Preferred Direction of Damage to Concrete Block Fences in the M6.7 Northridge Earthquake of 17 January 1994

2002 ◽  
Vol 18 (2) ◽  
pp. 369-379 ◽  
Author(s):  
David L. Snyder ◽  
Glenn Borchardt
Keyword(s):  
Failure Rate ◽  
Concrete Block ◽  
Insurance Companies ◽  
Northridge Earthquake ◽  
Single Family ◽  
The South ◽  
Preferred Direction ◽  
The North ◽  
Structural Reinforcement ◽  
East West

The Northridge earthquake toppled three times more concrete block fences that were oriented east-west than those oriented north-south. Toppled fences were twice as likely to fall to the north as to the south. This was discovered during damage causation studies for insurance companies in our survey of more than 200 single-family residences within 29 km of the epicenter. Two hundred nineteen fences were built within 11 degrees of either north (55%) or east (45%), providing an opportunity to study the effect of orientation. Of those fences that were completely toppled, 19 were oriented east-west, while only 7 were oriented north-south. This preferred direction of damage for toppled fences was observed in all four quadrants about the epicenter and at distances of up to 17 km. In the NW quadrant, immediately above the aftershock zone, all toppled fences were oriented E-W, none were oriented N-S. The 58 fences oriented within 11 degrees of either NE or SE had no preferred direction of damage. In general, the failure rate for all 297 fences correlated with Modified Mercalli Intensity, location on alluvium as opposed to bedrock, and lack of structural reinforcement.

The arc of the Western Alps : understanding its kinematics and formation mechanisms based on new structural and paleomagnetic datas, and thermo-mechanical modelling.

2021 ◽  
Author(s):  
Quentin Brunsmann ◽  
Claudio Rosenberg ◽  
Nicolas Bellahsen ◽  
Laetitia Le Pourhiet
Keyword(s):  
Western Alps ◽  
Strike Slip ◽  
Rheological Parameters ◽  
The South ◽  
Adriatic Plate ◽  
The North ◽  
Field Evidence ◽  
Internal Zone ◽  
The Alps ◽  
East West

<p>The Alps have an overall East-West orientation, which changes radically in their western termination, where they rotate southward into a N-S strike, and then eastward into an E-W strike, forming the arc of the Western Alps. This arc is commonly inferred to have formed during collision, due to indentation of the Adriatic plate into the European continental margin. Several models attempted to provide a kinematic explanation for the formation of this arched, lateral end of the Alps. Indeed, the radial nature of the transport directions observed along the arc of the Western Alps cannot be explained by a classic convergence model.<br>For more than 50 years the formation of this arc was been associated to westward-directed indentation of Adria, accommodated along East-West oriented strike-slip faults, a sinistral one in the South of the arc and a dextral one in the North. The dextral one correspond to the Insubric Fault. The sinistral strike-slip zone, inferred to be localized along the «Stura corridor» (Piedmont, Italy) would correspond to a displacement of 100 to 150 km according to palaeogeographical, and geometric analyses. However, field evidence is scarce and barely documented in the literature.<br>Vertical axis rotations of the Adriatic indenter also inferred to be syn-collisional could have influenced the acquisition of the morphology of the arc. Paleomagnetic analyses carried out in the Internal Zone and in the Po plain suggest a southward increading amount of counter-clockwise rotation of the Adriatic plate and the Internal Zone, varying from 20°-25° in the North to nearly 120° in the South.<br>Dextral shear zones possibly accommodating this rotation in some conceptual models is observed in several places below the Penninic Front and affect the Argentera massif to the south. However, the measured displacement quantities do not appear to be equivalent to those induced by such rotations.<br>The present study aims to constrain the kinematic evolution of the arc of the Western Alps through a multidisciplinary approach. The first aspect of this project is the structural analysis of the area (Stura corridor) inferred to accommodate large sinistral displacements allowing for the westward indentation of the Adriatic indenter. We discuss the general lack of field evidence supporting sinistral strike-slip movements, in contrast to large-scale compilation of structures suggesting the possible occurrence of such displacement. The second part consists of a palaeomagnetic study, in which new data are integred with a compilation of already existing data. This compilation shows that several parts of the arc in the External Zone did not suffer any Cenozoic rotations, hence suggesting that a proto-arc already axisted at the onset collision, as suggested by independent evidence of some paleogeographic reconstruction. Finally, 2D and 3D thermo-mechanical modeling in using the pTatin3D code is used to test which structural (geometrical), and rheological parameters affected the first-order morphology of the Western Alpin arc and its kinematics. The synthesis of these different approaches allows us to propose a new model explaining the kinematics and the mechanisms of formation of the Western Alps arc.</p>

Part II. The Perseia Fountain House

1953 ◽  
Vol 48 ◽  
pp. 19-29 ◽  
Author(s):  
A. J. B. Wace ◽  
M. R. Holland ◽  
M. S. F. Hood ◽  
A. G. Woodhead
Keyword(s):  
Soft Rock ◽  
The South ◽  
South Side ◽  
The North ◽  
North Side ◽  
Exact Position ◽  
Fountain House ◽  
East West

In 1892 Tsountas in the course of exploration on the top of the ridge between the ‘Tomb of Clytemnestra’ and the Lion Gate found a painted circular cap of poros (o·61 m. in diameter), which from the cuttings in it clearly seems to have been connected with some form of installation for water (Plate 14, b). It bears an inscription which as restored refers to Perseus. This inscribed cap Tsountas says he found among later ruins, but he did not specify the exact position. In 1922 therefore we investigated the ruins of apparently Hellenistic date which lie directly to the south of the modern carriage road on the top of the ridge to the north of the ‘Tomb of Clytemnestra’. A long terrace wall of ashlar work in poros was found running in an east-west direction along the south side of the modern road. In front of it, against its north side, lie two cement-lined basins (Plate 14, a). When these were first found and partially examined in 1922 it was suggested that they might be part of a gymnasium of Hellenistic date. At the same time a trial trench XIa by side of the steps was dug down about 0·25 m. into the soft rock below. In 1939 further trials were made behind (to the south of) the western part of the main terrace wall. Trench VII, which was dug to rock, was part of this work. At the same time the curved wall was exposed and part of the ‘votive deposit’ was excavated. The pottery then found, which was lost in the Nauplia Museum during the war, was of the same character as that found in 1952 and described below. In 1952, as part of the programme of exploration on the top and sides of the ridge which runs westward from the Lion Gate, it was decided to clear these ruins completely and study and plan them afresh.

scholarly journals Compressional and extensional tectonics in low-medium pressure granulites from the Larsemann Hills, East Antarctica

1995 ◽  
Vol 132 (2) ◽  
pp. 151-170 ◽  
Author(s):  
C. J. Carson ◽  
P. G. H. M. Dirks ◽  
M. Hand ◽  
J. P. Sims ◽  
C. J. L. Wilson
Keyword(s):  
High Strain ◽  
Shear Bands ◽  
Shear Zones ◽  
The South ◽  
Medium Pressure ◽  
Larsemann Hills ◽  
The North ◽  
Shear Sense ◽  
Low Pressures ◽  
East West

AbstractMeta-sediments in the Larsemann Hills that preserve a coherent stratigraphy, form a cover sequence deposited upon basement of mafic–felsic granulite. Their outcrop pattern defines a 10 kilometre wide east–west trending synclinal trough structure in which basement–cover contacts differ in the north and the south, suggesting tectonic interleaving during a prograde, D1 thickening event. Subsequent conditions reached low-medium pressure granulite grade, and structures can be divided into two groups, D2 and D3, each defined by a unique lineation direction and shear sense. D2 structures which are associated with the dominant gneissic foliation in much of the Larsemann Hills, contain a moderately east-plunging lineation indicative of west-directed thrusting. D2 comprises a colinear fold sequence that evolved from early intrafolial folds to late upright folds. D3 structures are associated with a high-strain zone, to the south of the Larsemann Hills, where S3 is the dominant gneissic layering and folds sequences resemble D2 folding. Outside the D3 high-strain zone occurs a low-strain D3 window, preserving low-strain D3 structures (minor shear bands and upright folds) that partly re-orient D2 structures. All structures are truncated by a series of planar pegmatites and parallel D4 mylonite zones, recording extensional dextral displacements.D2 assemblages include coexisting garnet–orthopyroxene pairs recording peak conditions of ∼ 7 kbar and ∼ 780°C. Subsequent retrograde decompression textures partly evolved during both D2 and D3 when conditions of ∼ 4–5 kbar and ∼ 750°C were attained. This is followed by D4 shear zones which formed around 3 kbar and ∼ 550°C.It is tempting to combine D2–4 structures in one tectonic cycle involving prograde thrusting and thickening followed by retrograde extension and uplift. The available geochronological data, however, present a number of interpretations. For example, D2 was possibly associated with a clockwise P–T path at medium pressures around ∼ 1000 Ma, by correlation with similar structures developed in the Rauer Group, whilst D3 and D4 events occurred in response to extension and heating at low pressures at ∼ 550 Ma, associated with the emplacement of numerous granitoid bodies. Thus, decompression textures typical for the Larsemann Hills granulites maybe the combined effect of two separate events.

The 1977 Protocols: a landmark in the development of international humanitarian law

1997 ◽  
Vol 37 (320) ◽  
pp. 483-505 ◽  
Author(s):  
René Kosirnik
Keyword(s):  
Initial Period ◽  
The Political ◽  
International Humanitarian Law ◽  
Humanitarian Law ◽  
The South ◽  
The North ◽  
The World ◽  
The Hague ◽  
The Law ◽  
East West

By adopting on 8 June 1977 the two Protocols additional to the 1949 Conventions, the States meeting in Geneva brought to a successful conclusion four years of arduous negotiations. The Protocols took four years, the Conventions only four months. Why such a huge difference?In 1949, once the initial period of instinctive rejection of anything related to war had passed, a natural consensus emerged regarding the main evils which needed to be banned by law. Besides, the delicate subject of the rules governing the conduct of hostilities — the law of The Hague, as it is called, also part of humanitarian law — was left out of the discussions. It was also a time when the political map of the world was fairly monolithic, in the sense that the North still dominated the South, and East-West tensions had not yet escalated.

scholarly journals The Central Component Of Centaurus A

1966 ◽  
Vol 19 (3) ◽  
pp. 421 ◽  
Keyword(s):  
Central Component ◽  
The South ◽  
Central Source ◽  
The North ◽  
North Eastern ◽  
The Right ◽  
Right Ascension ◽  
East West ◽  
Centaurus A

Transit observations of Centaurus A with a fan beam 1'�5 wide at 73 cm show that the north-eastern component of the central source has an east-west width of 1'�7 and that the south-western source has a width of 2'�3. Since the situation at 9�1 cm is roughly the reverse of this, the two components must have sharply different spectra. The right ascensions observed are 13h 22m 48s . 0 and 13h 22m 20s�2�os�2 (1950). The right ascension of the centre of NGC5128 has been separately determined as 13h 22m 31s�6�os�3, showing that the two components are at significantly unequal distances from the optical object.

Déformation coaxiale en bordure de la discontinuité structurale de Lyndhurst, sous-province de l'Abitibi

1992 ◽  
Vol 29 (4) ◽  
pp. 783-792 ◽  
Author(s):  
Jean-Yves Labbé ◽  
Real Daigneault ◽  
Pierre A. Cousineau
Keyword(s):  
Structural Analysis ◽  
Deformation Zone ◽  
Thrust Fault ◽  
The South ◽  
Mesoscopic Scale ◽  
The North ◽  
The Poor ◽  
Crenulation Cleavage ◽  
Deformation Regime ◽  
East West

The Lyndhurst discontinuity is a major east–west structure located some 40 km north of Rouyn–Noranda. It separates the rhyolitic and sedimentary units of the Hunter Mine Group to the north from the basalts of the Kinojévis Group to the south. Evidence of deformation is observed only in the rhyolites and sediments along the south edge of the Hunter Mine Group. The deformation zone is approximately 1 km wide and is continuous for about 30 km. The Kinojévis Group rocks are not deformed. Deformed rhyolites show a strong sericite and chlorite alteration of hydrothermal origin. The competency of the rhyolites is significantly reduced by the presence of these phyllosilicates, which results in the deformation being preferentially localized in the more altered rocks. Competency contrasts observed on a mesoscopic scale are also valid on the microscopic and megascopic scales. The structural analysis of the deformation zone reveals different arrays that characterize three distinct sectors. These arrays reflect competency contrasts of the lithology and a crenulation cleavage. The stretching lineation is generally steeply plunging. Although the deformation seems significant in a zone contiguous to the Lyndhurst discontinuity, the poor development of the stretching lineation, the preservation of the original crystalline shapes of phenocrysts in the rhyolites, and the constant symmetry of the pressure shadows suggest a global coaxial deformation. This deformation regime is difficult to reconcile with a compressive fault such as a thrust fault.

scholarly journals On the location and structure of the artificial 630-nm airglow patch over Sura facility

2007 ◽  
Vol 25 (3) ◽  
pp. 689-700 ◽  
Author(s):  
S. M. Grach ◽  
M. J. Kosch ◽  
V. A. Yashnov ◽  
E. N. Sergeev ◽  
M. A. Atroshenko ◽  
...  
Keyword(s):  
Pump Beam ◽  
Atomic Oxygen ◽  
Optical Emission ◽  
The South ◽  
Heating Facility ◽  
The North ◽  
Straight Line ◽  
Northern Edge ◽  
Magnetic Zenith ◽  
East West

Abstract. Results are presented of the artificial optical emission of the atomic oxygen red line (the radiation of level O(1D) with a wavelength of 630 nm) from the HF-pumped ionosphere, obtained in September 2004 at the SURA heating facility situated near Nizhny Novgorod, Russia. For vertical pumping the airglow patch was increasingly displaced to the north, up to 7–8°, with increasing reflection altitude. For large brightness of the emission, the airglow patch started to develop at the northern edge of the pump beam and later expanded to the south. These effects are attributed to the precipitation of supra-thermal electrons from the pump wave upper hybrid resonance altitude to lower altitudes where excitation of the O(1D) level is more effective due to the larger density of atomic oxygen, and the O(1D) lifetime is shorter. For a pump beam inclination of 12° to the south, the optical spot was displaced by 4–5° to the south relative to the straight-line projection of the pump beam onto the sky. This exceeds that expected from the ray tracing and may be related, most probably, to the so-called "magnetic zenith" effect. In addition, mid-scale (1–10 km) magnetic field-aligned structures were observed in the pumped volume of the ionosphere. The east-west motions of the airglow patches are also analyzed.

Strain patterns of Sichuan and Yunnan, China from GPS data and comparison between seismic and geodetic moment release

2020 ◽  
Author(s):  
Jingyang Zhao ◽  
Yanqiang Wu ◽  
Hongbao Liang ◽  
Kaifu Du
Keyword(s):  
Strain Rate ◽  
Shear Strain ◽  
Earthquake Catalog ◽  
Shear Strain Rate ◽  
The South ◽  
Maximum Shear Strain ◽  
Block Boundary ◽  
The North ◽  
Geodetic Strain ◽  
East West

<p>We processed data from ~600 GPS stations, covering the period 1999-2018, to provide new insights into the crustal motion and deformation of Sichuan and Yunnan, China. We used the derived velocity field to evaluate two-dimensional strain rate tensors, and mapped the main, maximum shear, dilatation, east-west and north-south strain rates.The spatial distribution of the main strain rate in the Sichuan-Yunnan region generally shows an orderly deflection. The minimum principal strain rate is northeastward in the west of the Sichuan-Yunnan block boundary, gradually deflects eastward and southeastward toward the east and south, and returns to the northeast direction until the southwestern edge of Sichuan-Yunnan. This reflects the complex tectonic dynamics background of the study area. The high value of the maximum shear strain rate is mainly distributed along the eastern boundary of the Sichuan-Yunnan block, especially near the Xianshuihe-Xiaojiang fault, where the maximum shear strain rate exceeds 4.0 × 10<sup>-8</sup> / a. The area strain rate in the study region shows that the areas of compression and expansion are comparable, with weak tensions prevailing in the interior and compression in the marginal areas. The strain rate result also shows that the east-west strain rate component in the southern Sichuan-Yunnan is dominated by positive value, and the north is dominated by negative value. It indicates that the east-west deformation in the south of the Sichuan-Yunnan is dominated by expansion, and in the north is dominated by contraction. The north-south component strain rate shows that there is a significant positive high-value zone in and around the Xianshuihe fault zone, while southern Sichuan-Yunnan is a more significant negative-value zone, and the distribution of negative high-value zones is controlled by the south boundary of the Sichuan-Yunnan block. Based on the fault activity and focal mechanism data, the study area was divided into several seismic source zones. We translated the geodetic strain rates into rates of seismic moment release in each zone and compared them with earthquake catalog-based moment rates, to evaluate the potential of seismic activity of the region. The analysis shows the geodetic strain is completely released seismically for most of the study area. However, for the southern Yunnan，the geodesy-based moment rates are more than 2 times higher than the earthquake-based rates. This result indicates that at least a large earthquake may occur in southern Yunnan in the future.</p>

Thoughts on Utah Archaeology

1944 ◽  
Vol 9 (3) ◽  
pp. 319-328 ◽  
Author(s):  
Carling Malouf
Keyword(s):  
North America ◽  
Salt Lake ◽  
Salt Lake City ◽  
Maximum Height ◽  
The South ◽  
Wasatch Mountains ◽  
The North ◽  
Lake City ◽  
Number Of Passes ◽  
East West

Utah is nearly bisected north-south by the Wasatch Mountains. Between Ogden and Nephi, Utah, these mountains have undergone extensive folding and faulting and reach a maximum height of 12,000 feet at Mt. Timpanogas. South of Nephi this range branches into three great fingers with narrow valleys between. Flanking the Wasatch, east of Salt Lake City, are the lofty Uintah Mountains. These, unlike other ranges in North America, have an east-west axis forming a barrier between Pueblo-dominated lands to the south and the territory of nomads living in the Wyoming Basin to the north. Little evidence of Pueblo occupation has been observed in southeast Wyoming, though there are a number of passes through which occasional hunting parties from the plateaus to the south may have ventured north into the plains of southern Wyoming. This, of course, could only have occurred in the summer, as the area is free from snow for only three or four months of the year.

A shift in reptile diversity and abundance over the last 25 years

2019 ◽  
Vol 65 (1-2) ◽  
pp. 10-20
Author(s):  
Rachel Schwarz ◽  
Gavin Stark ◽  
Shai Meiri
Keyword(s):  
Habitat Preferences ◽  
Abundant Species ◽  
The South ◽  
Detection Ability ◽  
The North ◽  
Abundance Patterns ◽  
Reptile Species ◽  
Current Survey ◽  
Study Teams ◽  
East West

The south-facing slopes in canyons, oriented along an east-west axis north of the equator, are often hotter and drier than north-facing slopes, promoting differences in the biotic and abiotic characteristics of the opposing slopes. We studied how diversity and abundance patterns have changed in Oren stream (Carmel Mountains, Israel) during the last 25 years. We tested whether temperature and habitat preferences of reptiles affected observation frequencies, to assess potential effects of global warming on the reptiles. We compared the results of a 1993–1994 survey in Oren stream to a survey we conducted during 2017–2018, using similar methods, survey area and effort. Species composition and abundance in Oren stream did not significantly change between studies, but the proportion of observations differed significantly across slopes for four out of the six most abundant species. The number of observations increased monotonically with increasing temperatures on the south-facing slope, but decreased on the north-facing slope above a temperature of 22°C. The major biome species inhabit globally was unrelated to the number of observations across slopes or studies, but species inhabiting warmer ranges were more frequently observed in the current survey. Our results suggest that as global temperatures rise, reptile species which can tolerate higher temperatures, and those which can avoid the hottest temperatures of the day, may be able to cope better. These results however may also derive from better detection ability of some species over others between study teams.

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