Source parameters of selected earthquakes on the central and western margin of Afar
9
Citation
34
Reference
10
Related Paper
Citation Trend
Keywords:
Seismogram
Seismic moment
Moment magnitude scale
In this study we analyse records from the 'Les Saintes' seismic sequence following the Mw= 6.3 earthquake of 2004 November 11, which occurred close to Guadeloupe (French West Indies). 485 earthquakes with magnitudes from 2 to 6, recorded at distances between 5 and 150 km are used. S-waves Fourier spectra are analysed to simultaneously determine source, path and site terms. The results show that the duration magnitude routinely estimated for the events that occurred in the region underestimate moment magnitude by 0.5 magnitude units over the whole magnitude range. From the inverted seismic moments and corner frequencies, we compute Brune′s stress drops. We show that stress drops increase with increasing magnitude. The same pattern is observed on apparent stresses (i.e. the seismic energy-to-moment ratio). However, the rate of increase diminishes at high magnitudes, which is consistent with a constant stress drop model for large events. Using the results of the inversions, we perform ground motion simulations for the entire data set using the SMSIM stochastic simulation tool. The results show that a good fit (s= 0.25) with observed data is achieved when the source is properly described by its moment magnitude and stress drop, and when site effects are taken into account. Although the magnitude-dependent stress drop model is giving better results than the constant stress drop model, the interevent variability remains high, which could suggest that stress drop depends on other parameters such as the depth of the hypocentre. In any case, the overall variability is of the same order of magnitude as usually observed in empirical ground motion prediction equations.
Moment magnitude scale
Seismic moment
Richter magnitude scale
Cite
Citations (38)
Moment magnitude scale
Spectral acceleration
Earthquake magnitude
Seismic moment
Cite
Citations (24)
The existence of magnitude type variation from existing earthquake catalogue sources show that uniforming process is necessary. Beside that these type of magnitude will saturates in certain value, which are different with moment magnitude (Mw) which is not saturated and can describe earthquake process better. Our research initially did compatibility test between summary magnitude which is largely used by BMKG with other magnitude type. Furthermore, the purpose of our research is determination of empirical relation between magnitude type summary magnitude (M), local magnitude (ML), body-wave magnitude (mb), dan surface magnitude (Ms) which are usually used by earthquake catalogues to Mw. Method used in this research is linear regression using data set from BMKG, ISC-EHB, USGS, and Global CMT catalogues with are limited in West Nusa Tenggara and surrounding area. Data used in this research contains of 24.703 earthquake events during period May 9th 1922 until June 27th 2020. The result of this research shows there was good relation between M magnitude type with others magnitude type. Our research also found a conversion formula of M, ML, MLv, mb, and Ms to Mw with well-defined correlation.
Moment magnitude scale
Maximum magnitude
Richter magnitude scale
Absolute magnitude
Earthquake magnitude
Cite
Citations (0)
Although there are many scales used to calculate earthquake magnitude, moment magnitude is currently considered the preferred magnitude scale for use in seismic hazard assessment in Canada. Historically, moment magnitude was not determined for eastern Canadian earthquakes although it has been routinely calculated for earthquakes of approximately magnitude 4.0 and greater, on regional magnitude scales, for the last decade. Thus, most moment magnitudes for eastern Canadian earthquakes must be obtained by converting from another magnitude scale or from felt information. This paper provides a moment magnitude catalog for the largest earthquakes in eastern Canada and vicinity. The study derives moment magnitudes for some events but also makes use of values from the published literature. Earthquakes are assessed individually using all available sources of information. The resulting catalog provides moment magnitudes for 254 events. Three additional events were evaluated but removed from the catalog as it is highly questionable whether they were earthquakes.
Moment magnitude scale
Richter magnitude scale
Maximum magnitude
Seismic moment
Earthquake magnitude
Cite
Citations (2)
Synthetic seismograms are used to investigate the dependence of the estimates for four magnitude types (Md, Ml, MS_BB, Mb_BB) on various parameters of the seismic sources, the Earth's structure and the receiver. Relations between the magnitudes and various parameters are well known and described by analytical equations, but it is hard to apply them directly in practice for a certain event or network configuration. We tested a model of an earthquake in the middle of the Balkan Peninsula region with a station configuration, similar to the stations from the Virtual Seismological Network of Sofia University (VSNSU). Syngine software package, available from the IRIS web page, was used to calculate synthetic seismograms. A number of tests were performed to investigate: the magnitude's dependence on the azimuth epicenter-station; the behavior of magnitude estimates for epicentral distances ranging from 100 to 1000 km; the changes in magnitude for earthquakes with a varying depth between 0 and 300 km; the magnitude variations changing focal mechanism parameters (strike, dip and rake); the impact of different velocity models on the magnitude estimates; the influence of errors in the coordinates; and the magnitude behavior changing the seismic moment of the event. All tests demonstrate variations in different magnitude estimates up to 2 magnitude units. In the last test, we compared the magnitudes measured by synthetic seismograms and several real seismograms from VSNSU. Tested earthquake has magnitude Ml=4.5, origin time 2016-05-22, 08:58:31 UTC, location 41.62° N, 23.29° E, and depth 1 km. Seismograms from stations RDO, TIR, DJES, DIVS, TIRR and APE were used in the calculations. Observed differences are mainly due to the usage of a global model in the generation of synthetics instead of a regional one as well as the fact that the periods of the synthetics are in the range 2 -100 s while smaller periods are typical for local and regional events.
Seismogram
Epicenter
Moment magnitude scale
Richter magnitude scale
Cite
Citations (0)
Moment magnitude scale
Seismic moment
Richter magnitude scale
Earthquake magnitude
Cite
Citations (80)
The Gulf of Corinth is one of the most active tectonic rifts around the world. Data used in the present study are obtained by the four digital stations of the Cornet Network which was installed in 1995 around the Eastern Gulf of Corinth. A velocity model was calculated, while the majority of local events were located within the Gulf of Corinth. Main scope of the study is the determination of a reliable earthquake magnitude. Concerning the duration magnitude Mo, a multiple linear regression technique was developed for the determination of the constants α, β and γ with very satisfactory values of errors. The coefficient of determination (goodness of fit) R2 was found equal to 0.99. Following, the moment magnitude Mw, which is considered to be the most reliable magnitude scale, was determined. Spectral analysis was applied for the calculation of the seismic moment M0 and a seismic catalogue was created. After the determination of the moment magnitude Mw and of the duration magnitude MD for the same dataset, a relationship between them was obtained, according to which Mw is systematically larger than Mjy Relationships between these magnitudes, the local magnitude ML and the body wave magnitude mb were also obtained.
Moment magnitude scale
Richter magnitude scale
Maximum magnitude
Earthquake magnitude
Cite
Citations (15)