Resolutions relating to the International Seismological Centre

1964 ◽  
Vol 54 (3) ◽  
pp. 1021-1022
Keyword(s):  
International Seismological Centre

Reassessment of source parameters of ‘major’ southern African earthquakes

2020 ◽  
Vol 123 (1) ◽  
pp. 59-74
Author(s):  
V. Midzi ◽  
T. Pule ◽  
T. Mulabisana ◽  
B. Zulu ◽  
B. Manzunzu
Keyword(s):  
Source Parameters ◽  
Ground Truth ◽  
Velocity Model ◽  
Parametric Data ◽  
Reliable Source ◽  
Hazard And Risk ◽  
Location Algorithm ◽  
Phase Data ◽  
International Seismological Centre ◽  
Large Earthquakes

Abstract Moderate to large earthquakes within an earthquake catalogue contribute significantly to the seismic hazard and risk assessment results of any region. Thus it is prudent to ensure these events have reliable source parameters (epicentres and magnitude). The dataset of events compiled in this study contains a total of 117 instrumentally recorded events of magnitude M ≥5.0, whose parameters were obtained from the Council for Geoscience (CGS) and International Seismological Centre (ISC) databases. The events are mostly located in South Africa with a few in neighbouring countries. Parametric data made up of all available phase data and amplitudes associated with each of the earthquakes were compiled. The availability of these data enabled the earthquake epicentres and magnitude values to be recalculated using the velocity model and the local magnitude relation that are currently being used by the CGS in its analysis of national seismic data. The accuracy of the relocations was determined by producing and analysing three parameters, the azimuthal distribution of seismograph stations (GAP), root-mean-square of travel time residuals (RMS) and epicenter location error data. The analysis of these parameters showed that there was an improvement in the accuracy of the relocated events. Using the ISC location algorithm, iLOC, eight preselected events were further analysed. From this analysis, two earthquakes were found to satisfy the conditions for Ground Truth (GT595%) candidacy whilst four events satisfied the criteria for GT2090% candidacy.

scholarly journals Long-term accumulation and improvements in seismic event data for the polar regions by the International Seismological Centre

Polar Science ◽  
2015 ◽  
Vol 9 (1) ◽  
pp. 5-16 ◽  
Author(s):  
Dmitry A. Storchak ◽  
Masaki Kanao ◽  
Emily Delahaye ◽  
James Harris
Keyword(s):  
Seismic Event ◽  
Polar Regions ◽  
Event Data ◽  
International Seismological Centre

scholarly journals The Finnish National Seismic Network

2018 ◽  
Vol 52 (I) ◽  
pp. 41-52 ◽  
Author(s):  
Jari Kortström ◽  
Marja Uski ◽  
Kati Oinonen
Keyword(s):  
Seismic Network ◽  
International Seismological Centre

Jari Kortström, Marja Uski and Kati Oinonen report on the Finnish National Seismic Network for the Summary of the Bulletin of the International Seismological Centre.

scholarly journals Monitoring System of the Institute of Geophysical Research of the Ministry of Energy of the Republic of Kazakhstan

2019 ◽  
Vol 53 (I) ◽  
pp. 27-38 ◽  
Author(s):  
Natalya N. Mikhailova ◽  
Inna N. Sokolova
Keyword(s):  
Monitoring System ◽  
Geophysical Research ◽  
The Republic ◽  
International Seismological Centre

Natalya N. Mikhailova and Inna N. Sokolova report on the Kazakhstan Monitoring System of the Institute of Geophysical Research of the Ministry of Energy for the Summary of the Bulletin of the International Seismological Centre.

The ISC Electronic Archive of Printed Station and Network Bulletins

2021 ◽  
Author(s):  
Domenico Di Giacomo ◽  
Daniela Olaru ◽  
Adrian Armstrong ◽  
James Harris ◽  
Dmitry A. Storchak
Keyword(s):  
Electronic Archive ◽  
The Past ◽  
Single Station ◽  
International Seismological Centre ◽  
The Town ◽  
Wide Community

Abstract We present an archive of scanned instrumental seismic bulletins pertaining to either a single station or a set of stations (network). This new service by the International Seismological Centre (ISC), called the ISC Electronic Archive of Station and Network Bulletins, is openly available at the ISC website. The archive is likely to be the most comprehensive to date, thanks to the collection from various sources done by the ISC in the past several decades. The search for scans of a seismic bulletin is based on the location of the town of the institution producing a bulletin. As such, the electronic archive is easy to use and is likely to facilitate the work of a wide community interested in studying past earthquakes and involved in preservation and digitization of analog recordings.

scholarly journals Complementing regional moment magnitudes to GCMT: a perspective from the rebuilt International Seismological Centre Bulletin

2021 ◽  
Vol 13 (5) ◽  
pp. 1957-1985
Author(s):  
Domenico Di Giacomo ◽  
James Harris ◽  
Dmitry A. Storchak
Keyword(s):  
Body Wave ◽  
Moment Tensor ◽  
Specific Area ◽  
Centroid Moment Tensor ◽  
Earthquake Catalogues ◽  
Origin Time ◽  
Earthquake Parameters ◽  
Short Period ◽  
The Moment ◽  
International Seismological Centre

Abstract. Seismologists and geoscientists often need earthquake catalogues for various types of research. This input usually contains basic earthquake parameters such as location (longitude, latitude, depth, and origin time), as well as magnitude information. For the latter, the moment magnitude Mw has become the most sought after magnitude scale in the seismological community to characterize the size of an earthquake. In this contribution we provide an informative account of the Mw content for the newly rebuilt Bulletin of the International Seismological Centre (ISC, http://www.isc.ac.uk, last access: May 2021), which is regarded as the most comprehensive record of the Earth's seismicity. From this data, we extracted a list of hypocentres with Mw from a multitude of agencies reporting data to the ISC. We first summarize the main temporal and spatial features of the Mw provided by global (i.e. providing results for moderate to great earthquakes worldwide) and regional agencies (i.e. also providing results for small earthquakes in a specific area). Following this, we discuss their comparisons, by considering not only Mw but also the surface wave magnitude MS and short-period body wave magnitude mb. By using the Global Centroid Moment Tensor solutions as an authoritative global agency, we identify regional agencies that best complement it and show examples of frequency–magnitude distributions in different areas obtained both from the Global Centroid Moment Tensor alone and complemented by Mw from regional agencies. The work done by the regional agencies in terms of Mw is fundamental to improve our understanding of the seismicity of an area, and we call for the implementation of procedures to compute Mw in a systematic way in areas currently not well covered in this respect, such as vast parts of continental Asia and Africa. In addition, more studies are needed to clarify the causes of the apparent overestimation of global Mw estimations compared to regional Mw. Such difference is also observed in the comparisons of Mw with MS and mb. The results presented here are obtained from the dataset (Di Giacomo and Harris, 2020, https://doi.org/10.31905/J2W2M64S) stored at the ISC Dataset Repository (http://www.isc.ac.uk/dataset_repository/, last access: May 2021).

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 Korelasi Tingkat Seismisitas dan Periode Ulang Gempa Bumi di Kepulauan Mentawai dengan Menggunakan Metode Guttenberg-Richter

2018 ◽  
Vol 7 (1) ◽  
pp. 84-89
Author(s):  
Rahma Fidia ◽  
Dwi Pujiastuti ◽  
Andiyansyah Sabarani
Keyword(s):  
International Seismological Centre

Analisis tingkat seismisitas dan periode ulang gempa bumi berdasarkan magnitudo telah dilakukan pada daerah Kepulauan Mentawai dan sekitarnya. Data yang digunakan adalah gempa bumi dengan magnitudo sama atau besar dari 5 Skala Richter dan kedalaman 0-100 km untuk periode 1914-2015. Data ini bersumber dari katalog ISC (International Seismological Centre) dan BMKG Padang Panjang. Tingkat keaktifan gempa bumi dihitung dengan menggunakan metode Likelihood, sedangkan nilai periode ulang gempa dihitung dengan menggunakan metode Guttenberg-Richter. Berdasarkan hasil perhitungan,  diperoleh nilai  b sebesar 0,8372 dan nilai a sebesar 6,8094 serta nilai indeks seismisitas untuk magnitudo 5-8 berkisar antara 2,1580-0,0066. Hal ini menunjukkan bahwa daerah penelitian memiliki tingkat keaktifan kegempaan yang tinggi. Untuk magnitudo 5-8 diperoleh nilai periode ulang antara 0,4633-150,5033 tahun. Secara umum dapat disimpulkan bahwa daerah Kepulauan Mentawai memiliki tingkat seismisitas tinggi dan rawan bencana gempa bumi. Hal ini dibuktikan dengan tingginya tingkat keaktifan gempa dan nilai periode ulang yang singkat.Kata Kunci : Gempa, Metode Guttenberg-Richter, Indeks Seismisitas, Kepulauan Mentawai

Revised world seismicity catalog (1950-1997) for strong (Ms ≧ 6) shallow (h ≦ 70 km) earthquakes

1999 ◽  
Vol 89 (2) ◽  
pp. 335-341 ◽  
Author(s):  
Omar J. Pérez
Keyword(s):  
Earthquake Catalog ◽  
Shallow Earthquakes ◽  
Seismicity Rates ◽  
Worldwide Web ◽  
Seismicity Catalog ◽  
International Seismological Centre ◽  
Seismograph Network ◽  
National Earthquake Information Center ◽  
Magnitude Determination ◽  
Scalar Moment

Abstract Using the standard earthquake catalogs provided by the International Seismological Centre (ISC), its predecessor the International Seismological Summary (ISS), and the National Earthquake Information Center (NEIC), I analyze the worldwide consistency of teleseismic reporting, completeness of the seismicity record, and homogeneity of magnitude determination, for strong shallow earthquakes (surface-wave magnitude, Ms ≥ 6; depth, h ≤ 70 km) for the period 1950 to 1997. Under the postulates that the rate of earthquake occurrence for the entire world is constant on a time scale of decades and that well after the installation of the World-Wide Standardized Seismograph Network in the middle 1960s the earthquake catalog for strong (Ms ≥ 6) shocks is complete, and the seismicity rates are typical of all periods in the century, we find that, due to the use of different formulations and criteria to calculate the parameter magnitude, the Ms of moderate (6 ≤ Ms < 7) events during the period 1950 to 1963 was systematically overestimated by as much as 0.5 magnitude unit, relative to the Ms assigned to shocks occurring after 1963. When this correction is taken into account, the new catalog of events with Ms (corrected) ≥ 6 in the period 1950 to 1997 becomes largely homogeneous in Ms. Under the foregoing postulates, this new catalog is shown to list nearly all and only the strong shocks [Ms (corrected) ≥ 6; h ≤ 70 km] that occurred in the Earth during the period, a notable exception being the time span from 1964 to 1968. The revised catalog, including the scalar moment and moment magnitude for each event, is listed on the worldwide web page http://www.ldc.usb.ve/~ojperez/catalog.

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