Nonlinear frequency-magnitude relationships for the Hokkaido corner, Japan

1990 ◽  
Vol 80 (2) ◽  
pp. 340-353
Author(s):  
D. W. A. Taylor ◽  
J. A. Snoke ◽  
I. S. Sacks ◽  
T. Takanami
Keyword(s):  
Source Region ◽  
Pacific Plate ◽  
Common Origin ◽  
Maximum Depth ◽  
Nonlinear Frequency ◽  
Eurasian Plate ◽  
Epicentral Area ◽  
Magnitude Range ◽  
Hokkaido Island ◽  
Frequency Magnitude

Abstract Frequency-magnitude relationships are determined for a source region defined by a circular epicentral area of 50 km radius centered on the Carnegie broadband seismograph at KMU in the southeast corner of Hokkaido Island, Japan. Within this region, bounded by a maximum depth of 125 km, more than 11,100 earthquakes were detected and cataloged by the Hokkaido University network during the period July 1976 through January 1987. The seismicity is divided into two effectively decoupled suites: crustal (Eurasian plate) and subduction (Pacific plate). The frequency-magnitude recurrence distributions exhibit departures from linearity which are statistically significant below md = 2.5 for the crustal data suite and md = 3.5 for the subduction data suite. Three independent tests show the nonlinearity is not caused by incompleteness; the catalog is complete down to magnitude 2.0 or less for both data suites. These observations are therefore inconsistent with the linear Gutenberg-Richter relationship, which is assumed to be valid over any magnitude range for which the data are complete. There are relatively more large events and fewer small events in the subduction suite. The logarithm of the ratio of the number of crustal events to the number of subduction events versus magnitude is monotonically decreasing and remarkably linear over the magnitude range 1.0 to 5.0. This suggests that the observed nonlinearity of these two frequency-magnitude relationships has a common origin.

scholarly journals The foreshock activity of the 1971 San Fernando earthquake, California

1978 ◽  
Vol 68 (5) ◽  
pp. 1265-1279
Author(s):  
Mizuho Ishida ◽  
Hiroo Kanamori
Keyword(s):  
Small Area ◽  
Main Shock ◽  
Source Region ◽  
Structural Heterogeneity ◽  
Propagation Path ◽  
Wave Form ◽  
Epicentral Area ◽  
Complex Wave ◽  
Wave Forms ◽  
San Fernando

abstract All of the earthquakes which occurred in the epicentral area of the 1971 San Fernando earthquake during the period from 1960 to 1970 were relocated by using the master-event method. Five events from 1969 to 1970 are located within a small area around the main shock epicenter. This cluster of activity is clearly separated spatially from the activity in the surrounding area, so these five events are considered foreshocks. The wave forms of these foreshocks recorded at Pasadena are, without exception, very complex, yet they are remarkably similar from event to event. The events which occurred in the same area prior to 1969 have less complex wave forms with a greater variation among them. The complexity is most likely the effect of the propagation path. A well located aftershock which occurred in the immediate vicinity of the main shock of the San Fernando earthquake has a wave form similar to that of the foreshocks, which suggests that the foreshocks are also located very close to the main shock. This complexity is probably caused by a structural heterogeneity in the fault zone near the hypocenter. The seismic rays from the foreshocks in the inferred heterogeneous zone are interpreted as multiple-reflected near the source region which yielded the complex wave form. The mechanisms of the five foreshocks are similar to each other but different from either the main shock or the aftershocks, suggesting that the foreshocks originated from a small area of stress concentration where the stress field is locally distorted from the regional field. The number of small events with S-P times between 3.8 to 6 sec recorded at Mt. Wilson each month suggests only a slight increase in activity of small earthquakes near the epicentral area during the 2-month period immediately before the main shock. However, because of our inability to locate these events, the evidence is not definitive. Since the change in the wave forms is definite the present result suggests that detailed analyses of wave forms, spectra, and mechanism can provide a powerful diagnostic method for identifying a foreshock sequence.

scholarly journals Geochemical Characterization of Intraplate Magmatism from Quaternary Alkaline Volcanic Rocks on Jeju Island, South Korea

2021 ◽  
Vol 11 (15) ◽  
pp. 7030
Author(s):  
Cheolhong Kim ◽  
Naing Aung Khant ◽  
Yongmun Jeon ◽  
Heejung Kim ◽  
Chungwan Lim
Keyword(s):  
Fractional Crystallization ◽  
Upper Mantle ◽  
Volcanic Rocks ◽  
Pacific Plate ◽  
Mantle Xenoliths ◽  
Jeju Island ◽  
Eurasian Plate ◽  
Intraplate Magmatism ◽  
The Pacific ◽  
Host Basalt

The major and trace elements of Quaternary alkaline volcanic rocks on Jeju Island were analyzed to determine their origin and formation mechanism. The samples included tephrite, trachybasalts, basaltic trachyandesites, tephriphonolites, trachytes, and mantle xenoliths in the host basalt. Although the samples exhibited diversity in SiO2 contents, the relations of Zr vs. Nb and La vs. Nb indicated that the rocks were formed from the fractional crystallization of a single parent magma with slight continental crustal contamination (r: 0–0.3 by AFC modeling), rather than by the mixing of different magma sources. The volcanic rocks had an enriched-mantle-2-like ocean island basalt signature and the basalt was formed by partial melting of the upper mantle, represented by the xenolith samples of our study. The upper mantle of Jeju was affected by arc magmatism, associated with the subduction of the Pacific Plate beneath the Eurasian Plate. Therefore, we inferred that two separate magmatic events occurred on Jeju Island: one associated with the subduction of the Pacific Plate beneath the Eurasian Plate (represented by xenoliths), and another associated with a divergent setting when intraplate magmatism occurred (represented by the host rocks). With AFC modeling, it can be proposed that the Jeju volcanic rocks were formed by the fractional crystallization of the upper mantle combined with assimilation of the continental crust. The xenoliths in this study had different geochemical patterns from previously reported xenoliths, warranting further investigations.

scholarly journals Pemakaian Bracing Pada Bangunan Tahan Gempa dengan Analisis Pushover (The Usage of Bracing on Earthquake Resistant Buildings with Pushover Analysis)

2016 ◽  
Vol 1 (01) ◽  
pp. 84
Author(s):  
Dwi Wahyu Anggraeni ◽  
Erno Widayanto ◽  
Dwi Nurtanto
Keyword(s):  
Collision Energy ◽  
Pushover Analysis ◽  
Pacific Plate ◽  
Earthquake Response ◽  
Eurasian Plate ◽  
High Rise ◽  
Australian Plate ◽  
The Pacific ◽  
Earthquake Resistant ◽  
The Difference

AbstractMost of Indonesia area is an earthquake- prone region. This is caused by the confluence of three major plates world that are subduction. Indo-Australian Plate colliding with the Eurasian plate off the coast of Sumatra, Java and Nusa Tenggara, while the Pacific plate in northern Guinea and North Maluku. In the vicinity of the meeting location this plate collision energy accumulated in the form of earthquake. The quake destroyed much of the multi-storey buildings that do not have adequate strength. Therefore , the higher the building, the greater the effects of the earthquake were received by the building. One way to acquire resistance to earthquake response was to add rigidity to a building. How to obtain the stiffness of a building is to install bracing for high-rise buildings. The purpose of this analysis was conducted to determine usage behavior particularly bracing displacement. The Results of this analysis showed a reduction in horizontal deviation of the building due to the addition of frame bracing. The difference in the percentage of horizontal deviation without bresing building and building using bresing X is 82.519%. While the difference in the percentage of horizontal deviation without order bresing building and building using bresing V is 64.904%.Keywords: pushover analysis , bracing, displacement,earthquake AbstrakSebagian besar wilayah Indonesia merupakan wilayah rawan gempa. Hal ini disebabkan oleh pertemuan tiga lempeng utama dunia yang bersifat subdaksi. Lempeng Indo- Australia bertabrakan dengan lempeng Eurasia di lepas pantai Sumatra, Jawa dan Nusa Tenggara, sedangkan lempeng Pasific di utara Irian dan Maluku Utara. Di sekitar lokasi pertemuan lempeng ini akumulasi energi tabrakan terkumpul sehingga lepas berupa gempa bumi. Gempa banyak menghancurkan bangunan- bangunan bertingkat yang tidak mempunyai kekuatan yang memadai. Oleh karena itu, semakin tinggi bangunan maka semakin besar pula efek gempa yang diterima oleh bangunan tersebut. Salah satu cara untuk memperoleh ketahanan terhadap respon gempa adalah menambah kekakuan pada suatu bangunan. Cara memperoleh kekakuan suatu bangunan adalah dengan memasang pengekang (bracing) untuk bangunan tinggi. Tujuan dari analisa ini dilakukan untuk mengetahui perilaku pemakaian bracing khususnya displacement. Hasil dari analisa ini menunjukkan terjadinya pengurangan simpangan horizontal gedung karena adanya penambahan rangka bracing. Selisih presentase simpangan horizontal gedung tanpa bresing dan gedung dengan menggunakan bresing X adalah 82,519%. Sedangkan selisih presentase simpangan horizontal gedung tanpa rangka bresing dan gedung dengan menggunakan bresing V adalah 64,904%.Kata kunci: analisa pushover , bracing, displacement, gempa

Detrital zircon geochronology of Late Cretaceous successions in the Ganzhou basin, South China: Evidence of a major tectonic transition

2022 ◽  
pp. SP521-2021-168
Author(s):  
Jun Wang ◽  
Yujie Yuan ◽  
Dexian Zhang ◽  
Su-Chin Chang
Keyword(s):  
Late Cretaceous ◽  
South China ◽  
Detrital Zircon ◽  
Pacific Plate ◽  
Eurasian Plate ◽  
Content Type ◽  
Detrital Zircon Geochronology ◽  
Tectonic Transition ◽  
Supplementary Material ◽  
Lacustrine Facies

AbstractSituated within the southern segment of the South China Block (SCB), the Ganzhou Basin formed due to subduction of the paleo-Pacific plate beneath to the SCB. Late Cretaceous successions in this basin consist of fluvial and lacustrine facies red beds hosting abundant dinosaur and dinosaur egg fossils. This study reports detrital zircon geochronological data from a crystallized tuff and four sandstones found in the Late Cretaceous Ganzhou Group of the Ganzhou Basin. Age distributions included four major age subpopulations of predominantly Triassic, Devonian-Ordovician, Neoproterozoic and Paleoproterozoic ages. These indicate source material derived from Yanshanian and Triassic granitoids as well as from Kwangsian and Jiangnan orogens. Age signatures generally resemble those recorded in the adjacent Nanxiong Basin but also include distinctive features. Provenance signatures from successive units indicate a tectonic transition from intracontinental extension at ∼120 Ma to compression near the Cretaceous/Paleogene boundary. This tectonic transition was probably driven by continent-continent collision between the Indian and Eurasian plates, as well as by a shift in the subduction direction of the paleo-Pacific plate beneath the Eurasian plate.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5776518

Damage to Civil Engineering Structures by Oct. 8, 2005 Kashmir Earthquake and Recommendations for Recovery and Reconstruction

2006 ◽  
Vol 1 (3) ◽  
pp. 435-443 ◽  
Author(s):  
Ömer Aydan ◽  
◽  
Masanori Hamada ◽  
Keyword(s):  
River Flow ◽  
Indian Plate ◽  
Slope Failures ◽  
Eurasian Plate ◽  
Rock Falls ◽  
Engineering Structures ◽  
Ground Acceleration ◽  
Kashmir Earthquake ◽  
Epicentral Area ◽  
2005 Kashmir Earthquake

At 8:50 (3:50 UTC) on October 8, 2005, a huge earthquake devastated Kashmir in Pakistan. Depth and magnitude were estimated 10 km and 7.6, respectively. The earthquake resulted from subduction of Indian plate beneath the Eurasian plate, and thrust faulting. Despite lack of no surface ruptures from as faulting, extensive slope failures occurred along the expected surface trace of the causative fault. Maximum ground acceleration for Balakot was estimated to exceed 0.9 g, based on overturned vehicles parallel to the valley axis. This probably represents the largest ground acceleration near the epicenter. Balakot is on the hangingwall side of the causative fault. One of the most distinct characteristics of 2005 Kashmir earthquake is the widespread slope failures all over the epicentral area. The earthquake extensively damaged housing and structures on sloping soil deposits. Extensive natural and cut-slope failures occurred along the Neelum, Jhelum and Kunhar valleys obstructing both river flow and roads. Many slope failures associated with highly sheared and weathered dolomitic limestone occurred along the presumed surface trace of the earthquake fault. Given the topography and possibility of slope failures, several alternative routes involving the construction of viaducts, tunnels and bridges are desirable in the area against road blockage by rock falls and slope failures.

Progress in the compilation of the FK5

1978 ◽  
Vol 48 ◽  
pp. 421-432 ◽  
Author(s):  
W. Fricke ◽  
W. Gliese
Keyword(s):  
Status Report ◽  
Magnitude Range

Abstract:Presented is a status report on work on FK5 giving information on the following items: (a) the intended increase of the number of fundamental stars and their magnitude range in FK5, (b) available material for the improvement of the system, (c) methods for the determination of systematic differences, (d) the determination of equator and equinox of FK5, and (e) the elimination of the motion of the FK4 equinox.

The S-SH Confusion Test and the Effects of Frequency Lowering

2019 ◽  
Vol 62 (5) ◽  
pp. 1486-1505
Author(s):  
Joshua M. Alexander
Keyword(s):  
Cognitive Processing ◽  
Hearing Aids ◽  
Response Times ◽  
Nonlinear Frequency ◽  
Low Frequencies ◽  
Frequency Compression ◽  
Negative Side ◽  
Minimal Word ◽  
Low Pass ◽  
Negative Side Effects

PurposeFrequency lowering in hearing aids can cause listeners to perceive [s] as [ʃ]. The S-SH Confusion Test, which consists of 66 minimal word pairs spoken by 6 female talkers, was designed to help clinicians and researchers document these negative side effects. This study's purpose was to use this new test to evaluate the hypothesis that these confusions will increase to the extent that low frequencies are altered.MethodTwenty-one listeners with normal hearing were each tested on 7 conditions. Three were control conditions that were low-pass filtered at 3.3, 5.0, and 9.1 kHz. Four conditions were processed with nonlinear frequency compression (NFC): 2 had a 3.3-kHz maximum audible output frequency (MAOF), with a start frequency (SF) of 1.6 or 2.2 kHz; 2 had a 5.0-kHz MAOF, with an SF of 1.6 or 4.0 kHz. Listeners' responses were analyzed using concepts from signal detection theory. Response times were also collected as a measure of cognitive processing.ResultsOverall, [s] for [ʃ] confusions were minimal. As predicted, [ʃ] for [s] confusions increased for NFC conditions with a lower versus higher MAOF and with a lower versus higher SF. Response times for trials with correct [s] responses were shortest for the 9.1-kHz control and increased for the 5.0- and 3.3-kHz controls. NFC response times were also significantly longer as MAOF and SF decreased. The NFC condition with the highest MAOF and SF had statistically shorter response times than its control condition, indicating that, under some circumstances, NFC may ease cognitive processing.ConclusionsLarge differences in the S-SH Confusion Test across frequency-lowering conditions show that it can be used to document a major negative side effect associated with frequency lowering. Smaller but significant differences in response times for correct [s] trials indicate that NFC can help or hinder cognitive processing, depending on its settings.

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