Standardization of the earthquake magnitude scale

Kárník, Vít; Kondorskaya, N.V.; Riznitchenko, Ju. V.; Savarensky, E. F.; Soloviev, S. L.; Shebalin, N. V.; Vaněk, Jiřı́; Zátopek, A.

doi:10.1007/bf02590040

Cited by 69 publications

(5 citation statements)

References 3 publications

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“…In the case of Event II, we recomputed conventional magnitude estimates from those reports of ground amplitude for which associations could be made, using established formulae and guidelines (Kárník et al, 1962;Geller & Kanamori, 1977;Ambraseys & Douglas, 2000). Our best estimate of MS is 7.1, which represents an average for Manila (6.98) and Osaka (7.17).…”

Section: Conventional Magnitude Estimatesmentioning

confidence: 99%

Reassessment of the 1907 Sumatra “Tsunami Earthquake” Based on Macroseismic, Seismological, and Tsunami Observations, and Modeling

Martin

Okal

et al. 2019

Pure Appl. Geophys.

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On 4 January 1907 an earthquake occurred off the west coast of Sumatra, Indonesia, with an instrumental surface-wave magnitude (MS) in the range of 7.5 to 8.0 at periods of ~40s. The tsunami it generated was destructive on the islands of Nias and Simeulue where it killed hundreds and gave rise to the legend of the S'mong. This tsunami also appears in records in other parts of the Indian Ocean basin, and as far as La Réunion island. Relative to its instrumented magnitude, the size of the tsunami was anomalous qualifying it as a "tsunami earthquake." However, unusually for a tsunami earthquake the shaking on Nias was severe (6-7 EMS). We revisited the 1907 earthquake with a multidisciplinary approach by extracting evidence describing shaking effects or the tsunami from written documents and by acquiring new seismograms. Combining these, we discriminated two large earthquakes within an hour of each other with clear differences in seismological character. The first we interpret to be a tsunami earthquake with characteristic low levels of shaking and for which we estimate an average seismic moment (M0) 2.5 x10 28 dynes*cm (MW ≈ 8.2) in the frequency band 6 -8 mHz. These records document a regular growth of moment with period: at the longest resolvable period (~170 s) the moment magnitude approaches MW ≈ 8.4. Our relocations suggest an epicentral location close to the trench for the mainshock. For the second earthquake that was damaging on Nias, we estimate MS ≈ 7 based on seismograms and phase data from Manila and Osaka. We also identified two MS ≈ 6 aftershocks within 24 hours of the mainshock. We propose a model of seismic rupture which provides an acceptable fit to our new dataset of tsunami run-up and inundation values from 88 local and far-field locations in the Indian Ocean basin.

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Section: Conventional Magnitude Estimatesmentioning

confidence: 99%

Reassessment of the 1907 Sumatra “Tsunami Earthquake” Based on Macroseismic, Seismological, and Tsunami Observations, and Modeling

Martin

Okal

et al. 2019

Pure Appl. Geophys.

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“…Lg wave and local surface wave both propagate in the upper crust. After analytic comparison with a vast amount of seismic data, Kárnǐk et al (1962) found that the period of surface wave is approximately 3 s if the epicentral distance for measuring a surface wave diminishes to 2°.…”

Section: Comparison Between M L and M Smentioning

confidence: 98%

Comparison between different earthquake magnitudes determined by China Seismograph Network

et al. 2007

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By linear regression and orthogonal regression methods, comparisons are made between different magnitudes (local magnitude M L , surface wave magnitudes M S and M S7 , long-period body wave magnitude m B and short-period body wave magnitude m b ) determined by Institute of Geophysics, China Earthquake Administration, on the basis of observation data collected by China Seismograph Network between 1983 and 2004. Empirical relations between different magnitudes have been obtained. The result shows that: 1 As different magnitude scales reflect radiated energy by seismic waves within different periods, earthquake magnitudes can be described more objectively by using different scales for earthquakes of different magnitudes. When the epicentral distance is less than 1 000 km, local magnitude M L can be a preferable scale; In case M<4.5, there is little difference between the magnitude scales; In case 4.5M S , i.e., M S underestimates magnitudes of such events, therefore, m B can be a better choice; In case M>6.0, M S >m B >m b , both m B and m b underestimate the magnitudes, so M S is a preferable scale for determining magnitudes of such events (6.08.5, a saturation phenomenon appears in M S , which cannot give an accurate reflection of the magnitudes of such large events; 2 In China, when the epicentral distance is less than 1 000 km, there is almost no difference between M L and M S , and thus there is no need to convert between the two magnitudes in practice; 3 Although M S and M S7 are both surface wave magnitudes, M S is in general greater than M S7 by 0.2~0.3 magnitude, because different instruments and calculation formulae are used; 4 m B is almost equal to m b for earthquakes around m B 4.0, but m B is larger than m b for those of m B ≥4.5, because the periods of seismic waves used for measuring m B and m b are different though the calculation formulae are the same.

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“…where I i is the intensity degree (MSK-64) of the i-th isoseismal and I 0 is the epicentral intensity, M LH is the magnitude defined by Karnik et al [26], h is the hypocentral depth (in km), and r i (in km) is the equivalent radius of i-th isoseismal area, calculated as…”

Section: Evaluation Of Seismological Parameters From the Re-evaluated...mentioning

confidence: 99%

Reassessing the Location, Magnitude, and Macroseismic Intensity Map of the 8 April 1893 Svilajnac (Serbia) Earthquake

Manić,

Bulajić

2024

Applied Sciences

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A devastating earthquake took place on 8 April 1893, close to the town of Svilajnac, central Serbia. Over the past decade, significant historical data on the effects of this earthquake has been collected from a variety of sources, including books, scientific publications, reports, newspapers, and coeval chronicles. Additionally, this earthquake was recorded 750 km from the epicenter at the seismological station Rocca di Papa in Rome, Italy. Based on critical review and analysis of the historical data, we demonstrate that the epicentral area of this earthquake was 531 km2, and the macroseismic effects were recorded at epicentral distances up to 600 km towards the west (Vienna, Austria) towards the north, up to 500 km (Košice–Michalovce, Slovakia), towards the east up to 460 km (Brašov–Borsec, Romania); and towards the south up to about 300 km (Radoviš, North Macedonia). Finally, we show that the key parameters of the 1893 Svilajnac earthquake are as follows: (1) epicentral intensity, I0 = IX EMS-98, (2) the estimations of the moment magnitude and focal depth based on the observed intensities, MW = 6.8 and h = 13 km, respectively, and (3) the epicenter coordinates, 44.160° N and 21.354° E.

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Standardization of the earthquake magnitude scale

Cited by 69 publications

References 3 publications

Reassessment of the 1907 Sumatra “Tsunami Earthquake” Based on Macroseismic, Seismological, and Tsunami Observations, and Modeling

Reassessment of the 1907 Sumatra “Tsunami Earthquake” Based on Macroseismic, Seismological, and Tsunami Observations, and Modeling

Comparison between different earthquake magnitudes determined by China Seismograph Network

Reassessing the Location, Magnitude, and Macroseismic Intensity Map of the 8 April 1893 Svilajnac (Serbia) Earthquake

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