystems were also strongly disturbed by the earthquakes and tsunamis. TEAMS (Tohoku Ecosystem-Associated Marine Sciences) has started for monitoring recovering process of marine ecosystems. The project continues ten years. First five years are mainly monitored recovery process, then we should transfer our knowledge to fishermen and citizens for restoration of fishery and social systems. But, how can we actually transfer our knowledge from science to citizens? This is new experience for us. Socio-technology constructs a "high quality risk communication" model how scientific knowledge or technologies from scientific communities to citizens. They are progressing as follows, "observation, measurements and data", → "modeling and synthesis" → "information process" → "delivery to society" → " take action in society". These steps show detailed transition from inter-disciplinarity to trans-disciplinarity in science and technology. In our presentation, we plan to show a couple of case studies that are going forward from science to society.

Assessing tsunami-induced groundwater salinization and its temporal change: a numerical modelling study on the Niijima Island, Japan

NASA Astrophysics Data System (ADS)

Liu, Jiaqi; Tokunaga, Tomochika

2016-04-01

Groundwater is vulnerable to many natural hazards, including tsunami. As reported after the 2004 Indian Ocean earthquake and the 2011 Great East Japan earthquake, the generated massive tsunami inundations resulted in unexpected groundwater salinization in coastal areas. Water supply was strongly disturbed due to the significantly elevated salinity in groundwater. Supplying fresh water is one of the prioritized concerns in the immediate aftermath of disaster, and during long-term post-disaster reconstruction as well. The aim of this study is to assess the impact of tsunami on coastal groundwater system and provide guidelines on managing water resources in post-tsunami period. We selected the study area as the Niijima Island, a tsunami-prone area in Japan, which is under the risk of being attacked by a devastated tsunami with its wave height up to 30 m. A three-dimension (3-D) numerical model of the groundwater system on the Niijima Island was developed by using the simulation code FEFLOW which can handle both density- dependent groundwater flow and saturated-unsaturated flow processes. The model was justified by the measured water table data obtained from the field work in July, 2015. By using this model, we investigated saltwater intrusion and aquifer recovery process under different tsunami scenarios. Modelling results showed that saltwater could fully saturate the vadose zone and come into contact with groundwater table in just 10 mins. The 0.6 km2 of inundation area introduced salt mass equivalent to approximately 9×104 t of NaCl into the vadose zone. After the retreat of tsunami waves, the remained saltwater in vadose zone continuously intruded into the groundwater and dramatically salinized the aquifer up to about 10,000 mg/L. In the worst tsunami scenario, it took more than 10 years for the polluted aquifer to be entirely recovered by natural rainfall. Given that the groundwater is the only freshwater source on the Niijima Island, we can provide suggestions

New constraints on the magnitude of the 4 January 1907 tsunami earthquake off Sumatra, Indonesia, and its Indian Ocean-wide tsunami

NASA Astrophysics Data System (ADS)

Martin, S. S.; Li, L.; Okal, E.; Kanamori, H.; Morin, J.; Sieh, K.; Switzer, A.

2017-12-01

On 4 January 1907, an earthquake and tsunami occurred off the west coast of Sumatra, Indonesia, causing at least 2,188 fatalities. The earthquake was given an instrumental surface-wave magnitude (MS) in the range of 7.5 to 8.0 at periods of ≈40s. The tsunami it triggered was destructive on the islands of Nias and Simeulue; on the latter, this gave rise to the legend of the S'mong. This tsunami appears in records in India, Pakistan, Sri Lanka, and as far as the island of La Réunion. In relation to published seismic magnitudes for the earthquake, the tsunami was anomalously large, qualifying it as a "tsunami earthquake." Relocations using reported arrival times suggest an epicentral location near the trench. However, unusually for a tsunami earthquake the reported macroseismic intensities were higher than expected on Nias (6-7 EMS). We present a new study of this event based on macroseismic and tsunami observations culled from published literature and colonial press reports, as well as existing and newly acquired digitized or print seismograms. This multidisciplinary combination of macroseismic and seismological data with tsunami modelling has yielded new insights into this poorly understood but scientifically and societally important tsunami earthquake in the Indian Ocean. With these new data, we discriminated two large earthquakes within an hour of each other with clear differences in seismological character. The first, we interpret to be a tsunami earthquake with low levels of shaking (3-4 EMS). For this event, we estimate a seismic moment (M0) between 0.8 and 1.2 x1021 Nm (≈MW 7.9 to 8.0) based on digitized Wiechert records at Göttingen in the frequency band 6-8 mHz. These records document a regular growth of moment with period and suggest possibly larger values of M0 at even longer periods. The second earthquake caused damage on Nias (6-7 EMS). We estimate MS 6 ¾ - 7 for the second event based on seismograms from Manila, Mizusawa, and Osaka. We also

Comparison between Observed Tsunami Heights and Numerical Simulation of the 1854 Ansei-Tokai Earthquake Tsunami in Gokasho Bay, central Japan

NASA Astrophysics Data System (ADS)

Naruhashi, R.; Satake, K.; Heidarzadeh, M.; Harada, T.

2014-12-01

　Gokasho Bay is a blockade inner bay which has typical ria coasts and drowned valleys. It is located in the central Kii Peninsula and faces the Nankai Trough subduction zone. This Kumano-nada coastal area has been repeatedly striked by historical great tsunamis. For the 1854 Ansei-Tokai earthquake and its tsunami, there are comparatively many historical records including historical documents and oral traditions for tsunami behavior and damages along the coast.　Based on these records, a total of 42 tsunami heights were measured by using a laser range finder and a hand level on the basis of spot elevation given by 1/2500 topographical maps. The average inundation height of whole bay area was approximately 4 - 5 m. On the whole, in the closed-off section of the bay, large values were obtained. For example, the average value in Gokasho-ura town area was 4 m, and the maximum run-up height along the Gokasho river was 6.8 m. Particularly in Konsa, located in the most closed-off section of the bay, tsunami heights ranged between 4 - 11 m, and were higher than those in other districts. It was comparatively high along the eastern coast and eastern baymouth.　We simulate the distribution of the tsunami wave heights using numerical modeling, and compare the simulation results and above-mentioned actual historical data and results of our field survey. Based on fault models by Ando (1975), Aida (1981), and Annaka et al. (2003), the tsunami simulation was performed.　After comparing the calculated results by three fault models, the wave height based on the model by Annaka et al. (2003) was found to have better agreement with observations. Moreover, the wave height values in a closed-off section of bay and at the eastern baymouth are high consistent with our survey data.

S-net : Construction of large scale seafloor observatory network for tsunamis and earthquakes along the Japan Trench

NASA Astrophysics Data System (ADS)

Mochizuki, M.; Uehira, K.; Kanazawa, T.; Shiomi, K.; Kunugi, T.; Aoi, S.; Matsumoto, T.; Sekiguchi, S.; Yamamoto, N.; Takahashi, N.; Nakamura, T.; Shinohara, M.; Yamada, T.

2017-12-01

NIED has launched the project of constructing a seafloor observatory network for tsunamis and earthquakes after the occurrence of the 2011 Tohoku Earthquake to enhance reliability of early warnings of tsunamis and earthquakes. The observatory network was named "S-net". The S-net project has been financially supported by MEXT.The S-net consists of 150 seafloor observatories which are connected in line with submarine optical cables. The total length of submarine optical cable is about 5,500 km. The S-net covers the focal region of the 2011 Tohoku Earthquake and its vicinity regions. Each observatory equips two units of a high sensitive pressure gauges as a tsunami meter and four sets of three-component seismometers. The S-net is composed of six segment networks. Five of six segment networks had been already installed. Installation of the last segment network covering the outer rise area have been finally finished by the end of FY2016. The outer rise segment has special features like no other five segments of the S-net. Those features are deep water and long distance. Most of 25 observatories on the outer rise segment are located at the depth of deeper than 6,000m WD. Especially, three observatories are set on the seafloor of deeper than about 7.000m WD, and then the pressure gauges capable of being used even at 8,000m WD are equipped on those three observatories. Total length of the submarine cables of the outer rise segment is about two times longer than those of the other segments. The longer the cable system is, the higher voltage supply is needed, and thus the observatories on the outer rise segment have high withstanding voltage characteristics. We employ a dispersion management line of a low loss formed by combining a plurality of optical fibers for the outer rise segment cable, in order to achieve long-distance, high-speed and large-capacity data transmission Installation of the outer rise segment was finished and then full-scale operation of S-net has started

The 25 October 2010 Mentawai tsunami earthquake, from real-time discriminants, finite-fault rupture, and tsunami excitation

USGS Publications Warehouse

Newman, A.V.; Hayes, G.; Wei, Y.; Convers, J.

2011-01-01

The moment magnitude 7.8 earthquake that struck offshore the Mentawai islands in western Indonesia on 25 October 2010 created a locally large tsunami that caused more than 400 human causalities. We identify this earthquake as a rare slow-source tsunami earthquake based on: 1) disproportionately large tsunami waves; 2) excessive rupture duration near 125 s; 3) predominantly shallow, near-trench slip determined through finite-fault modeling; and 4) deficiencies in energy-to-moment and energy-to-duration-cubed ratios, the latter in near-real time. We detail the real-time solutions that identified the slow-nature of this event, and evaluate how regional reductions in crustal rigidity along the shallow trench as determined by reduced rupture velocity contributed to increased slip, causing the 5-9 m local tsunami runup and observed transoceanic wave heights observed 1600 km to the southeast. Copyright 2011 by the American Geophysical Union.

Recurrence of great earthquakes and tsunamis, Aceh Province, Sumatra

NASA Astrophysics Data System (ADS)

Rubin, C. M.; Horton, B.; Sieh, K.; Pilarczyk, J.; Hawkes, A. D.; Daly, P.; Kelsey, H. M.; McKinnon, E.; Ismail, N.; Daryono, M. R.

2013-12-01

The timing and characterization of ancient earthquakes and tsunamis inferred from a variety of geologic studies in Aceh Province, Sumatra, are helping to understand predecessors of the 2004 event in the Indian Ocean region. We report results from three different depositional environments along the western and northern coast of Aceh Province, Sumatra, that illuminate the history of tsunamis through the past several millennia. Within a coastal cave along the western coast is an extraordinary sedimentary deposit that contains a 7,000-year long sequence of tsunami sands separated by bat guano. In two sea cliff exposures along the northern coast of Aceh is evidence for two closely timed predecessors of the giant 2004 tsunami that destroyed communities along the coast about 500 years ago. In addition, coastal wetlands along the western coast document land-level changes and tsunamis associated with the earthquake cycle in the early- to mid-Holocene. Together these records show a marked variability in recurrence of large tsunamis along the Acehnese coast. Time between inundations averages close to 500 years but range from a few centuries to a millennium.

A Benchmarking setup for Coupled Earthquake Cycle - Dynamic Rupture - Tsunami Simulations

NASA Astrophysics Data System (ADS)

Behrens, Joern; Bader, Michael; van Dinther, Ylona; Gabriel, Alice-Agnes; Madden, Elizabeth H.; Ulrich, Thomas; Uphoff, Carsten; Vater, Stefan; Wollherr, Stephanie; van Zelst, Iris

2017-04-01

We developed a simulation framework for coupled physics-based earthquake rupture generation with tsunami propagation and inundation on a simplified subduction zone system for the project "Advanced Simulation of Coupled Earthquake and Tsunami Events" (ASCETE, funded by the Volkswagen Foundation). Here, we present a benchmarking setup that can be used for complex rupture models. The workflow begins with a 2D seismo-thermo-mechanical earthquake cycle model representing long term deformation along a planar, shallowly dipping subduction zone interface. Slip instabilities that approximate earthquakes arise spontaneously along the subduction zone interface in this model. The absolute stress field and material properties for a single slip event are used as initial conditions for a dynamic earthquake rupture model.The rupture simulation is performed with SeisSol, which uses an ADER discontinuous Galerkin discretization scheme with an unstructured tetrahedral mesh. The seafloor displacements resulting from this rupture are transferred to the tsunami model with a simple coastal run-up profile. An adaptive mesh discretizing the shallow water equations with a Runge-Kutta discontinuous Galerkin (RKDG) scheme subsequently allows for an accurate and efficient representation of the tsunami evolution and inundation at the coast. This workflow allows for evaluation of how the rupture behavior affects the hydrodynamic wave propagation and coastal inundation. We present coupled results for differing earthquake scenarios. Examples include megathrust only ruptures versus ruptures with splay fault branching off the megathrust near the surface. Coupling to the tsunami simulation component is performed either dynamically (time dependent) or statically, resulting in differing tsunami wave and inundation behavior. The simplified topographical setup allows for systematic parameter studies and reproducible physical studies.

Geologic Evidence of Earthquakes and Tsunamis in the Mexican Subduction zone - Guerrero

NASA Astrophysics Data System (ADS)

Ramirez-Herrera, M.; Lagos, M.; Hutchinson, I.; Ruiz-Fernández, A.; Machain, M.; Caballero, M.; Rangel, V.; Nava, H.; Corona, N.; Bautista, F.; Kostoglodov, V.; Goguitchaichrili, A.; Morales, J.; Quintana, P.

2010-12-01

A study of large historic and prehistoric earthquakes and their tsunamis using a multiproxy approach (geomorphic features, sediment deposits, microfossils, sediment geochemistry and more recently the use of magnetic properties) has provided valuable information in the assessment of earthquake and tsunami record. The Pacific coast of Mexico is located over the active subduction zone (~1000 km) that has experienced numerous large magnitude earthquakes in historical time (Mw>7.5), and more than 50 documented tsunamis since 1732. Geomorphic and stratigraphic studies through test pits at 13 sites on the Guerrero coast reveal distinct stratigraphic changes with depth, indicating clear rapid change in depositional environments over time. Microfossil ecology (diatoms and foraminifera), sediment geochemistry (concentration increment in elements such as Sr, Ba, Ca, P, Si, K), stratigraphy, sediment magnetic properties (magnetic susceptibility anisotropy for the first time applied in tsunami deposits identification) and other proxies are indicative of sudden changes in land level and tsunami deposits. Buried evidence of liquefaction confirms the occurrence of a large earthquake at Barra de Potosi and Ixtapa, Guerrero. Preliminary 210Pb analysis suggests a sedimentation rate of ca. 0.1±0.01 cm/year and an estimated minimum age of ~ 100 years (maximum age at ca. 450 years?) for the most recent earthquake. At least three large events can be recognized by sharp contacts and sand layers in the sedimentary record. Ongoing C14, OSL and 210Pb dating will constrain the timing of these events. Deposits from three marine inwash events (tsunamis) dating from the past 4600 years have been identified on the Guerrero coast. A near-surface sand bed with a sharp basal contact overlying soil at sites near Ixtapa and Barra de Potosi most probably marks the tsunami following the 1985 Mw 8.2 earthquake. Interviews with Barra de Potosi fishermen and locals corroborate that these sites were

Seismically generated tsunamis.

PubMed

Arcas, Diego; Segur, Harvey

2012-04-13

People around the world know more about tsunamis than they did 10 years ago, primarily because of two events: a tsunami on 26 December 2004 that killed more than 200,000 people around the shores of the Indian Ocean; and an earthquake and tsunami off the coast of Japan on 11 March 2011 that killed nearly 15,000 more and triggered a nuclear accident, with consequences that are still unfolding. This paper has three objectives: (i) to summarize our current knowledge of the dynamics of tsunamis; (ii) to describe how that knowledge is now being used to forecast tsunamis; and (iii) to suggest some policy changes that might protect people better from the dangers of future tsunamis.

Geological Evidence of Predecessors to the 2010 Earthquake and Tsunami in South-Central Chile

NASA Astrophysics Data System (ADS)

Ely, L. L.; Cisternas, M.; Wesson, R. L.; Lagos, M.

2010-12-01

On February 27, 2010 a great M 8.8 earthquake and accompanying tsunami struck the region between Constitución and Concepción in south-central Chile. In the year immediately preceding this event, we described and surveyed deposits from previous tsunamis at several sites in the Concepción region (36.5°-38.5° S. Lat). This research positioned us to document the geomorphic and tectonic effects of the 2010 earthquake and tsunami. Following the 2010 earthquake we quantified the inundation, inland extent, erosion and deposition of the 2010 tsunami at our study sites and compared with those of previous tsunamis. The 2010 tsunami deposits were also utilized to guide the search for repositories where stratigraphic records of multiple paleotsunami deposits are likely to be preserved. The characteristic of the 2010 tsunami were similar to those reported after the penultimate earthquake in the Concepción region, which occurred in 1835. A sand sheet from the 2010 tsunami blanketed sites at Tirua (38.5° S. Lat) and the Andalien River, (36.7° S. Lat), where we had identified preexisting anomalous, laterally-continuous sand sheets that thin landward and are interbedded with coastal marsh deposits. The great similarity between these and the 2010 tsunami sands substantiated our interpretation that they were also left by previous tsunamis. At the Tirua River estuary, the 2010 tsunami sand sheet is underlain by at least three earlier tsunami deposits. This site lies at the boundary between the northern end of the rupture zone from the M 9.5 earthquake in 1960 and the southernmost reports of the 1835 and 2010 tsunamis. Prominent, laterally-continuous bands of these tsunami sands are interbedded with silty peats along the bank of the Tirua River, 0.8 to 1.8 km inland from the coast. Based on buried historic artifacts and testimonies of local survivors, the youngest pre-2010 sand sheet was deposited by the 1960 tsunami. Preliminary radiocarbon and OSL ages on the lower two sand

Examination of the largest-possible tsunamis (Level 2) generated along the Nankai and Suruga troughs during the past 4000 years based on studies of tsunami deposits from the 2011 Tohoku-oki tsunami

NASA Astrophysics Data System (ADS)

Kitamura, Akihisa

2016-12-01

Japanese historical documents reveal that Mw 8 class earthquakes have occurred every 100-150 years along the Suruga and Nankai troughs since the 684 Hakuho earthquake. These earthquakes have commonly caused large tsunamis with wave heights of up to 10 m in the Japanese coastal area along the Suruga and Nankai troughs. From the perspective of tsunami disaster management, these tsunamis are designated as Level 1 tsunamis and are the basis for the design of coastal protection facilities. A Mw 9.0 earthquake (the 2011 Tohoku-oki earthquake) and a mega-tsunami with wave heights of 10-40 m struck the Pacific coast of the northeastern Japanese mainland on 11 March 2011, and far exceeded pre-disaster predictions of wave height. Based on the lessons learned from the 2011 Tohoku-oki earthquake, the Japanese Government predicted the tsunami heights of the largest-possible tsunami (termed a Level 2 tsunami) that could be generated in the Suruga and Nankai troughs. The difference in wave heights between Level 1 and Level 2 tsunamis exceeds 20 m in some areas, including the southern Izu Peninsula. This study reviews the distribution of prehistorical tsunami deposits and tsunami boulders during the past 4000 years, based on previous studies in the coastal area of Shizuoka Prefecture, Japan. The results show that a tsunami deposit dated at 3400-3300 cal BP can be traced between the Shimizu, Shizuoka and Rokken-gawa lowlands, whereas no geologic evidence related to the corresponding tsunami (the Rokken-gawa-Oya tsunami) was found on the southern Izu Peninsula. Thus, the Rokken-gawa-Oya tsunami is not classified as a Level 2 tsunami.

The disaster at Japan's Fukushima-Daiichi nuclear power plant after the March 11, 2011 earthquake and tsunami, and the resulting spread of radioisotope contamination.

PubMed

Ohnishi, Takeo

2012-01-01

On March 11, 2011 eastern Japan was struck by a magnitude 9.0 earthquake and an enormous tsunami, over 13 m in height, which together killed over 20,500 people and resulted in the evacuation of over 320,000 people from the devastated areas. This paper describes the damage sustained by the Fukushima-Daiichi nuclear power plant during this unpredicted major natural disaster and the events that happened in the months after this accident. The events occurring at the Fukushima-Daiichi nuclear power plant, the actions taken to minimize the effects of the damage to the plant and to protect the public, and the points at which the responses proved to be inadequate all offer lessons that will be of value to those planning for and responding to future natural disasters and accidents in Japan and around the world.

The 2011 Great East Japan earthquake: a report of a regional hospital in Fukushima Prefecture coping with the Fukushima nuclear disaster.

PubMed

Irisawa, Atsushi

2012-05-01

A catastrophic undersea megathrust earthquake of magnitude 9.0 off the coast of Japan occurred at 14:46 JST on Friday, 11 March 2011. The earthquake triggered powerful tsunami waves, and the tsunami precipitated Fukushima nuclear accidents. After the terrible earthquake, many people fled from the nuclear accident and arrived at places far from the nuclear power plant. In this article, I present a story of one measure devised to deal with the problem of the Fukushima nuclear accident at a regional hospital of Fukushima prefecture, Aizu General Hospital, which is located far from the Fukushima nuclear plant. In addition, I briefly report the current situation of Fukushima prefecture after the 2011 Great East Japan earthquake. In our hospital, the countermeasure headquarters was established to supply medical care for those who had been injured by tsunami waves and the Fukushima nuclear accident. Especially, the screening for radioactive exposure using a dosimeter to take decontamination measures for cases of external exposure was extremely important task. Nevertheless, because the accurate knowledge related to radioactive contamination didn't provide, most medical staff fell into confusion. Fukushima prefecture has been 'shrinking' since the nuclear accident. However, today, although some hot spots remain in residential areas, the radioactive contamination is decreasing little by little. Many people in Fukushima Prefecture advance as one, facing forward. Recently, decontamination projects started. Efforts must be continued over a long period. © 2012 The Author. Digestive Endoscopy © 2012 Japan Gastroenterological Endoscopy Society.

Overview of Historical Earthquake Document Database in Japan and Future Development

NASA Astrophysics Data System (ADS)

Nishiyama, A.; Satake, K.

2014-12-01

In Japan, damage and disasters from historical large earthquakes have been documented and preserved. Compilation of historical earthquake documents started in the early 20th century and 33 volumes of historical document source books (about 27,000 pages) have been published. However, these source books are not effectively utilized for researchers due to a contamination of low-reliability historical records and a difficulty for keyword searching by characters and dates. To overcome these problems and to promote historical earthquake studies in Japan, construction of text database started in the 21 century. As for historical earthquakes from the beginning of the 7th century to the early 17th century, "Online Database of Historical Documents in Japanese Earthquakes and Eruptions in the Ancient and Medieval Ages" (Ishibashi, 2009) has been already constructed. They investigated the source books or original texts of historical literature, emended the descriptions, and assigned the reliability of each historical document on the basis of written age. Another database compiled the historical documents for seven damaging earthquakes occurred along the Sea of Japan coast in Honshu, central Japan in the Edo period (from the beginning of the 17th century to the middle of the 19th century) and constructed text database and seismic intensity data base. These are now publicized on the web (written only in Japanese). However, only about 9 % of the earthquake source books have been digitized so far. Therefore, we plan to digitize all of the remaining historical documents by the research-program which started in 2014. The specification of the data base will be similar for previous ones. We also plan to combine this database with liquefaction traces database, which will be constructed by other research program, by adding the location information described in historical documents. Constructed database would be utilized to estimate the distributions of seismic intensities and tsunami

Field survey of the March 28, 2005 Nias-Simeulue earthquake and Tsunami

USGS Publications Warehouse

Borrero, J.C.; McAdoo, B.; Jaffe, B.; Dengler, L.; Gelfenbaum, G.; Higman, B.; Hidayat, R.; Moore, A.; Kongko, W.; ,; Peters, R.; Prasetya, G.; Titov, V.; Yulianto, E.

2011-01-01

On the evening of March 28, 2005 at 11:09 p.m. local time (16:09 UTC), a large earthquake occurred offshore of West Sumatra, Indonesia. With a moment magnitude (Mw) of 8.6, the event caused substantial shaking damage and land level changes between Simeulue Island in the north and the Batu Islands in the south. The earthquake also generated a tsunami, which was observed throughout the source region as well as on distant tide gauges. While the tsunami was not as extreme as the tsunami of December 26th, 2004, it did cause significant flooding and damage at some locations. The spatial and temporal proximity of the two events led to a unique set of observational data from the earthquake and tsunami as well as insights relevant to tsunami hazard planning and education efforts. ?? 2010 Springer Basel AG.

Novel Algorithms Enabling Rapid, Real-Time Earthquake Monitoring and Tsunami Early Warning Worldwide

NASA Astrophysics Data System (ADS)

Lomax, A.; Michelini, A.

2012-12-01

We have introduced recently new methods to determine rapidly the tsunami potential and magnitude of large earthquakes (e.g., Lomax and Michelini, 2009ab, 2011, 2012). To validate these methods we have implemented them along with other new algorithms within the Early-est earthquake monitor at INGV-Rome (http://early-est.rm.ingv.it, http://early-est.alomax.net). Early-est is a lightweight software package for real-time earthquake monitoring (including phase picking, phase association and event detection, location, magnitude determination, first-motion mechanism determination, ...), and for tsunami early warning based on discriminants for earthquake tsunami potential. In a simulation using archived broadband seismograms for the devastating M9, 2011 Tohoku earthquake and tsunami, Early-est determines: the epicenter within 3 min after the event origin time, discriminants showing very high tsunami potential within 5-7 min, and magnitude Mwpd(RT) 9.0-9.2 and a correct shallow-thrusting mechanism within 8 min. Real-time monitoring with Early-est givess similar results for most large earthquakes using currently available, real-time seismogram data. Here we summarize some of the key algorithms within Early-est that enable rapid, real-time earthquake monitoring and tsunami early warning worldwide: >>> FilterPicker - a general purpose, broad-band, phase detector and picker (http://alomax.net/FilterPicker); >>> Robust, simultaneous association and location using a probabilistic, global-search; >>> Period-duration discriminants TdT0 and TdT50Ex for tsunami potential available within 5 min; >>> Mwpd(RT) magnitude for very large earthquakes available within 10 min; >>> Waveform P polarities determined on broad-band displacement traces, focal mechanisms obtained with the HASH program (Hardebeck and Shearer, 2002); >>> SeisGramWeb - a portable-device ready seismogram viewer using web-services in a browser (http://alomax.net/webtools/sgweb/info.html). References (see also: http

The Study to Improve Tsunami Preparedness Education in Turkey

NASA Astrophysics Data System (ADS)

Sakamoto, Mayumi; Tanırcan, Gülüm; Kaneda, Yoshiyuki; Puskulcu, Seyhun; Kumamoto, Kunihiko

2016-04-01

Compared to its long history on disastrous earthquakes, disaster education history in Turkey is rather short. It has just started with an initiative of Disaster Preparedness Education Unit of Bogazici University (BU/DPEU) after 1999 Kocaeli Earthquake. Training modules and materials on disaster preparedness were prepared both for students, teachers and community. Regarding to the school education, the Ministry of National Education (MoNE) reformed their education plan in 2003, and disaster education became one of eight focused components for primary-middle education. In 2011-2014 MoNE had conducted "School-based Disaster Education Project" in collaboration with Japan International Cooperation Agency (JICA). The majority of the school education materials focus more on earthquake and there are very few education programs on tsunami. Within the MarDiM (Earthquake and Tsunami Disaster Mitigation in the Marmara Region and Disaster Education in Turkey) project between Turkey and Japan a multidisciplinary engineering research as well as development of disaster education, tsunami education booklet and video were newly developed in 2015. In order to investigate students' knowledge natural disasters and disaster preparedness with focus on tsunami, a questionnaire based survey was conducted. The survey aims to clarify following questions: 1) how students obtain natural disaster information, 2) how students prepare for natural disaster, 3) knowledge on tsunami (hazard mechanism, evacuation behavior, historical disaster). The study was conducted by BU/DPEU in 2015 and 375 students answered the questionnaire. Results showed that students have more interest on earthquake, flood, tsunami and landslide followed it. Most students have heard about tsunami and the school is a key resource of their information. They know relatively well about tsunami mechanism, however, they have less knowledge on tsunami evacuation behavior and tsunami history in Turkey. In order to let students have

Possible worst-case tsunami scenarios around the Marmara Sea from combined earthquake and landslide sources

NASA Astrophysics Data System (ADS)

Latcharote, Panon; Suppasri, Anawat; Imamura, Fumihiko; Aytore, Betul; Yalciner, Ahmet Cevdet

2016-12-01

This study evaluates tsunami hazards in the Marmara Sea from possible worst-case tsunami scenarios that are from submarine earthquakes and landslides. In terms of fault-generated tsunamis, seismic ruptures can propagate along the North Anatolian Fault (NAF), which has produced historical tsunamis in the Marmara Sea. Based on the past studies, which consider fault-generated tsunamis and landslide-generated tsunamis individually, future scenarios are expected to generate tsunamis, and submarine landslides could be triggered by seismic motion. In addition to these past studies, numerical modeling has been applied to tsunami generation and propagation from combined earthquake and landslide sources. In this study, tsunami hazards are evaluated from both individual and combined cases of submarine earthquakes and landslides through numerical tsunami simulations with a grid size of 90 m for bathymetry and topography data for the entire Marmara Sea region and validated with historical observations from the 1509 and 1894 earthquakes. This study implements TUNAMI model with a two-layer model to conduct numerical tsunami simulations, and the numerical results show that the maximum tsunami height could reach 4.0 m along Istanbul shores for a full submarine rupture of the NAF, with a fault slip of 5.0 m in the eastern and western basins of the Marmara Sea. The maximum tsunami height for landslide-generated tsunamis from small, medium, and large of initial landslide volumes (0.15, 0.6, and 1.5 km3, respectively) could reach 3.5, 6.0, and 8.0 m, respectively, along Istanbul shores. Possible tsunamis from submarine landslides could be significantly higher than those from earthquakes, depending on the landslide volume significantly. These combined earthquake and landslide sources only result in higher tsunami amplitudes for small volumes significantly because of amplification within the same tsunami amplitude scale (3.0-4.0 m). Waveforms from all the coasts around the Marmara Sea

Invesion of tsunami height using GPS TEC data. The case of the 2012 Haida Gwaii tsunami and Earthquake.

NASA Astrophysics Data System (ADS)

Rakoto, V.; Lognonne, P. H.; Rolland, L. M.

2015-12-01

Large earthquakes (i.eM>6) and tsunamis associated are responsible for ionospheric perturbations. These perturbations can be observed in the total electron content (TEC) measured from multi- frequency Global Navigation Satellite systems (GNSS) data (e.g GPS). We will focus on the studies of the Haïda Gwaii earthquake and tsunami case. It happened the 28 october 2012 along the Queen Charlotte fault of the Canada Western Coast. First, we compare GPS data of perturbation TEC to our model. We model the TEC perturbation in several steps. (1) First, we compute tsunami normal modes modes in atmosphere in using PREM model with 4.7km of oceanic layer. (2) We sum all the tsunami modes to obtain the neutral displacement. (3) We couple the ionosphere with the neutral atmosphere. (4) We integrate the perturbed electron density along each satellite station line of sight. At last, we present first results of TEC inversion in order to retrieve the waveform of the tsunami. This inversion has been done on synthetics data assuming Queen Charlotte Earthquake and Tsunami can be considered as a point source in far field.

Differences in tsunami generation between the December 26, 2004 and March 28, 2005 Sumatra earthquakes

USGS Publications Warehouse

Geist, E.L.; Bilek, S.L.; Arcas, D.; Titov, V.V.

2006-01-01

Source parameters affecting tsunami generation and propagation for the Mw > 9.0 December 26, 2004 and the Mw = 8.6 March 28, 2005 earthquakes are examined to explain the dramatic difference in tsunami observations. We evaluate both scalar measures (seismic moment, maximum slip, potential energy) and finite-source repre-sentations (distributed slip and far-field beaming from finite source dimensions) of tsunami generation potential. There exists significant variability in local tsunami runup with respect to the most readily available measure, seismic moment. The local tsunami intensity for the December 2004 earthquake is similar to other tsunamigenic earthquakes of comparable magnitude. In contrast, the March 2005 local tsunami was deficient relative to its earthquake magnitude. Tsunami potential energy calculations more accurately reflect the difference in tsunami severity, although these calculations are dependent on knowledge of the slip distribution and therefore difficult to implement in a real-time system. A significant factor affecting tsunami generation unaccounted for in these scalar measures is the location of regions of seafloor displacement relative to the overlying water depth. The deficiency of the March 2005 tsunami seems to be related to concentration of slip in the down-dip part of the rupture zone and the fact that a substantial portion of the vertical displacement field occurred in shallow water or on land. The comparison of the December 2004 and March 2005 Sumatra earthquakes presented in this study is analogous to previous studies comparing the 1952 and 2003 Tokachi-Oki earthquakes and tsunamis, in terms of the effect slip distribution has on local tsunamis. Results from these studies indicate the difficulty in rapidly assessing local tsunami runup from magnitude and epicentral location information alone.

Weight Gain in Survivors Living in Temporary Housing in the Tsunami-Stricken Area during the Recovery Phase following the Great East Japan Earthquake and Tsunami

PubMed Central

Yonekura, Yuki; Sasaki, Ryohei; Yokoyama, Yukari; Tanno, Kozo; Sakata, Kiyomi; Ogawa, Akira; Kobayashi, Seichiro; Yamamoto, Taro

2016-01-01

Introduction Survivors who lost their homes in the Great East Japan Earthquake and Tsunami were forced to live in difficult conditions in temporary housing several months after the disaster. Body weights of survivors living in temporary housing for a long period might increase due to changes in their life style and psychosocial state during the medium-term and long-term recovery phases. The aim of this study was to determine whether there were differences between body weight changes of people living in temporary housing and those not living in temporary housing in a tsunami-stricken area during the medium-term and long-term recovery phases. Materials and methods Health check-ups were performed about 7 months after the disaster (in 2011) and about 18 months after the disaster (in 2012) for people living in a tsunami-stricken area (n = 6,601, mean age = 62.3 y). We compared the changes in body weight in people living in temporary housing (TH group, n = 2,002) and those not living in temporary housing (NTH group, n = 4,599) using a multiple linear regression model. Results While there was no significant difference between body weights in the TH and NTH groups in the 2011 survey, there was a significant difference between the mean changes in body weight in both sexes. We found that the changes in body weight were significantly greater in the TH group than in the NTH group in both sexes. The partial regression coefficients of mean change in body weight were +0.52 kg (P-value < 0.001) in males in the TH group and +0.56 kg (P-value < 0.001) in females in the TH group (reference: NTH group). Conclusion Analysis after adjustment for life style, psychosocial factors and cardiovascular risk factors found that people living in temporary housing in the tsunami- stricken area had a significant increase in body weight. PMID:27907015

Earthquake- and tsunami-induced ionospheric disturbances detected by GPS total electron content observation

NASA Astrophysics Data System (ADS)

Tsugawa, T.; Nishioka, M.; Matsumura, M.; Shinagawa, H.; Maruyama, T.; Ogawa, T.; Saito, A.; Otsuka, Y.; Nagatsuma, T.; Murata, T.

2012-12-01

Ionospheric disturbances induced by the 2011 Tohoku earthquake and tsunami were studied by the high-resolution GPS total electron content (TEC) observation in Japan and in the world. The initial ionospheric disturbance appeared as sudden depletions by about 6 TEC unit (20%) about seven minutes after the earthquake onset, near the epicenter. From 06:00UT to 06:15UT, circular waves with short propagation distance propagated in the radial direction in the propagation velocity of 3,457, 783, 423 m/s for the first, second, third peak, respectively. Following these waves, concentric waves with long propagation distance appeared to propagate at the velocity of 138-288 m/s. In the vicinity of the epicenter, shortperiod oscillations with period of about 4 minutes were observed after 06:00 UT for 3 hours or more. We focus on the the circular and concentric waves in this paper. The circular or concentric structures indicate that these ionospheric disturbances had a point source. The center of these structures, termed as "ionospheric epicenter", was located around 37.5 deg N of latitude and 144.0 deg E of longitude, 170 km far from the epicenter to the southeast direction, and corresponded to the tsunami source. Comparing to the results of a numerical simulation using non-hydrostatic compressible atmosphere-ionosphere model, the first peak of circular wave would be caused by the acoustic waves generated from the propagating Rayleigh wave. The second and third waves would be caused by atmospheric gravity waves excited in the lower ionosphere due to the acoustic wave propagations from the tsunami source. The fourth and following waves are considered to be caused by the atmospheric gravity waves induced by the wavefronts of traveling tsunami. Long-propagation of these TEC disturbances were studied also using high-resolution GPS-TEC data in North America and Europe. Medium-scale wave structures with wavelengths of several 100 km appeared in the west part of North America at the

Tsunami waveform inversion of the 2007 Bengkulu, southern Sumatra earthquake

NASA Astrophysics Data System (ADS)

Fujii, Y.; Satake, K.

2007-12-01

We have performed tsunami waveform inversion for the 2007 Bengkulu, southern Sumatra earthquake on September 12, 2007 (4.520°S, 101.374°E, Mw=8.4 at 11:10:26 UTC according to USGS), and found that the large slips were located on deeper part (> 20 km) of the fault plane, more than 100 km from the trench axis. The deep slip might have contributed the relatively small tsunami for its earthquake size. The largest slips more than 6 m were located beneath Pagais Islands, about 100-200 km northwest of the epicenter. The obtained slip distribution yields a total seismic moment of 3.6 × 1021 Nm (Mw = 8.3). The tsunami generated by this earthquake was recorded at many tide gauge stations located in and around the Indian Ocean. The DART system installed in deep ocean and maintained by Thai Meteorological Department (TMD) also captured this tsunami. We have downloaded the tsunami waveforms at 16 stations from University of Hawaii Sea Level Center's (UHSLC) and National Oceanic & Atmospheric Administration's (NOAA) web sites. The observed tsunami records indicate that the tsunami amplitudes were less than several tens of cm at most stations, around 1 m at Padang, nearest station to the source, and a few cm at DART station. For the tsunami waveforms inversion, we divided the source area (length: 250 km, width: 200 km) into 20 subfaults. Tsunami waveforms from each subfault (50 km × 50 km) or Greens functions were calculated by numerically solving the linear shallow-water long-wave equations. We adopted the focal mechanism of Global CMT solution (strike: 327°, dip: 12°, rake: 114°) for each subfault, and assumed a rise time of 1 min. The computed tsunami waveforms from the estimated slip distribution explain the observed waveforms at most of tide gauges and DART station.

Coastal evidence for Holocene subduction-zone earthquakes and tsunamis in central Chile

USGS Publications Warehouse

Dure, Tina; Cisternas, Marco; Horton, Benjamin; Ely, Lisa; Nelson, Alan R.; Wesson, Robert L.; Pilarczyk, Jessica

2015-01-01

The ∼500-year historical record of seismicity along the central Chile coast (30–34°S) is characterized by a series of ∼M 8.0–8.5 earthquakes followed by low tsunamis (<4 m) occurring on the megathrust about every 80 years. One exception is the AD 1730 great earthquake (M 9.0–9.5) and high tsunami (>10 m), but the frequency of such large events is unknown. We extend the seismic history of central Chile through a study of a lowland stratigraphic sequence along the metropolitan coast north of Valparaíso (33°S). At this site, higher relative sea level during the mid Holocene created a tidal marsh and the accommodation space necessary for sediment that preserves earthquake and tsunami evidence. Within this 2600-yr-long sequence, we traced six laterally continuous sand beds probably deposited by high tsunamis. Plant remains that underlie the sand beds were radiocarbon dated to 6200, 5600, 5000, 4400, 3800, and 3700 cal yr BP. Sediment properties and diatom assemblages of the sand beds—for example, anomalous marine planktonic diatoms and upward fining of silt-sized diatom valves—point to a marine sediment source and high-energy deposition. Grain-size analysis shows a strong similarity between inferred tsunami deposits and modern coastal sediment. Upward fining sequences characteristic of suspension deposition are present in five of the six sand beds. Despite the lack of significant lithologic changes between the sedimentary units under- and overlying tsunami deposits, we infer that the increase in freshwater siliceous microfossils in overlying units records coseismic uplift concurrent with the deposition of five of the sand beds. During our mid-Holocene window of evidence preservation, the mean recurrence interval of earthquakes and tsunamis is ∼500 years. Our findings imply that the frequency of historical earthquakes in central Chile is not representative of the greatest earthquakes and tsunamis that the central Chilean subduction zone has

Earthquake and Tsunami Disaster Mitigation in The Marmara Region and Disaster Education in Turkey (SATREPS Project: Science and Technology Research Partnership for Sustainable Development by JICA-JST)

NASA Astrophysics Data System (ADS)

Kaneda, Yoshiyuki

2015-04-01

Earthquake and Tsunami Disaster Mitigation in The Marmara Region and Disaster Education in Turkey (SATREPS Project: Science and Technology Research Partnership for Sustainable Development by JICA-JST) Yoshiyuki KANEDA Disaster mitigation center Nagoya University/ Japan Agency for Marine-Earth Science and Technology (JAMSTEC) Mustafa ELDIK Boğaziçi University, Kandilli Observatory and 　　　　　　Earthquake Researches Institute (KOERI) and Members of SATREPS Japan-Turkey project The target of this project is the Marmara Sea earthquake after the Izmit (Kocaeli) Earthquake 1999 along to the North Anatolian fault. According to occurrences of historical Earthquakes, epicenters have moved from East to West along to the North Anatolian Fault. There is a seismic gap in the Marmara Sea. In Marmara region, there is Istanbul with high populations such as Tokyo. Therefore, Japan and Turkey can share our own experiences during past damaging earthquakes and we can prepare for future large Earthquakes and Tsunamis in cooperation with each other in SATREPS project. This project is composed of Multidisciplinary research project including observation researches, simulation researches, educational researches, and goals are as follows, ① To develop disaster mitigation policy and strategies based on Multidisciplinary research activities. ② To provide decision makers with newly found knowledge for its implementation to the current regulations. ③ To organize disaster education programs in order to increase disaster awareness in Turkey. ④ To contribute the evaluation of active fault studies in Japan. In this SATREPS project, we will integrate Multidisciplinary research results for disaster mitigation in Marmara region and .disaster education in Turkey.

Escherichia coli pneumonia in combination with fungal sinusitis and meningitis in a tsunami survivor after the Great East Japan Earthquake.

PubMed

Igusa, Ryotaro; Narumi, Sodai; Murakami, Koji; Kitawaki, Yuko; Tamii, Toru; Kato, Masahiro; Sato, Mineshige; Tsuboi, Masahiro; Ota, Kozo

2012-07-01

Individuals who survive near drowning often suffer from complicated infections, including multi-organ and polymicrobial events. This pattern may be especially pronounced among patients exposed to infectious agents during catastrophic events like that of the Great East Japan Earthquake and the associated tsunami disaster. We report here on a patient who presented with Escherichia coli (E. coli) pneumonia in combination with fungal sinusitis and meningitis. A 73-year-old woman survived the tsunami that engulfed the Sanriku coast. By the time of hospital admission, the patient exhibited high fever, severe cough, and sputum production. Chest X-ray and CT scan showed consolidation in the left upper lobe. Administration of an antibacterial agent improved this pneumonia. However, the patient's consciousness was increasingly impaired. Brain CT showed the low-density lesions and partial high-density spot in the sinus, which suggests the fungal infection. MRI showed the inflammation in the sinus spread into the central nerve system. The examination of the cerebrospinal fluid showed the low glucose level, high mononuclear cell count, and highβ-D glucan level, the findings of which supported the diagnosis of fungal meningitis. Although the patient improved temporarily in response to combination treatment with anti-fungal agents, no further improvement was seen. In conclusion, this patient, who suffered from infections of pneumonia, sinusitis, and meningitis, presented a quite rare clinical progress. We propose that fungal infection should be taken into consideration in individuals who suffered near drowning, a profile expected to be frequent among tsunami survivors.

Impact of the Great East Japan Earthquake and tsunami on health, medical care and public health systems in Iwate Prefecture, Japan, 2011.

PubMed

Nohara, Masaru

2011-10-01

The Great East Japan Earthquake was one of the largest earthquakes ever recorded in global history. The damage was spread over a wide area, with the worst-hit areas being Iwate, Miyagi and Fukushima prefectures. In this paper we report on the damage and the impact of the damage to describe the health consequences among disaster victims in Iwate Prefecture. In Iwate Prefecture the tsunami claimed 4659 lives, with 1633 people missing. In addition to electricity, water and gas being cut off following the disaster, communication functions were paralysed and there was a lack of gasoline. Medical and public health teams from Iwate Prefecture and around the country, including many different specialists, engaged in a variety of public health activities mainly at evacuation centres, including medical and mental health care and activities to prevent infectious diseases. Given the many fatalities, there were relatively few patients who required medical treatment for major injuries. However, there were significant medical needs in the subacute and chronic phases of care in evacuation centres, with great demand for medical treatment and public health assistance, measures to counteract infection and mental health care. By referring to past experiences of national and international large-scale disasters, it was possible to respond effectively to the health-related challenges. However, there are still challenges concerning how to share information and coordinate overall activities among multiple public health response teams. Further examination will be required to ensure better preparedness in response to future disasters.

Tsunami Source Estimate for the 1960 Chilean Earthquake from Near- and Far-Field Observations

NASA Astrophysics Data System (ADS)

Ho, T.; Satake, K.; Watada, S.; Fujii, Y.

2017-12-01

The tsunami source of the 1960 Chilean earthquake was estimated from the near- and far-field tsunami data. The 1960 Chilean earthquake is known as the greatest earthquake instrumentally ever recorded. This earthquake caused a large tsunami which was recorded by 13 near-field tidal gauges in South America, and 84 far-field stations around the Pacific Ocean at the coasts of North America, Asia, and Oceania. The near-field stations had been used for estimating the tsunami source [Fujii and Satake, Pageoph, 2013]. However, far-field tsunami waveforms have not been utilized because of the discrepancy between observed and simulated waveforms. The observed waveforms at the far-field stations are found systematically arrived later than the simulated waveforms. This phenomenon has been also observed in the tsunami of the 2004 Sumatra earthquake, the 2010 Chilean earthquake, and the 2011 Tohoku earthquake. Recently, the factors for the travel time delay have been explained [Watada et al., JGR, 2014; Allgeyer and Cummins, GRL, 2014], so the far-field data are usable for tsunami source estimation. The phase correction method [Watada et al., JGR, 2014] converts the tsunami waveforms computed by the linear long wave into the dispersive waveform which accounts for the effects of elasticity of the Earth and ocean, ocean density stratification, and gravitational potential change associated with tsunami propagation. We apply the method to correct the computed waveforms. For the preliminary initial sea surface height inversion, we use 12 near-field stations and 63 far-field stations, located in the South and North America, islands in the Pacific Ocean, and the Oceania. The estimated tsunami source from near-field stations is compared with the result from both near- and far-field stations. Two estimated sources show a similar pattern: a large sea surface displacement concentrated at the south of the epicenter close to the coast and extended to south. However, the source estimated from

The 1997 Kronotsky earthquake and tsunami and their predecessors, Kamchatka, Russia

NASA Astrophysics Data System (ADS)

Bourgeois, Joanne; Pinegina, Tatiana K.

2018-01-01

The northern part of the Kamchatka subduction zone (KSZ) experienced three tsunamigenic earthquakes in the 20th century - February 1923, April 1923, December 1997 - events that help us better understand the behavior of this segment. A particular focus of this study is the nature and location of the 5 December 1997 Kronotsky rupture (Mw ˜ 7.8) as elucidated by tsunami runup north of Kronotsky Peninsula in southern to central Kamchatsky Bay. Some studies have characterized the subduction zone off Kronotsky Peninsula as either more locked or more smoothly slipping than surrounding areas and have placed the 1997 rupture south of this promontory. However, 1997 tsunami runup north of the peninsula, as evidenced by our mapping of tsunami deposits, requires the rupture to extend farther north. Previously reported runup (1997 tsunami) on Kronotsky Peninsula was no more than 2-3 m, but our studies indicate tsunami heights for at least 50 km north of Kronotsky Peninsula in Kamchatsky Bay, ranging from 3.4 to 9.5 m (average 6.1 m), exceeding beach ridge heights of 5.3 to 8.3 m (average 7.1 m). For the two 1923 tsunamis, we cannot distinguish among their deposits in southern to central Kamchatsky Bay, but the deposits are more extensive than the 1997 deposit. A reevaluation of the April 1923 historical tsunami suggests that its moment magnitude could be revised upward, and that the 1997 earthquake filled a gap between the two 1923 earthquake ruptures. Characterizing these historical earthquakes and tsunamis in turn contributes to interpreting the prehistoric record, which is necessary to evaluate recurrence intervals for such events. Deeper in time, the prehistoric record back to ˜ AD 300 in southern to central Kamchatsky Bay indicates that during this interval, there were no local events significantly larger than those of the 20th century. Together, the historic and prehistoric tsunami record suggests a more northerly location of the 1997 rupture compared to most other

Web-based Tsunami Early Warning System: a case study of the 2010 Kepulaunan Mentawai Earthquake and Tsunami

NASA Astrophysics Data System (ADS)

Ulutas, E.; Inan, A.; Annunziato, A.

2012-06-01

This study analyzes the response of the Global Disasters Alerts and Coordination System (GDACS) in relation to a case study: the Kepulaunan Mentawai earthquake and related tsunami, which occurred on 25 October 2010. The GDACS, developed by the European Commission Joint Research Center, combines existing web-based disaster information management systems with the aim to alert the international community in case of major disasters. The tsunami simulation system is an integral part of the GDACS. In more detail, the study aims to assess the tsunami hazard on the Mentawai and Sumatra coasts: the tsunami heights and arrival times have been estimated employing three propagation models based on the long wave theory. The analysis was performed in three stages: (1) pre-calculated simulations by using the tsunami scenario database for that region, used by the GDACS system to estimate the alert level; (2) near-real-time simulated tsunami forecasts, automatically performed by the GDACS system whenever a new earthquake is detected by the seismological data providers; and (3) post-event tsunami calculations using GCMT (Global Centroid Moment Tensor) fault mechanism solutions proposed by US Geological Survey (USGS) for this event. The GDACS system estimates the alert level based on the first type of calculations and on that basis sends alert messages to its users; the second type of calculations is available within 30-40 min after the notification of the event but does not change the estimated alert level. The third type of calculations is performed to improve the initial estimations and to have a better understanding of the extent of the possible damage. The automatic alert level for the earthquake was given between Green and Orange Alert, which, in the logic of GDACS, means no need or moderate need of international humanitarian assistance; however, the earthquake generated 3 to 9 m tsunami run-up along southwestern coasts of the Pagai Islands where 431 people died. The post

Dynamic models of an earthquake and tsunami offshore Ventura, California

USGS Publications Warehouse

Kenny J. Ryan,; Geist, Eric L.; Barall, Michael; David D. Oglesby,

2015-01-01

The Ventura basin in Southern California includes coastal dip-slip faults that can likely produce earthquakes of magnitude 7 or greater and significant local tsunamis. We construct a 3-D dynamic rupture model of an earthquake on the Pitas Point and Lower Red Mountain faults to model low-frequency ground motion and the resulting tsunami, with a goal of elucidating the seismic and tsunami hazard in this area. Our model results in an average stress drop of 6 MPa, an average fault slip of 7.4 m, and a moment magnitude of 7.7, consistent with regional paleoseismic data. Our corresponding tsunami model uses final seafloor displacement from the rupture model as initial conditions to compute local propagation and inundation, resulting in large peak tsunami amplitudes northward and eastward due to site and path effects. Modeled inundation in the Ventura area is significantly greater than that indicated by state of California's current reference inundation line.

The geological record of prehistorical tsunami at a coastal area of Beppu Bay in eastern Kyushu, Japan

NASA Astrophysics Data System (ADS)

Yamada, M.; Fujino, S.; Chiba, T.; Shinozaki, T.; Okuwaki, R.; Takeda, D.

2015-12-01

Tsunamis are typically generated by plate-boundary ruptures at subduction zones, but also vertical displacement associated with intraplate earthquakes. Historical written records documented that coasts of Beppu Bay, eastern Kyushu, Japan was devastated by a tsunami associated with the AD 1596 Keicho-Bungo earthquake (M7.0). It is considered that the earthquake occurred at submarine active faults in the bay. The aim of this study is to unravel the occurrence age and source of tsunamis that struck the coast of the bay in prehistorical ages. This study may also make a contribution to the understanding of tsunami-generating system at submarine active faults. We conducted a coring survey at paddy fields along the north coast of the bay. The 10 cm thick muddy sand layer with a few granules (hereinafter, sand layer), bounded by sharp contacts, was evident in the 1.7 m long sediment core taken at 700 m from the shoreline. Plant materials obtained from mud above the sand layer was dated to 1880-2000 cal. yr BP. Sharp contacts between sand and surrounding muds imply that the sand layer is formed by a sudden event. Existence of mud clast in the sand layer indicates erosion of surface mud. There were no brackish-marine diatoms in surrounding mud, but they accounted for 5-6% of the total within the sand layer, indicating that the sand grains were sourced at least in part from brackish-marine environment. Mean grain size/sorting of the sand layer and beach sand were 2.31/0.94 and 2.03/0.41 phi. The difference in sorting probably suggests that the sand layer partly contains the onshore sediments eroded in inundation process. Additional coring surveys would clarify the distribution of prehistorical tsunami deposits and source of past tsunamis.

The "Tsunami Earthquake" of 13 April 1923 in Northern Kamchatka: Seismological and Hydrodynamic Investigations

NASA Astrophysics Data System (ADS)

Salaree, Amir; Okal, Emile A.

2018-04-01

We present a seismological and hydrodynamic investigation of the earthquake of 13 April 1923 at Ust'-Kamchatsk, Northern Kamchatka, which generated a more powerful and damaging tsunami than the larger event of 03 February 1923, thus qualifying as a so-called "tsunami earthquake". On the basis of modern relocations, we suggest that it took place outside the fault area of the mainshock, across the oblique Pacific-North America plate boundary, a model confirmed by a limited dataset of mantle waves, which also confirms the slow nature of the source, characteristic of tsunami earthquakes. However, numerical simulations for a number of legitimate seismic models fail to reproduce the sharply peaked distribution of tsunami wave amplitudes reported in the literature. By contrast, we can reproduce the distribution of reported wave amplitudes using an underwater landslide as a source of the tsunami, itself triggered by the earthquake inside the Kamchatskiy Bight.

Seismic Regime in the Vicinity of the 2011 Tohoku Mega Earthquake (Japan, M w = 9)

NASA Astrophysics Data System (ADS)

Rodkin, M. V.; Tikhonov, I. N.

2014-12-01

The 2011 Tohoku mega earthquake ( M w = 9) is unique due to a combination of its large magnitude and the high level of detail of regional seismic data. The authors analyzed the seismic regime in the vicinity of this event using data from the Japan Meteorological Agency catalog and world databases. It was shown that a regional decrease in b-value and of the number of main shocks took place in the 6-7 years prior to the Tohoku mega earthquake. The space-time area of such changes coincided with the development of precursor effects in this area, as revealed by Lyubushin (Geofiz Prots Biosfera 10:9-35, 2011) from the analysis of microseisms recorded by the broadband seismic network F-net in Japan. The combination of episodes of growth in the number of earthquakes, accompanied by a corresponding decrease in the b-value and average depth of the earthquakes, was observed for the foreshock and aftershock sequences of the 2011 Tohoku earthquake. Some of these anomalies were similar to those observed (also post factum) by Katsumata (Earth Planets Space 63:709-712, 2011), Nanjo et al. (Geophys Res Lett 39, 2012), and Huang and Ding (Bull Seismol Soc Am 102:1878-1883, 2012), whereas others were not described before. The correlation of the periods of growth in seismic activity with the decrease of the average depth of earthquakes can be explained by the growth of fluid activity and the tendency of a penetration of low density fluids into the upper horizons of the lithosphere. The unexpectedly strong Tohoku mega earthquake with a rather small rupture area caused an unexpectedly high tsunami wave. From here it seems plausible that M9+ earthquakes with a large tsunami could occur in other subduction zones where such cases were suggested before to be impossible.

Evaluation of earthquake and tsunami on JSFR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chikazawa, Y.; Enuma, Y.; Kisohara, N.

2012-07-01

Evaluation of earthquake and tsunami on JSFR has been analyzed. For seismic design, safety components are confirmed to maintain their functions even against recent strong earthquakes. As for Tsunami, some parts of reactor building might be submerged including component cooling water system whose final heat sink is sea water. However, in the JSFR design, safety grade components are independent from component cooling water system (CCWS). The JSFR emergency power supply adopts a gas turbine system with air cooling, since JSFR does not basically require quick start-up of the emergency power supply thanks to the natural convection DHRS. Even in casemore » of long station blackout, the DHRS could be activated by emergency batteries or manually and be operated continuously by natural convection. (authors)« less

U.S. Tsunami Information technology (TIM) Modernization: Performance Assessment of Tsunamigenic Earthquake Discrimination System

NASA Astrophysics Data System (ADS)

Hagerty, M. T.; Lomax, A.; Hellman, S. B.; Whitmore, P.; Weinstein, S.; Hirshorn, B. F.; Knight, W. R.

2015-12-01

Tsunami warning centers must rapidly decide whether an earthquake is likely to generate a destructive tsunami in order to issue a tsunami warning quickly after a large event. For very large events (Mw > 8 or so), magnitude and location alone are sufficient to warrant an alert. However, for events of smaller magnitude (e.g., Mw ~ 7.5), particularly for so-called "tsunami earthquakes", magnitude alone is insufficient to issue an alert and other measurements must be rapidly made and used to assess tsunamigenic potential. The Tsunami Information technology Modernization (TIM) is a National Oceanic and Atmospheric Administration (NOAA) project to update and standardize the earthquake and tsunami monitoring systems currently employed at the U.S. Tsunami Warning Centers in Ewa Beach, Hawaii (PTWC) and Palmer, Alaska (NTWC). We (ISTI) are responsible for implementing the seismic monitoring components in this new system, including real-time seismic data collection and seismic processing. The seismic data processor includes a variety of methods aimed at real-time discrimination of tsunamigenic events, including: Mwp, Me, slowness (Theta), W-phase, mantle magnitude (Mm), array processing and finite-fault inversion. In addition, it contains the ability to designate earthquake scenarios and play the resulting synthetic seismograms through the processing system. Thus, it is also a convenient tool that integrates research and monitoring and may be used to calibrate and tune the real-time monitoring system. Here we show results of the automated processing system for a large dataset of subduction zone earthquakes containing recent tsunami earthquakes and we examine the accuracy of the various discrimation methods and discuss issues related to their successful real-time application.

The 339 Years of Living Dangerously in Indonesia: Earthquakes and Tsunamis in the Indonesian Region from 1538 to 1877

NASA Astrophysics Data System (ADS)

Harris, R. A.; Major, J.

2013-05-01

Using 339 years of Dutch records of geophysical events in Indonesia and tsunami modeling, we have identified previously unknown mega-thrust earthquake sources in eastern Indonesia that caused severe devastation in the past and are likely to reoccur in the near future. Indonesia has experienced some of the most extreme geohazards known (Toba, Krakatoa, Tambora, Indian Ocean tsunami). Although most of well known events occurred in western Indonesia, historical records reveal that eastern Indonesia is actually more hazardous. Strain rates in eastern Indonesia are twice those in Sumatra and tsunamis are much more frequent. Adding to the disaster potential in Indonesia is its rapid population growth and urbanization, especially in coastal regions. When the events documented in historical records reoccur in eastern Indonesia, as they have in western Indonesia, ten times more people and assets will be in harms way. Arthur Wichmann's Die Erdbeben Des Indischen Archipels [The Earthquakes of the Indian Archipelago] (1918) documents >100 destructive earthquakes and 68 tsunamis between 1600 and 1877. The largest and best documented are the events of 1629, 1674 and 1852 in the Banda Sea region, 1770 and 1859 in the Molucca Sea region, 1820 in Makassar, 1857 in Dili, Timor, 1815 in Bali and Lombak, 1699, 1771, 1780, 1815, 1848 and 1852 in Java and 1799, 1833 and 1861 in Sumatra. All of these events caused damage over a broad region notwithstanding high seismic attenuation rates, and are associated with years of temporal and spatial clustering of earthquakes. Several tsunami are recorded with run-up heights > 15 meters. Many islands were engulfed and coastal communities washed away. The earthquakes associated with these events were felt over a region as large as the 2011 Tohoku Earthquake in Japan and were followed by decades of aftershocks. Over the past 160 years no major shallow earthquakes have struck eastern Indonesia, which is characterized as an area incapable of mega

Probability of a great earthquake to recur in the Tokai district, Japan: reevaluation based on newly-developed paleoseismology, plate tectonics, tsunami study, micro-seismicity and geodetic measurements

NASA Astrophysics Data System (ADS)

Rikitake, T.

1999-03-01

In light of newly-acquired geophysical information about earthquake generation in the Tokai area, Central Japan, where occurrence of a great earthquake of magnitude 8 or so has recently been feared, probabilities of earthquake occurrence in the near future are reevaluated. Much of the data used for evaluation here relies on recently-developed paleoseismology, tsunami study and GPS geodesy.The new Weibull distribution analysis of recurrence tendency of great earthquakes in the Tokai-Nankai zone indicates that the mean return period of great earthquakes there is estimated as 109 yr with a standard deviation amounting to 33 yr. These values do not differ much from those of previous studies (Rikitake, 1976, 1986; Utsu, 1984).Taking the newly-determined velocities of the motion of Philippine Sea plate at various portions of the Tokai-Nankai zone into account, the ultimate displacements to rupture at the plate boundary are obtained. A Weibull distribution analysis results in the mean ultimate displacement amounting to 4.70 m with a standard deviation estimated as 0.86 m. A return period amounting to 117 yr is obtained at the Suruga Bay portion by dividing the mean ultimate displacement by the relative plate velocity.With the aid of the fault models as determined from the tsunami studies, the increases in the cumulative seismic slips associated with the great earthquakes are examined at various portions of the zone. It appears that a slip-predictable model can better be applied to the occurrence mode of great earthquakes in the zone than a time-predictable model. The crustal strain accumulating over the Tokai area as estimated from the newly-developed geodetic work including the GPS observations is compared to the ultimate strain presumed by the above two models.The probabilities for a great earthquake to recur in the Tokai district are then estimated with the aid of the Weibull analysis parameters obtained for the four cases discussed in the above. All the probabilities

Impact of Near-Field, Deep-Ocean Tsunami Observations on Forecasting the 7 December 2012 Japanese Tsunami

NASA Astrophysics Data System (ADS)

Bernard, Eddie; Wei, Yong; Tang, Liujuan; Titov, Vasily

2014-12-01

Following the devastating 11 March 2011 tsunami, two deep-ocean assessment and reporting of tsunamis (DART®)(DART® and the DART® logo are registered trademarks of the National Oceanic and Atmospheric Administration, used with permission) stations were deployed in Japanese waters by the Japanese Meteorological Agency. Two weeks after deployment, on 7 December 2012, a M w 7.3 earthquake off Japan's Pacific coastline generated a tsunami. The tsunami was recorded at the two Japanese DARTs as early as 11 min after the earthquake origin time, which set a record as the fastest tsunami detecting time at a DART station. These data, along with those recorded at other DARTs, were used to derive a tsunami source using the National Oceanic and Atmospheric Administration tsunami forecast system. The results of our analysis show that data provided by the two near-field Japanese DARTs can not only improve the forecast speed but also the forecast accuracy at the Japanese tide gauge stations. This study provides important guidelines for early detection and forecasting of local tsunamis.

Preliminary report on crustal deformation surveys and tsunami measurements due to the July 17, 2006 Java Earthquake and Tsunami, Indonesia

NASA Astrophysics Data System (ADS)

Kato, T.; Ito, T.; Abidin, H. Z.; Agustan, A.

2006-12-01

A large earthquake along a plate boundary occurred in the south of Java Island on July 17, 2006, whose magnitude was 7.7 (USGS) and caused significant tsunami. We made GPS observations and tsunami heights measurements during the period from July 24 to August 1, 2006. The earthquake seems to be due to an interplate low angle reverse faulting (e.g. Yagi, 2006). Yet, there would be a possibility of high angle faulting within the subducting lithosphere (e.g., Yamanaka, 2006). Crustal deformation distribution due to the earthquake, aided by tsunami heights measurements, might clarify which would be the case. We occupied 29 sites by GPS in the area of southern Java Island encompassing the area from 107.8E to 109.50E. These sites were occupied once before the earthquake so that co-seismic displacements might be seen. If we assume that the slip on the fault surface is as that estimated assuming magnitude to be 7.7, co- seismic displacements would be as small as a few centimeters or less. However, the tsunami heights measurements at 11 sites that were conducted along with the GPS observation were 6-7m along the southern coast of Java Islands and indicates that the observed heights are systematically higher than that estimated from numerical simulations (e.g., Koshimura, 2006). This might suggest that fault offsets have been larger nearly double - than that estimated using seismic analysis. If this is the case, the co-seismic crustal movements might be larger than above estimation. This might lead us to an idea that the rupture was very slow and did not radiate enough seismic energy to underestimate the earthquake magnitude. If this is the case, the earthquake might have been a "tsunami earthquake" that is similar to the one that occurred on June 2, 1994 in the east of the present earthquake.

The effect of compliant prisms on subduction zone earthquakes and tsunamis

NASA Astrophysics Data System (ADS)

Lotto, Gabriel C.; Dunham, Eric M.; Jeppson, Tamara N.; Tobin, Harold J.

2017-01-01

Earthquakes generate tsunamis by coseismically deforming the seafloor, and that deformation is largely controlled by the shallow rupture process. Therefore, in order to better understand how earthquakes generate tsunamis, one must consider the material structure and frictional properties of the shallowest part of the subduction zone, where ruptures often encounter compliant sedimentary prisms. Compliant prisms have been associated with enhanced shallow slip, seafloor deformation, and tsunami heights, particularly in the context of tsunami earthquakes. To rigorously quantify the role compliant prisms play in generating tsunamis, we perform a series of numerical simulations that directly couple dynamic rupture on a dipping thrust fault to the elastodynamic response of the Earth and the acoustic response of the ocean. Gravity is included in our simulations in the context of a linearized Eulerian description of the ocean, which allows us to model tsunami generation and propagation, including dispersion and related nonhydrostatic effects. Our simulations span a three-dimensional parameter space of prism size, prism compliance, and sub-prism friction - specifically, the rate-and-state parameter b - a that determines velocity-weakening or velocity-strengthening behavior. We find that compliant prisms generally slow rupture velocity and, for larger prisms, generate tsunamis more efficiently than subduction zones without prisms. In most but not all cases, larger, more compliant prisms cause greater amounts of shallow slip and larger tsunamis. Furthermore, shallow friction is also quite important in determining overall slip; increasing sub-prism b - a enhances slip everywhere along the fault. Counterintuitively, we find that in simulations with large prisms and velocity-strengthening friction at the base of the prism, increasing prism compliance reduces rather than enhances shallow slip and tsunami wave height.

Ionospheric Method of Detecting Tsunami-Generating Earthquakes.

ERIC Educational Resources Information Center

Najita, Kazutoshi; Yuen, Paul C.

1978-01-01

Reviews the earthquake phenomenon and its possible relation to ionospheric disturbances. Discusses the basic physical principles involved and the methods upon which instrumentation is being developed for possible use in a tsunami disaster warning system. (GA)

Real-time determination of the worst tsunami scenario based on Earthquake Early Warning

NASA Astrophysics Data System (ADS)

Furuya, Takashi; Koshimura, Shunichi; Hino, Ryota; Ohta, Yusaku; Inoue, Takuya

2016-04-01

In recent years, real-time tsunami inundation forecasting has been developed with the advances of dense seismic monitoring, GPS Earth observation, offshore tsunami observation networks, and high-performance computing infrastructure (Koshimura et al., 2014). Several uncertainties are involved in tsunami inundation modeling and it is believed that tsunami generation model is one of the great uncertain sources. Uncertain tsunami source model has risk to underestimate tsunami height, extent of inundation zone, and damage. Tsunami source inversion using observed seismic, geodetic and tsunami data is the most effective to avoid underestimation of tsunami, but needs to expect more time to acquire the observed data and this limitation makes difficult to terminate real-time tsunami inundation forecasting within sufficient time. Not waiting for the precise tsunami observation information, but from disaster management point of view, we aim to determine the worst tsunami source scenario, for the use of real-time tsunami inundation forecasting and mapping, using the seismic information of Earthquake Early Warning (EEW) that can be obtained immediately after the event triggered. After an earthquake occurs, JMA's EEW estimates magnitude and hypocenter. With the constraints of earthquake magnitude, hypocenter and scaling law, we determine possible multi tsunami source scenarios and start searching the worst one by the superposition of pre-computed tsunami Green's functions, i.e. time series of tsunami height at offshore points corresponding to 2-dimensional Gaussian unit source, e.g. Tsushima et al., 2014. Scenario analysis of our method consists of following 2 steps. (1) Searching the worst scenario range by calculating 90 scenarios with various strike and fault-position. From maximum tsunami height of 90 scenarios, we determine a narrower strike range which causes high tsunami height in the area of concern. (2) Calculating 900 scenarios that have different strike, dip, length

Tsunami waveform inversion of the 2007 Bengkulu, southern Sumatra, earthquake

NASA Astrophysics Data System (ADS)

Fujii, Y.; Satake, K.

2008-09-01

We performed tsunami waveform inversions for the Bengkulu, southern Sumatra, earthquake on September 12, 2007 (Mw 8.4 by USGS). The tsunami was recorded at many tide gauge stations around the Indian Ocean and by a DART system in the deep ocean. The observed tsunami records indicate that the amplitudes were less than several tens of centimeters at most stations, around 1 m at Padang, the nearest station to the source, and a few centimeters at the DART station. For the tsunami waveform inversions, we adopted 20-, 15- and 10-subfault models. The tsunami waveforms computed from the estimated slip distributions explain the observed waveforms at most stations, regardless of the subfault model. We found that large slips were consistently estimated at the deeper part (>24 km) of the fault plane, located more than 100 km from the trench axis. The largest slips of 6-9 m were located about 100-200 km northwest of the epicenter. The deep slips may have contributed to the relatively small tsunami for its earthquake size. The total seismic moment is calculated as 4.7 × 1021 N m (Mw = 8.4) for the 10-subfault model, our preferred model from a comparison of tsunami waveforms at Cocos and the DART station.

What caused a large number of fatalities in the Tohoku earthquake?

NASA Astrophysics Data System (ADS)

Ando, M.; Ishida, M.; Nishikawa, Y.; Mizuki, C.; Hayashi, Y.

2012-04-01

The Mw9.0 earthquake caused 20,000 deaths and missing persons in northeastern Japan. 115 years prior to this event, there were three historical tsunamis that struck the region, one of which is a "tsunami earthquake" resulted with a death toll of 22,000. Since then, numerous breakwaters were constructed along the entire northeastern coasts and tsunami evacuation drills were carried out and hazard maps were distributed to local residents on numerous communities. However, despite the constructions and preparedness efforts, the March 11 Tohoku earthquake caused numerous fatalities. The strong shaking lasted three minutes or longer, thus all residents recognized that this is the strongest and longest earthquake that they had been ever experienced in their lives. The tsunami inundated an enormous area at about 560km2 over 35 cities along the coast of northeast Japan. To find out the reasons behind the high number of fatalities due to the March 11 tsunami, we interviewed 150 tsunami survivors at public evacuation shelters in 7 cities mainly in Iwate prefecture in mid-April and early June 2011. Interviews were done for about 30min or longer focused on their evacuation behaviors and those that they had observed. On the basis of the interviews, we found that residents' decisions not to evacuate immediately were partly due to or influenced by earthquake science results. Below are some of the factors that affected residents' decisions. 1. Earthquake hazard assessments turned out to be incorrect. Expected earthquake magnitudes and resultant hazards in northeastern Japan assessed and publicized by the government were significantly smaller than the actual Tohoku earthquake. 2. Many residents did not receive accurate tsunami warnings. The first tsunami warning were too small compared with the actual tsunami heights. 3. The previous frequent warnings with overestimated tsunami height influenced the behavior of the residents. 4. Many local residents above 55 years old experienced

Implications of the 26 December 2004 Sumatra-Andaman earthquake on tsunami forecast and assessment models for great subduction-zone earthquakes

USGS Publications Warehouse

Geist, Eric L.; Titov, Vasily V.; Arcas, Diego; Pollitz, Fred F.; Bilek, Susan L.

2007-01-01

Results from different tsunami forecasting and hazard assessment models are compared with observed tsunami wave heights from the 26 December 2004 Indian Ocean tsunami. Forecast models are based on initial earthquake information and are used to estimate tsunami wave heights during propagation. An empirical forecast relationship based only on seismic moment provides a close estimate to the observed mean regional and maximum local tsunami runup heights for the 2004 Indian Ocean tsunami but underestimates mean regional tsunami heights at azimuths in line with the tsunami beaming pattern (e.g., Sri Lanka, Thailand). Standard forecast models developed from subfault discretization of earthquake rupture, in which deep- ocean sea level observations are used to constrain slip, are also tested. Forecast models of this type use tsunami time-series measurements at points in the deep ocean. As a proxy for the 2004 Indian Ocean tsunami, a transect of deep-ocean tsunami amplitudes recorded by satellite altimetry is used to constrain slip along four subfaults of the M >9 Sumatra–Andaman earthquake. This proxy model performs well in comparison to observed tsunami wave heights, travel times, and inundation patterns at Banda Aceh. Hypothetical tsunami hazard assessments models based on end- member estimates for average slip and rupture length (Mw 9.0–9.3) are compared with tsunami observations. Using average slip (low end member) and rupture length (high end member) (Mw 9.14) consistent with many seismic, geodetic, and tsunami inversions adequately estimates tsunami runup in most regions, except the extreme runup in the western Aceh province. The high slip that occurred in the southern part of the rupture zone linked to runup in this location is a larger fluctuation than expected from standard stochastic slip models. In addition, excess moment release (∼9%) deduced from geodetic studies in comparison to seismic moment estimates may generate additional tsunami energy, if the

Ionospheric total electron content seismo-perturbation after Japan's March 11, 2011, M=9.0 Tohoku earthquake under a geomagnetic storm; a nonlinear principal component analysis

NASA Astrophysics Data System (ADS)

Lin, Jyh-Woei

2012-10-01

Nonlinear principal component analysis (NLPCA) is implemented to analyze the spatial pattern of total electron content (TEC) anomalies 3 hours after Japan's Tohoku earthquake that occurred at 05:46:23 on 11 March, 2011 (UTC) ( M w =9). A geomagnetic storm was in progress at the time of the earthquake. NLPCA and TEC data processing were conducted on the global ionospheric map (GIM) for the time between 08:30 to 09:30 UTC, about 3 hours after this devastating earthquake and ensuing tsunami. Analysis results show stark earthquake-associated TEC anomalies that are widespread, and appear to have been induced by two acoustic gravity waves due to strong shaking (vertical acoustic wave) and the generation of the tsunami (horizontal Rayleigh mode gravity wave). The TEC anomalies roughly fit the initial mainshock and movement of the tsunami. Observation of the earthquake-associated TEC anomalies does not appear to be affected by a contemporaneous geomagnetic storm.

Geomorphic impacts of the 2011 tsunami on the lower reaches of the R. Natori, northeast Japan

NASA Astrophysics Data System (ADS)

Shimazu, H.

2012-04-01

The tsunami caused by "the 2011 off the Pacific coast of Tohoku Earthquake" attacked Japan's east coast and inundated a large extent of the lowlands. The strong flood flow went upstream in the lower reaches of the rivers. The lower reaches of the rivers in Japan usually have unprotected dry riverbeds separated by dykes from floodplains where people live. The tsunami went upstream not only in the channels but also in the dry riverbeds. There is 1 kilometers wide unprotected dry riverbed in the lower reaches of the R. Natori, northeast Japan and they were used for vegetable farmlands. This study aims to discuss the geomorphic impacts of the tsunami on the dry riverbed in the lower reaches of the R. Natori. Surface sediments, micro-landforms and damages to agricultural facilities such as small poly tunnels, plastic mulches and support posts were examined to reconstruct the geomorphic impacts. Fieldworks were carried out at the beginning of May, 50 days after the tsunami disaster, and the end of August. Height of the tsunami near the river mouth was estimated over 3 meters. The flood flow went upstream to the sites at an elevation of 4 meters, 9 kilometers from the river mouth in the channel and 6.5 kilometers in the dry riverbed. Because the tsunami deposits are light colored sand and silt containing salinity, they could be distinguished from brown cultivated soil easily. The geomorphic impacts on the dry riverbed changed longitudinally. In the lowest 2.5 kilometers reaches strong flood flow and ebb flow caused strong erosion. It accounted for thin tsunami deposits with seashells and beach gravels, eroded scar, and dunes of downstream direction in the dry riverbed. In the next 1.5 kilometers reaches agricultural facilities were washed away or fell over upstream direction. Although the flood flow was still devastating, strength of the ebb flow gradually weakened. In this reaches dominant sedimentation process caused the tsunami deposits over 10 centimeters thick. In

Interseismic Coupling-Based Earthquake and Tsunami Scenarios for the Nankai Trough

NASA Astrophysics Data System (ADS)

Baranes, H.; Woodruff, J. D.; Loveless, J. P.; Hyodo, M.

2018-04-01

Theoretical modeling and investigations of recent subduction zone earthquakes show that geodetic estimates of interseismic coupling and the spatial distribution of coseismic rupture are correlated. However, the utility of contemporary coupling in guiding construction of rupture scenarios has not been evaluated on the world's most hazardous faults. Here we demonstrate methods for scaling coupling to slip to create rupture models for southwestern Japan's Nankai Trough. Results show that coupling-based models produce distributions of ground surface deformation and tsunami inundation that are similar to historical and geologic records of the largest known Nankai earthquake in CE 1707 and to an independent, quasi-dynamic rupture model. Notably, these models and records all support focused subsidence around western Shikoku that makes the region particularly vulnerable to flooding. Results imply that contemporary coupling mirrors the slip distribution of a full-margin, 1707-type rupture, and Global Positioning System measurements of surface motion are connected with the trough's physical characteristics.

Tsunami Simulation Method Assimilating Ocean Bottom Pressure Data Near a Tsunami Source Region

NASA Astrophysics Data System (ADS)

Tanioka, Yuichiro

2018-02-01

A new method was developed to reproduce the tsunami height distribution in and around the source area, at a certain time, from a large number of ocean bottom pressure sensors, without information on an earthquake source. A dense cabled observation network called S-NET, which consists of 150 ocean bottom pressure sensors, was installed recently along a wide portion of the seafloor off Kanto, Tohoku, and Hokkaido in Japan. However, in the source area, the ocean bottom pressure sensors cannot observe directly an initial ocean surface displacement. Therefore, we developed the new method. The method was tested and functioned well for a synthetic tsunami from a simple rectangular fault with an ocean bottom pressure sensor network using 10 arc-min, or 20 km, intervals. For a test case that is more realistic, ocean bottom pressure sensors with 15 arc-min intervals along the north-south direction and sensors with 30 arc-min intervals along the east-west direction were used. In the test case, the method also functioned well enough to reproduce the tsunami height field in general. These results indicated that the method could be used for tsunami early warning by estimating the tsunami height field just after a great earthquake without the need for earthquake source information.

The SAFRR tsunami scenario: improving resilience for California

USGS Publications Warehouse

Ross, Stephanie L.; Jones, Lucile M.; Miller, Kevin H.; Porter, Keith A.; Wein, Anne; Wilson, Rick I.; Bahng, Bohyun; Barberopoulou, Aggeliki; Borrero, Jose C.; Brosnan, Deborah M.; Bwarie, John T.; Geist, Eric L.; Johnson, Laurie A.; Kirby, Stephen H.; Knight, William R.; Long, Kate; Lynett, Patrick; Mortensen, Carl E.; Nicolsky, Dmitry J.; Perry, Suzanne C.; Plumlee, Geoffrey S.; Real, Charles R.; Ryan, Kenneth; Suleimani, Elena; Thio, Hong Kie; Titov, Vasily V.; Whitmore, Paul M.; Wood, Nathan J.

2013-01-01

On March 11, 2011, the Tohoku earthquake and the resulting tsunami devastated Japan with a disaster of unfathomable proportions. Five thousand miles away, the waves from Tohoku caused $50 to 100 million in damages in California. Although this pales in comparison to the loss of lives and property in Japan, the U.S. Government must ask whether California, and the national economy, will someday face worse consequences from other distant-source tsunamis. Unfortunately, the answer is “yes.”

Peptic Ulcers in Fukushima Prefecture Related to the Great East Japan Earthquake, Tsunami and Nuclear Accident

PubMed Central

Hikichi, Takuto; Sato, Masaki; Watanabe, Ko; Nakamura, Jun; Kikuchi, Hitomi; Ejiri, Yutaka; Ishihata, Ryoichi; Irisawa, Atsushi; Takahashi, Yuta; Saito, Hironobu; Takagi, Tadayuki; Suzuki, Rei; Sugimoto, Mitsuru; Konno, Naoki; Waragai, Yuichi; Asama, Hiroyuki; Takasumi, Mika; Sato, Yuki; Ohira, Hiromasa; Obara, Katsutoshi

2017-01-01

Objective Due to the Great East Japan Earthquake, which occurred in March 2011, many residents of Fukushima Prefecture were affected by a radiation accident in addition to suffering loss or damage from the earthquake and the subsequent tsunami. The aim of this study was to evaluate the actual condition of patients with peptic ulcers related to the disaster. Methods Patients with peptic ulcers at six hospitals in three different regions of Fukushima Prefecture during the two months following the disaster and the corresponding period of the year before and the year after the disaster were enrolled in this study. Changes by period and region in the number of esophagogastroduodenoscopy (EGD) examinations and the number of peptic ulcer patients were evaluated as the primary endpoints. Changes in the frequencies of hemorrhagic ulcers were evaluated by period and by region as secondary endpoints. Results The numbers of EGDs and peptic ulcer cases compared to the previous year decreased in 2011 and then increased in 2012. However, the ratio of hemorrhagic ulcers to peptic ulcers was higher in 2011 (51.9%) than in 2010 (38.1%) and 2012 (31.1%), and the 2011 hemorrhagic ulcer ratio was the highest at 63.6% in the coastal area. Regarding bleeding cases during 2011, the rate at 1 month after the disaster (64.1%) was higher than the rate at 2 months after the disaster (40.5%) (p=0.033). Conclusion The number of patients with peptic ulcers did not increase immediately following the disaster in Fukushima Prefecture. However, the rate of bleeding patients increased soon after the disaster, especially in the coastal area. PMID:29269647

The Redwood Coast Tsunami Work Group: a unique organization promoting earthquake and tsunami resilience on California's North Coast

NASA Astrophysics Data System (ADS)

Dengler, L.; Henderson, C.; Larkin, D.; Nicolini, T.; Ozaki, V.

2012-12-01

The Northern California counties of Del Norte, Humboldt, and Mendocino account for over 30% of California's coastline and is one of the most seismically active areas of the contiguous 48 states. The region is at risk from earthquakes located on- and offshore and from tsunamis generated locally from faults associated with the Cascadia subduction zone (CSZ) and from distant sources elsewhere in the Pacific. In 1995 the California Geological Survey (CGS) published a scenario for a CSZ earthquake that included both strong ground shaking effects and a tsunami. As a result of the scenario, the Redwood Coast Tsunami Work Group (RCTWG), an organization of government agencies, tribes, service groups, academia and the private sector, was formed to coordinate and promote earthquake and tsunami hazard awareness and mitigation in the three-county region. The RCTWG and its member agencies projects include education/outreach products and programs, tsunami hazard mapping, signage and siren planning. Since 2008, RCTWG has worked with the California Emergency Management Agency (Cal EMA) in conducting tsunami warning communications tests on the North Coast. In 2007, RCTWG members helped develop and carry out the first tsunami training exercise at FEMA's Emergency Management Institute in Emmitsburg, MD. The RCTWG has facilitated numerous multi-agency, multi-discipline coordinated exercises, and RCTWG county tsunami response plans have been a model for other regions of the state and country. Eight North Coast communities have been recognized as TsunamiReady by the National Weather Service, including the first National Park the first State Park and only tribe in California to be so recognized. Over 500 tsunami hazard zone signs have been posted in the RCTWG region since 2008. Eight assessment surveys from 1993 to 2010 have tracked preparedness actions and personal awareness of earthquake and tsunami hazards in the county and additional surveys have tracked public awareness and tourist

Earthquake and Tsunami Disaster Mitigation in The Marmara Region and Disaster Education in Turkey Part2 Yoshiyuki KANEDA Nagoya University Japan Agency for Marine-Earth Science and Technology (JAMSTEC) Haluk OZENER Boğaziçi University, Earthquake Researches Institute (KOERI) and Members of SATREPS Japan-Turkey project

NASA Astrophysics Data System (ADS)

Kaneda, Y.; Ozener, H.

2015-12-01

The 1999 Izumit Earthquake as the destructive earthquake occurred near the Marmara Sea. The Marmara Sea should be focused on because of a seismic gap in the North Anatolian fault. Istanbul is located around the Marmara Sea, so, if next earthquake will occur near Istanbul, fatal damages will be generated. The Japan and Turkey can share our own experiences during past damaging earthquakes and we can prepare for future large earthquakes in cooperation with each other. In earthquakes in Tokyo area and Istanbul area as the destructive earthquakes near high population cities, there are common disaster researches and measures. For disaster mitigation, we are progressing multidisciplinary researches. Our goals of this SATREPS project are as follows, To develop disaster mitigation policy and strategies based on multidisciplinary research activities. To provide decision makers with newly found knowledge for its implementation to the current regulations. To organize disaster education programs in order to increase disaster awareness in Turkey. To contribute the evaluation of active fault studies in Japan. This project is composed of four research groups. The first group is Marmara Earthquake Source region observationally research group. This group has 4 sub-themes such as Seismicity, Geodesy, Electromagnetics and Trench analyses. The second group focuses on scenario researches of earthquake occurrence along the North Anatolia fault and precise tsunami simulation in the Marmara region. Aims of the third group are improvements and constructions of seismic characterizations and damage predictions based on observation researches and precise simulations. The fourth group is promoting disaster educations using research result visuals. In this SATREPS project, we will integrate these research results for disaster mitigation in Marmara region and .disaster education in Turkey. We will have a presentation of the updated results of this SATREPS project.

Assessing the Mental Health Impact of the 2011 Great Japan Earthquake, Tsunami, and Radiation Disaster on Elementary and Middle School Children in the Fukushima Prefecture of Japan

PubMed Central

2017-01-01

Background On March 11, 2011, a magnitude 9.0 earthquake occurred off of Japan’s Pacific coast, which was followed by huge tsunamis that destroyed many coastal cities in the area. Due to the earthquake and subsequent tsunami, malfunctions occurred at the Fukushima Daiichi (Fukushima I) nuclear power plant, resulting in the release of radioactive material in the region. While recent studies have investigated the effects of these events on the mental health of adults in the region, no studies have yet been performed investigating similar effects among children. Methods and Findings This study aims to fill that gap by: 1) assessing the mental health of elementary and middle school children living within the Fukushima prefecture of Japan, and 2) identifying risk and protective factors that are associated with the children’s mental health scores. These factors were quantified using an original demographics survey, the Strengths and Difficulties Questionnaire (SDQ), and the Impact of Event Scale–Revised (IES-R), the latter two of which have been previously validated in a Japanese setting. The surveys were distributed to approximately 3,650 elementary and middle school students during the months of February and March, 2012. The data suggests that those children who had been relocated to the city of Koriyama had significantly higher SDQ scores than those children who were native to Koriyama (p < .05) as well as a control group that lived outside of the Fukushima prefecture (p < .01). Using a multivariate regression, we also found that younger age and parental trauma were significantly correlated with higher SDQ scores (p < .001), while gender, displacement from one’s home, and exposure to violence were not. Conclusions These results suggest that, among children affected by natural disasters, younger children and those with parents suffering from trauma-related distress are particularly vulnerable to the onset of pediatric mental disturbances. PMID:28099497

USGS contributions to earthquake and tsunami monitoring in the Caribbean Region

NASA Astrophysics Data System (ADS)

McNamara, D.; Caribbean Project Team, U.; Partners, C.

2007-05-01

USGS Caribbean Project Team: Lind Gee, Gary Gyure, John Derr, Jack Odum, John McMillan, David Carver, Jim Allen, Susan Rhea, Don Anderson, Harley Benz Caribbean Partners: Christa von Hillebrandt-Andrade-PRSN, Juan Payero ISU-UASD,DR, Eduardo Camacho - UPAN, Panama, Lloyd Lynch - SRU,Gonzalo Cruz - UNAH,Honduras, Margaret Wiggins-Grandison - Jamaica, Judy Thomas - CERO Barbados, Sylvan McIntyre - NADMA Grenada, E. Bermingham - STRI. The magnitude-9 Sumatra-Andaman Islands earthquake of December 26, 2004, increased global awareness of the destructive hazard posed by earthquakes and tsunamis. In response to this tragedy, the US government undertook a collaborative project to improve earthquake and tsunami monitoring along a major portion of vulnerable coastal regions, in the Caribbean Sea, the Gulf of Mexico, and the Atlantic Ocean. Seismically active areas of the Caribbean Sea region pose a tsunami risk for Caribbean islands, coastal areas along the Gulf of Mexico, and the Atlantic seaboard of North America. Nearly 100 tsunamis have been reported for the Caribbean region in the past 500 years, including 14 tsunamis reported in Puerto Rico and the U.S. Virgin Islands. Partners in this project include the United States Geological Survey (USGS), the Smithsonian Institute, the National Oceanic and Aeronautic Administration (NOAA), and several partner institutions in the Caribbean region. This presentation focuses on the deployment of nine broadband seismic stations to monitor earthquake activity in the Caribbean region that are affiliated with the Global Seismograph Network (GSN). By the end of 2006, five stations were transmitting data to the USGS National Earthquake Information Service (NEIS), and regional partners through Puerto Rico seismograph network (PRSN) Earthworm systems. The following stations are currently operating: SDDR - Sabaneta Dam Dominican Republic, BBGH - Gun Hill Barbados, GRGR - Grenville, Grenada, BCIP - Barro Colorado, Panama, TGUH - Tegucigalpa

The great East Japan earthquake of March 11, 2011, from the vantage point of blood banking and transfusion medicine.

PubMed

Nollet, Kenneth E; Ohto, Hitoshi; Yasuda, Hiroyasu; Hasegawa, Arifumi

2013-01-01

The Great East Japan Earthquake of March 11, 2011, and subsequent tsunami took nearly 20 000 lives in Tohoku, the northeastern part of Japan's main island. Most victims were either carried away by the tsunami or drowned. The ability to collect blood was disrupted on the Pacific coast of Tohoku. Inland areas were less affected, but allogeneic blood collected in Tohoku is tested at the Miyagi Red Cross Blood Center (Miyagi Center) in the coastal city of Sendai. Miyagi Center was damaged and could not test for 2 months. The aims of this study are as follows: (1) to assess transfusion practice at 8 disaster response hospitals in Tohoku's Fukushima Prefecture, for equal intervals before and after March 11, 2011; (2) to report activities related to blood collection and distribution in response to the disaster; and (3) to describe the Great East Japan Earthquake in the context of other disasters. Data were collected through a survey of transfusion services at 8 major disaster response hospitals, communication at transfusion conferences, and literature review. Transfused patients and units transfused were about 70% and 60% of normal in the surveyed hospitals because this was a disaster of mass casualty rather than mass injury, and patients requiring chronic care were evacuated out. A nationally coordinated effort allowed excess blood collected outside Tohoku to be transported in, despite infrastructure damage. Japan's national system of blood collection and distribution responded effectively to local needs after the Great East Japan Earthquake. Disasters such as Japan's 3.11 should guide discourse about emergency preparedness and centralization of services. Copyright © 2013. Published by Elsevier Inc.

Towards an Earthquake and Tsunami Early Warning in the Caribbean

NASA Astrophysics Data System (ADS)

Huerfano Moreno, V. A.; Vanacore, E. A.

2017-12-01

The Caribbean region (CR) has a documented history of large damaging earthquakes and tsunamis that have affected coastal areas, including the events of Jamaica in 1692, Virgin Islands in 1867, Puerto Rico in 1918, the Dominican Republic in 1946 and Haiti in 2010. There is clear evidence that tsunamis have been triggered by large earthquakes that deformed the ocean floor around the Caribbean Plate boundary. The CR is monitored jointly by national/regional/local seismic, geodetic and sea level networks. All monitoring institutions are participating in the UNESCO ICG/Caribe EWS, the purpose of this initiative is to minimize loss of life and destruction of property, and to mitigate against catastrophic economic impacts via promoting local research, real time (RT) earthquake, geodetic and sea level data sharing and improving warning capabilities and enhancing education and outreach strategies. Currently more than, 100 broad-band seismic, 65 sea levels and 50 GPS high rate stations are available in real or near real-time. These real-time streams are used by Local/Regional or Worldwide detection and warning institutions to provide earthquake source parameters in a timely manner. Currently, any Caribbean event detected to have a magnitude greater than 4.5 is evaluated, and sea level is measured, by the TWC for tsumanigenic potential. The regional cooperation is motivated both by research interests as well as geodetic, seismic and tsunami hazard monitoring and warning. It will allow the imaging of the tectonic structure of the Caribbean region to a high resolution which will consequently permit further understanding of the seismic source properties for moderate and large events and the application of this knowledge to procedures of civil protection. To reach its goals, the virtual network has been designed following the highest technical standards: BB sensors, 24 bits A/D converters with 140 dB dynamic range, real-time telemetry. Here we will discuss the state of the PR

Source models of M-7 class earthquakes in the rupture area of the 2011 Tohoku-Oki Earthquake by near-field tsunami modeling

NASA Astrophysics Data System (ADS)

Kubota, T.; Hino, R.; Inazu, D.; Saito, T.; Iinuma, T.; Suzuki, S.; Ito, Y.; Ohta, Y.; Suzuki, K.

2012-12-01

We estimated source models of small amplitude tsunami associated with M-7 class earthquakes in the rupture area of the 2011 Tohoku-Oki Earthquake using near-field records of tsunami recorded by ocean bottom pressure gauges (OBPs). The largest (Mw=7.3) foreshock of the Tohoku-Oki earthquake, occurred on 9 Mar., two days before the mainshock. Tsunami associated with the foreshock was clearly recorded by seven OBPs, as well as coseismic vertical deformation of the seafloor. Assuming a planer fault along the plate boundary as a source, the OBP records were inverted for slip distribution. As a result, the most of the coseismic slip was found to be concentrated in the area of about 40 x 40 km in size and located to the north-west of the epicenter, suggesting downdip rupture propagation. Seismic moment of our tsunami waveform inversion is 1.4 x 10^20 Nm, equivalent to Mw 7.3. On 2011 July 10th, an earthquake of Mw 7.0 occurred near the hypocenter of the mainshock. Its relatively deep focus and strike-slip focal mechanism indicate that this earthquake was an intraslab earthquake. The earthquake was associated with small amplitude tsunami. By using the OBP records, we estimated a model of the initial sea-surface height distribution. Our tsunami inversion showed that a pair of uplift/subsiding eyeballs was required to explain the observed tsunami waveform. The spatial pattern of the seafloor deformation is consistent with the oblique strike-slip solution obtained by the seismic data analyses. The location and strike of the hinge line separating the uplift and subsidence zones correspond well to the linear distribution of the aftershock determined by using local OBS data (Obana et al., 2012).

Recent Progress of Seismic Observation Networks in Japan

NASA Astrophysics Data System (ADS)

Okada, Y.

2013-04-01

Before the occurrence of disastrous Kobe earthquake in 1995, the number of high sensitivity seismograph stations operated in Japan was nearly 550 and was concentrated in the Kanto and Tokai districts, central Japan. In the wake of the Kobe earthquake, Japanese government has newly established the Headquarters for Earthquake Research Promotion and started the reconstruction of seismic networks to evenly cover the whole Japan. The basic network is composed of three seismographs, i.e. high sensitivity seismograph (Hi-net), broadband seismograph (F-net), and strong motion seismograph (K-NET). A large majority of Hi-net stations are also equipped with a pair of strong motion sensors at the bottom of borehole and the ground surface (KiK-net). A plenty of high quality data obtained from these networks are circulated at once and is producing several new seismological findings as well as providing the basis for the Earthquake Early Warning system. In March 11, 2011, "Off the Pacific coast of Tohoku Earthquake" was generated with magnitude 9.0, which records the largest in the history of seismic observation in Japan. The greatest disaster on record was brought by huge tsunami with nearly 20 thousand killed or missing people. We are again noticed that seismic observation system is quite poor in the oceanic region compared to the richness of it in the inland region. In 2012, NIED has started the construction of ocean bottom seismic and tsunami observation network along the Japan Trench. It is planned to layout 154 stations with an average spacing of 30km, each of which is equipped with an accelerometer for seismic observation and a water pressure gauge for tsunami observation. We are expecting that more rapid and accurate warning of earthquake and tsunami becomes possible by this observing network.

Multi-segment earthquakes and tsunami potential of the Aleutian megathrust

USGS Publications Warehouse

Shennan, I.; Bruhn, R.; Plafker, G.

2009-01-01

Large to great earthquakes and related tsunamis generated on the Aleutian megathrust produce major hazards for both the area of rupture and heavily populated coastlines around much of the Pacific Ocean. Here we use paleoseismic records preserved in coastal sediments to investigate whether segment boundaries control the largest ruptures or whether in some seismic cycles segments combine to produce earthquakes greater than any observed since instrumented records began. Virtually the entire megathrust has ruptured since AD1900, with four different segments generating earthquakes >M8.0. The largest was the M9.2 great Alaska earthquake of March 1964 that ruptured ???800 km of the eastern segment of the megathrust. The tsunami generated caused fatalities in Alaska and along the coast as far south as California. East of the 1964 zone of deformation, the Yakutat microplate experienced two >M8.0 earthquakes, separated by a week, in September 1899. For the first time, we present evidence that earthquakes ???900 and ???1500 years ago simultaneously ruptured adjacent segments of the Aleutian megathrust and the Yakutat microplate, with a combined area ???15% greater than 1964, giving an earthquake of greater magnitude and increased tsunamigenic potential. ?? 2008 Elsevier Ltd. All rights reserved.

Far field tsunami simulations of the 1755 Lisbon earthquake: Implications for tsunami hazard to the U.S. East Coast and the Caribbean

USGS Publications Warehouse

Barkan, R.; ten Brink, Uri S.; Lin, J.

2009-01-01

The great Lisbon earthquake of November 1st, 1755 with an estimated moment magnitude of 8.5-9.0 was the most destructive earthquake in European history. The associated tsunami run-up was reported to have reached 5-15??m along the Portuguese and Moroccan coasts and the run-up was significant at the Azores and Madeira Island. Run-up reports from a trans-oceanic tsunami were documented in the Caribbean, Brazil and Newfoundland (Canada). No reports were documented along the U.S. East Coast. Many attempts have been made to characterize the 1755 Lisbon earthquake source using geophysical surveys and modeling the near-field earthquake intensity and tsunami effects. Studying far field effects, as presented in this paper, is advantageous in establishing constraints on source location and strike orientation because trans-oceanic tsunamis are less influenced by near source bathymetry and are unaffected by triggered submarine landslides at the source. Source location, fault orientation and bathymetry are the main elements governing transatlantic tsunami propagation to sites along the U.S. East Coast, much more than distance from the source and continental shelf width. Results of our far and near-field tsunami simulations based on relative amplitude comparison limit the earthquake source area to a region located south of the Gorringe Bank in the center of the Horseshoe Plain. This is in contrast with previously suggested sources such as Marqu??s de Pombal Fault, and Gulf of C??diz Fault, which are farther east of the Horseshoe Plain. The earthquake was likely to be a thrust event on a fault striking ~ 345?? and dipping to the ENE as opposed to the suggested earthquake source of the Gorringe Bank Fault, which trends NE-SW. Gorringe Bank, the Madeira-Tore Rise (MTR), and the Azores appear to have acted as topographic scatterers for tsunami energy, shielding most of the U.S. East Coast from the 1755 Lisbon tsunami. Additional simulations to assess tsunami hazard to the U.S. East

Solomon Islands 2007 Tsunami Near-Field Modeling and Source Earthquake Deformation

NASA Astrophysics Data System (ADS)

Uslu, B.; Wei, Y.; Fritz, H.; Titov, V.; Chamberlin, C.

2008-12-01

The earthquake of 1 April 2007 left behind momentous footages of crust rupture and tsunami impact along the coastline of Solomon Islands (Fritz and Kalligeris, 2008; Taylor et al., 2008; McAdoo et al., 2008; PARI, 2008), while the undisturbed tsunami signals were also recorded at nearby deep-ocean tsunameters and coastal tide stations. These multi-dimensional measurements provide valuable datasets to tackle the challenging aspects at the tsunami source directly by inversion from tsunameter records in real time (available in a time frame of minutes), and its relationship with the seismic source derived either from the seismometer records (available in a time frame of hours or days) or from the crust rupture measurements (available in a time frame of months or years). The tsunami measurements in the near field, including the complex vertical crust motion and tsunami runup, are particularly critical to help interpreting the tsunami source. This study develops high-resolution inundation models for the Solomon Islands to compute the near-field tsunami impact. Using these models, this research compares the tsunameter-derived tsunami source with the seismic-derived earthquake sources from comprehensive perceptions, including vertical uplift and subsidence, tsunami runup heights and their distributional pattern among the islands, deep-ocean tsunameter measurements, and near- and far-field tide gauge records. The present study stresses the significance of the tsunami magnitude, source location, bathymetry and topography in accurately modeling the generation, propagation and inundation of the tsunami waves. This study highlights the accuracy and efficiency of the tsunameter-derived tsunami source in modeling the near-field tsunami impact. As the high- resolution models developed in this study will become part of NOAA's tsunami forecast system, these results also suggest expanding the system for potential applications in tsunami hazard assessment, search and rescue operations

Revisiting the 1912 Murefet, Turkey earthquake and tsunami

NASA Astrophysics Data System (ADS)

Baptista, M.; Aksoy, M. M.; Ferreira, H.; Ucarkus, G.; Meghraoui, M.; Çakir, Z.

2012-12-01

The 9 August 1912 Mürefte Earthquake M 7.4 is one of the largest destructive earthquakes of the 20th century, in the Balkan region. The tremor struck at 03:30 a.m. and was felt in a wide region including Greece and Bulgaria. The damage was localized in the western part of the Sea of Marmara, between Tekirdag and Çanakkale with maximum intenstiy IX-X MSK near the Mürefte village. The damage killed 2800 and injured 7000 people. It totally destroyed 12600 houses, damaged 12100 beyond repair and caused serious damage to another 15,400. The earthquake occurred on the westernmost segment of the North Anatolian Fault (NAF), limited by the Marmara Sea and the Aegean Sea on both ends. The event was accompanied with major surface faulting and co-seismic slip all along the on land and offshore sections. Up to date several faulting scenarios were proposed for this event claiming surface ruptures ranging from 50- 150 km. The tsunami reports of this event are scarce Contemporary accounts reported several onshore and offshore natural events that can be related to a tsunami caused by submarine surface faulting. Receding of the sea and inundations were observed along the northern shores of the Sea of Marmara. Besides, most of the coastal area of the Strait of the Dardanelles (Çanakkale) experienced flooding. Strong sea waves hit the northern coasts of Hayirsiz Ada and at Yesilköy (near Istanbul) a rowing-boat has been lifted up to a height of 2.7 m. In this study we present a summary of the tsunami observations and perform tsunami numerical simulations using a nonlinear shallow water code (NSLW7) that uses an explicit leap-frog finite difference scheme to solve the non-linear shallow water equations and high resolution DEM (Digital Earth Model) including bathymetry and topography in order to compute inundation. The initial condition of the tsunami propagation model is the static vertical displacement of the ocean floor due to the submarine earthquake that is computed Mansinha

Impact of the Great East Japan Earthquake on Regional Obstetrical Care in Miyagi Prefecture.

PubMed

Sugawara, Junichi; Hoshiai, Tetsuro; Sato, Kazuyo; Tokunaga, Hideki; Nishigori, Hidekazu; Arai, Takanari; Okamura, Kunihiro; Yaegashi, Nobuo

2016-06-01

The authors report the results of surveys on the emergency transport or evacuation status of obstetric patients conducted in Miyagi prefecture, one of the major disaster areas of the Great East Japan Earthquake and tsunami. The surveys examined the damages to maternity institutions, evacuation status and transport of pregnant women, and prehospital childbirths and were conducted in 50 maternity institutions and 12 fire departments in Miyagi. Two coastal institutions were destroyed completely, and four institutions were destroyed partially by the tsunami, forcing them to stop medical services. In the two-month period after the disaster, 217 pregnant women received hospital transport or gave birth after evacuation. Satisfactory perinatal outcomes were maintained. Emergency obstetric transport increased to approximately 1.4 fold the number before the disaster. Twenty-three women had prehospital childbirths, indicating a marked increase to approximately three times the number of the previous year. In the acute phase of the tsunami disaster, maternity institutions were damaged severely and perinatal transport was not possible; as a result, pregnant women inevitably gave birth in unplanned institutions, and the number of prehospital births was increased extremely. To obtain satisfactory obstetric outcomes, it is necessary to construct a future disaster management system and to re-recognize pregnant women as people with special needs in disaster situations. Sugawara J , Hoshiai T , Sato K , Tokunaga H , Nishigori H , Arai T , Okamura K , Yaegashi N . Impact of the Great East Japan Earthquake on regional obstetrical care in Miyagi Prefecture. Prehosp Disaster Med. 2016;31(3):255- 258.

Discriminants and Detectors: Seismological Studies of Tsunami Earthquakes and Hurricane Microseisms

NASA Astrophysics Data System (ADS)

Ebeling, Carl W.

High energy natural hazards have potential to cause great damage and significant loss of life, but understanding of many lags behind what is required to mitigate their impacts. Of specific concern here are the estimation of tsunami hazard in the eastern Mediterranean; the more timely identification of tsunami earthquakes; and the use of microseisms to identify “missing” hurricanes, thus augmenting the traditional—but short, incomplete, and biased—observational hurricane record. Earthquake energy estimation and time- and frequency-domain time-series analyses applied to an array of historical analog and modern digital seismological data are used to address these problems. Improved estimations of the location, depth, moment magnitude, and focal mechanism of four of the largest Hellenic Arc earthquakes in the last century help to better understand seismic hazard there. Seismological reassessments combined with hydrodynamic simulations show that the tsunamis associated with two of them were not triggered by the earthquakes themselves but instead involved submarine slumping. Moments and estimates of radiated energy from 67 earthquakes taking place in the last twenty years in oceanic environments and recorded at regional and teleseismic distances are used to develop an empirical correction to the robust tsunami earthquake discriminant Theta. This extends its applicability to regional distances, thereby allowing earlier discrimination of tsunami earthquakes. Microseisms, which result from the interaction of ocean swell generated by energetic storms, are shown here to carry information about parent hurricanes and under favorable conditions can be used to detect them. Power variations of microseisms recorded at the Harvard, Massachusetts seismic station demonstrate that Saffir-Simpson category 5 hurricane Andrew (1992) can be identified when it is ˜2,000 km from the station and still at sea. Applied to an expanded data set of 66 hurricanes between 1992 and 2007 with

The Pacific tsunami warning system

USGS Publications Warehouse

Pararas-Carayannis, G.

1986-01-01

The impact of tsunamis on human societies can be traced back in written history to 480 BC, when the Minoan civilization in the Eastern Mediterranean was wiped out by great tsunami waves generated by the volcanic explosion of the island of Santorin. In the Pacific Ocean where the majority of these waves have been generated, the historical record, although brief, shows tremendous destruction. In Japan which has one of the most populated coastal regions in the world and a long history of earthquake activity, tsunamis have destroyed entire coastal communities. There is also history of tsunami destruction in Alaska, in Hawaiian Islands, and in South America. 

Multiple geophysical observations indicate possible splay fault activation during the 2006 Java Tsunami earthquake

NASA Astrophysics Data System (ADS)

Fan, W.; Bassett, D.; Denolle, M.; Shearer, P. M.; Ji, C.; Jiang, J.

2017-12-01

The 2006 Mw 7.8 Java earthquake was a tsunami earthquake, exhibiting frequency-dependent seismic radiation along strike. High-frequency global back-projection results suggest two distinct rupture stages. The first stage lasted 65 s with a rupture speed of 1.2 km/s, while the second stage lasted from 65 to 150 s with a rupture speed of 2.7 km/s. In addition, P-wave high-frequency radiated energy and fall-off rates indicate a rupture transition at 60 s. High-frequency radiators resolved with back-projection during the second stage spatially correlate with splay fault traces mapped from residual free-air gravity anomalies. These splay faults also collocate with a major tsunami source associated with the earthquake inferred from tsunami first-crest back-propagation simulation. These correlations suggest that the splay faults may have been reactivated during the Java earthquake, as has been proposed for other tsunamigenic earthquakes, such as the 1944 Mw 8.1 Tonankai earthquake in the Nankai Trough.

Near-field tsunami edge waves and complex earthquake rupture

USGS Publications Warehouse

Geist, Eric L.

2013-01-01

The effect of distributed coseismic slip on progressive, near-field edge waves is examined for continental shelf tsunamis. Detailed observations of edge waves are difficult to separate from the other tsunami phases that are observed on tide gauge records. In this study, analytic methods are used to compute tsunami edge waves distributed over a finite number of modes and for uniformly sloping bathymetry. Coseismic displacements from static elastic theory are introduced as initial conditions in calculating the evolution of progressive edge-waves. Both simple crack representations (constant stress drop) and stochastic slip models (heterogeneous stress drop) are tested on a fault with geometry similar to that of the M w = 8.8 2010 Chile earthquake. Crack-like ruptures that are beneath or that span the shoreline result in similar longshore patterns of maximum edge-wave amplitude. Ruptures located farther offshore result in reduced edge-wave excitation, consistent with previous studies. Introduction of stress-drop heterogeneity by way of stochastic slip models results in significantly more variability in longshore edge-wave patterns compared to crack-like ruptures for the same offshore source position. In some cases, regions of high slip that are spatially distinct will yield sub-events, in terms of tsunami generation. Constructive interference of both non-trapped and trapped waves can yield significantly larger tsunamis than those that produced by simple earthquake characterizations.

Large Historical Tsunamigenic Earthquakes in Italy: The Neglected Tsunami Research Point of View

NASA Astrophysics Data System (ADS)

Armigliato, A.; Tinti, S.; Pagnoni, G.; Zaniboni, F.

2015-12-01

It is known that tsunamis are rather rare events, especially when compared to earthquakes, and the Italian coasts are no exception. Nonetheless, a striking evidence is that 6 out of 10 earthquakes occurred in the last thousand years in Italy, and having equivalent moment magnitude equal or larger than 7 where accompanied by destructive or heavily damaging tsunamis. If we extend the lower limit of the equivalent moment magnitude down to 6.5 the percentage decreases (around 40%), but is still significant. Famous events like those occurred on 30 July 1627 in Gargano, on 11 January 1693 in eastern Sicily, and on 28 December 1908 in the Messina Straits are part of this list: they were all characterized by maximum run-ups of several meters (13 m for the 1908 tsunami), significant maximum inundation distances, and large (although not precisely quantifiable) numbers of victims. Further evidences provided in the last decade by paleo-tsunami deposit analyses help to better characterize the tsunami impact and confirm that none of the cited events can be reduced to local or secondary effects. Proper analysis and simulation of available tsunami data would then appear as an obvious part of the correct definition of the sources responsible for the largest Italian tsunamigenic earthquakes, in a process in which different datasets analyzed by different disciplines must be reconciled rather than put into contrast with each other. Unfortunately, macroseismic, seismic and geological/geomorphological observations and data typically are assigned much heavier weights, and in-land faults are often assigned larger credit than the offshore ones, even when evidence is provided by tsunami simulations that they are not at all capable of justifying the observed tsunami effects. Tsunami generation is imputed a-priori to only supposed, and sometimes even non-existing, submarine landslides. We try to summarize the tsunami research point of view on the largest Italian historical tsunamigenic

Preliminary report on crustal deformation surveys and tsunami measurements caused by the July 17, 2006 South off Java Island Earthquake and Tsunami, Indonesia

NASA Astrophysics Data System (ADS)

Kato, T.; Ito, T.; Abidin, H. Z.; Agustan

2007-09-01

A large earthquake (Mw=7.7) along a plate boundary occurred in the south of Java Island on July 17, 2006, and caused a significant tsunami. We made GPS observations and tsunami heights measurements during the period from July 24 to August 1, 2006. The earthquake seems to be due to an interplate low angle reverse faulting, though there might be a possibility of high angle faulting within the subducting lithosphere. Crustal deformation distribution due to the earthquake, aided by tsunami heights measurements, might clarify which would be the case. We occupied 29 sites by GPS in the area of southern Java encompassing the area from 107.8 E to 109.50 E. These sites were occupied once before the earthquake. However, we were not able to detect significant co-seismic displacements. The obtained displacements, most of which span several years, show ESE direction in ITRF2000 frame. This represents the direction of Sunda block motion. The tsunami heights measured at 11 sites were 6-7 m along the southern coast of Java and indicate that the observed heights are systematically higher than those estimated from numerical simulations that are based on seismic data analysis. This might suggest that fault offsets might have been larger - nearly double - than those estimated using seismic analysis. These results lead us to an idea that the rupture was very slow. If this is the case, the earthquake might have been a "tsunami earthquake" that is similar to the one that occurred on June 2, 1994 in the east of the present earthquake.

Slip distribution of the 1952 Tokachi-Oki earthquake (M 8.1) along the Kuril Trench deduced from tsunami waveform inversion

USGS Publications Warehouse

Hirata, K.; Geist, E.; Satake, K.; Tanioka, Y.; Yamaki, S.

2003-01-01

We inverted 13 tsunami waveforms recorded in Japan to estimate the slip distribution of the 1952 Tokachi-Oki earthquake (M 8.1), which occurred southeast off Hokkaido along the southern Kuril subduction zone. The previously estimated source area determined from tsunami travel times [Hatori, 1973] did not coincide with the observed aftershock distribution. Our results show that a large amount of slip occurred in the aftershock area east of Hatori's tsunami source area, suggesting that a portion of the interplate thrust near the trench was ruptured by the main shock. We also found more than 5 m of slip along the deeper part of the seismogenic interface, just below the central part of Hatori's tsunami source area. This region, which also has the largest stress drop during the main shock, had few aftershocks. Large tsunami heights on the eastern Hokkaido coast are better explained by the heterogeneous slip model than previous uniform-slip fault models. The total seismic moment is estimated to be 1.87 ?? 1021 N m, giving a moment magnitude of Mw = 8.1. The revised tsunami source area is estimated to be 25.2 ?? 103 km2, ???3 times larger than the previous tsunami source area. Out of four large earthquakes with M ??? 7 that subsequently occurred in and around the rupture area of the 1952 event, three were at the edges of regions with relatively small amount of slip. We also found that a subducted seamount near the edge of the rupture area possibly impeded slip along the plate interface.

Influence of Earthquake Parameters on Tsunami Wave Height and Inundation

NASA Astrophysics Data System (ADS)

Kulangara Madham Subrahmanian, D.; Sri Ganesh, J.; Venkata Ramana Murthy, M.; V, R. M.

2014-12-01

After Indian Ocean Tsunami (IOT) on 26th December, 2004, attempts are being made to assess the threat of tsunami originating from different sources for different parts of India. The Andaman - Sumatra trench is segmented by transcurrent faults and differences in the rate of subduction which is low in the north and increases southward. Therefore key board model with initial deformation calculated using different strike directions, slip rates, are used. This results in uncertainties in the earthquake parameters. This study is made to identify the location of origin of most destructive tsunami for Southeast coast of India and to infer the influence of the earthquake parameters in tsunami wave height travel time in deep ocean as well as in the shelf and inundation in the coast. Five tsunamigenic sources were considered in the Andaman - Sumatra trench taking into consideration the tectonic characters of the trench described by various authors and the modeling was carried out using TUNAMI N2 code. The model results were validated using the travel time and runup in the coastal areas and comparing the water elevation along Jason - 1's satellite track. The inundation results are compared from the field data. The assessment of the tsunami threat for the area south of Chennai city the metropolitan city of South India shows that a tsunami originating in Car Nicobar segment of the Andaman - Sumatra subduction zone can generate the most destructive tsunami. Sensitivity analysis in the modelling indicates that fault length influences the results significantly and the tsunami reaches early and with higher amplitude. Strike angle is also modifying the tsunami followed by amount of slip.

Seismogeodesy and Rapid Earthquake and Tsunami Source Assessment

NASA Astrophysics Data System (ADS)

Melgar Moctezuma, Diego

This dissertation presents an optimal combination algorithm for strong motion seismograms and regional high rate GPS recordings. This seismogeodetic solution produces estimates of ground motion that recover the whole seismic spectrum, from the permanent deformation to the Nyquist frequency of the accelerometer. This algorithm will be demonstrated and evaluated through outdoor shake table tests and recordings of large earthquakes, notably the 2010 Mw 7.2 El Mayor-Cucapah earthquake and the 2011 Mw 9.0 Tohoku-oki events. This dissertations will also show that strong motion velocity and displacement data obtained from the seismogeodetic solution can be instrumental to quickly determine basic parameters of the earthquake source. We will show how GPS and seismogeodetic data can produce rapid estimates of centroid moment tensors, static slip inversions, and most importantly, kinematic slip inversions. Throughout the dissertation special emphasis will be placed on how to compute these source models with minimal interaction from a network operator. Finally we will show that the incorporation of off-shore data such as ocean-bottom pressure and RTK-GPS buoys can better-constrain the shallow slip of large subduction events. We will demonstrate through numerical simulations of tsunami propagation that the earthquake sources derived from the seismogeodetic and ocean-based sensors is detailed enough to provide a timely and accurate assessment of expected tsunami intensity immediately following a large earthquake.

Bodrum-Kos (Turkey-Greece) Mw 6.6 earthquake and tsunami of 20 July 2017: a test for the Mediterranean tsunami warning system

NASA Astrophysics Data System (ADS)

Heidarzadeh, Mohammad; Necmioglu, Ocal; Ishibe, Takeo; Yalciner, Ahmet C.

2017-12-01

Various Tsunami Service Providers (TSPs) within the Mediterranean Basin supply tsunami warnings including CAT-INGV (Italy), KOERI-RETMC (Turkey), and NOA/HL-NTWC (Greece). The 20 July 2017 Bodrum-Kos (Turkey-Greece) earthquake (Mw 6.6) and tsunami provided an opportunity to assess the response from these TSPs. Although the Bodrum-Kos tsunami was moderate (e.g., runup of 1.9 m) with little damage to properties, it was the first noticeable tsunami in the Mediterranean Basin since the 21 May 2003 western Mediterranean tsunami. Tsunami waveform analysis revealed that the trough-to-crest height was 34.1 cm at the near-field tide gauge station of Bodrum (Turkey). Tsunami period band was 2-30 min with peak periods at 7-13 min. We proposed a source fault model for this tsunami with the length and width of 25 and 15 km and uniform slip of 0.4 m. Tsunami simulations using both nodal planes produced almost same results in terms of agreement between tsunami observations and simulations. Different TSPs provided tsunami warnings at 10 min (CAT-INGV), 19 min (KOERI-RETMC), and 18 min (NOA/HL-NTWC) after the earthquake origin time. Apart from CAT-INGV, whose initial Mw estimation differed 0.2 units with respect to the final value, the response from the other two TSPs came relatively late compared to the desired warning time of 10 min, given the difficulties for timely and accurate calculation of earthquake magnitude and tsunami impact assessment. It is argued that even if a warning time of 10 min was achieved, it might not have been sufficient for addressing near-field tsunami hazards. Despite considerable progress and achievements made within the upstream components of NEAMTWS (North East Atlantic, Mediterranean and Connected seas Tsunami Warning System), the experience from this moderate tsunami may highlight the need for improving operational capabilities of TSPs, but more importantly for effectively integrating civil protection authorities into NEAMTWS and strengthening

Speeding up tsunami wave propagation modeling

NASA Astrophysics Data System (ADS)

Lavrentyev, Mikhail; Romanenko, Alexey

2014-05-01

Trans-oceanic wave propagation is one of the most time/CPU consuming parts of the tsunami modeling process. The so-called Method Of Splitting Tsunami (MOST) software package, developed at PMEL NOAA USA (Pacific Marine Environmental Laboratory of the National Oceanic and Atmospheric Administration, USA), is widely used to evaluate the tsunami parameters. However, it takes time to simulate trans-ocean wave propagation, that is up to 5 hours CPU time to "drive" the wave from Chili (epicenter) to the coast of Japan (even using a rather coarse computational mesh). Accurate wave height prediction requires fine meshes which leads to dramatic increase in time for simulation. Computation time is among the critical parameter as it takes only about 20 minutes for tsunami wave to approach the coast of Japan after earthquake at Japan trench or Sagami trench (as it was after the Great East Japan Earthquake on March 11, 2011). MOST solves numerically the hyperbolic system for three unknown functions, namely velocity vector and wave height (shallow water approximation). The system could be split into two independent systems by orthogonal directions (splitting method). Each system can be treated independently. This calculation scheme is well suited for SIMD architecture and GPUs as well. We performed adaptation of MOST package to GPU. Several numerical tests showed 40x performance gain for NVIDIA Tesla C2050 GPU vs. single core of Intel i7 processor. Results of numerical experiments were compared with other available simulation data. Calculation results, obtained at GPU, differ from the reference ones by 10^-3 cm of the wave height simulating 24 hours wave propagation. This allows us to speak about possibility to develop real-time system for evaluating tsunami danger.

Unusual geologic evidence of coeval seismic shaking and tsunamis shows variability in earthquake size and recurrence in the area of the giant 1960 Chile earthquake

USGS Publications Warehouse

Cisternas, M.; Garrett, E; Wesson, Robert L.; Dura, T.; Ely, L. L

2017-01-01

An uncommon coastal sedimentary record combines evidence for seismic shaking and coincident tsunami inundation since AD 1000 in the region of the largest earthquake recorded instrumentally: the giant 1960 southern Chile earthquake (Mw 9.5). The record reveals significant variability in the size and recurrence of megathrust earthquakes and ensuing tsunamis along this part of the Nazca-South American plate boundary. A 500-m long coastal outcrop on Isla Chiloé, midway along the 1960 rupture, provides continuous exposure of soil horizons buried locally by debris-flow diamicts and extensively by tsunami sand sheets. The diamicts flattened plants that yield geologically precise ages to correlate with well-dated evidence elsewhere. The 1960 event was preceded by three earthquakes that probably resembled it in their effects, in AD 898 - 1128, 1300 - 1398 and 1575, and by five relatively smaller intervening earthquakes. Earthquakes and tsunamis recurred exceptionally often between AD 1300 and 1575. Their average recurrence interval of 85 years only slightly exceeds the time already elapsed since 1960. This inference is of serious concern because no earthquake has been anticipated in the region so soon after the 1960 event, and current plate locking suggests that some segments of the boundary are already capable of producing large earthquakes. This long-term earthquake and tsunami history of one of the world's most seismically active subduction zones provides an example of variable rupture mode, in which earthquake size and recurrence interval vary from one earthquake to the next.

Disturbance of Shallow Marine Soft-Bottom Environments and Megabenthos Assemblages by a Huge Tsunami Induced by the 2011 M9.0 Tohoku-Oki Earthquake

PubMed Central

Seike, Koji; Shirai, Kotaro; Kogure, Yukihisa

2013-01-01

Huge tsunami waves associated with megathrust earthquakes have a severe impact on shallow marine ecosystems. We investigated the impact of a tsunami generated by the 2011 M9.0 Tohoku-Oki earthquake on the seafloor and large benthic animals in muddy and sandy ria coasts (Otsuchi and Funakoshi bays) in northeastern Japan. We conducted underwater field surveys using scuba equipment in water depths of <20 m before the tsunami (September 2010) and after the tsunami (September 2011 and September 2012). During the study period, episodic changes in topography and grain-size composition occurred on the seafloor of the study area. Megabenthos sampling revealed a distinct pattern of distribution succession for each benthic species. For example, the protobranch bivalve Yoldia notabilis (Bivalvia: Nuculanidae) and the heterodont bivalve Felaniella usta (Bivalvia: Ungulinidae) disappeared after the tsunami event, whereas the distribution of the venus clam Gomphina melanaegis (Bivalvia: Veneridae) remained unchanged. In addition, the patterns of succession for a single species, such as the giant button top shell Umbonium costatum (Gastropoda: Trochidae) and the heart urchin Echinocardium cordatum (Echinoidea: Loveniidae), varied between the two bays studied. Our data also show that reestablishment of some benthic animal populations began within 18 months of the tsunami disturbance. PMID:23762365

Disturbance of shallow marine soft-bottom environments and megabenthos assemblages by a huge tsunami induced by the 2011 M9.0 Tohoku-Oki earthquake.

PubMed

Seike, Koji; Shirai, Kotaro; Kogure, Yukihisa

2013-01-01

Huge tsunami waves associated with megathrust earthquakes have a severe impact on shallow marine ecosystems. We investigated the impact of a tsunami generated by the 2011 M9.0 Tohoku-Oki earthquake on the seafloor and large benthic animals in muddy and sandy ria coasts (Otsuchi and Funakoshi bays) in northeastern Japan. We conducted underwater field surveys using scuba equipment in water depths of <20 m before the tsunami (September 2010) and after the tsunami (September 2011 and September 2012). During the study period, episodic changes in topography and grain-size composition occurred on the seafloor of the study area. Megabenthos sampling revealed a distinct pattern of distribution succession for each benthic species. For example, the protobranch bivalve Yoldia notabilis (Bivalvia: Nuculanidae) and the heterodont bivalve Felaniella usta (Bivalvia: Ungulinidae) disappeared after the tsunami event, whereas the distribution of the venus clam Gomphina melanaegis (Bivalvia: Veneridae) remained unchanged. In addition, the patterns of succession for a single species, such as the giant button top shell Umbonium costatum (Gastropoda: Trochidae) and the heart urchin Echinocardium cordatum (Echinoidea: Loveniidae), varied between the two bays studied. Our data also show that reestablishment of some benthic animal populations began within 18 months of the tsunami disturbance.

Slip reactivation model for the 2011 Mw9 Tohoku earthquake: Dynamic rupture, sea floor displacements and tsunami simulations.

NASA Astrophysics Data System (ADS)

Galvez, P.; Dalguer, L. A.; Rahnema, K.; Bader, M.

2014-12-01

The 2011 Mw9 Tohoku earthquake has been recorded with a vast GPS and seismic network given unprecedented chance to seismologists to unveil complex rupture processes in a mega-thrust event. In fact more than one thousand near field strong-motion stations across Japan (K-Net and Kik-Net) revealed complex ground motion patterns attributed to the source effects, allowing to capture detailed information of the rupture process. The seismic stations surrounding the Miyagi regions (MYGH013) show two clear distinct waveforms separated by 40 seconds. This observation is consistent with the kinematic source model obtained from the inversion of strong motion data performed by Lee's et al (2011). In this model two rupture fronts separated by 40 seconds emanate close to the hypocenter and propagate towards the trench. This feature is clearly observed by stacking the slip-rate snapshots on fault points aligned in the EW direction passing through the hypocenter (Gabriel et al, 2012), suggesting slip reactivation during the main event. A repeating slip on large earthquakes may occur due to frictional melting and thermal fluid pressurization effects. Kanamori & Heaton (2002) argued that during faulting of large earthquakes the temperature rises high enough creating melting and further reduction of friction coefficient. We created a 3D dynamic rupture model to reproduce this slip reactivation pattern using SPECFEM3D (Galvez et al, 2014) based on a slip-weakening friction with sudden two sequential stress drops . Our model starts like a M7-8 earthquake breaking dimly the trench, then after 40 seconds a second rupture emerges close to the trench producing additional slip capable to fully break the trench and transforming the earthquake into a megathrust event. The resulting sea floor displacements are in agreement with 1Hz GPS displacements (GEONET). The seismograms agree roughly with seismic records along the coast of Japan.The simulated sea floor displacement reaches 8-10 meters of

Computed inundation heights of the 2011 Tohoku tsunami compared to measured run-up data: hints for tsunami source inversion

NASA Astrophysics Data System (ADS)

Pagnoni, G.; Tinti, S.; Armigliato, A.

2012-04-01

The 11 March 2011 earthquake that took place off the Pacific coast of Tohoku, North Honshu, with Mw = 9.0, is the largest earthquake ever occurred in Japan, and generated a big tsunami that spread across the Pacific Ocean, causing devastating effects in the prefectures of Aomori, Iwate, Miyagi and Fukushima. It caused more than 15,000 casualties, swept away the low-land quarters of several villages and moreover was the primary cause of the severe nuclear accident in the Fukushima Nuclear Power Plant. There is a very large set of observations covering both the earthquake and the tsunami, and almost certainly this is the case with the most abundant dataset of high-quality data in the history of seismology and of tsunami science. Local and global seismic networks, continuous GPS networks, coastal tide gauges in Japan ports and across the Pacific, local buoys cabled deep ocean-bottom pressure gauges (OBPG) and deep-ocean buoys (such as DART) mainly along the foot of the margins of the pacific continents, all contributed essential data to constrain the source of the earthquake and of the tsunami. In this paper we will use also the observed run-up data to put further constraints on the source and to better determine the distribution of the slip on the offshore fault. This will be done through trial-and-error forward modeling, that is by comparing inundation data calculated by means of numerical tsunami simulations in the near field to tsunami run-up heights measured during field surveys conducted by several teams and made available on the net. Major attention will be devoted to reproduce observations in the prefectures that were more affected and where run-up heights are very large (namely Iwate and Miyagi). The simulations are performed by means of the finite-difference code UBO-TSUFD, developed and maintained by the Tsunami Research Team of the University of Bologna, Italy, that can solve both the linear and non-linear versions of the shallow-water equations on nested

Medical relief for the 2011 Japan earthquake: a nursing account.

PubMed

Mitani, Satoko; Kako, Mayumi; Mayner, Lidia

2014-03-01

In 2011 the east coast of Japan experienced a massive earthquake which triggered a devastating tsunami destroying many towns and killing over 15 000 people. The work presented in this paper is a personal account that outlines the relief efforts of the Humanitarian Medical Assistance team and describes the efforts to provide medical assistance to evacuees. The towns most affected had a large proportion of older people who were more likely to have chronic conditions and required medication to sustain their health. Since personal property was destroyed in the tsunami many older people were left without medication and also did not remember which type of medication they were taking. Some evacuees had brought a list of their medication with them, this assisted relief teams in obtaining the required medication for these people. The more successful evacuation centers had small numbers of evacuees who were given tasks to administer the center that kept them occupied and active. © 2013 Wiley Publishing Asia Pty Ltd.

Re-examination of Magnitude of the AD 869 Jogan Earthquake, a Possible Predecessor of the 2011 Tohoku Earthquake, from Tsunami Deposit Distribution and Computed Inundation Distances

NASA Astrophysics Data System (ADS)

Namegaya, Y.; Satake, K.

2012-12-01

We re-examined the magnitude of the AD 869 Jogan earthquake by comparing the inland limit of tsunami deposit and computed inundation distance for various fault models. The 869 tsunami deposit is distributed 3-4 km inland from the estimated past shorelines in Ishinomaki and Sendai plains (Shishikura et al., 2007, Annual Report on Active Fault and Paleoearthquake Researches; Sawai et al., 2007 ibid). In the previous studies (Satake et al., 2008 and Namegaya et al. 2010, ibid), we assumed 14 fault models of the Jogan earthquake including outer-rise normal fault, tsunami earthquake, interplate earthquakes, and an active fault in Sendai bay. The computed inundation area from an interplate earthquake with Mw of 8.4 (length: 200 km, width: 100 km, slip 7 m) covers the distribution of tsunami deposits in Ishinomaki and Sendai plains. However, the previous studies yielded the minimum magnitude, because we assumed that the inland limit of tsunami deposits and the computed inundation limit were the same. A post-2011 field survey indicate that the 2011 tsunami inundation distance was about 1.6 times the inland limit of tsunami deposits (e.g. Goto et al., 2011, Marine Geology). In this study, we computed tsunami inundation areas from interplate earthquake with different magnitude, fault length, and slip amount. The moment magnitude ranges from 8.0 to 8.7, the fault length ranges from 100 to 400 km, and the slip ranged from 3 to 9 m. The fault width is fixed at 100 km. The distance ratios of computed inundation to the inland limit of tsunami deposit (Inundation to Deposit Ratio or IDR) were calculated along 8 transects on Sendai and Ishinomaki plains. The results show that IDR increases with magnitude, up to Mw=8.4, when IDR becomes one, or the computed inundation is almost the same as the inland limit of tsunami deposit. IDR increases for a larger magnitude, but at a much smaller rate. This confirms that the magnitude of the 869 Jogan earthquake was at least 8.4, but it could

Far-field tsunami of 2017 Mw 8.1 Tehuantepec, Mexico earthquake recorded by Chilean tide gauge network: Implications for tsunami warning systems

NASA Astrophysics Data System (ADS)

González-Carrasco, J. F.; Benavente, R. F.; Zelaya, C.; Núñez, C.; Gonzalez, G.

2017-12-01

The 2017 Mw 8.1, Tehuantepec earthquake generated a moderated tsunami, which was registered in near-field tide gauges network activating a tsunami threat state for Mexico issued by PTWC. In the case of Chile, the forecast of tsunami waves indicate amplitudes less than 0.3 meters above the tide level, advising an informative state of threat, without activation of evacuation procedures. Nevertheless, during sea level monitoring of network we detect wave amplitudes (> 0.3 m) indicating a possible change of threat state. Finally, NTWS maintains informative level of threat based on mathematical filtering analysis of sea level records. After 2010 Mw 8.8, Maule earthquake, the Chilean National Tsunami Warning System (NTWS) has increased its observational capabilities to improve early response. Most important operational efforts have focused on strengthening tide gauge network for national area of responsibility. Furthermore, technological initiatives as Integrated Tsunami Prediction and Warning System (SIPAT) has segmented the area of responsibility in blocks to focus early warning and evacuation procedures on most affected coastal areas, while maintaining an informative state for distant areas of near-field earthquake. In the case of far-field events, NTWS follow the recommendations proposed by Pacific Tsunami Warning Center (PTWC), including a comprehensive monitoring of sea level records, such as tide gauges and DART (Deep-Ocean Assessment and Reporting of Tsunami) buoys, to evaluate the state of tsunami threat in the area of responsibility. The main objective of this work is to analyze the first-order physical processes involved in the far-field propagation and coastal impact of tsunami, including implications for decision-making of NTWS. To explore our main question, we construct a finite-fault model of the 2017, Mw 8.1 Tehuantepec earthquake. We employ the rupture model to simulate a transoceanic tsunami modeled by Neowave2D. We generate synthetic time series at

Non-linear resonant coupling of tsunami edge waves using stochastic earthquake source models

USGS Publications Warehouse

Geist, Eric L.

2016-01-01

Non-linear resonant coupling of edge waves can occur with tsunamis generated by large-magnitude subduction zone earthquakes. Earthquake rupture zones that straddle beneath the coastline of continental margins are particularly efficient at generating tsunami edge waves. Using a stochastic model for earthquake slip, it is shown that a wide range of edge-wave modes and wavenumbers can be excited, depending on the variability of slip. If two modes are present that satisfy resonance conditions, then a third mode can gradually increase in amplitude over time, even if the earthquake did not originally excite that edge-wave mode. These three edge waves form a resonant triad that can cause unexpected variations in tsunami amplitude long after the first arrival. An M ∼ 9, 1100 km-long continental subduction zone earthquake is considered as a test case. For the least-variable slip examined involving a Gaussian random variable, the dominant resonant triad includes a high-amplitude fundamental mode wave with wavenumber associated with the along-strike dimension of rupture. The two other waves that make up this triad include subharmonic waves, one of fundamental mode and the other of mode 2 or 3. For the most variable slip examined involving a Cauchy-distributed random variable, the dominant triads involve higher wavenumbers and modes because subevents, rather than the overall rupture dimension, control the excitation of edge waves. Calculation of the resonant period for energy transfer determines which cases resonant coupling may be instrumentally observed. For low-mode triads, the maximum transfer of energy occurs approximately 20–30 wave periods after the first arrival and thus may be observed prior to the tsunami coda being completely attenuated. Therefore, under certain circumstances the necessary ingredients for resonant coupling of tsunami edge waves exist, indicating that resonant triads may be observable and implicated in late, large-amplitude tsunami arrivals.

Field Investigations and a Tsunami Modeling for the 1766 Marmara Sea Earthquake, Turkey

NASA Astrophysics Data System (ADS)

Aykurt Vardar, H.; Altinok, Y.; Alpar, B.; Unlu, S.; Yalciner, A. C.

2016-12-01

Turkey is located on one of the world's most hazardous earthquake zones. The northern branch of the North Anatolian fault beneath the Sea of Marmara, where the population is most concentrated, is the most active fault branch at least since late Pliocene. The Sea of Marmara region has been affected by many large tsunamigenic earthquakes; the most destructive ones are 549, 553, 557, 740, 989, 1332, 1343, 1509, 1766, 1894, 1912 and 1999 events. In order to understand and determine the tsunami potential and their possible effects along the coasts of this inland sea, detailed documentary, geophysical and numerical modelling studies are needed on the past earthquakes and their associated tsunamis whose effects are presently unknown.On the northern coast of the Sea of Marmara region, the Kucukcekmece Lagoon has a high potential to trap and preserve tsunami deposits. Within the scope of this study, lithological content, composition and sources of organic matters in the lagoon's bottom sediments were studied along a 4.63 m-long piston core recovered from the SE margin of the lagoon. The sedimentary composition and possible sources of the organic matters along the core were analysed and their results were correlated with the historical events on the basis of dating results. Finally, a tsunami scenario was tested for May 22nd 1766 Marmara Sea Earthquake by using a widely used tsunami simulation model called NAMIDANCE. The results show that the candidate tsunami deposits at the depths of 180-200 cm below the lagoons bottom were related with the 1766 (May) earthquake. This work was supported by the Scientific Research Projects Coordination Unit of Istanbul University (Project 6384) and by the EU project TRANSFER for coring.

PROPOSAL FOR IMPROVEMENT OF BUINESS CONTINUITY PLAN (BCP) BASED ON THE LESSONS OF THE GREAT EAST JAPAN EARTHQUAKE

NASA Astrophysics Data System (ADS)

Maruya, Hiroaki

For most Japanese companies and organizations, the enormous damage of the Great East Japan Earthquake was more than expected. In addition to great tsunami and earthquake motion, the lack of electricity and fuel disturbed to business activities seriously, and they should be considered important constraint factors in future earthquakes. Furthermore, disruption of supply chains also led considerable decline of production in many industries across Japan and foreign countries. Therefore it becomes urgent need for Japanese government and industries to utilize the lessons of the Great Earthquake and execute effective countermeasures, considering great earthquakes such as Tonankai & Nankai earthquakes and Tokyo Inland Earthquakes. Obviously most basic step is improving earthquake-resistant ability of buildings and facilities. In addition the spread of BCP and BCM to enterprises and organizations is indispensable. Based on the lessons, the BCM should include the point of view of the supply chain management more clearly, and emphasize "substitute strategy" more explicitly because a company should survive even if it completely loses its present production base. The central and local governments are requested, in addition to develop their own BCP, to improve related systematic conditions for BCM of the private sectors.

Rupture evolution of the 2006 Java tsunami earthquake and the possible role of splay faults

NASA Astrophysics Data System (ADS)

Fan, Wenyuan; Bassett, Dan; Jiang, Junle; Shearer, Peter M.; Ji, Chen

2017-11-01

The 2006 Mw 7.8 Java earthquake was a tsunami earthquake, exhibiting frequency-dependent seismic radiation along strike. High-frequency global back-projection results suggest two distinct rupture stages. The first stage lasted ∼65 s with a rupture speed of ∼1.2 km/s, while the second stage lasted from ∼65 to 150 s with a rupture speed of ∼2.7 km/s. High-frequency radiators resolved with back-projection during the second stage spatially correlate with splay fault traces mapped from residual free-air gravity anomalies. These splay faults also colocate with a major tsunami source associated with the earthquake inferred from tsunami first-crest back-propagation simulation. These correlations suggest that the splay faults may have been reactivated during the Java earthquake, as has been proposed for other tsunamigenic earthquakes, such as the 1944 Mw 8.1 Tonankai earthquake in the Nankai Trough.

Impacts of the 2011 tsunami on the subtidal polychaete assemblage and the following recolonization in Onagawa Bay, northeastern Japan.

PubMed

Abe, Hirokazu; Kobayashi, Genki; Sato-Okoshi, Waka

2015-12-01

The ecological impacts of the 2011 Great East Japan Earthquake and tsunami and the following recolonization of the subtidal benthic polychaete community were examined by monthly pre- and post-quake field surveys that were conducted in Onagawa Bay from 2007 to 2013. Before the tsunami, the species composition in this benthic community was constant and was dominated by cirratulid and magelonid polychaetes. The density and biomass of benthic polychaetes drastically decreased after the tsunami, and the polychaete community fluctuated during the 2 years after the natural disaster. Spionid and capitellid polychaetes were dominant at this period. In June 2013, the community entered a new constant stage dominated by maldanids, which is different from the pre-quake community. Ecological impacts due to chemical pollution were suggested in addition to the tsunami disturbance. These overlapping effects and physical, chemical and biological factors affected the recovery and recolonization of the polychaete community after the natural disaster. Copyright © 2015 Elsevier Ltd. All rights reserved.

Development of a Probabilistic Tsunami Hazard Analysis in Japan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toshiaki Sakai; Tomoyoshi Takeda; Hiroshi Soraoka

2006-07-01

It is meaningful for tsunami assessment to evaluate phenomena beyond the design basis as well as seismic design. Because once we set the design basis tsunami height, we still have possibilities tsunami height may exceeds the determined design tsunami height due to uncertainties regarding the tsunami phenomena. Probabilistic tsunami risk assessment consists of estimating for tsunami hazard and fragility of structures and executing system analysis. In this report, we apply a method for probabilistic tsunami hazard analysis (PTHA). We introduce a logic tree approach to estimate tsunami hazard curves (relationships between tsunami height and probability of excess) and present anmore » example for Japan. Examples of tsunami hazard curves are illustrated, and uncertainty in the tsunami hazard is displayed by 5-, 16-, 50-, 84- and 95-percentile and mean hazard curves. The result of PTHA will be used for quantitative assessment of the tsunami risk for important facilities located on coastal area. Tsunami hazard curves are the reasonable input data for structures and system analysis. However the evaluation method for estimating fragility of structures and the procedure of system analysis is now being developed. (authors)« less

Structural control on the Tohoku earthquake rupture process investigated by 3D FEM, tsunami and geodetic data

PubMed Central

Romano, F.; Trasatti, E.; Lorito, S.; Piromallo, C.; Piatanesi, A.; Ito, Y.; Zhao, D.; Hirata, K.; Lanucara, P.; Cocco, M.

2014-01-01

The 2011 Tohoku earthquake (Mw = 9.1) highlighted previously unobserved features for megathrust events, such as the large slip in a relatively limited area and the shallow rupture propagation. We use a Finite Element Model (FEM), taking into account the 3D geometrical and structural complexities up to the trench zone, and perform a joint inversion of tsunami and geodetic data to retrieve the earthquake slip distribution. We obtain a close spatial correlation between the main deep slip patch and the local seismic velocity anomalies, and large shallow slip extending also to the North coherently with a seismically observed low-frequency radiation. These observations suggest that the friction controlled the rupture, initially confining the deeper rupture and then driving its propagation up to the trench, where it spreads laterally. These findings are relevant to earthquake and tsunami hazard assessment because they may help to detect regions likely prone to rupture along the megathrust, and to constrain the probability of high slip near the trench. Our estimate of ~40 m slip value around the JFAST (Japan Trench Fast Drilling Project) drilling zone contributes to constrain the dynamic shear stress and friction coefficient of the fault obtained by temperature measurements to ~0.68 MPa and ~0.10, respectively. PMID:25005351

Structural control on the Tohoku earthquake rupture process investigated by 3D FEM, tsunami and geodetic data.

PubMed

Romano, F; Trasatti, E; Lorito, S; Piromallo, C; Piatanesi, A; Ito, Y; Zhao, D; Hirata, K; Lanucara, P; Cocco, M

2014-07-09

The 2011 Tohoku earthquake (Mw = 9.1) highlighted previously unobserved features for megathrust events, such as the large slip in a relatively limited area and the shallow rupture propagation. We use a Finite Element Model (FEM), taking into account the 3D geometrical and structural complexities up to the trench zone, and perform a joint inversion of tsunami and geodetic data to retrieve the earthquake slip distribution. We obtain a close spatial correlation between the main deep slip patch and the local seismic velocity anomalies, and large shallow slip extending also to the North coherently with a seismically observed low-frequency radiation. These observations suggest that the friction controlled the rupture, initially confining the deeper rupture and then driving its propagation up to the trench, where it spreads laterally. These findings are relevant to earthquake and tsunami hazard assessment because they may help to detect regions likely prone to rupture along the megathrust, and to constrain the probability of high slip near the trench. Our estimate of ~40 m slip value around the JFAST (Japan Trench Fast Drilling Project) drilling zone contributes to constrain the dynamic shear stress and friction coefficient of the fault obtained by temperature measurements to ~0.68 MPa and ~0.10, respectively.

Comparing the Performance of Japan's Earthquake Hazard Maps to Uniform and Randomized Maps

NASA Astrophysics Data System (ADS)

Brooks, E. M.; Stein, S. A.; Spencer, B. D.

2015-12-01

The devastating 2011 magnitude 9.1 Tohoku earthquake and the resulting shaking and tsunami were much larger than anticipated in earthquake hazard maps. Because this and all other earthquakes that caused ten or more fatalities in Japan since 1979 occurred in places assigned a relatively low hazard, Geller (2011) argued that "all of Japan is at risk from earthquakes, and the present state of seismological science does not allow us to reliably differentiate the risk level in particular geographic areas," so a map showing uniform hazard would be preferable to the existing map. Defenders of the maps countered by arguing that these earthquakes are low-probability events allowed by the maps, which predict the levels of shaking that should expected with a certain probability over a given time. Although such maps are used worldwide in making costly policy decisions for earthquake-resistant construction, how well these maps actually perform is unknown. We explore this hotly-contested issue by comparing how well a 510-year-long record of earthquake shaking in Japan is described by the Japanese national hazard (JNH) maps, uniform maps, and randomized maps. Surprisingly, as measured by the metric implicit in the JNH maps, i.e. that during the chosen time interval the predicted ground motion should be exceeded only at a specific fraction of the sites, both uniform and randomized maps do better than the actual maps. However, using as a metric the squared misfit between maximum observed shaking and that predicted, the JNH maps do better than uniform or randomized maps. These results indicate that the JNH maps are not performing as well as expected, that what factors control map performance is complicated, and that learning more about how maps perform and why would be valuable in making more effective policy.

Land cover changes induced by the great east Japan earthquake in 2011

NASA Astrophysics Data System (ADS)

Ishihara, Mitsunori; Tadono, Takeo

2017-03-01

The east Japan earthquake that occurred on March 11, 2011 was a big natural disaster, comprising the large earthquake shock, tsunami, and Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. These disasters caused changes in the land use and land cover (LULC) in Japan’s Tohoku district. While the LULC map created before the disaster is available, as yet there is no precise LULC map of the district after the disaster. In this study, we created a precise LULC map for the years 2013-2015 post-disaster with 30-m spatial resolution using the Landsat-8 with the Operational Land Imager (OLI) to evaluate the changes in LULC induced by the disaster. Our results indicate many changes in areas categorized as rice paddies primarily into grass categories along the coast damaged by the tsunami and in the evacuation zone around the FDNPP. Since there is a possibility of future LULC changes according to the change of the evacuation zone and implementation of reconstruction and revitalization efforts, we recommend continual monitoring of the changes in LULC by the use of satellite data in order to evaluate the long-term effects of the disaster.

The 8 September 2017 Tsunami Triggered by the M w 8.2 Intraplate Earthquake, Chiapas, Mexico

NASA Astrophysics Data System (ADS)

Ramírez-Herrera, María Teresa; Corona, Néstor; Ruiz-Angulo, Angel; Melgar, Diego; Zavala-Hidalgo, Jorge

2018-01-01

The 8 September 2017, M w 8.2 earthquake offshore Chiapas, Mexico, is the largest earthquake in recorded history in Chiapas since 1902. It caused damage in the states of Oaxaca, Chiapas and Tabasco, including more than 100 fatalities, over 1.5 million people were affected, and 41,000 homes were damaged in the state of Chiapas alone. This earthquake, an intraplate event on a normal fault on the oceanic subducting plate, generated a tsunami recorded at several tide gauge stations in Mexico and on the Pacific Ocean. Here, we report the physical effects of the tsunami on the Chiapas coast and analyze the societal implications of this tsunami on the basis of our post-tsunami field survey. The associated tsunami waves were recorded first at Huatulco tide gauge station at 5:04 (GMT) 12 min after the earthquake. We covered ground observations along 41 km of the coast of Chiapas, encompassing the sites with the highest projected wave heights based on our preliminary tsunami model (maximum tsunami amplitudes between 94.5° and 93.0°W). Runup and inundation distances were measured along eight sites. The tsunami occurred at low tide. The maximum runup was 3 m at Boca del Cielo, and maximum inundation distance was 190 m in Puerto Arista, corresponding to the coast in front of the epicenter and in the central sector of the Gulf of Tehuantepec. Tsunami scour and erosion was evident along the Chiapas coast. Tsunami deposits, mainly sand, reached up to 32 cm thickness thinning landward up to 172 m distance.

Sedimentary Environment Changes between Tsunami Events in the Central Fukushima Prefecture, Japan

NASA Astrophysics Data System (ADS)

Kusumoto, S.; Goto, T.; Satake, K.; Sugai, T.; Yoneda, M.; Omori, T.; Ozaki, H.

2016-12-01

Many tsunami deposits were found in the Tohoku region, Japan from recent and past tsunamis. Study of tsunami deposits is particularly important in the central to southern Fukushima Prefecture, which is the southern limit of the distributions of tsunami deposits of the 869 Jogan, 1454 Kyotoku and 1611 Keicho-Sanriku earthquakes. Previous studies reported that there were at least five tsunami deposits (EV1-EV5) consisted of fine-middle sand and the sedimentary environment was inner-bay or lagoon for the past 2,600 years (Goto and Aoyama, 2005; JpGU, Oikawa et al., 2011; JpGU, Oota and Hoyanagi, 2014; GSJ, Kusumoto et al., 2016; JpGU). However, the sedimentary environment changes between or across historical tsunamis have not been examined. In this study, we try to estimate the sedimentary environment changes using Total Organic Carbon (TOC), Total Nitrogen (TN) concentrations and organic Carbon-to-Nitrogen (C/N) ratio. We took 13 geological core samples of length 2.0-2.5 m at 11 locations 0.6-2.7 km from the coast. The deposits consisted of silt and massive sand with graded beddings, laminas and rip-up clasts. For samples, we performed grain-size analysis, radiocarbon age measurement and CN elemental analysis. We found three interesting characteristics. First, grain size of ordinary deposits between EV4 and EV5 tend to fine upward slightly. It suggests that tidal current became gradually weak. Second, C/N ratio is about 5-10 at every depth, meaning that organic material source was phytoplankton or zooplankton (Müller, 1977; GCA). Finally, TOC and TN concentrations slowly increase between EV4 and EV5, and they rapidly decrease across EV3 and EV4. Their slow increases correspond to sedimentary environment change from anaerobic to aerobic, whereas rapid decreases correspond to sedimentary environment change from aerobic to anaerobic. These characteristics might indicate development of sand bar between tsunami events and sudden collapse of sand bar by historical

Analysis of the tsunami generated by the MW 7.8 1906 San Francisco earthquake

USGS Publications Warehouse

Geist, E.L.; Zoback, M.L.

1999-01-01

We examine possible sources of a small tsunami produced by the 1906 San Francisco earthquake, recorded at a single tide gauge station situated at the opening to San Francisco Bay. Coseismic vertical displacement fields were calculated using elastic dislocation theory for geodetically constrained horizontal slip along a variety of offshore fault geometries. Propagation of the ensuing tsunami was calculated using a shallow-water hydrodynamic model that takes into account the effects of bottom friction. The observed amplitude and negative pulse of the first arrival are shown to be inconsistent with small vertical displacements (~4-6 cm) arising from pure horizontal slip along a continuous right bend in the San Andreas fault offshore. The primary source region of the tsunami was most likely a recently recognized 3 km right step in the San Andreas fault that is also the probable epicentral region for the 1906 earthquake. Tsunami models that include the 3 km right step with pure horizontal slip match the arrival time of the tsunami, but underestimate the amplitude of the negative first-arrival pulse. Both the amplitude and time of the first arrival are adequately matched by using a rupture geometry similar to that defined for the 1995 MW (moment magnitude) 6.9 Kobe earthquake: i.e., fault segments dipping toward each other within the stepover region (83??dip, intersecting at 10 km depth) and a small component of slip in the dip direction (rake=-172??). Analysis of the tsunami provides confirming evidence that the 1906 San Francisco earthquake initiated at a right step in a right-lateral fault and propagated bilaterally, suggesting a rupture initiation mechanism similar to that for the 1995 Kobe earthquake.

Proceedings of the 11th United States-Japan natural resources panel for earthquake research, Napa Valley, California, November 16–18, 2016

USGS Publications Warehouse

Detweiler, Shane; Pollitz, Fred

2017-10-18

The UJNR Panel on Earthquake Research promotes advanced research toward a more fundamental understanding of the earthquake process and hazard estimation. The Eleventh Joint meeting was extremely beneficial in furthering cooperation and deepening understanding of problems common to both Japan and the United States.The meeting included productive exchanges of information on approaches to systematic observation and modeling of earthquake processes. Regarding the earthquake and tsunami of March 2011 off the Pacific coast of Tohoku and the 2016 Kumamoto earthquake sequence, the Panel recognizes that further efforts are necessary to achieve our common goal of reducing earthquake risk through close collaboration and focused discussions at the 12th UJNR meeting.

Development of pulmonary alveolar proteinosis following exposure to dust after the Great East Japan Earthquake.

PubMed

Hisata, Shu; Moriyama, Hiroshi; Tazawa, Ryushi; Ohkouchi, Shinya; Ichinose, Masakazu; Ebina, Masahito

2013-12-01

We report a unique case of pulmonary alveolar proteinosis that developed 3 weeks after the Great East Japan Earthquake and the subsequent tsunami. The patient had inhaled dust repeatedly while visiting her devastated neighborhood without wearing a protective mask. Five weeks after the earthquake, lung samples taken from the patient showed foreign particle deposition; however, her serum was negative for GM-CSF autoantibody. The patient's clinical symptoms resolved following whole lung lavage. We conclude that inhalation of fine dust particles after natural disasters may cause the onset of pulmonary alveolar proteinosis. Copyright © 2013 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.

Large Historical Earthquakes and Tsunami Hazards in the Western Mediterranean: Source Characteristics and Modelling

NASA Astrophysics Data System (ADS)

Harbi, Assia; Meghraoui, Mustapha; Belabbes, Samir; Maouche, Said

2010-05-01

The western Mediterranean region was the site of numerous large earthquakes in the past. Most of these earthquakes are located at the East-West trending Africa-Eurasia plate boundary and along the coastline of North Africa. The most recent recorded tsunamigenic earthquake occurred in 2003 at Zemmouri-Boumerdes (Mw 6.8) and generated ~ 2-m-high tsunami wave. The destructive wave affected the Balearic Islands and Almeria in southern Spain and Carloforte in southern Sardinia (Italy). The earthquake provided a unique opportunity to gather instrumental records of seismic waves and tide gauges in the western Mediterranean. A database that includes a historical catalogue of main events, seismic sources and related fault parameters was prepared in order to assess the tsunami hazard of this region. In addition to the analysis of the 2003 records, we study the 1790 Oran and 1856 Jijel historical tsunamigenic earthquakes (Io = IX and X, respectively) that provide detailed observations on the heights and extension of past tsunamis and damage in coastal zones. We performed the modelling of wave propagation using NAMI-DANCE code and tested different fault sources from synthetic tide gauges. We observe that the characteristics of seismic sources control the size and directivity of tsunami wave propagation on both northern and southern coasts of the western Mediterranean.

The 1945 Balochistan earthquake and probabilistic tsunami hazard assessment for the Makran subduction zone

NASA Astrophysics Data System (ADS)

Höchner, Andreas; Babeyko, Andrey; Zamora, Natalia

2014-05-01

Iran and Pakistan are countries quite frequently affected by destructive earthquakes. For instance, the magnitude 6.6 Bam earthquake in 2003 in Iran with about 30'000 casualties, or the magnitude 7.6 Kashmir earthquake 2005 in Pakistan with about 80'000 casualties. Both events took place inland, but in terms of magnitude, even significantly larger events can be expected to happen offshore, at the Makran subduction zone. This small subduction zone is seismically rather quiescent, but a tsunami caused by a thrust event in 1945 (Balochistan earthquake) led to about 4000 casualties. Nowadays, the coastal regions are more densely populated and vulnerable to similar events. Additionally, some recent publications raise the question of the possiblity of rare but huge magnitude 9 events at the Makran subduction zone. We first model the historic Balochistan event and its effect in terms of coastal wave heights, and then generate various synthetic earthquake and tsunami catalogs including the possibility of large events in order to asses the tsunami hazard at the affected coastal regions. Finally, we show how an effective tsunami early warning could be achieved by the use of an array of high-precision real-time GNSS (Global Navigation Satellite System) receivers along the coast.

Scenario-Based Tsunami Hazard Assessment from Earthquake and Landslide Sources for Eastern Sicily, Italy

NASA Astrophysics Data System (ADS)

Tinti, S.; Armigliato, A.; Pagnoni, G.; Paparo, M. A.; Zaniboni, F.

2016-12-01

Eastern Sicily was theatre of the most damaging tsunamis that ever struck Italy, such as the 11 January 1693 and the 28 December 1908 tsunamis. Tectonic studies and paleotsunami investigations extended historical records of tsunami occurrence back of several thousands of years. Tsunami sources relevant for eastern Sicily are both local and remote, the latter being located in the Ionian Greece and in the Western Hellenic Arc. Here in 365 A.D. a large earthquake generated a tsunami that was seen in the whole eastern and central Mediterranean including the Sicilian coasts. The objective of this study is the evaluation of tsunami hazard along the coast of eastern Sicily, central Mediterranean, Italy via a scenario-based technique, which has been preferred to the PTHA approach because, when dealing with tsunamis induced by landslides, uncertainties are usually so large to undermine the PTHA results. Tsunamis of earthquake and landslide origin are taken into account for the entire coast of Sicily, from the Messina to the Siracusa provinces. Landslides are essentially local sources and can occur underwater along the unstable flanks of the Messina Straits or along the steep slopes of the Hyblaean-Malta escarpment. The method is based on a two-step procedure. After a preliminary step where very many earthquake and landslide sources are taken into account and tsunamis are computed on a low-resolution grid, the worst-case scenarios are selected and tsunamis are simulated on a finer-resolution grid allowing for a better calculation of coastal wave height and tsunami penetration. The final result of our study is given in the form of aggregate fields computed from individual scenarios. Also interesting is the contribution of the various tsunami sources in different localities along the coast. It is found that the places with the highest level of hazard are the low lands of La Playa south of Catania and of the Bay of Augusta, which is in agreement also with historical

Tsunami runup and tide-gauge observations from the 14 November 2016 M7.8 Kaikōura earthquake, New Zealand

NASA Astrophysics Data System (ADS)

Power, William; Clark, Kate; King, Darren N.; Borrero, Jose; Howarth, Jamie; Lane, Emily M.; Goring, Derek; Goff, James; Chagué-Goff, Catherine; Williams, James; Reid, Catherine; Whittaker, Colin; Mueller, Christof; Williams, Shaun; Hughes, Matthew W.; Hoyle, Jo; Bind, Jochen; Strong, Delia; Litchfield, Nicola; Benson, Adrian

2017-07-01

The 2016 M w 7.8 Kaikōura earthquake was one of the largest earthquakes in New Zealand's historical record, and it generated the most significant local source tsunami to affect New Zealand since 1947. There are many unusual features of this earthquake from a tsunami perspective: the epicentre was well inland of the coast, multiple faults were involved in the rupture, and the greatest tsunami damage to residential property was far from the source. In this paper, we summarise the tectonic setting and the historical and geological evidence for past tsunamis on this coast, then present tsunami tide gauge and runup field observations of the tsunami that followed the Kaikōura earthquake. For the size of the tsunami, as inferred from the measured heights, the impact of this event was relatively modest, and we discuss the reasons for this which include: the state of the tide at the time of the earthquake, the degree of co-seismic uplift, and the nature of the coastal environment in the tsunami source region.

Deposition by the 2011 Tohoku-oki tsunami on coastal lowland controlled by beach ridges near Sendai, Japan

NASA Astrophysics Data System (ADS)

Takashimizu, Yasuhiro; Urabe, Atsushi; Suzuki, Koji; Sato, Yoshiki

2012-12-01

A study of the 2011 Tohoku-oki tsunami deposits on the coastal lowland of the Sendai Plain, Japan was carried out along a shore-perpendicular survey line in the Arahama area. Field descriptions and tsunami water depth measurements were complemented by sedimentary analyses, including grain size, grain fabric and diatom analysis. The tsunami deposits show a generally fining-inland trend along the 3.4 km long transect. The depositional facies, grain size analysis and grain fabric data suggest that most of the tsunami deposits were laid down during the tsunami inflow, except at one site. These tsunami deposits are characterized by parallel-laminated or massive sand and silt with pieces of woods, fragments of glass, rip-up mud clasts and an erosional base. Minor backwash deposits overlying the inflow sand layer were only observed on one beach ridge and attributed to the topographic high. Marine diatom species comprised only approximately 2% of the diatom assemblage in tsunami deposits and their content decreased landward. In this study, diatom assemblages were similar in the rice field soil and tsunami layers, suggesting that the muddy fraction of the deposits mainly consists of sediments derived from the tsunami-eroded rice field soil. As a result of soil erosion, the tsunami had a high suspended sediment load. Furthermore, after the first tsunami inundation, seawater left by the tsunami did not drain completely to the sea because of the high coastal beach ridge and/or coastal subsidence due to the massive earthquake. Therefore, strong tsunami outflows to the sea did not occur and these areas were covered by mud deposited from stagnant water.

Comparison of Tsunami Deposits Surveyed in 2010 and 2015 From the 2010 Maule Earthquake and Tsunami in South-Central Chile.

NASA Astrophysics Data System (ADS)

Ruiz, A. C.; MacInnes, B. T.; Ely, L. L.; Cisternas, M. A.; Gelfenbaum, G. R.; Richmond, B. M.; Meneses, D. J.

2015-12-01

The February 27, 2010 Mw 8.8 Maule earthquake and tsunami that struck south-central Chile altered the coastal landscape, leaving a depositional record at many locations along the coast. Our research is questioning whether tsunami deposits originally described during post-tsunami surveys in La Trinchera, Constitución and Coliumo soon after the event change significantly over time. The deposits initially described in 2010 were revisited 5 years later to determine if taphonomic changes occurred and to assess the long-term preservation potential of deposits with different initial characteristics and settings. We recently made measurements of deposit thickness, grain size, grading, sedimentary structures, incipient soil development and accumulation of organic material. Results indicate that deposit thickness and the maximum inland extent of recognizable deposits had decreased slightly since 2010, while overlying soil development and accumulation of organic matter increased. Few deposits had been altered by bioturbation. We will use the inland extent of the deposits surveyed in 2015 to model a minimum size of the 2010 earthquake and tsunami in GeoClaw. The results will be compared with independent geophysical models of the rupture characteristics. This can be used as a case study that can be applied to earlier paleo-earthquake and tsunami events in which seismic data is sparse or non-existent and the most reliable record is the inundation distance as determined by tsunami deposits. Studying the change of deposits in the geologic record over time can provide key insights into how tsunami deposits are preserved, which is important when working with paleo-deposits that may have been altered since deposition.

Possible Dual Earthquake-Landslide Source of the 13 November 2016 Kaikoura, New Zealand Tsunami

NASA Astrophysics Data System (ADS)

Heidarzadeh, Mohammad; Satake, Kenji

2017-10-01

A complicated earthquake ( M w 7.8) in terms of rupture mechanism occurred in the NE coast of South Island, New Zealand, on 13 November 2016 (UTC) in a complex tectonic setting comprising a transition strike-slip zone between two subduction zones. The earthquake generated a moderate tsunami with zero-to-crest amplitude of 257 cm at the near-field tide gauge station of Kaikoura. Spectral analysis of the tsunami observations showed dual peaks at 3.6-5.7 and 5.7-56 min, which we attribute to the potential landslide and earthquake sources of the tsunami, respectively. Tsunami simulations showed that a source model with slip on an offshore plate-interface fault reproduces the near-field tsunami observation in terms of amplitude, but fails in terms of tsunami period. On the other hand, a source model without offshore slip fails to reproduce the first peak, but the later phases are reproduced well in terms of both amplitude and period. It can be inferred that an offshore source is necessary to be involved, but it needs to be smaller in size than the plate interface slip, which most likely points to a confined submarine landslide source, consistent with the dual-peak tsunami spectrum. We estimated the dimension of the potential submarine landslide at 8-10 km.

Ironic Effects of the Destructive Tsunami on Public Risk Judgment

NASA Astrophysics Data System (ADS)

Oki, S.; Nakayachi, K.

2011-12-01

The 2011 Tohoku earthquake caused more than 20,000 casualties, with most of the dead and missing in an enormous tsunami. Survivors had simply evacuated to higher ground within approximately 30 minutes of its arrival. This reflects the importance of public perception of tsunami risks represented by its heights. Our question is how the devastating tsunami affected people in the western Japan where a great earthquake is anticipated in near future. Existing risk analysis researches show that the experience of natural disasters increases risk perception, even with indirect experiences such as seeing photographs of disaster scenes or thinking about a major natural calamity. No doubt, we can assume that the devastating tsunami would have led people to have a greater sense of associated risks. Our result, however, shows that the destructive tsunami of Tohoku earthquake lowered the risk assessment of tsunami heights. One possible explanation to this paradoxical result is the anchoring heuristic. It defines that laypersons are highly inclined to judge based on the numbers first presented to them. Media's repeating report of record-breaking tsunamis of 30 m or more anchored people to elevate the height to evacuate. The results of our survey pose a significant problem for disaster prevention. The survey area is at high risk of giant earthquake, and according to our results, more than 50% of the people surveyed no longer sensed the danger of a 1-m-high tsunami, whereas about 70% had perceived its peril before the Tohoku earthquake. This is also of great importance in Indonesia or Chile where huge earthquakes had occurred recently. We scientists need to face up to the fact that improvement of quick calculation of tsunami heights is not sufficient at all to mitigate the tsunami disasters, but reorient how we should inform laypersons to evacuate at the emergency situation.

Tsunamis: stochastic models of occurrence and generation mechanisms

USGS Publications Warehouse

Geist, Eric L.; Oglesby, David D.

2014-01-01

The devastating consequences of the 2004 Indian Ocean and 2011 Japan tsunamis have led to increased research into many different aspects of the tsunami phenomenon. In this entry, we review research related to the observed complexity and uncertainty associated with tsunami generation, propagation, and occurrence described and analyzed using a variety of stochastic methods. In each case, seismogenic tsunamis are primarily considered. Stochastic models are developed from the physical theories that govern tsunami evolution combined with empirical models fitted to seismic and tsunami observations, as well as tsunami catalogs. These stochastic methods are key to providing probabilistic forecasts and hazard assessments for tsunamis. The stochastic methods described here are similar to those described for earthquakes (Vere-Jones 2013) and volcanoes (Bebbington 2013) in this encyclopedia.

Association between relocation and changes in cardiometabolic risk factors: a longitudinal study in tsunami survivors of the 2011 Great East Japan Earthquake.

PubMed

Takahashi, Shuko; Nakamura, Motoyuki; Yonekura, Yuki; Tanno, Kozo; Sakata, Kiyomi; Ogawa, Akira; Kobayashi, Seiichiro

2016-05-12

The aim of this study is to determine changes in atherosclerotic cardiovascular risk factors with and without serious disaster-related mental and socioeconomic problems represented by relocation (REL). A longitudinal survey. Multiphasic health check-ups for the general population affected by the 2011 Great East Japan Earthquake and Tsunami. A total 6528 disaster survivors in heavily tsunami-damaged municipalities were recruited. Two sequential surveys were conducted and the data were analysed. Multiphasic health check-ups including investigation of lifestyle and psychological and socioeconomic measures were performed in two sequential phases (8 and 18 months) after the disaster for tsunami survivors with REL (n=3160) and without REL (n=3368). Longitudinal changes in cardiometabolic risk factors between the two phases were compared in the REL and non-REL groups. In sex/age-adjusted analysis, we found increases in body weight and waist circumference between the two phases that were significantly greater in the REL group than in the non-REL group (body weight:+0.31 (0.23∼0.39) versus -0.24 (-0.32∼-0.16) kg, p<0.001; waist circumference:+0.58 (0.48∼0.68) versus+0.05 (-0.05∼0.15) cm, p<0.001)). A decrease in serum HDLC levels was found and again was significantly greater in the REL group than in the non-REL group (-0.65 (-0.96∼-0.34) versus -0.09 (-0.39∼0.21) mg/dL, p=0.009). In addition, deterioration in physical activity, mental health and socioeconomic status was more prevalent in the REL group than in the non-REL group (all p<0.001). This study suggests that relocation after the devastating tsunami was related to weight gain and decreasing HDLC among survivors, and this change was associated with prolonged psychological distress and socioeconomic problems after the disaster. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Recent improvements in earthquake and tsunami monitoring in the Caribbean

NASA Astrophysics Data System (ADS)

Gee, L.; Green, D.; McNamara, D.; Whitmore, P.; Weaver, J.; Huang, P.; Benz, H.

2007-12-01

Following the catastrophic loss of life from the December 26, 2004, Sumatra-Andaman Islands earthquake and tsunami, the U.S. Government appropriated funds to improve monitoring along a major portion of vulnerable coastal regions in the Caribbean Sea, the Gulf of Mexico, and the Atlantic Ocean. Partners in this project include the United States Geological Survey (USGS), the National Oceanic and Atmospheric Administration (NOAA), the Puerto Rico Seismic Network (PRSN), the Seismic Research Unit of the University of the West Indies, and other collaborating institutions in the Caribbean region. As part of this effort, the USGS is coordinating with Caribbean host nations to design and deploy nine new broadband and strong-motion seismic stations. The instrumentation consists of an STS-2 seismometer, an Episensor accelerometer, and a Q330 high resolution digitizer. Six stations are currently transmitting data to the USGS National Earthquake Information Center, where the data are redistributed to the NOAA's Tsunami Warning Centers, regional monitoring partners, and the IRIS Data Management Center. Operating stations include: Isla Barro Colorado, Panama; Gun Hill Barbados; Grenville, Grenada; Guantanamo Bay, Cuba; Sabaneta Dam, Dominican Republic; and Tegucigalpa, Honduras. Three additional stations in Barbuda, Grand Turks, and Jamaica will be completed during the fall of 2007. These nine stations are affiliates of the Global Seismographic Network (GSN) and complement existing GSN stations as well as regional stations. The new seismic stations improve azimuthal coverage, increase network density, and provide on-scale recording throughout the region. Complementary to this network, NOAA has placed Deep-ocean Assessment and Reporting of Tsunami (DART) stations at sites in regions with a history of generating destructive tsunamis. Recently, NOAA completed deployment of 7 DART stations off the coasts of Montauk Pt, NY; Charleston, SC; Miami, FL; San Juan, Puerto Rico; New

Very shallow source of the October 2010 Mentawai tsunami earthquake from tsunami field data and high-rate GPS

NASA Astrophysics Data System (ADS)

Hill, E. M.; Qiu, Q.; Borrero, J. C.; Huang, Z.; Banerjee, P.; Elosegui, P.; Fritz, H. M.; Macpherson, K. A.; Li, L.; Sieh, K. E.

2011-12-01

"Tsunami earthquakes," which produce very large tsunamis compared to those expected from their magnitude, have long puzzled geoscientists, in part because only a handful have occurred within the time of modern instrumentation. The Mw 7.8 Mentawai earthquake of 25 October 2010, which occurred seaward of the southern Mentawai islands of Sumatra, was such an event. This earthquake triggered a very large tsunami, causing substantial damage and 509 casualties. Detailed field surveys we conducted immediately after the earthquake reveal maximum runup in excess of 16 m. The Sumatra GPS Array (SuGAr) recorded beautiful 1-sec data for this event at sites on the nearby islands, making this the first tsunami earthquake to be recorded by a dense, high-rate, and proximal GPS network, and giving us a unique opportunity to study these rare events from a new perspective. We estimate a maximum horizontal coseismic GPS displacement of 22 cm, at a site ~50 km from the epicenter. Vertical displacements show subsidence of the islands, but are on the order of only a few cm. Comparison of coseismic offsets from 1-sec and 24-hr GPS solutions indicates that rapid afterslip following the earthquake amounts to ~30% of the displacement estimated by the 24-hr solutions. The coseismic displacements are smaller than expected, and an unconstrained inversion of the GPS displacements indicates maximum fault slip of ~90 cm. Slip of this magnitude will produce maximum seafloor uplift of <15 cm, which is clearly not enough to produce tsunami runup of 16 m. However, investigation of the model resolution from GPS indicates that we are limited in our ability to resolve slip very close to the trench. We therefore deduce that to obtain the adequate level of slip and seafloor uplift to trigger the tsunami, the rupture must have occurred outside the resolution of the GPS network, i.e., at very shallow depths close to the trench. We therefore place prior slip constraints on the GPS inversion, based on

Suicide risk among young children after the Great East Japan Earthquake: A follow-up study.

PubMed

Fujiwara, Takeo; Yagi, Junko; Homma, Hiroaki; Mashiko, Hirobumi; Nagao, Keizo; Okuyama, Makiko

2017-07-01

On 11 March 2011, the Great East Japan Earthquake and subsequent tsunami hit East Japan. We aim to investigate the impact of trauma experiences related to the earthquake on suicide risk among young children, stratified by child sex. Participants at baseline were children who were exposed to the 2011 disaster at preschool age (affected area, n=198; unaffected area, n=82, total n=280). From July 2013 to May 2014, suicide risk was assessed using the Mini International Neuropsychiatric Interview for Children and Adolescents (MINI-KID) in a follow-up interview conducted by a child psychiatrist or psychologist (N=210, follow-up rate: 75%). Among young girls in the affected area, 12 out of 65 (18.5%) showed suicidal ideation, which is significantly higher than girls in the unaffected area (4.7%, p for chi-square=0.036). In the multivariate model adjusted for potential confounders and mediators, the odds ratio for 4 or more trauma experiences related to the earthquake was 5.74 (95% confidence interval: 0.83-39.6, p=0.076) compared to no trauma experience related to the earthquake. Among young boys, trauma exposure was not associated with suicidal ideation. Our findings showed that young girls who experienced earthquake-related trauma at preschool age had a higher suicidal ideation 3 years after the earthquake. Copyright © 2017. Published by Elsevier B.V.

7th U.S. / Japan Natural Resources (UJNR) Panel on Earthquake Research: Abstract Volume and Technical Program

USGS Publications Warehouse

Detweiler, Shane T.; Ellsworth, William L.

2008-01-01

The U.S. / Japan Natural Resources (UJNR) Panel on Earthquake Research promotes advanced study toward a more fundamental understanding of the earthquake process and hazard estimation. The Panel promotes basic and applied research to improve our understanding of the causes and effects of earthquakes and to facilitate the transmission of research results to those who implement hazard reduction measures on both sides of the Pacific and around the world. Meetings are held every other year, and alternate between countries with short presentation on current research and local field trips being the highlights. The 5th Joint Panel meeting was held at Asilomar, California in October, 2004. The technical sessions featured reports on the September 28, 2004 Parkfield, California earthquake, progress on earthquake early warning and rapid post-event assessment technology, probabilistic earthquake forecasting and the newly discovered phenomenon of nonvolcanic tremor. The Panel visited the epicentral region of the M 6.0 Parkfield earthquake and viewed the surface ruptures along the San Andreas Fault. They also visited the San Andreas Fault Observatory at Depth (SAFOD), which had just completed the first phase of drilling into the fault. The 6th Joint Panel meeting was held in Tokushima, Japan in November, 2006. The meeting included very productive exchanges of information on approaches to systematic observation of earthquake processes. Sixty eight technical papers were presented during the meeting on a wide range of subjects, including interplate earthquakes in subduction zones, slow slip and nonvolcanic tremor, crustal deformation, recent earthquake activity and hazard mapping. Through our discussion, we reaffirmed the benefits of working together to achieve our common goal of reducing earthquake hazard, continued cooperation on issues involving densification of observation networks and the open exchange of data among scientific communities. We also reaffirmed the importance of

Tsunami Defense Efforts at Samcheok Port, Korea

NASA Astrophysics Data System (ADS)

Cho, Y. S.

2016-02-01

Tsunamis mainly triggered by impulsive undersea motions are long waves and can propagate a long distance. Thus, they can cause huge casualties not only neighboring countries but also distant countries. Recently, several devastating tsunamis have been occurred around the Pacific Ocean rim. Among them, the Great East Japan tsunami occurred on March 11, 2011 is probably recorded as one of the most destructive tsunamis during last several decades. The Tsunami killed more than 20,000 people (including missing people) and deprived of property damage of approximately 300 billion USD. The eastern coast of the Korean Peninsula has been attacked historically by unexpected tsunami events. These tsunamis were generated by undersea earthquakes occurred off the west coast of Japan. For example, the Central East Sea Tsunami occurred on May 26, 1983 killed 3 people and caused serious property damage at Samcheok Port located at the eastern coast of Korea. Thus, a defense plan against unexpected tsunami strikes is an essential task for the port authority to protect lives of human beings and port facilities. In this study, a master plan of tsunami defense is introduced at Samcheok Port. A tsunami hazard map is also made by employing both propagation and inundation models. Detailed defense efforts are described including the procedure of development of a tsunami hazard map. Keywords: tsunami, hazard map, run-up height, emergency action plan

Residential relocation and change in social capital: A natural experiment from the 2011 Great East Japan Earthquake and Tsunami.

PubMed

Hikichi, Hiroyuki; Sawada, Yasuyuki; Tsuboya, Toru; Aida, Jun; Kondo, Katsunori; Koyama, Shihoko; Kawachi, Ichiro

2017-07-01

Social connections in the community ("social capital") represent an important source of resilience in the aftermath of major disasters. However, little is known about how residential relocation due to housing destruction affects survivors' social capital. We examined changes in social capital among survivors of the 2011 Great East Japan Earthquake and Tsunami. People who lost their homes were resettled to new locations by two primary means: (i) group relocation to public temporary trailer housing or (ii) individual relocation, in which victims moved into government-provided housing by lottery or arranged for their own accommodation (market rental housing or private purchase/new construction). The baseline for our natural experiment was established 7 months before the 11 March 2011 disaster, when we conducted a survey of older community-dwelling adults who lived 80-km west of the earthquake epicenter. Approximately 2.5 years after the disaster, the follow-up survey gathered information about personal experiences of disaster as well as health status and social capital. Among 3421 people in our study, 79 people moved via group relocation to public temporary trailer housing, whereas 96 people moved on their own. The individual fixed-effects model showed that group relocation was associated with improved informal socializing and social participation (β coefficient = 0.053, 95% confidence interval: 0.011 to 0.095). In contrast, individual relocation was associated with declining informal socializing and social participation (β coefficient = -0.039, 95% confidence interval: -0.074 to -0.003). Group relocation, as compared to individual relocation, appeared to preserve social participation and informal socializing in the community.

Preliminary Report Summarizes Tsunami Impacts and Lessons Learned from the September 7, 2017, M8.1 Tehuantepec Earthquake

NASA Astrophysics Data System (ADS)

Wilson, R. I.; Ramirez-Herrera, M. T.; Dengler, L. A.; Miller, K.; LaDuke, Y.

2017-12-01

The preliminary tsunami impacts from the September 7, 2017, M8.1 Tehuantepec Earthquake have been summarized in the following report: https://www.eeri.org/wp-content/uploads/EERI-Recon-Rpt-090717-Mexico-tsunami_fn.pdf. Although the tsunami impacts were not as significant as those from the earthquake itself (98 fatalities and 41,000 homes damaged), the following are highlights and lessons learned: The Tehuantepec earthquake was one of the largest down-slab normal faulting events ever recorded. This situation complicated the tsunami forecast since forecast methods and pre-event modeling are primarily associated with megathrust earthquakes where the most significant tsunamis are generated. Adding non-megathrust source modeling to the tsunami forecast databases of conventional warning systems should be considered. Offshore seismic and tsunami hazard analyses using past events should incorporate the potential for large earthquakes occurring along sources other than the megathrust boundary. From an engineering perspective, initial reports indicate there was only minor tsunami damage along the Mexico coast. There was damage to Marina Chiapas where floating docks overtopped their piles. Increasing pile heights could reduce the potential for damage to floating docks. Tsunami warning notifications did not get to the public in time to assist with evacuation. Streamlining the messaging in Mexico from the warning system directly to the public should be considered. And, for local events, preparedness efforts should place emphasis on responding to feeling the earthquake and not waiting to be notified. Although the U.S. tsunami warning centers were timely with their international and domestic messaging, there were some issues with how those messages were presented and interpreted. The use of a "Tsunami Threat" banner on the new main warning center website created confusion with emergency managers in the U.S. where no tsunami threat was expected to exist. Also, some U.S. states and

First application of tsunami back-projection and source inversion for the 2012 Haida Gwaii earthquake using tsunami data recorded on a dense array of seafloor pressure gauges

NASA Astrophysics Data System (ADS)

Gusman, A. R.; Satake, K.; Sheehan, A. F.; Mulia, I. E.; Heidarzadeh, M.; Maeda, T.

2015-12-01

Adaption of absolute or differential pressure gauges (APG or DPG) to Ocean Bottom Seismometers has provided the opportunity to study tsunamis. Recently we extracted tsunami waveforms of the 28 October 2012 Haida Gwaii earthquake recoded by the APG and DPG of Cascadia Initiative program (Sheehan et al., 2015, SRL). We applied such dense tsunami observations (48 stations) together with other records from DARTs (9 stations) to characterize the tsunami source. This study is the first study that used such a large number of offshore tsunami records for earthquake source study. Conventionally the curves of tsunami travel times are drawn backward from station locations to estimate the tsunami source region. Here we propose a more advanced technique called tsunami back-projection to estimate the source region. Our image produced by tsunami back-projection has the largest value or tsunami centroid that is very close to the epicenter and above the Queen Charlotte transform fault (QCF), whereas the negative values are mostly located east of Haida Gwaii in the Hecate Strait. By using tsunami back-projection we avoid picking initial tsunami phase which is a necessary step in the conventional method that is rather subjective. The slip distribution of the 2012 Haida Gwaii earthquake estimated by tsunami waveform inversion shows large slip near the trench (4-5 m) and also on a plate interface southeast the epicenter (3-4 m) below QCF. From the slip distribution, the calculated seismic moment is 5.4 × 1020 N m (Mw 7.8). The steep bathymetry offshore Haida Gwaii and the horizontal movement caused by the earthquake possibly affects the sea surface deformation. The potential tsunami energy calculated from the sea-surface deformation of pure faulting is 2.20 × 1013 J, while that from the bathymetry effect is 0.12 × 1013 J or about 5% of the total potential energy. The significant deformation above the steep slope is confirmed by another tsunami inversion that disregards fault

Preliminary analysis of the earthquake (MW 8.1) and tsunami of April 1, 2007, in the Solomon Islands, southwestern Pacific Ocean

USGS Publications Warehouse

Fisher, Michael A.; Geist, Eric L.; Sliter, Ray; Wong, Florence L.; Reiss, Carol; Mann, Dennis M.

2007-01-01

On April 1, 2007, a destructive earthquake (Mw 8.1) and tsunami struck the central Solomon Islands arc in the southwestern Pacific Ocean. The earthquake had a thrust-fault focal mechanism and occurred at shallow depth (between 15 km and 25 km) beneath the island arc. The combined effects of the earthquake and tsunami caused dozens of fatalities and thousands remain without shelter. We present a preliminary analysis of the Mw-8.1 earthquake and resulting tsunami. Multichannel seismic-reflection data collected during 1984 show the geologic structure of the arc's frontal prism within the earthquake's rupture zone. Modeling tsunami-wave propagation indicates that some of the islands are so close to the earthquake epicenter that they were hard hit by tsunami waves as soon as 5 min. after shaking began, allowing people scant time to react.

Tsunami Scenarios Based on Interseismic Models Along the Nankai Trough, Japan, From Seafloor and Onshore Geodesy

NASA Astrophysics Data System (ADS)

Watanabe, Shun-ichi; Bock, Yehuda; Melgar, Diego; Tadokoro, Keiichi

2018-03-01

The recent availability of Global Positioning System-Acoustic seafloor geodetic observations enables us to resolve the spatial distribution of the slip deficit rate near the Nankai trough, southwestern Japan. Considering a tectonic block model and the transient deformation due to the major earthquakes in this area, the slip deficit rate between the two relevant blocks can be estimated. In this study, we remove the time-dependent postseismic deformation of the 2004 southeastern off the Kii Peninsula earthquakes (MJMA 7.1, 7.4), which had led to the underestimation of the slip deficit rate in earlier studies. We model the postearthquake viscoelastic relaxation using the 3D finite element model with bi-viscous Burgers rheology, as well as the afterslip on the finite faults. The corrected Global Positioning System-Acoustic and land-based Global Navigation Satellite Systems data are aligned to the existing tectonic model and used to estimate the slip deficit rate on the plate boundary. We then calculate the coseismic displacements and tsunami wave propagation with the simple assumption that a hundred years of constant slip deficit accumulation was released instantaneously. To evaluate the influence of uncertainties in the plate interface geometry on a tsunami model for the Nankai trough, we investigated two different geometries and performed checkerboard inversion simulations. Although the two models indicate roughly similar results, the peak height of the tsunami wave and its arrival time at several points are significantly different in terms of the expected hazard.

The AD 365 earthquake: high resolution tsunami inundation for Crete and full scale simulation exercise

NASA Astrophysics Data System (ADS)

Kalligeris, N.; Flouri, E.; Okal, E.; Synolakis, C.

2012-04-01

In the eastern Mediterranean, historical and archaeological records document major earthquake and tsunami events in the past 2000 year (Ambraseys and Synolakis, 2010). The 1200km long Hellenic Arc has allegedly caused the strongest reported earthquakes and tsunamis in the region. Among them, the AD 365 and AD 1303 tsunamis have been extensively documented. They are likely due to ruptures of the Central and Eastern segments of the Hellenic Arc, respectively. Both events had widespread impact due to ground shaking, and e triggered tsunami waves that reportedly affected the entire eastern Mediterranean. The seismic mechanism of the AD 365 earthquake, located in western Crete, has been recently assigned a magnitude ranging from 8.3 to 8.5 by Shaw et al., (2008), using historical, sedimentological, geomorphic and archaeological evidence. Shaw et al (2008) have inferred that such large earthquakes occur in the Arc every 600 to 800 years, with the last known the AD 1303 event. We report on a full-scale simulation exercise that took place in Crete on 24-25 October 2011, based on a scenario sufficiently large to overwhelm the emergency response capability of Greece and necessitating the invocation of the Monitoring and Information Centre (MIC) of the EU and triggering help from other nations . A repeat of the 365 A.D. earthquake would likely overwhelm the civil defense capacities of Greece. Immediately following the rupture initiation it will cause substantial damage even to well-designed reinforced concrete structures in Crete. Minutes after initiation, the tsunami generated by the rapid displacement of the ocean floor would strike nearby coastal areas, inundating great distances in areas of low topography. The objective of the exercise was to help managers plan search and rescue operations, identify measures useful for inclusion in the coastal resiliency index of Ewing and Synolakis (2011). For the scenario design, the tsunami hazard for the AD 365 event was assessed for

Tsunamis triggered by the 12 January 2010 Earthquake in Haiti

NASA Astrophysics Data System (ADS)

Fritz, H. M.; Hillaire, J. V.; Molière, E.; Mohammed, F.; Wei, Y.

2010-12-01

On 12 January 2010 a magnitude Mw 7.0 earthquake occurred 25 km west-southwest of Haiti’s Capital of Port-au-Prince, which resulted in more than 230,000 fatalities. In addition tsunami waves triggered by the earthquake caused at least 3 fatalities at Petit Paradis. Unfortunately, the people of Haiti had neither ancestral knowledge nor educational awareness of tsunami hazards despite the 1946 Dominican Republic tsunami at Hispaniola’s northeast coast. In sharp contrast Sri Lankan UN-soldiers on duty at Jacmel self-evacuated given the memory of the 2004 Indian Ocean tsunami. The International Tsunami Survey Team (ITST) documented flow depths, runup heights, inundation distances, sediment deposition, damage patterns at various scales, and performance of the man-made infrastructure and impact on the natural environment. The 31 January to 7 February 2010 ITST covered the greater Bay of Port-au-Prince and more than 100 km of Hispaniola’s south coast between Pedernales, Dominican Republic and Jacmel, Haiti. The Hispaniola survey data includes more than 20 runup and flow depth measurements. The tsunami impacts peaked with maximum flow depths exceeding 3 m both at Petit Paradis inside the Bay of Grand Goâve located 45 km west-southwest of Port-au-Prince and at Jacmel on Haiti’s south coast. A significant variation in tsunami impact was observed on Hispaniola and tsunami runup of more than 1 m was still observed at Pedernales in the Dominican Republic. Jacmel, which is near the center of the south coast, represents an unfortunate example of a village and harbor that was located for protection from storm waves but is vulnerable to tsunami waves with runup doubling from the entrance to the head of the bay. Inundation and damage was limited to less than 100 m inland at both Jacmel and Petit Paradis. Differences in wave period were documented between the tsunami waves at Petit Paradis and Jacmel. The Petit Paradis tsunami is attributed to a coastal submarine landslide

Tsunami Simulations in the Western Makran Using Hypothetical Heterogeneous Source Models from World's Great Earthquakes

NASA Astrophysics Data System (ADS)

Rashidi, Amin; Shomali, Zaher Hossein; Keshavarz Farajkhah, Nasser

2018-03-01

The western segment of Makran subduction zone is characterized with almost no major seismicity and no large earthquake for several centuries. A possible episode for this behavior is that this segment is currently locked accumulating energy to generate possible great future earthquakes. Taking into account this assumption, a hypothetical rupture area is considered in the western Makran to set different tsunamigenic scenarios. Slip distribution models of four recent tsunamigenic earthquakes, i.e. 2015 Chile M w 8.3, 2011 Tohoku-Oki M w 9.0 (using two different scenarios) and 2006 Kuril Islands M w 8.3, are scaled into the rupture area in the western Makran zone. The numerical modeling is performed to evaluate near-field and far-field tsunami hazards. Heterogeneity in slip distribution results in higher tsunami amplitudes. However, its effect reduces from local tsunamis to regional and distant tsunamis. Among all considered scenarios for the western Makran, only a similar tsunamigenic earthquake to the 2011 Tohoku-Oki event can re-produce a significant far-field tsunami and is considered as the worst case scenario. The potential of a tsunamigenic source is dominated by the degree of slip heterogeneity and the location of greatest slip on the rupture area. For the scenarios with similar slip patterns, the mean slip controls their relative power. Our conclusions also indicate that along the entire Makran coasts, the southeastern coast of Iran is the most vulnerable area subjected to tsunami hazard.

Tsunami Simulations in the Western Makran Using Hypothetical Heterogeneous Source Models from World's Great Earthquakes

NASA Astrophysics Data System (ADS)

Rashidi, Amin; Shomali, Zaher Hossein; Keshavarz Farajkhah, Nasser

2018-04-01

The western segment of Makran subduction zone is characterized with almost no major seismicity and no large earthquake for several centuries. A possible episode for this behavior is that this segment is currently locked accumulating energy to generate possible great future earthquakes. Taking into account this assumption, a hypothetical rupture area is considered in the western Makran to set different tsunamigenic scenarios. Slip distribution models of four recent tsunamigenic earthquakes, i.e. 2015 Chile M w 8.3, 2011 Tohoku-Oki M w 9.0 (using two different scenarios) and 2006 Kuril Islands M w 8.3, are scaled into the rupture area in the western Makran zone. The numerical modeling is performed to evaluate near-field and far-field tsunami hazards. Heterogeneity in slip distribution results in higher tsunami amplitudes. However, its effect reduces from local tsunamis to regional and distant tsunamis. Among all considered scenarios for the western Makran, only a similar tsunamigenic earthquake to the 2011 Tohoku-Oki event can re-produce a significant far-field tsunami and is considered as the worst case scenario. The potential of a tsunamigenic source is dominated by the degree of slip heterogeneity and the location of greatest slip on the rupture area. For the scenarios with similar slip patterns, the mean slip controls their relative power. Our conclusions also indicate that along the entire Makran coasts, the southeastern coast of Iran is the most vulnerable area subjected to tsunami hazard.

Broadband Analysis of the Energetics of Earthquakes and Tsunamis in the Sunda Forearc from 1987-2012

NASA Astrophysics Data System (ADS)

Choy, G. L.; Kirby, S. H.; Hayes, G. P.

2013-12-01

In the eighteen years before the 2004 Sumatra Mw 9.1 earthquake, the forearc off Sumatra experienced only one large (Mw > 7.0) thrust event and experienced no earthquakes that generated measurable tsunami wave heights. In the subsequent eight years, twelve large thrust earthquakes occurred of which half generated measurable tsunamis. The number of broadband earthquakes (those events with Mw > 5.5 for which broadband teleseismic waveforms have sufficient signal to compute depths, focal mechanisms, moments and radiated energies) jumped six fold after 2004. The progression of tsunami earthquakes, as well as the profuse increase in broadband activity, strongly suggests regional stress adjustments following the Sumatra 2004 megathrust earthquake. Broadband source parameters, published routinely in the Source Parameters (SOPAR) database of the USGS's NEIC (National Earthquake Information Center), have provided the most accurate depths and locations of big earthquakes since the implementation of modern digital seismographic networks. Moreover, radiated energy and seismic moment (also found in SOPAR) are related to apparent stress which is a measure of fault maturity. In mapping apparent stress as a function of depth and focal mechanism, we find that about 12% of broadband thrust earthquakes in the subduction zone are unequivocally above or below the slab interface. Apparent stresses of upper-plate events are associated with failure on mature splay faults, some of which generated measurable tsunamis. One unconventional source for local wave heights was a large intraslab earthquake. High-energy upper-plate events, which are dominant in the Aceh Basin, are associated with immature faults, which may explain why the region was bypassed by significant rupture during the 2004 Sumatra earthquake. The majority of broadband earthquakes are non-randomly concentrated under the outer-arc high. They appear to delineate the periphery of the contiguous rupture zones of large earthquakes

Premenstrual symptoms and posttraumatic stress disorder in Japanese high school students 9 months after the great East-Japan earthquake.

PubMed

Takeda, Takashi; Tadakawa, Mari; Koga, Shoko; Nagase, Satoru; Yaegashi, Nobuo

2013-07-01

On March 11, 2011, the Great East-Japan Earthquake occurred and a massive tsunami hit the northeastern coast of Japan. Catastrophic disasters such as earthquakes and war cause tremendous damage, not only physically but also mentally. Posttraumatic stress disorder (PTSD) is an anxiety disorder that occurs in the aftermath of a traumatic event. Premenstrual syndrome (PMS) is a cluster of psychological and somatic symptoms that are limited to the late luteal phase of the menstrual cycle. Premenstrual dysphoric disorder (PMDD) is considered a severe form of PMS. To determine the relationship between premenstrual symptoms and natural disaster-induced PTSD among Japanese adolescent girls, we conducted a cross-sectional study. Overall, 1489 high school students who belong to two high schools in Sendai, the largest city in northeastern Japan, were assessed 9 months after the earthquake. These schools are located inland, far from the seashore, and were not damaged by the tsunami. Premenstrual symptoms were assessed using the Premenstrual Symptoms Questionnaire, and PTSD symptoms were assessed using the Japanese-language version of Impact of Event Scale-Revised, which is a widely used self-assessment questionnaire about PTSD symptoms. We analyzed the data of 1,180 girls who completed the questionnaires and 118 girls (10.0%) were classified as having PTSD. The prevalence rates of PMDD and moderate to severe PMS increased according to the comorbidity of PTSD (p < 0.001), showing a correlation between the severity of PMS/PMDD and natural disaster-induced PTSD. The comorbidity of PMS/PMDD and PTSD may complicate the follow-up of both conditions.

Seafloor Displacement after the 2011 Tohoku-oki Earthquake in the Northern Japan Trench Examined by Repeated Bathymetric Surveys

NASA Astrophysics Data System (ADS)

Fujiwara, T.; dos Santos Ferreira, C.; Bachmann, A. K.; Strasser, M.; Wefer, G.; Sun, T.; Kanamatsu, T.; Kodaira, S.

2017-12-01

Maximum tsunami height caused by the 11 March 2011 Tohoku-oki earthquake was observed at the coast of Sanriku, the northern Tohoku, Japan [The 2011 Tohoku Earthquake Tsunami Joint Survey Group, 2011]. In order to explain the tsunami source, some papers have introduced additional large slip of the megathrust up to 36 m in the shallow part near the northern Japan Trench [e.g. Satake et al., BSSA 2013]. Alternatively, others preferred to put a large change in seafloor elevation, 90 m uplift and down-drop, associated with a submarine landslide along the lower trench slope [e.g. Tappin et al., Marine Geol. 2014]. We conducted repeated multibeam bathymetric surveys offshore Sanriku in 2016 and also 2012. We examined seafloor displacement for tsunami source by means of the difference in bathymetry before and after the earthquake. Acquired two bathymetric survey tracks are crossing the trench at 39.2°N and 39.5°N. These tracks overlap the Satake et al. [2013]'s slip area and also the Tappin et al. [2014]'s landslide area. The German research vessel Sonne performed the surveys along the same tracks (SO219A, SO251A cruises). Previous survey tracks had been obtained by the JAMSTEC R/V Kairei in 2007 and 2010 (KR07-08, KR10-12 cruises). Horizontal and vertical seafloor displacements were estimated by comparison of the bathymetry before and after the earthquake. Apparent offsets of the absolute values of depth soundings and the uncertainty of ship position were examined on the seaward side because the seaward was thought to have suffered little change from the earthquake. The horizontal displacement was estimated by calculating the offset distance to maximize cross-correlation of the bathymetry dataset. The seafloor displacements were less than 20 m in trenchward horizontal displacement and several meters in vertical displacement, these values are within the ranges of error of the analysis, and relatively small displacements are evaluated. Thus localized very large fault slip

Relationships between traumatic symptoms and environmental damage conditions among children 8 months after the 2011 Japan earthquake and tsunami.

PubMed

Usami, Masahide; Iwadare, Yoshitaka; Kodaira, Masaki; Watanabe, Kyota; Aoki, Momoko; Katsumi, Chiaki; Matsuda, Kumi; Makino, Kazunori; Iijima, Sonoko; Harada, Maiko; Tanaka, Hiromi; Sasaki, Yoshinori; Tanaka, Tetsuya; Ushijima, Hirokage; Saito, Kazuhiko

2012-01-01

To evaluate relationships between traumatic symptoms and environmental damage conditions among children who survived the 2011 Great East Japan Earthquake and Tsunami. The subjects were 12,524 children in kindergartens, elementary schools, and junior high schools in Ishinomaki City, Miyagi Prefecture, Japan. The Post Traumatic Stress Symptoms for Children 15 items (PTSSC-15), a self-completion questionnaire on traumatic symptoms, was distributed to the children and a questionnaire regarding environmental damage conditions affecting the children was distributed to their teachers. Of 12,524 questionnaires distributed, an effective response was obtained from 11,692 (93.3%). The PTSSC-15 score was significantly higher in females than in males among 4(th) to 6(th) grade students in elementary schools and among junior high school students. In terms of traumatic symptoms and environmental damage conditions, with the exception of kindergartners, children who had their houses damaged or experienced separation from family members had a significantly higher PTSSC-15 score than children who did not experience environmental damage. Except for kindergartners and 4(th)- to 6(th)-grade elementary school students, children who experienced evacuation had a significantly higher PTSSC-15 score. This study demonstrated relationships between traumatic symptoms and environmental damage conditions in children who had suffered from the disaster. Factors examined in studying the relationship between environmental damage conditions and traumatic symptoms were gender, age, house damage, evacuation experience, and bereavement experience. It was critical not only to examine the traumatic symptoms of the children but also to collect accurate information about environmental damage conditions.

Relationships between Traumatic Symptoms and Environmental Damage Conditions among Children 8 Months after the 2011 Japan Earthquake and Tsunami

PubMed Central

Usami, Masahide; Iwadare, Yoshitaka; Kodaira, Masaki; Watanabe, Kyota; Aoki, Momoko; Katsumi, Chiaki; Matsuda, Kumi; Makino, Kazunori; Iijima, Sonoko; Harada, Maiko; Tanaka, Hiromi; Sasaki, Yoshinori; Tanaka, Tetsuya; Ushijima, Hirokage; Saito, Kazuhiko

2012-01-01

Background To evaluate relationships between traumatic symptoms and environmental damage conditions among children who survived the 2011 Great East Japan Earthquake and Tsunami. Methods The subjects were 12,524 children in kindergartens, elementary schools, and junior high schools in Ishinomaki City, Miyagi Prefecture, Japan. The Post Traumatic Stress Symptoms for Children 15 items (PTSSC-15), a self-completion questionnaire on traumatic symptoms, was distributed to the children and a questionnaire regarding environmental damage conditions affecting the children was distributed to their teachers. Of 12,524 questionnaires distributed, an effective response was obtained from 11,692 (93.3%). Results The PTSSC-15 score was significantly higher in females than in males among 4th to 6th grade students in elementary schools and among junior high school students. In terms of traumatic symptoms and environmental damage conditions, with the exception of kindergartners, children who had their houses damaged or experienced separation from family members had a significantly higher PTSSC-15 score than children who did not experience environmental damage. Except for kindergartners and 4th- to 6th-grade elementary school students, children who experienced evacuation had a significantly higher PTSSC-15 score. Conclusions This study demonstrated relationships between traumatic symptoms and environmental damage conditions in children who had suffered from the disaster. Factors examined in studying the relationship between environmental damage conditions and traumatic symptoms were gender, age, house damage, evacuation experience, and bereavement experience. It was critical not only to examine the traumatic symptoms of the children but also to collect accurate information about environmental damage conditions. PMID:23209817

Fault Slip Distribution of the 2016 Fukushima Earthquake Estimated from Tsunami Waveforms

NASA Astrophysics Data System (ADS)

Gusman, Aditya Riadi; Satake, Kenji; Shinohara, Masanao; Sakai, Shin'ichi; Tanioka, Yuichiro

2017-08-01

The 2016 Fukushima normal-faulting earthquake (Mjma 7.4) occurred 40 km off the coast of Fukushima within the upper crust. The earthquake generated a moderate tsunami which was recorded by coastal tide gauges and offshore pressure gauges. First, the sensitivity of tsunami waveforms to fault dimensions and depths was examined and the best size and depth were determined. Tsunami waveforms computed based on four available focal mechanisms showed that a simple fault striking northeast-southwest and dipping southeast (strike = 45°, dip = 41°, rake = -95°) yielded the best fit to the observed waveforms. This fault geometry was then used in a tsunami waveform inversion to estimate the fault slip distribution. A large slip of 3.5 m was located near the surface and the major slip region covered an area of 20 km × 20 km. The seismic moment, calculated assuming a rigidity of 2.7 × 1010 N/m2 was 3.70 × 1019 Nm, equivalent to Mw = 7.0. This is slightly larger than the moments from the moment tensor solutions (Mw 6.9). Large secondary tsunami peaks arrived approximately an hour after clear initial peaks were recorded by the offshore pressure gauges and the Sendai and Ofunato tide gauges. Our tsunami propagation model suggests that the large secondary tsunami signals were from tsunami waves reflected off the Fukushima coast. A rather large tsunami amplitude of 75 cm at Kuji, about 300 km north of the source, was comparable to those recorded at stations located much closer to the epicenter, such as Soma and Onahama. Tsunami simulations and ray tracing for both real and artificial bathymetry indicate that a significant portion of the tsunami wave was refracted to the coast located around Kuji and Miyako due to bathymetry effects.

A possible space-based tsunami early warning system using observations of the tsunami ionospheric hole.

PubMed

Kamogawa, Masashi; Orihara, Yoshiaki; Tsurudome, Chiaki; Tomida, Yuto; Kanaya, Tatsuya; Ikeda, Daiki; Gusman, Aditya Riadi; Kakinami, Yoshihiro; Liu, Jann-Yenq; Toyoda, Atsushi

2016-12-01

Ionospheric plasma disturbances after a large tsunami can be detected by measurement of the total electron content (TEC) between a Global Positioning System (GPS) satellite and its ground-based receivers. TEC depression lasting for a few minutes to tens of minutes termed as tsunami ionospheric hole (TIH) is formed above the tsunami source area. Here we describe the quantitative relationship between initial tsunami height and the TEC depression rate caused by a TIH from seven tsunamigenic earthquakes in Japan and Chile. We found that the percentage of TEC depression and initial tsunami height are correlated and the largest TEC depressions appear 10 to 20 minutes after the main shocks. Our findings imply that Ionospheric TEC measurement using the existing ground receiver networks could be used in an early warning system for near-field tsunamis that take more than 20 minutes to arrive in coastal areas.

A possible space-based tsunami early warning system using observations of the tsunami ionospheric hole

PubMed Central

Kamogawa, Masashi; Orihara, Yoshiaki; Tsurudome, Chiaki; Tomida, Yuto; Kanaya, Tatsuya; Ikeda, Daiki; Gusman, Aditya Riadi; Kakinami, Yoshihiro; Liu, Jann-Yenq; Toyoda, Atsushi

2016-01-01

Ionospheric plasma disturbances after a large tsunami can be detected by measurement of the total electron content (TEC) between a Global Positioning System (GPS) satellite and its ground-based receivers. TEC depression lasting for a few minutes to tens of minutes termed as tsunami ionospheric hole (TIH) is formed above the tsunami source area. Here we describe the quantitative relationship between initial tsunami height and the TEC depression rate caused by a TIH from seven tsunamigenic earthquakes in Japan and Chile. We found that the percentage of TEC depression and initial tsunami height are correlated and the largest TEC depressions appear 10 to 20 minutes after the main shocks. Our findings imply that Ionospheric TEC measurement using the existing ground receiver networks could be used in an early warning system for near-field tsunamis that take more than 20 minutes to arrive in coastal areas. PMID:27905487

Introduction to thematic collection "Historical and geological studies of earthquakes"

NASA Astrophysics Data System (ADS)

Satake, Kenji; Wang, Jian; Hammerl, Christa; Malik, Javed N.

2017-12-01

This thematic collection contains eight papers mostly presented at the 2016 AOGS meeting in Beijing. Four papers describe historical earthquake studies in Europe, Japan, and China; one paper uses modern instrumental data to examine the effect of giant earthquakes on the seismicity rate; and three papers describe paleoseismological studies using tsunami deposit in Japan, marine terraces in Philippines, and active faults in Himalayas. Hammerl (Geosci Lett 4:7, 2017) introduced historical seismological studies in Austria, starting from methodology which is state of the art in most European countries, followed by a case study for an earthquake of July 17, 1670 in Tyrol. Albini and Rovida (Geosci Lett 3:30, 2016) examined 114 historical records for the earthquake on April 6, 1667 on the east coast of the Adriatic Sea, compiled 37 Macroseismic Data Points, and estimated the epicenter and the size of the earthquake. Matsu'ura (Geosci Lett 4:3, 2017) summarized historical earthquake studies in Japan which resulted in about 8700 Intensity Data Points, assigned epicenters for 214 earthquakes between AD 599 and 1872, and estimated focal depth and magnitudes for 134 events. Wang et al. (Geosci Lett 4:4, 2017) introduced historical seismology in China, where historical earthquake archives include about 15,000 sources, and parametric catalogs include about 1000 historical earthquakes between 2300 BC and AD 1911. Ishibe et al. (Geosci Lett 4:5, 2017) tested the Coulomb stress triggering hypothesis for three giant (M 9) earthquakes that occurred in recent years, and found that at least the 2004 Sumatra-Andaman and 2011 Tohoku earthquakes caused the seismicity rate change. Ishimura (2017) re-estimated the ages of 11 tsunami deposits in the last 4000 years along the Sanriku coast of northern Japan and found that the average recurrence interval of those tsunamis as 350-390 years. Ramos et al. (2017) studied 1000-year-old marine terraces on the west coast of Luzon Island, Philippines

Burden and Management of Noncommunicable Diseases After Earthquakes and Tsunamis.

PubMed

Suneja, Amit; Gakh, Maxim; Rutkow, Lainie

This integrative review examines extant literature assessing the burden and management of noncommunicable diseases 6 months or more after earthquakes and tsunamis. We conducted an integrative review to identify and characterize the strength of published studies about noncommunicable disease-specific outcomes and interventions at least 6 months after an earthquake and/or tsunami. We included disasters that occurred from 2004 to 2016. We focused primarily on the World Health Organization noncommunicable disease designations to define chronic disease, but we also included chronic renal disease, risk factors for noncommunicable diseases, and other chronic diseases or symptoms. After removing duplicates, our search yielded 6,188 articles. Twenty-five articles met our inclusion criteria, some discussing multiple noncommunicable diseases. Results demonstrate that existing medical conditions may worsen and subsequently improve, new diseases may develop, and risk factors, such as weight and cholesterol levels, may increase for several years after an earthquake and/or tsunami. We make 3 recommendations for practitioners and researchers: (1) plan for noncommunicable disease management further into the recovery period of disaster; (2) increase research on the burden of noncommunicable diseases, the treatment modalities employed, resulting population-level outcomes in the postdisaster setting, and existing models to improve stakeholder coordination and action regarding noncommunicable diseases after disasters; and (3) coordinate with preexisting provision networks, especially primary care.

Observations and Modeling of the August 27, 2012 Earthquake and Tsunami affecting El Salvador and Nicaragua

NASA Astrophysics Data System (ADS)

Borrero, Jose C.; Kalligeris, Nikos; Lynett, Patrick J.; Fritz, Hermann M.; Newman, Andrew V.; Convers, Jaime A.

2014-12-01

On 27 August 2012 (04:37 UTC, 26 August 10:37 p.m. local time) a magnitude M w = 7.3 earthquake occurred off the coast of El Salvador and generated surprisingly large local tsunami. Following the event, local and international tsunami teams surveyed the tsunami effects in El Salvador and northern Nicaragua. The tsunami reached a maximum height of ~6 m with inundation of up to 340 m inland along a 25 km section of coastline in eastern El Salvador. Less severe inundation was reported in northern Nicaragua. In the far-field, the tsunami was recorded by a DART buoy and tide gauges in several locations of the eastern Pacific Ocean but did not cause any damage. The field measurements and recordings are compared to numerical modeling results using initial conditions of tsunami generation based on finite-fault earthquake and tsunami inversions and a uniform slip model.

Perceptions of earthquake and tsunami issues in U.S. Pacific Northwest port and harbor communities

USGS Publications Warehouse

Wood, Nathan J.; Good, James W.

2005-01-01

Although there is considerable energy focused on assessing natural hazards associated with earthquakes and tsunamis in the U.S. Pacific Northwest, little has been done to understand societal vulnerability to these hazards. Part of understanding societal vulnerability includes assessing the perceptions and priorities of public sector individuals with traditional emergency management responsibilities and of private citizens who could play key roles in community recovery. In response to this knowledge gap, we examine earthquake and tsunami perceptions of stakeholders and decision makers from coastal communities in the U.S. Pacific Northwest, focusing on perceptions of (1) regional hazards and societal vulnerability, (2) the current state of readiness, and (3) priorities for future hazard adjustment efforts. Results of a mailed survey suggest that survey participants believe that earthquakes and tsunamis are credible community threats. Most communities are focusing on regional mitigation and response planning, with less effort devoted to recovery plans or to making individual organizations more resilient. Significant differences in expressed perceptions and priorities were observed between Oregon and Washington respondents, mainly on tsunami issues. Significant perception differences were also observed between private and public sector respondents. Our results suggest the need for further research and for outreach and planning initiatives in the Pacific Northwest to address significant gaps in earthquake and tsunami hazard awareness and readiness.

Tsunami Hazard Assessment in Guam

NASA Astrophysics Data System (ADS)

Arcas, D.; Uslu, B.; Titov, V.; Chamberlin, C.

2008-12-01

The island of Guam is located approximately 1500 miles south of Japan, in the vicinity of the Mariana Trench. It is surrounded in close proximity by three subduction zones, Nankai-Taiwan, East Philippines and Mariana Trench that pose a considerable near to intermediate field tsunami threat. Tsunami catalogues list 14 tsunamigenic earthquake with Mw≥8.0 since 1900 only in this region, (Soloviev and Go, 1974; Lander, 1993; Iida, 1984; Lander and Lowell, 2002), however the island has not been significantly affected by some of the largest far-field events of the past century, such as the 1952 Kamchatka, 1960 Chile, and the 1964 Great Alaska earthquake. An assessment of the tsunami threat to the island from both near and far field sources, using forecast tools originally developed at NOAA's Pacific Marine Environmental Laboratory (PMEL) for real-time forecasting of tsunamis is presented here. Tide gauge records from 1952 Kamchatka, 1964 Alaska, and 1960 Chile earthquakes at Apra Harbor are used to validate our model set up, and to explain the limited impact of these historical events on Guam. Identification of worst-case scenarios, and determination of tsunamigenic effective source regions are presented for five vulnerable locations on the island via a tsunami sensitivity study. Apra Harbor is the site of a National Ocean Service (NOS) tide gauge and the biggest harbor on the island. Tumon Bay, Pago Bay, Agana Bay and Inarajan Bay are densely populated areas that require careful investigation. The sensitivity study shows that earthquakes from Eastern Philippines present a major threat to west coast facing sites, whereas the Marina Trench poses the biggest concern to the east coast facing sites.

Nowcasting Earthquakes and Tsunamis

NASA Astrophysics Data System (ADS)

Rundle, J. B.; Turcotte, D. L.

2017-12-01

. As another application, we can define large rectangular regions of subduction zones and shallow depths to compute the progress of the fault zone towards the next major tsunami-genic earthquake. We can then rank the relative progress of the major subduction zones of the world through their cycles of large earthquakes using this method to determine which zones are most at risk.

Regional differences in post-traumatic stress symptoms among children after the 2011 tsunami in Higashi-Matsushima, Japan.

PubMed

Kuwabara, Hitoshi; Araki, Tsuyoshi; Yamasaki, Syudo; Ando, Shuntaro; Kano, Yukiko; Kasai, Kiyoto

2015-01-01

On 11 March 2011, a massive undersea earthquake, measuring 9.0 on the Richter scale, caused a tsunami that devastated the shoreline of east Japan. It is estimated that over 20,000 people lost their lives as a result. It is recommended that clinical effort after a tsunami disaster concentrate on a high-impact area rather than cover a large area. However, regional differences in post-traumatic stress symptoms among children after a tsunami disaster are not well clarified. This study evaluated post-traumatic stress symptoms and reported the findings of early-phase screening of 2259 students from Higashi-Matsushima City, Japan, 6 weeks after a tsunami hit the city. The sample was divided into two age groups: elementary school students (n=1102) and junior high school students (n=1157). Of these groups, 289 (26.2%) elementary school students and 123 (10.6%) junior high school students attended the four schools that were located in the area struck by the tsunami; the mortality rate of the area exceeded 4%. We referred to these students as the "high-impact group." The "lower-impact group" consisted of 813 (73.8%) elementary school students and 1034 (89.4%) junior high school students who attended the remaining ten schools. The severity of post-traumatic stress symptoms did not significantly differ between areas with relatively high and low impact. However, among the junior high school students, those attending the school in the highly impacted area showed higher post-traumatic symptoms scores than did the students of the less-impacted area. When planning a mass intervention after a disaster, especially in the early phase when the resources for intervention are not sufficient, it might be useful to consider the degree of age-dependent impact effect. Copyright © 2014 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Comparison of the incidence of acute decompensated heart failure before and after the major tsunami in Northeast Japan.

PubMed

Nakamura, Motoyuki; Tanaka, Fumitaka; Nakajima, Satoshi; Honma, Miho; Sakai, Toshiaki; Kawakami, Mikio; Endo, Hiroshi; Onodera, Masayuki; Niiyama, Masanobu; Komatsu, Takashi; Sakamaki, Kentaro; Onoda, Toshiyuki; Sakata, Kiyomi; Morino, Yoshihiro; Takahashi, Tomohiro; Makita, Shinji

2012-12-15

On March 11, 2011, a huge tsunami attacked the northeastern coast of Japan after a magnitude 9 earthquake. No reports have investigated the impact of tsunamis on the incidence of cardiovascular disease, especially heart failure (HF). We investigated the number and clinical characteristics of hospitalized patients with acute decompensated HF (ADHF) in the east coast of Iwate hit by the tsunami (tsunami area) for a 12-week period around the disaster. For comparison with previous years, numbers of ADHF were surveyed in the corresponding area in 2009 and 2010. In addition, to elucidate the impact of the tsunami, a similar study was performed in a remote area where the tsunami had minimal effect (control area). After the disaster, the number of patients with ADHF in the tsunami area was significantly increased compared to the predisaster period (relative risk 1.97, 95% confidence interval 1.50 to 2.59). The peak was found 3 to 4 weeks after the disaster. In contrast, in the control area, no significant change in ADHF events was observed (relative risk 1.29, 95% confidence interval 0.94 to 1.78). There was a significant correlation between changes in the number of ADHF admissions and percent tsunami flood area (r = 0.73, p <0.001) or the number of shelter evacuees (r = 0.83, p <0.001). In conclusion, these findings suggest that large and sudden changes in daily life and the trauma associated with a devastating tsunami have a significant impact on the incidence of ADHF. Copyright © 2012 Elsevier Inc. All rights reserved.

Impact of earthquake source complexity and land elevation data resolution on tsunami hazard assessment and fatality estimation

NASA Astrophysics Data System (ADS)

Muhammad, Ario; Goda, Katsuichiro

2018-03-01

This study investigates the impact of model complexity in source characterization and digital elevation model (DEM) resolution on the accuracy of tsunami hazard assessment and fatality estimation through a case study in Padang, Indonesia. Two types of earthquake source models, i.e. complex and uniform slip models, are adopted by considering three resolutions of DEMs, i.e. 150 m, 50 m, and 10 m. For each of the three grid resolutions, 300 complex source models are generated using new statistical prediction models of earthquake source parameters developed from extensive finite-fault models of past subduction earthquakes, whilst 100 uniform slip models are constructed with variable fault geometry without slip heterogeneity. The results highlight that significant changes to tsunami hazard and fatality estimates are observed with regard to earthquake source complexity and grid resolution. Coarse resolution (i.e. 150 m) leads to inaccurate tsunami hazard prediction and fatality estimation, whilst 50-m and 10-m resolutions produce similar results. However, velocity and momentum flux are sensitive to the grid resolution and hence, at least 10-m grid resolution needs to be implemented when considering flow-based parameters for tsunami hazard and risk assessments. In addition, the results indicate that the tsunami hazard parameters and fatality number are more sensitive to the complexity of earthquake source characterization than the grid resolution. Thus, the uniform models are not recommended for probabilistic tsunami hazard and risk assessments. Finally, the findings confirm that uncertainties of tsunami hazard level and fatality in terms of depth, velocity and momentum flux can be captured and visualized through the complex source modeling approach. From tsunami risk management perspectives, this indeed creates big data, which are useful for making effective and robust decisions.

Oceanographer tracks marine debris from the Japan tsunami and other incidents

NASA Astrophysics Data System (ADS)

Showstack, Randy

2011-09-01

In the wake of the 11 March 2011 Tohoku earthquake and resulting tsunami that struck Japan, much of the debris that washed out to sea continues to float slowly on ocean currents across the Pacific Ocean. The leading edge of a dispersed field of debris that has not already sunk or biodegraded was estimated by a computer model to be about halfway across the Pacific, north of Midway Island, as of 31 July, 142 days after the tsunami. According to Curtis Ebbesmeyer, a consulting oceanographer who has been involved with tracking various kinds of ocean flotsam for decades, the debris field, which encompasses an area about the size of California, could begin to reach the U.S. West Coast by March 2012. The National Oceanic and Atmospheric Administration's (NOAA) Satellite and Information Service was able to track the debris field until mid-April, when the debris became too dispersed to be detected in satellite imagery. Ebbesmeyer, formerly an oceanographer with Mobil and Standard Oil, told Eos that he does not have any recent physical evidence of the debris field because it is now widely dispersed and still far away from any landfall. Ebbesmeyer said, though, that his confidence level for the debris field's estimated size and location is “very high.”

Tsunami Source Inversion Using Tide Gauge and DART Tsunami Waveforms of the 2017 Mw8.2 Mexico Earthquake

NASA Astrophysics Data System (ADS)

Adriano, Bruno; Fujii, Yushiro; Koshimura, Shunichi; Mas, Erick; Ruiz-Angulo, Angel; Estrada, Miguel

2018-01-01

On September 8, 2017 (UTC), a normal-fault earthquake occurred 87 km off the southeast coast of Mexico. This earthquake generated a tsunami that was recorded at coastal tide gauge and offshore buoy stations. First, we conducted a numerical tsunami simulation using a single-fault model to understand the tsunami characteristics near the rupture area, focusing on the nearby tide gauge stations. Second, the tsunami source of this event was estimated from inversion of tsunami waveforms recorded at six coastal stations and three buoys located in the deep ocean. Using the aftershock distribution within 1 day following the main shock, the fault plane orientation had a northeast dip direction (strike = 320°, dip = 77°, and rake =-92°). The results of the tsunami waveform inversion revealed that the fault area was 240 km × 90 km in size with most of the largest slip occurring on the middle and deepest segments of the fault. The maximum slip was 6.03 m from a 30 × 30 km2 segment that was 64.82 km deep at the center of the fault area. The estimated slip distribution showed that the main asperity was at the center of the fault area. The second asperity with an average slip of 5.5 m was found on the northwest-most segments. The estimated slip distribution yielded a seismic moment of 2.9 × 10^{21} Nm (Mw = 8.24), which was calculated assuming an average rigidity of 7× 10^{10} N/m2.