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Author: Harold Kuehn Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
The largest and most destructive earthquakes nucleate on the seismogenic parts of megathrust faults along subduction zones. Understanding the controls of rupture propagation in along-trench and dip direction is a key factor to estimate size and location of future megathrust earthquakes. Various geologic features and subduction-related processes have been proposed to affect megathrust segmentation along the plate boundary zone, however, inaccessibility due to its deep location makes a detailed investigation challenging. The ALEUT project aims to overcome these difficulties by acquisition of state-of-the-art deep penetrating multichannel seismic reflection data combined with coinciding ocean bottom seismometer refraction data for a large section of the eastern Alaska-Aleutian subduction zone (AASZ). This thesis discusses results based on the ALEUT dataset and provides unique insights into possible morphological controls on along-strike rupture organization of the subduction thrust and new constraints on its seismogenic down-dip limit. Plate interface reflections recorded throughout the survey area were used to construct a 3D model of the interplate interface, on which two major crest-like have been identified. The spatial coincidence of these geometrical highs, interpreted to represent subducted seamounts chains, with boundaries of the region's great earthquake ruptures indicates that the megathrust geometry is the primary factor controlling the segmentation of the eastern AASZ. Furthermore, the plate interface reflection signatures appear to increase significantly with depth and have been correlated to 1) seismogenic, 2) conditionally stable and, 3) aseismic slip behavior. The results confirm the spatial extent of rupture areas derived from existing information, such as aftershock locations, inverse tsunami waveform modelling and the intersection of a serpentinized mantle wedge. However, contrary to recent geodetic dislocation models that suggest a widely free slipping segment along the ASSZ (Shumagin Gap), the results suggest a seismogenic plate interface for this area that extents from the trench up to 100 km landward. A partially seismogenic Shumagin Gap area could become part of a great future megathrust event as shallow rupture is propagating into this area and exposing it to strong ground shaking and large tsunami waves, as it might have happened in the 18th and 19th century.
Author: Harold Kuehn Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
The largest and most destructive earthquakes nucleate on the seismogenic parts of megathrust faults along subduction zones. Understanding the controls of rupture propagation in along-trench and dip direction is a key factor to estimate size and location of future megathrust earthquakes. Various geologic features and subduction-related processes have been proposed to affect megathrust segmentation along the plate boundary zone, however, inaccessibility due to its deep location makes a detailed investigation challenging. The ALEUT project aims to overcome these difficulties by acquisition of state-of-the-art deep penetrating multichannel seismic reflection data combined with coinciding ocean bottom seismometer refraction data for a large section of the eastern Alaska-Aleutian subduction zone (AASZ). This thesis discusses results based on the ALEUT dataset and provides unique insights into possible morphological controls on along-strike rupture organization of the subduction thrust and new constraints on its seismogenic down-dip limit. Plate interface reflections recorded throughout the survey area were used to construct a 3D model of the interplate interface, on which two major crest-like have been identified. The spatial coincidence of these geometrical highs, interpreted to represent subducted seamounts chains, with boundaries of the region's great earthquake ruptures indicates that the megathrust geometry is the primary factor controlling the segmentation of the eastern AASZ. Furthermore, the plate interface reflection signatures appear to increase significantly with depth and have been correlated to 1) seismogenic, 2) conditionally stable and, 3) aseismic slip behavior. The results confirm the spatial extent of rupture areas derived from existing information, such as aftershock locations, inverse tsunami waveform modelling and the intersection of a serpentinized mantle wedge. However, contrary to recent geodetic dislocation models that suggest a widely free slipping segment along the ASSZ (Shumagin Gap), the results suggest a seismogenic plate interface for this area that extents from the trench up to 100 km landward. A partially seismogenic Shumagin Gap area could become part of a great future megathrust event as shallow rupture is propagating into this area and exposing it to strong ground shaking and large tsunami waves, as it might have happened in the 18th and 19th century.
Author: Jeffrey T. Freymueller Publisher: American Geophysical Union ISBN: Category : Science Languages : en Pages : 446
Book Description
"This multi-disciplinary monograph provides the first modern integrative summary of the most spectacular active tectonic systems in North America. Encompassing seismology, tectonics, geology, and geodesy, it includes papers that summarize the state of knowledge, including background material for those unfamiliar with the region; address global hypotheses using data from Alaska; and test important global hypotheses using data from this region. It is organized around four major themes: subduction and great earthquakes at the Aleutian Arc; the transition from strike-slip to collision tectonics in the Yakutat Block accretion; the Denali fault and related structures and their role in accommodating permanent deformation of the overriding plate, and; regional integration and large-scale models, and the use of data from Alaska to address important global questions and hypotheses."--Cover description.
Author: Mitchell Grace Publisher: LAP Lambert Academic Publishing ISBN: 9783659430312 Category : Languages : en Pages : 64
Book Description
The Alaska-Aleutian subduction zone is among one of the most seismically active regions in the world with a history of megathrust earthquakes measuring up to Magnitude 9.2 (The 1964 Alaskan Earthquake). The largest earthquakes in the world occur at these subduction megathrusts and thus pose a great hazard to coastal communities. Seismicity in these subduction zones behaves differently along the margin and is in part controlled by the bathymetry and geometry of the down going portion of the lithosphere, which also varies along the strike of the margin. It is therefore of importance to understand the geometry of the subducting lithosphere to better understand seismic hazards along a subduction thrust. -- For imaging of the complex seafloor geometry, multichannel seismic profiles were acquired with the 6600 cu. in. source of the Langseth and two 8 km streamers, both perpendicular and parallel with the trench. The deep sea portion of a trench-normal line and a trench-parallel line were processed and interpreted to draw conclusions on implications the seafloor geometry will have on future seismicity.
Author: Serge Lallemand Publisher: Springer Science & Business Media ISBN: 3540879749 Category : Science Languages : en Pages : 278
Book Description
Subduction is a major process that plays a first-order role in the dynamics of the Earth. The sinking of cold lithosphere into the mantle is thought by many authors to be the most important source of energy for plates driving forces. It also deeply modifies the thermal and chemical structure of the mantle, producing arc volcanism and is responsible for the release of most of the seismic energy on Earth. There has been considerable achievements done during the past decades regarding the complex interactions between the various processes acting in subduction zones. This volume contains a collection of contributions that were presented in June 2007 in Montpellier (France) during a conference that gave a state of the art panorama and discussed the perspectives about "Subduction Zone Geodynamics". The papers included in this special volume offer a unique multidisciplinary picture of the recent research on subduction zones geodynamics. They are organized into five main topics: Subduction zone geodynamics, Seismic tomography and anisotropy, Great subduction zone earthquakes, Seismogenic zone characterization, Continental and ridge subduction processes. Each of the 13 papers collected in the present volume is primarily concerned with one of these topics. However, it is important to highlight that papers always treat more than one topic so that all are related lighting on different aspects of the complex and fascinating subduction zones geodynamics.
Author: Dhamsith Asiri Weerasinghe Publisher: ISBN: Category : Earth movements Languages : en Pages : 0
Book Description
The Alaska-Aleutian subduction zone is well known for several distinct long-term Slow Slip Events (SSEs) in the past. During the long-term SSE that occurred in the Upper Cook Inlet from 2008 to 2013, a short-term SSE was also observed in September 2010 which lasted three weeks. Visual analysis of the time series data from the GPS stations showed evidence for more potential short-term SSEs in the region. The objectives of this study are to identify these short-term SSEs using GPS time series data and compare the results with the available tremor data in the region for possible correlation. GPS time series data from 12 continuous stations in the Upper Cook Inlet area were analyzed. A hyperbolic tangent curve was used to fit the GPS time series data in a selected temporal window to obtain the surface displacements from the potential short-term SSEs. The surface displacements were then inverted for slip distribution on fault interface using the damped least square inversion method. This study identified 15 potential short-term SSEs in the region, with 11 events having correlation with the tremor time series. The results revealed that 5 of the short-term SSEs showed a typical trench normal (south-southeast) displacement, while 10 short-term SSEs showed trench parallel displacement (south-southwest), which has not been observed previously in the Alaska region. The moment magnitudes (Mw) of the short-term SSEs ranged from 6.81 to 7.54. The slip area of all the SSEs were located close to the proximity of the long-term SSE observed between 2008 and 2013. All 15 events showed an approximate area of fault slip ranging from around 11,300 km2 to 31,300 km2. It was also observed that the short-term SSEs occurred in depths ranging from about 36.5 to 91.05 km. The average depth of all the events was approximated to be 57.5 km, which lies up dip of the region where most of the tremors were observed.
Author: David W. Simpson Publisher: American Geophysical Union ISBN: Category : Nature Languages : en Pages : 698
Book Description
Published by the American Geophysical Union as part of the Maurice Ewing Series, Volume 4. From May 12 to May 16, 1980, eighty-eight scientists from eleven countries attended a Symposium on Earthquake Prediction at Mohonk Mountain House, Mohonk, New York. This was the third in a biennial series honoring Maurice Ewing, first director of Lamont-Doherty Geological Observatory. The Symposium was one of several events that were held in 1980 to celebrate the 100th anniversary of the Graduate School of Arts and Sciences at Columbia University. The two earlier Ewing Symposia, on island arcs and deep sea drilling, reflected Ewing's lifelong interest in the structure and evolution of the ocean floor. In the Third Ewing Symposium we touch another area—earthquake seismology—that played an important part in Ewing's career. Work on surface waves and long-period seismology under Ewing's direction during the 1950's and 1960's, along with his exploration of the earth beneath the oceans, provided much of the framework on which current ideas on earthquake generation and plate tectonics are based.
Author: John Eichelberger Publisher: John Wiley & Sons ISBN: 1118672003 Category : Science Languages : en Pages : 924
Book Description
Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 172 .The Kamchatka Peninsula and contiguous North Pacific Rim is among the most active regions in the world. Kamchatka itself contains 29 active volcanoes, 4 now in a state of semi-continuous eruption, and I has experienced 14 magnitude 7 or greater earthquakes since accurate recording began in 1962. At its heart is the uniquely acute subduction cusp where the Kamchatka and Aleutian Arcs and Emperor Seamount Chain meet. Volcanism and Subduction covers coupled magmatism and tectonics in this spectacular region, where the torn North Pacific slab dives into hot mantle. Senior Russian and American authors grapple with the dynamics of the cusp with perspectives from the west and east of it, respectively, while careful tephrostratigraphy yields a remarkably precise record of behavior of storied volcanoes such as Kliuchevskoi and Shiveluch. Towards the south, Japanese researchers elucidate subduction earthquake processes with unprecedented geodetic resolution. Looking eastward, new insights on caldera formation, monitoring, and magma ascent are presented for the Aleutians. This is one of the first books of its kind printed in the English language. Students and scientists beginning research in the region will find in this book a useful context and introduction to the region's scientific leaders. Others who wish to apply lessons learned in the North Pacific to their areas of interest will find the volume a valuable reference.
Author: Harold Kuehn
Author: Harold Kuehn
Author: Jeffrey T. Freymueller
Author: Mitchell Grace
Author: Serge Lallemand
Author: P. R. Vogt
Author: Dhamsith Asiri Weerasinghe
Author: David W. Simpson
Author: John Eichelberger
Author: George Plafker
Author: Zhijian Li