scholarly journals A new earthquake catalogue for Bulgaria and the conterminous Balkan high hazard region

2007 ◽  
Vol 7 (3) ◽  
pp. 345-359 ◽  
Author(s):  
T. J. Bayliss ◽  
P. W. Burton
Keyword(s):  
Seismic Hazard Assessment ◽  
Earthquake Catalogue ◽  
Time Interval ◽  
Magnitude Conversion ◽  
Historical Catalogue ◽  
Balkan Area ◽  
High Hazard ◽  
Instrumental Period ◽  
Conversion Equation ◽  
International Seismological Centre

Abstract. A new homogenous earthquake catalogue covering Bulgaria and the surrounding Balkan area has been created with intention of performing a consistent seismic hazard assessment across the region. In keeping with modern requirements of cataloguing seismicity, this catalogue has been made homogenous as far as possible with regards to magnitude, which has been provided on any of four different reported scales for each event; mb, Ms, Mw and ML. A key historical catalogue for the region has been used to represent the early instrumental period of earthquake recording (1900 to 1963), whilst data have been obtained from the International Seismological Centre (ISC), National Earthquake Information Center (NEIC) and National Observatory of Athens (NOA) to cover the instrumental period of earthquake recording (1964 to 2004). ISC data have also been used to develop a new mb→Ms magnitude conversion equation for the catalogued region. Application of this new magnitude conversion relation, in combination with other selected magnitude scale correlations, ensures reported magnitudes can be systematically rendered onto homogenized Ms and Mw scales for all earthquakes. This catalogue contains 3681 events with homogenized magnitudes ≥4.0 Mw, for the time interval 1900 to 2004 (inclusive), located in the region bounded by 39°–45° N, 19°–29° E, at focal depths of 0.0 km to 401.0 km and in a magnitude range 4.0≤Mw≤7.2. Selected large magnitude (M≥6.0 Ms) earthquakes have had their reported magnitudes reassessed – and adjusted if necessary – in light of work by other authors. Applied statistical approaches aimed at determining the lower threshold to magnitude completeness suggest this catalogue is complete down to a homogenized surface-wave magnitude of 4.6 Ms.

Impact of earthquakes and its dependence on magnitude: testing the Greek seismicity

2020 ◽  
Author(s):  
Ioanna Triantafyllou ◽  
Gerassimos Papadopoulos ◽  
Efthimios Lekkas
Keyword(s):  
Time Interval ◽  
Environment Impact ◽  
Earthquake Catalogues ◽  
Earthquake Parameters ◽  
Gradual Improvement ◽  
Research And Innovation ◽  
Magnitude Conversion ◽  
Property Losses ◽  
Instrumental Period ◽  
Earthquake Impact

<p>Strong earthquakes cause significant impact on both the built and natural environment. Impact databases are of fundamental importance for seismic risk assessment in a region. Such data include human and property losses as well as secondary effects including ground failures and tsunamis. The earthquake impact, EI, depends on many factors, one of the most important being the earthquake magnitude, M. To test the dependence of EI on M we selected the Greek seismicity which is the highest in the Mediterranean region with record of earthquakes since the antiquity. Although various descriptive and parametric earthquake catalogues as well as inventories of intensity observation points are available for Greece no database for EI has been organized so far. For a first time we organized a Greek Earthquake Impact Database (GEID) which covers the time interval from 1800 to 2019 and includes earthquake parameters and three main quantitative impact elements: building damage, fatalities and injuries. Data on tsunami impact are also included in the GEID. A long number of sources have been utilized, some of them remaining unknown so far in the seismological community. To select the most appropriate magnitude for each earthquake event occurring in the instrumental period of seismology, i.e. from 1900 onwards, we compared the catalogues produced by the ISC-GEM and by three academic institutions. After completeness testing and examination for magnitude homogeneity we performed magnitude closeness analysis and produced formulas for magnitude conversion from one catalogue to another. For the 19<sup>th</sup> century earthquakes we again compared various catalogues, collected new data from documentary sources and compiled a new catalogue by re-calculating macroseismic magnitudes equivalent to Mw from intensity/M relations developed for Greek earthquakes of the instrumental period. We found that for single earthquake events the level of impact generally depends on magnitude but this is not valid for offshore events. However, the time distribution of the three impact elements over the period examined showed a relative decrease of the totally collapsed buildings which implied drastic decrease of the fatality rate but not of the injuries rate. This is attributed to the gradual improvement of the building construction particularly after the enforcement of antiseismic building codes in the country. Τhe first author was supported by the Hellenic Foundation for Research and Innovation (HFRI) and the General Secretariat for Research and Technology (GSRT), under the HFRI PhD Fellowship grant (GA. no. 490).</p>

scholarly journals Tectonic Geomorphology and Paleoseismology of the Sharkhai fault: a new source of seismic hazard for Ulaanbaatar (Mongolia)

2021 ◽  
Author(s):  
Abeer Al-Ashkar ◽  
Antoine Schlupp ◽  
Matthieu Ferry ◽  
Ulziibat Munkhuu
Keyword(s):  
Seismic Hazard ◽  
Scaling Laws ◽  
Active Faults ◽  
Seismic Hazard Assessment ◽  
Capital City ◽  
Tectonic Geomorphology ◽  
Time Interval ◽  
Coseismic Slip ◽  
Slip Rates ◽  
Large Earthquakes

Abstract. We present new constraints from tectonic geomorphology and paleoseismology along the newly discovered Sharkhai fault near the capital city of Mongolia. Detailed observations from high resolution Pleiades satellite images and field investigations allowed us to map the fault in detail, describe its geometry and segmentation, characterize its kinematics, and document its recent activity and seismic behavior (cumulative displacements and paleoseismicity). The Sharkhai fault displays a surface length of ~40 km with a slightly arcuate geometry, and a strike ranging from N42° E to N72° E. It affects numerous drainages that show left-lateral cumulative displacements reaching 57 m. Paleoseismic investigations document the faulting and deposition record for the last ~3000 yr and reveal that the penultimate earthquake (PE) occurred between 1515 ± 90 BC and 945 ± 110 BC and the most recent event (MRE) occurred after 860 ± 85 AD. The resulting time interval of 2080 ± 470 years is the first constraint on the Sharkhai fault for large earthquakes. On the basis of our mapping of the surface rupture and the resulting segmentation analysis, we propose two possible scenarios for large earthquakes with likely magnitudes between 6.4 ± 0.2 and 7.1 ± 0.2. Furthermore, we apply scaling laws to infer coseismic slip values and derive preliminary estimates of long-term slip rates between 0.2 ± 0.2 and 1.0 ± 0.5 mm/y. Finally, we propose that these original observations and results from a newly discovered fault should be taken into account for the seismic hazard assessment for the city of Ulaanbaatar and help build a comprehensive model of active faults in that region.

scholarly journals An updated and unified earthquake catalog from 1787 to 2018 for seismic hazard assessment studies in Mexico

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Rashad Sawires ◽  
Miguel A. Santoyo ◽  
José A. Peláez ◽  
Raúl Daniel Corona Fernández
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
Large Earthquake ◽  
Seismic Source ◽  
Earthquake Catalog ◽  
Magnitude Conversion ◽  
Seismic Source Models ◽  
Source Models ◽  
Definition Of

Abstract Here we present a new updated and unified Poissonian earthquake catalog for Mexico. The details about the catalog compilation, the removal of duplicate events, unifying the magnitude scales, removal of dependent events through the declustering process and its completeness analysis are presented. Earthquake and focal mechanism data have been compiled from various local, regional and international sources. Large earthquake events (MW ≥ 6.5) have been carefully revised for their epicentral locations and magnitudes from trusted publications. Different magnitude-conversion relationships, compatible with available local and regional ones, has been established to obtain unified moment magnitude estimates for the whole catalog. Completeness periods for the declustered catalog were estimated for the definition of appropriate seismic source models for the whole territory. The final unified Poissonian earthquake catalog spans from 1787 to 2018, covering a spatial extent of 13° to 33°N and 91° to 117°W. This catalog is compatible with other published catalogs providing basis for new analysis related to seismicity, seismotectonics and seismic hazard assessment in Mexico.

scholarly journals A Homogeneous Earthquake Catalogue for Turkey and Surrounding Region

2020 ◽  
Author(s):  
Onur Tan
Keyword(s):  
Bootstrap Method ◽  
Regression Method ◽  
Earthquake Catalogue ◽  
Magnitude Of Completeness ◽  
The Caucasus ◽  
Earthquake Parameters ◽  
Orthogonal Regression ◽  
The Balkans ◽  
International Seismological Centre ◽  
The Bootstrap Method

Abstract. A new earthquake catalogue for Turkey and surrounding region (32°–47° N, 20°–52° E) is compiled for the period 1900–2017. The earthquake parameters are obtained from the Bulletin of International Seismological Centre that is fully updated in 2020. New conversion equations between moment magnitude and the other scales (md, ML, mb, Ms and M) are determined using in the General Orthogonal Regression method to build up a homogeneous catalogue, which is the essential data for seismic hazard studies. The 95 % confidence intervals are estimated using the bootstrap method with 1000 samples. The equivalent moment magnitudes (Mw*) for the entire catalogue are calculated using the magnitude relations to homogenise the catalogue. The magnitude of completeness is 2.9 Mw* and 3.0–3.2 Mw* for Turkey and Greece generally. The final dataset is not declustered or truncated using a threshold magnitude because of motivation for generating a widely usable catalogue. It contains not only Mw*, but also the average and median of the observed magnitudes for each event. Contrary to the limited earthquake parameters in the previous catalogues, the 45 parameters of approximately 700 k events occurred in a wide area from the Balkans to the Caucasus are presented.

scholarly journals A homogeneous earthquake catalogue for Turkey

2021 ◽  
Vol 21 (7) ◽  
pp. 2059-2073
Author(s):  
Onur Tan
Keyword(s):  
Seismic Hazard ◽  
Bootstrap Method ◽  
Regression Method ◽  
Earthquake Catalogue ◽  
The Other ◽  
Magnitude Of Completeness ◽  
Earthquake Parameters ◽  
Orthogonal Regression ◽  
International Seismological Centre ◽  
The Bootstrap Method

Abstract. A new homogenized earthquake catalogue for Turkey is compiled for the period 1900–2018. The earthquake parameters are obtained from the Bulletin of International Seismological Centre that was fully updated in 2020. New conversion equations between moment magnitude and the other scales (md, ML, mb, Ms, and M) are determined using the general orthogonal regression method to build up a homogeneous catalogue, which is the essential database for seismic hazard studies. The 95 % confidence intervals are estimated using the bootstrap method with 1000 samples. The equivalent moment magnitudes (Mw*) for the entire catalogue are calculated using the magnitude relations to homogenize the catalogue. The magnitude of completeness is 2.7 Mw*. The final catalogue is not declustered or truncated using a threshold magnitude in order to be a widely usable catalogue. It contains not only Mw* but also the average and median of the observed magnitudes for each event. Contrary to the limited earthquake parameters in the previous catalogues for Turkey, the 45 parameters of ∼378 000 events are presented in this study.

scholarly journals SEMI-MARKOV MODELS FOR SEISMIC HAZARD ASSESSMENT IN CERTAIN AREAS OF GREECE

2017 ◽  
Vol 43 (4) ◽  
pp. 2200
Author(s):  
I. Votsi ◽  
N. Limnios ◽  
G. Tsaklidis ◽  
E. Papadimitriou
Keyword(s):  
Markov Process ◽  
Seismic Hazard ◽  
Markov Models ◽  
Transition Probabilities ◽  
Waiting Times ◽  
Parametric Method ◽  
Seismic Hazard Assessment ◽  
Aegean Sea ◽  
Discrete State ◽  
Historical Catalogue

The long-term probabilistic seismic hazard is studied through the application of semi-Markov model. In this model a sequence of earthquakes is considered as a Markov process and the waiting time distributions depend only on the type of the last and the next event. The principal hypothesis of the model is the property of one-step memory, according to which the probability of moving to any future state depends only on the present state. The model under consideration defines a continuous-time, discrete-state stationary process in which successive state occupancies are governed by the transition probabilities of the Markov process. The space of states is considered to be finite and the process started far in the past has achieved stationarity. Firstly, a non-parametric method is applied in order to determine the waiting times. Then, the waiting times derived by means of the exponential and Weibull distributions will be compared to each other, as well as with the actual waiting times. Thus, the probability of occurrence of the anticipated earthquakes of a specific magnitude scale is calculated. The models are applied to an historical catalogue for Northern Aegean Sea.

scholarly journals A comprehensive earthquake catalogue for Nepal and its adjoining region

2018 ◽  
Vol 56 (1) ◽  
pp. 65-72
Author(s):  
Sudhir Rajaure ◽  
Lalu Prasad Paudel
Keyword(s):  
United States ◽  
Seismic Hazard ◽  
Seismic Activity ◽  
Historical Earthquakes ◽  
Earthquake Catalogue ◽  
United States Geological Survey ◽  
Adjacent Area ◽  
Earthquake Catalogues ◽  
International Seismological Centre ◽  
Earthquake Data

We have prepared a comprehensive earthquake catalogue for Nepal and its adjoining region. The catalogue contains magnitude - homogenized independent earthquakes of magnitude (Mw) between 4.0 and 8.5, which occurred between 1100 AD and 2018 AD. The catalogue contains date, time, latitude, longitude, depth, and magnitude of earthquakes, which are required in the study of seismic activity, tectonics and seismic hazard. Primary earthquake catalogues were collected from the International Seismological Centre (ISC, 2015), United States Geological Survey (USGS), which contain instrumentally recorded earthquake data and date back to 1900 AD. These primary catalogues of instrumentally recorded earthquakes were supplemented by historical earthquakes reported in published literatures, which occurred before 1900 AD. The collected primary catalogues were compiled and processed to develop a comprehensive catalogue. The developed comprehensive catalogue is expected to serve as a basic database for the study of seismic activity and seismic hazard in Nepal and its adjacent area.

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