Contribution to the investigation of small intermediate-depth earthquakes in the Vrancea region

Radu, Cornelius; Tobyáš, Vladimír

doi:10.1007/bf02585263

Cited by 5 publications

(3 citation statements)

References 3 publications

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“…Using numerous fault-plane solutions for intermediate-depth shocks, RADU (1967), NIKOLAEV andSHCHYUKIN (1975), andONCESCU andTRIFU (1987) show that the compressional axes are almost horizontal and directed SE-NW, and that the tensional axes are nearly vertical, suggesting that the slip is caused by gravitational forces.…”

Section: Introductionmentioning

confidence: 99%

Stress in the Descending Relic Slab beneath the Vrancea Region, Romania

Ismail‐Zadeh

Panza

Naimark

2000

Pure appl. geophys.

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We examine the effects of viscous flow, phase transition, and dehydration on the stress field of a relic slab to explain the intermediate-depth seismic activity in the Vrancea region. A 2-D finite-element model of a slab gravitationally sinking in the mantle predicts (1) downward extension in the slab as inferred from the stress axes of earthquakes, (2) the maximum stress occurring in the depth range of 70 km to 160 km, and (3) a very narrow area of the maximum stress. The depth distribution of the annual average seismic energy released in earthquakes has a shape similar to that of the depth distribution of the stress in the slab. Estimations of the cumulative annual seismic moment observed and associated with the volume change due to the basalt-eclogite phase changes in the oceanic slab indicate that a pure phase-transition model cannot solely explain the intermediate-depth earthquakes in the region. We consider that one of the realistic mechanisms for triggering these events in the Vrancea slab can be the dehydration of rocks which makes fluid-assisted faulting possible.

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Section: Introductionmentioning

confidence: 99%

Stress in the Descending Relic Slab beneath the Vrancea Region, Romania

Ismail‐Zadeh

Panza

Naimark

2000

Pure appl. geophys.

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“…In Romania, the first studies on ground motion models were developed by Lungu 1994 [16] and Radu 1994 [17]. The models were azimuth-dependent and predicted the peak ground acceleration (PGA).…”

Section: Ground Motion Modelmentioning

confidence: 99%

Ground Motion Model for Spectral Displacement of Intermediate-Depth Earthquakes Generated by Vrancea Seismic Source

Olteanu

Vǎcǎreanu

2020

Geosciences

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In support of displacement-based design (DBD), an attenuation model for the prediction of the spectral displacement of intermediate-depth earthquakes generated by Vrancea source is proposed. DBD is an alternative to force-based design, the main benefits being a better and confident description of the structural response and the removal of some of the inconsistencies of force-based code design. The basic input for DBD is the displacement response spectrum (DRS). Vrancea intermediate-depth source is responsible for the seismic hazard for most of the Romanian territory. The source produces, on average, two or three earthquakes with MW >7.0 per century, the prominent characteristics being the large displacement demand and large predominant periods (≈ 1.5 s) for sites located in the Romanian Plain. The model is applicable for sites positioned in front of the South-Eastern Carpathian Arc on type B and C soils. Equations predicting spectral displacement were developed by two-stage regression analysis, using a database containing national analog records of moderate-strong earthquakes and the available digital records, of smaller earthquakes. The model was extended for periods up to 8.0 s using national digital strong motion records and Japanese high-quality digital records of earthquakes triggered by a similar seismo-tectonic environment. The model successfully reproduced observed data, for both type B and C soils and the goodness of fit was tested using methods available in literature.

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“…In some cases, the observed data on the frequency of occurrence of earthquakes shows deviations from the linear trend of (1) or (2). Such cases are considered or analysed for example by Suzki (1959), Abe (1963), Niazi (1964), Mogi (1967), Suyehiro (1967), Radu & Tobyas (1968), Utsu (1968), Tomita and Utsu (1968), L~k k (1969,1971), Neunhofer (1969), Katsumata (1970), Shlien & Toksoz (1970), Nishida (1970), Butovskaya & Kuznetsova (1971), etc.…”

Section: Introductionmentioning

confidence: 99%

A New Magnitude-Frequency Relation for Earthquakes and a Classification of Relation Types

Purcaru

2007

Geophysical Journal of the Royal Astronomical Society

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In this paper some aspects of the deviations of frequency distributions of earthquakes from a linear trend are considered. For recurrence curves with inflexions, the formulais proposed as a magnitudefrequency relation, with critical magnitude Mcr. Comparison with actual data shows better agreement than other formulae. The slope of the frequency graph is considered in the most general case to be a function of M and some parameters p l , p z , ... .A classification of the types of magnitude-frequency relation is given and all known types of relations N : M and N : K (K = log E, E = seismic energy) are summarized.

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Contribution to the investigation of small intermediate-depth earthquakes in the Vrancea region

Cited by 5 publications

References 3 publications

Stress in the Descending Relic Slab beneath the Vrancea Region, Romania

Stress in the Descending Relic Slab beneath the Vrancea Region, Romania

Ground Motion Model for Spectral Displacement of Intermediate-Depth Earthquakes Generated by Vrancea Seismic Source

A New Magnitude-Frequency Relation for Earthquakes and a Classification of Relation Types

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