It has been suggested that crystalline “phase egg,” <svg style="vertical-align:-3.3907pt;width:73.337502px;" id="M1" height="16.450001" version="1.1" viewBox="0 0 73.337502 16.450001" width="73.337502" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><g transform="matrix(.017,-0,0,-.017,.062,12.162)"><path id="x41" d="M673 0h-245v28q47 6 58 16t1 39l-55 154h-213q-31 -87 -36 -129q-16 -47 -5 -61t68 -19v-28h-226v28q50 7 68.5 23.5t43.5 80.5l214 524l24 9l193 -536q23 -63 41.5 -79.5t68.5 -21.5v-28zM418 280l-81 255h-2q-74 -197 -101 -255h184z" /></g><g transform="matrix(.017,-0,0,-.017,11.843,12.162)"><path id="x6C" d="M238 0h-223v26q48 5 60 17t12 61v473q0 50 -10.5 60.5t-58.5 15.5v24q73 8 148 35v-608q0 -49 11.5 -61t60.5 -17v-26z" /></g><g transform="matrix(.017,-0,0,-.017,16.143,12.162)"><path id="x53" d="M409 504l-29 -5q-16 60 -44.5 96t-86.5 36q-54 0 -82.5 -32t-28.5 -77q0 -51 30.5 -82.5t96.5 -65.5l35.5 -18t33 -19.5t33.5 -23.5l27 -25.5t24.5 -32t13.5 -36.5t6 -45q0 -80 -62 -134.5t-160 -54.5q-47 0 -98 15q-22 7 -50 21q-8 23 -27 155l30 7q7 -27 18 -52&#xA;t30 -51.5t49 -42.5t67 -16q56 0 88 32.5t32 87.5q0 51 -31.5 82t-98.5 67q-80 44 -110 73q-55 53 -55 124q0 75 56 126.5t150 51.5q53 0 126 -23z" /></g><g transform="matrix(.017,-0,0,-.017,24.116,12.162)"><path id="x69" d="M135 536q-20 0 -35 15.5t-15 35.5q0 22 15 37t36 15t35.5 -15t14.5 -37q0 -21 -15 -36t-36 -15zM252 0h-220v26q48 5 59 17t11 63v206q0 47 -9 58t-54 18v24q78 12 142 39v-345q0 -51 11.5 -63t59.5 -17v-26z" /></g><g transform="matrix(.017,-0,0,-.017,28.671,12.162)"><path id="x4F" d="M381 665q131 0 226.5 -93t95.5 -239q0 -158 -96 -253t-238 -95q-137 0 -231 95t-94 238q0 142 92.5 244.5t244.5 102.5zM359 629q-89 0 -151 -74.5t-62 -208.5q0 -141 69 -233t175 -92q90 0 150.5 74t60.5 211q0 152 -69 237.5t-173 85.5z" /></g><g transform="matrix(.012,-0,0,-.012,41.375,16.25)"><path id="x33" d="M285 378v-2q65 -13 102 -54.5t37 -97.5q0 -57 -30.5 -104.5t-74 -75t-85.5 -42t-72 -14.5q-31 0 -59.5 11t-40.5 23q-19 18 -16 36q1 16 23 33q13 10 24 0q58 -51 124 -51q55 0 88 40t33 112q0 64 -39 96.5t-88 32.5q-29 0 -64 -11l-6 29q77 25 118 57.5t41 84.5&#xA;q0 45 -26.5 69.5t-68.5 24.5q-67 0 -120 -79l-20 20l43 63q51 56 127 56h1q66 0 107 -37t41 -95q0 -42 -31 -71q-22 -23 -68 -54z" /></g><g transform="matrix(.017,-0,0,-.017,47.7,12.162)"><use xlink:href="#x4F" /></g><g transform="matrix(.017,-0,0,-.017,60.262,12.162)"><path id="x48" d="M729 650v-28q-62 -5 -76 -19.5t-14 -75.5v-404q0 -62 13.5 -76t75.5 -19v-28h-268v28q65 5 79.5 19t14.5 76v199h-341v-199q0 -62 14 -76t76 -19v-28h-263v28q61 5 74.5 19t13.5 76v404q0 62 -14 76t-76 19v28h259v-28q-58 -5 -71 -19t-13 -76v-162h341v162&#xA;q0 61 -13.5 75.5t-72.5 19.5v28h261z" /></g></svg>, with a ratio <svg style="vertical-align:-2.22493pt;width:63.3125px;" id="M2" height="15" version="1.1" viewBox="0 0 63.3125 15" width="63.3125" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><g transform="matrix(.017,-0,0,-.017,.062,12.162)"><use xlink:href="#x41" /></g><g transform="matrix(.017,-0,0,-.017,11.843,12.162)"><use xlink:href="#x6C" /></g><g transform="matrix(.017,-0,0,-.017,16.143,12.162)"><path id="x2F" d="M368 703l-264 -866h-60l265 866h59z" /></g><g transform="matrix(.017,-0,0,-.017,23.147,12.162)"><use xlink:href="#x53" /></g><g transform="matrix(.017,-0,0,-.017,31.119,12.162)"><use xlink:href="#x69" /></g><g transform="matrix(.017,-0,0,-.017,40.384,12.162)"><path id="x3D" d="M535 323h-483v50h483v-50zM535 138h-483v50h483v-50z" /></g><g transform="matrix(.017,-0,0,-.017,55.087,12.162)"><path id="x31" d="M384 0h-275v27q67 5 81.5 18.5t14.5 68.5v385q0 38 -7.5 47.5t-40.5 10.5l-48 2v24q85 15 178 52v-521q0 -55 14.5 -68.5t82.5 -18.5v-27z" /></g></svg> could carry aluminum and water to the mantle but its natural occurrences are still speculative. An amorphous phase with a fixed and unique, deep metastable eutectic <svg style="vertical-align:-3.3907pt;width:60.4375px;" id="M3" height="16.450001" version="1.1" viewBox="0 0 60.4375 16.450001" width="60.4375" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"><g transform="matrix(.017,-0,0,-.017,.062,12.162)"><use xlink:href="#x41" /></g><g transform="matrix(.017,-0,0,-.017,11.843,12.162)"><use xlink:href="#x6C" /></g><g transform="matrix(.012,-0,0,-.012,16.162,16.25)"><path id="x32" d="M412 140l28 -9q0 -2 -35 -131h-373v23q112 112 161 170q59 70 92 127t33 115q0 63 -31 98t-86 35q-75 0 -137 -93l-22 20l57 81q55 59 135 59q69 0 118.5 -46.5t49.5 -122.5q0 -62 -29.5 -114t-102.5 -130l-141 -149h186q42 0 58.5 10.5t38.5 56.5z" /></g><g transform="matrix(.017,-0,0,-.017,22.5,12.162)"><use xlink:href="#x53" /></g><g transform="matrix(.017,-0,0,-.017,30.455,12.162)"><use xlink:href="#x69" /></g><g transform="matrix(.012,-0,0,-.012,35,16.25)"><use xlink:href="#x32" /></g><g transform="matrix(.017,-0,0,-.017,41.338,12.162)"><use xlink:href="#x4F" /></g><g transform="matrix(.012,-0,0,-.012,54.038,16.25)"><path id="x37" d="M447 623l8 -12l-283 -613l-74 -10l-7 11q174 283 297 551h-216q-48 0 -62.5 -12t-33.5 -63h-29q10 60 18 148h382z" /></g></svg> composition was produced in laboratory experiments wherein conditions favored kinetically controlled formation of amorphous solids. This experimentally produced kaolinite-dehydroxylate is highly reactive and it is proposed as the precursor of phase egg in subducting slabs of crustal rocks. If so, metastable phases play a role in subduction zones and it then follows that the processes and resulting conditions in these environments can be nonuniform and discontinuous at least at micrometer scales.

Frans J. M. Rietmeijer

Joseph A. Nuth

A Metastable Aluminosilica Compound for Aluminum and Water Transport to the Upper Mantle

Recognized meteorite impact features are relatively rare in the U.S. Midcontinent region, but recently with increased interest and research, the number has increased dramatically. We add another possibility to the growing list, the Edgerton structure in northwestern Miami County, Kansas. The feature is elliptical (&#x223C;5.5 &#x00D7; 6.5&#x2009;km, slightly elongated east-west) with radial surface drainage. The feature was first observed on hillshade maps of digitized topography of 7.5 minute quadrangles. Subsequent magnetic profiles show a higher magnetic value in the center of the ellipse with higher values around the edges; this shape is characteristic of an impact feature. Depth to the anomalous body is estimated to be about 1&#x2009;km, which puts it in the Precambrian crystalline basement under a cover of Paleozoic sediments. There are no deep boreholes in the vicinity and no seismic profiles are available. If it is an impact structure, it will be the second such feature documented in Kansas, the first being the Brenham meteorite crater at Haviland in Kiowa County in southwestern Kansas. It would be older than the other impact structures identified in the Midcontinent&#8212;Manson in Iowa, Ames in Oklahoma, Haswell Hole in Colorado, and possibly Belton in Missouri and Merna in Nebraska. There are at least two other prospective impact features in Kansas: the Goddard ring west of Wichita and Garden City ellipse north-west of Garden City.

Daniel  F. Merriam

Jianghai Xia

John W. Harbaugh

The Edgerton Structure: A Possible Meteorite Impact Feature in Eastern Kansas

Along the pacific margin offshore Costa Rica the Bottom Simulating Reflector (BSR) shows a patchy occurrence in 2-D seismic reflection profiles. The reason for this can be either lack of free gas beneath parts of the gas hydrate stability zone (GHSZ) or poor seismic imaging. We compare far to near offset stacked common midpoint sections to reduce imaging ambiguity utilizing the amplitude variation with offset effect and thus successfully distinguish BSRs from regular sediment reflections. In combination with 1-D modeling of the base of the GHSZ we disqualify or qualify reflections in the predicted depth range as BSR. Additionally we calculate the heat flow and compare it with an analytical solution to detect thermal anomalies, for example, at the frontal prism. The higher confidence in BSR depths based on the far offset stacks and heat flow calculations allows further analyses on gas hydrate concentration estimates and tectonic evolution of the margin.

Romina Gehrmann

Christian M&#xfc;ller

Peter Schikowsky

Thomas Henke

Michael Schnabel

Christian B&#xf6;nnemann

Model-Based Identification of the Base of the Gas Hydrate Stability Zone in Multichannel Reflection Seismic Data, Offshore Costa Rica

Various earthquake fault types, mechanism solutions and stress fields, as well as GPS and geothermal data are analyzed for the study of the crustal movements on the Tibetan plateau and their tectonic implications. The results show that a lot of the normal faulting type-event concentrated at altitudes greater than 4000 m on the central Tibetan plateau. The altitudes concentrating normal faulting type-events can be zoned two parts: the western part, the Lhasa block, and the eastern part, the Qiangtang-Changdu region. The azimuths of T-axes are in a general E-W direction in the Lhasa block and NW-SE or NNW-SSE in the Qiangtang-Changdu region at the altitudes of the Tibetan plateau. The tensional stresses in E-W direction and NW-SE direction predominate normal faulting earthquake occurrence in the Lhasa block and the Qiangtang-Changdu region, respectively. The slipping displacements of the normal-faulting-type events have great components in near E-W direction and NW-SE direction in the Lhasa block and the Qiangtang-Changdu region, respectively. The extensions are probably an eastward or southeastward extensional motion, being mainly tectonic activity phenomena in the plateau altitudes. The extensional motions due to normal-fault earthquakes are important tectonic activity regimes on the high altitudes of the plateau. The easterly crustal extensions on the plateau are attributable to the gravitational collapse of the high plateau and eastward extrusion of hotter mantle materials beneath the eastern boundary of the plateau. Numbers of thrust-fault and strike-slip-fault earthquakes with strong compressive stress in a general NNE-SSW direction occur on the edges of the plateau.

Jiren Xu

Zhixin Zhao

Extensional Seismogenic Stress and Tectonic Movement on the Central Region of the Tibetan Plateau

A gravimetric study was carried out in a region of the Central Andean Range between <svg     style="vertical-align:-0.1638pt;width:21.475px;" id="M1" height="13.1375" version="1.1" viewBox="0 0 21.475 13.1375" width="21.475"  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
			<g transform="matrix(.017,-0,0,-.017,.062,12.875)"><path id="x32" d="M412 140l28 -9q0 -2 -35 -131h-373v23q112 112 161 170q59 70 92 127t33 115q0 63 -31 98t-86 35q-75 0 -137 -93l-22 20l57 81q55 59 135 59q69 0 118.5 -46.5t49.5 -122.5q0 -62 -29.5 -114t-102.5 -130l-141 -149h186q42 0 58.5 10.5t38.5 56.5z" /></g><g transform="matrix(.017,-0,0,-.017,8.222,12.875)"><path id="x38" d="M249 635q70 0 116 -43t46 -105q0 -46 -28 -80q-22 -25 -80 -64q62 -35 97 -75t35 -99q0 -81 -63 -131t-135 -50q-83 0 -137.5 45.5t-54.5 123.5q0 52 45 95q29 28 89 64q-109 62 -109 155q0 66 50.5 115t128.5 49zM238 603q-42 0 -67.5 -31t-25.5 -72q0 -50 32.5 -79.5&#xA;t98.5 -62.5q61 48 61 124q0 59 -29.5 90t-69.5 31zM248 20q46 0 76.5 33.5t30.5 89.5q0 50 -39 85.5t-110 71.5q-81 -54 -81 -137q0 -67 35.5 -105t87.5 -38z" /></g>

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</svg> and <svg     style="vertical-align:-0.1638pt;width:21.475px;" id="M2" height="13.1375" version="1.1" viewBox="0 0 21.475 13.1375" width="21.475"  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
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			<g transform="matrix(.012,-0,0,-.012,16.375,4.712)"><use xlink:href="#x2218"/></g>

		
	
</svg> south latitudes 
 and from <svg     style="vertical-align:-0.1638pt;width:21.475px;" id="M3" height="13.1375" version="1.1" viewBox="0 0 21.475 13.1375" width="21.475"  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
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			<g transform="matrix(.012,-0,0,-.012,16.375,4.712)"><use xlink:href="#x2218"/></g>

		
	
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			<g transform="matrix(.017,-0,0,-.017,.062,12.875)"><path id="x36" d="M137 343l67 33q37 17 63 17q79 0 129.5 -53t50.5 -131q0 -92 -58 -156.5t-147 -64.5t-147 68t-58 182q0 63 17 119t43 95.5t61.5 72t69 52t67.5 31.5q62 22 128 33l6 -32q-56 -11 -108 -35q-149 -71 -184 -231zM227 337q-47 0 -95 -27q-6 -23 -6 -70q0 -93 36 -155.5&#xA;t96 -62.5q53 0 78 45.5t25 105.5q0 68 -35 116t-99 48z" /></g><g transform="matrix(.017,-0,0,-.017,8.222,12.875)"><use xlink:href="#x36"/></g>

			<g transform="matrix(.012,-0,0,-.012,16.375,4.712)"><use xlink:href="#x2218"/></g>

		
	
</svg> west longitudes. The seismological and gravimetrical Moho models were compared in a sector which coincides with the seismological stations of the CHARGE project. The comparison reveals discrepancies between the gravity Moho depths and those obtained from seismological investigations (CHARGE project), the latter giving deeper values than those resulting from the gravimetric inversion. These discrepancies are attenuated when the positive gravimetric effect of the Nazca plate is considered. Nonetheless, a small residuum of about 5&#x2009;km remains beneath the Cuyania terrane region, to the east of the main Andean chain. This residuum could be gravimetrically justified if the existence of a high density or eclogitized portion of the lower crust is considered. This result differed from the interpretations from Project &#x201c;CHARGE&#x201d; which revealed that the entire inferior crust extending from the Precordillera to the occidental &#x201c;Sierras Pampeanas&#x201d; could be &#x201c;eclogitized&#x201d;. In this same sector, we calculated the effective elastic thickness (Te) of the crust. These results indicated an anomalous value of Te = 30&#x2009;km below the Cuyania terrane. This is further conclusive evidence of the fact that the Cuyania terrane is allochthonous, for which also geological evidences exist.

Mario E. Gimenez

Carla Braitenberg

M. Patricia Martinez

Antonio Introcaso

A Comparative Analysis of Seismological and Gravimetric Crustal Thicknesses below the Andean Region with Flat Subduction of the Nazca Plate

The Eocene-Oligocene Makah Formation and subjacent middle Eocene Hoko River Formation of the northwestern Olympic Peninsula, Washington, yield mollusks, crustaceans, foraminifera, and early neocete whales; their age has never been precisely established. We sampled several sections; most samples showed a stable single-component remanence held largely in magnetite and passed a Class I reversal test. The upper Refugian (late Eocene) and lower Zemorrian (early Oligocene) rocks at Baada Point correlate with Chron C13r (33.7&#x2013;34.7 Ma) and Chron C12r (30&#x2013;33 Ma). The Ozette Highway section of the Makah Formation spanned the early Refugian to late Refugian, with a sequence that correlates with Chrons C15r-C13r (33.7&#x2013;35.3 Ma), and a long reversed early Zemorrian section that correlates with Chron C12r (30&#x2013;33 Ma). The type section of the Hoko River Formation correlates with Chron C18r (40.0&#x2013;41.2 Ma). The area sampled shows about <svg     style="vertical-align:-0.1638pt;width:21.475px;" id="M1" height="13.1375" version="1.1" viewBox="0 0 21.475 13.1375" width="21.475"  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
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</svg> of post-Oligocene counterclockwise tectonic rotation, consistent with results obtained from the Eocene-Oligocene rocks in the region.

Donald R. Prothero

Elizabeth Draus

Casey Burns

Magnetostratigraphy and Tectonic Rotation of the Eocene-Oligocene Makah and Hoko River Formations, Northwest Washington, USA

In the last years new methods of data acquisition and processing in geosciences, inspired by growing computer performance, have led to an increased amount of data, and this development will proceed surely. In this paper we present the conception and technical realization of an interdisciplinary research group's geodata management as a combination of a metadata catalog together with web mapping technology. Clearly related with the storage and retrieval of different datasets is the need of visualization. 3D visualization in geoscientific interpretation is a useful tool, if numerous, heterogenic datasets have to be visualized at the same time. Moreover, advanced sensing technology often generates native three-dimensional datasets. Using a case study from the Collaborative Research Centre “SFB 574”, we present the possibilities of our stereoscopic projection system and want to explain the benefit of 3D visualization for research in general and university education in particular, as low-cost systems become available nowadays.

T. Damm

H.-J. Götze

Modern Geodata Management: Application of Interdisciplinary Interpretation and Visualization in Central America

Most analyses of storm surge and inundation solve equations of continuity and momentum on fixed finite-difference/finite-element meshes. I develop a completely new approach that uses a momentum equation to accelerate bits or balls of water over variable depth topography. The thickness of the water column at any point equals the volume density of balls there. In addition to being more intuitive than traditional methods, the tsunami ball approach has several advantages. (a) By tracking water balls of fixed volume, the continuity equation is satisfied automatically and the advection term in the momentum equation becomes unnecessary. (b) The procedure is meshless in the finite-difference/finite-element sense. (c) Tsunami balls care little if they find themselves in the ocean or inundating land. (d) Tsunami ball calculations of storm surge can be done on a laptop computer. I demonstrate and calibrate the method by simulating storm surge and inundation around New Orleans, Louisiana caused by Hurricane Katrina in 2005 and by comparing model predictions with field observations. To illustrate the flexibility of the tsunami ball technique, I run two &#8220;What If&#8221; hurricane scenarios&#8212;Katrina over Savannah, Georgia and Katrina over Cape Cod, Massachusetts.

Steven N. Ward

A Tsunami Ball Approach to Storm Surge and Inundation: Application to Hurricane Katrina, 2005

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International Journal of Geophysics - Table of contents 2009

International Journal of Geophysics | Hindawi

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International Journal of Geophysics publishes research focused on all areas of theoretical, observational, applied and computational geophysics.

International Journal of Geophysics