Frequency Domain Response at Pacific Coast Harbors to Major Tsunamis of 2005–2011

Tsunamis waves caused by submarine earthquake or landslide might contain large wave energy, which could cause significant human loss and property damage locally as well as in distant region. The response of three harbors located at the Pacific coast (i.e. Crescent City Harbor, Los Angeles/Long Beach Port, and San Diego Harbor) to six well-known tsunamis events generated (both near-field and far-field) between 2005 and 2011 are examined and simulated using a hybrid finite element numerical model in frequency domain. The model incorporated the effects of wave refraction, wave diffraction, partial wave reflection from boundaries, entrance and bottom energy dissipation. It can be applied to harbor regions with arbitrary shapes and variable water depth. The computed resonant periods or modes of oscillation for three harbors are in good agreement with the energy spectral analysis of the time series of water surface elevations recorded at tide gauge stations inside three harbors during the six tsunamis events. The computed wave induced currents based on the present model are also in qualitative agreement with some of the reported eye-witness accounts absence of reliable current data. The simulated results show that each harbor responded differently and significantly amplified certain wave period(s) of incident wave trains according to the shape, topography, characteristic dimensions and water depth of the harbor basins.     

Introduction to “Historical and Recent Catastrophic Tsunamis in the World: Volume I. The 2011 Tohoku Tsunami”

Twenty-one papers on the 2011 Tohoku, Japan tsunami are included in Volume I of the PAGEOPH topical issue “Historical and Recent Catastrophic Tsunamis in the World.” Two papers discuss seismological aspects of the event with an emphasis on tsunami generation and warning. Five papers report the impacts and effects in Japan through field surveys of tsunami heights, building damage, and tsunami deposits or analysis of satellite data. Eight papers report the tsunami effects on other Pacific coasts, including the Kuril Islands, the USA, French Polynesia, the Galapagos Islands, Australia, and New Zealand. Three papers report on analyses of the instrumental records of the 2011 Tohoku tsunami, and two more papers report their modelling efforts of the tsunami. Several of the above papers also compare the 2011 Tohoku and 2010 Chile tsunamis.     

Introduction to ��Tsunamis in the World Ocean: Past, Present, and Future. Volume I��

Eighteen papers are included in Volume 1 of a PAGEOPH topical issue Tsunamis in the World Ocean: Past, Present, and Future. These papers are briefly introduced. They are grouped into three categories: case studies of earthquake-generated tsunamis; tsunami forecast and hazard assessments; and theoretical and computational modeling of tsunami generation, propagation, and coastal behavior. Most of the papers were presented at the 24th International Tsunami Symposium held 14?C16 July 2009 in Novosibirsk, Russia, and reflect the current state of tsunami science.     

Introduction to “Tsunamis in the World Ocean: Past,Present, and Future. Volume II”

Fifteen papers are included in Volume 2 of a PAGEOPH topical issue Tsunamis in the World Ocean: Past, Present, and Future. These papers are briefly introduced. They are grouped into three categories: reports and studies of recent tsunamis, studies on tsunami statistics and application to tsunami warning, and modeling studies of tsunami runup and inundation. Most of the papers were presented at the 24th International Tsunami Symposium held 14–16 July 2009 in Novosibirsk, Russia, and reflect the current state of tsunami science.     

Tsunamis on the Pacific Coast of Canada Recorded in 1994–2007

In the last 15 years there have been 16 tsunami events recorded at tide stations on the Pacific Coast of Canada. Eleven of these events were from distant sources covering almost all regions of the Pacific, as well as the December 26, 2004 Sumatra tsunami in the Indian Ocean. Three tsunamis were generated by local or regional earthquakes and two were meteorological tsunamis. The earliest four events, which occurred in the period 1994–1996, were recorded on analogue recorders; these tsunami records were recently re-examined, digitized and thoroughly analysed. The other 12 tsunami events were recorded using digital high-quality instruments, with 1-min sampling interval, installed on the coast of British Columbia (B.C.) in 1998. All 16 tsunami events were recorded at Tofino on the outer B.C. coast, and some of the tsunamis were recorded at eight or more stations. The tide station at Tofino has been in operation for 100 years and these recent observations add to the dataset of tsunami events compiled previously by S.O. Wigen (1983) for the period 1906–1980. For each of the tsunami records statistical analysis was carried out to determine essential tsunami characteristics for all events (arrival times, maximum amplitudes, frequencies and wave-train structure). The analysis of the records indicated that significant background noise at Langara, a key northern B.C. Tsunami Warning station located near the northern end of the Queen Charlotte Islands, creates serious problems in detecting tsunami waves. That station has now been moved to a new location with better tsunami response. The number of tsunami events observed in the past 15 years also justified re-establishing a tide gauge at Port Alberni, where large tsunami wave amplitudes were measured in March 1964. The two meteorological events are the first ever recorded on the B.C. coast. Also, there have been landslide generated tsunami events which, although not recorded on any coastal tide gauges, demonstrate, along with the recent investigation of a historical catastrophic event, the significant risk that landslide generated tsunami pose to coastal and inland regions of B.C.     

Tide Gauge Observations of 2004–2007 Indian Ocean Tsunamis from Sri Lanka and Western Australia

Tide gauge data collected from Sri Lanka (three stations) and Western Australia (eleven stations) during the Indian Ocean tsunamis, which occurred in December 2004, March 2005, July 2006, and September 2007, and incorporated five tsunamis, were examined to determine tsunami behaviour during these events. During the December 2004 tsunami, maximum wave heights of 3.87 m and 1.75 m were recorded at Colombo (Sri Lanka) and Bunbury (Western Australia), respectively. The results indicated that although the relative magnitudes of the tsunamis varied, the tsunami behaviour at each station was similar. This was due to the effect of the local and regional topography. At all tide gauges, the spectral energy corresponding to periods between 20 and 85 minutes increased during the tsunami. The sea-level data obtained from the west and south coasts of Sri Lanka (Colombo and Kirinda) indicated the importance of wave reflections from the Maldives Island chain, which produced the maximum wave two to three hours after the arrival of the first wave. In contrast, Trincomalee on the east coast did not show evidence of a reflected wave. Similarly, along the west coast of Australia, the highest waves occurred 15 hours after the arrival of the first wave. Here, based on travel times, we postulated that the waves were reflected from the Mascarene Ridge and/or the Island of Madagascar. Reflected waves were not present in the 2006 tsunami, where the primary waves propagated away from topographic features. One of the main influences of the tsunami was to set up oscillations at the local resonance frequency. Because Sri Lanka and Western Australia have relatively straight coastlines, these oscillations were related to the fundamental period of the shelf oscillation. For Colombo, this corresponded to 75-minute period, whereas in Geraldton and Busselton (Australia), the four-hour period was most prominent; at Jurien Bay and Fremantle, the resonance period was 2.7 hours.     

Numerical Study on the Effect of the Manila Seismic Tsunami on the Guangdong Coast——The Nonlinear Effects of Tides and Tsunamis

The coupling numerical model between astronomical tide and tsunamis was built based on the data of the COMCOT model, which was verified by the Japan "3·11" tsunami. The tsunami source of the Manila seismic tsunami was designed and computed to analyze the risk of tsunami which will happen in the Guangdong coast. According to the results, the maximum quantity of water increasing and the time of the tsunami arriving at the Guangdong seacoast were calculated. The coupling simulation between astronomical tide and tsunamis has significant meaning for evaluating the risk and early-warning of tsunamis in the Guangdong coastal area.     

Contributors to this issue

SHANG Xue-feng （尚学峰） Ph D Candidate of Department of Earth and Atmosphere Sciences in Massachusetts Institute of Technology. Graduated from School of Earth and Space Sciences in geophysics in 2004 and obtained his MS Degree from School of Earth and Space Sciences in geophysics in 2007. Now mainly engaged in researches on seismic wave theory and source failure dynamics.     

Contributors to this issue

HUANGFU Gang （皇甫岗） Professor of Earthquake Administration of Yunnan Province. Ph D student of School of Earth and Space Sciences, University of Science and Technology of China. Obtained his MS Degree from Institute of Geology, China Earthquake Administration in 1988. Mainly engaged in researches on seismology, seismogeology and rock mechanics. Member of Committee of Science and Technology, China Earthquake Administration.     

Contributors to this issue

SUN Xun-ying (孙荀英) Professor of Geophysical Department of Peking University. Graduated from Department of Mathematics & Mechanics, Peking University in 1958. She has been engaged in the teaching and research on geodynamics. Her research focus on the mathematical simulation of earthquake sequence and its migration, convection of mantle as well as plate motion by using 2-D, 3-D, 4-D and non-linear methods. Director of Mechanical Society of China. Member of Geophysical Society of Ch…     

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Ｇｕｏ－ＭｉｎＺＨＡＮＧ（张国民）ＧｏｔＢａｃｈｅｌｏｒａｎｄＭａｓｔｅｒＤｅｇｒｅｅｓｉｎＧｅｏｐｈｙｓｉｃａｌＤｅｐａｒｔｍｅｎｔ，ｔｈｅＳｃｉｅｎｃｅａｎｄＴｅｃｈｎｏｌｏｇｙＵｎｉｖｅｒｓｉｔｙ．ｏｆＣｈｉｎａｉｎ１９６５ａｎｄ１９６８ｒｅｓ...     

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ＣｏｎｔｒｉｂｕｔｏｒｓｔｏｔｈｉｓｉｓｓｕｅＳｈｉ－ＲｏｎｇＭＥＩ（梅世蓉）ＰｒｏｆｅｓｓｏｒｏｆｔｈｅＣｅｎｔｅｒｆｏｒＡｎａｌｙｓｉｓａｎｄＰｒｅｄｉｃｔｉｏｎ，ＳｔａｔｅＳｅｉｓｍｏｌｏｇｉｃａｌＢｕｒｅａｕ．Ｇｒａｄｕａｔｅｄｆｒｏｍｔｈｅ...     

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ＣｏｎｔｒｉｂｕｔｏｒｓｔｏｔｈｉｓｉｓｕｅＺＨＩ┐ＱＩＡＮＧＨＡＮ（韩志强）ＲｅｓｅａｒｃｈＡｓｓｉｓｔａｎｔｏｆＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃｓ，ＳｔａｔｅＳｅｉｓｍｏｌｏｇｉｃａｌＢｕｒｅａｕ．ＧｒａｄｕａｔｅｄｆｒｏｍｔｈｅＤｅｐａ...     

Contribution to this issue

YONG-ENCAI(蔡永恩)ProtbssoroftheDepartmentofGeophysics,PekingUniversity.Graduatedfromtherein1974.ReceivedhisMSdegreeintheDepartmentofGeology,PekingUniversityin1984.Mainlyengagedingeodynamics.rockmechanics,engineeringmechanicsandnumericalmethod.Amembe...     

Contributors to this issue

ＣｏｎｔｒｉｂｕｔｏｒｓｔｏｔｈｉｓｉｓｓｕｅＸｕｅ－ＳｈｅｎＪＩＮ（金学申）；ＡｓｓｏｃｉａｔｅＰｒｏｆｅｓｓｏｒａｔｔｈｅＳｅｉｓｍｏｌｏｇｉｃａｌＢｕｒｅａｕｏｆＨｅｂｅｉＰｒｏｖｉｎｃｅ．ＧｒａｄｕａｔｅｄｆｒｏｍｔｈｅＧｅｏｐｈｙｓｉｃａｌ...     

Contributors to this issue

ZENG Rong-sheng （曾融生） Professor of Institute of Geophysics, China Earthquake Administration （CEA）, Academician of Chinese Academy of Sciences. Graduated from Department of mathematics, Amoy University in 1946. Mainly engaged in researches on solid geophysics and earth dynamics. Members of Chinese Geophysical Society and member of Seismological Society of China.     

Contributors to this issue

SUN Shao-an （孙少安） Senior Engineer of Institute of Seismology, China Earthquake Administration （CEA）. Graduated from Department of Earth and Space Sciences, University of Science and Technology of China, in geophysics in 1988. Mainly engaged in monitoring and prediction of Earth gravity field and earthquake. Member of Seismological Society of Hubei Province.