On the relation between modified Mercalli intensity and body-wave magnitude

1979 ◽  
Vol 69 (3) ◽  
pp. 893-909
Author(s):  
Otto W. Nuttli ◽  
G. A. Bollinger ◽  
Donald W. Griffiths
Keyword(s):  
United States ◽  
South Carolina ◽  
San Francisco ◽  
Body Wave ◽  
Strong Motion ◽  
Historical Earthquakes ◽  
P Wave ◽  
Intensity Data ◽  
Lg Wave ◽  
Body Wave Magnitude

abstract This paper is concerned with estimating body-wave magnitude, mb, from the intensity distribution of an earthquake. Initially, it is assumed that modified Mercalli (MM) intensity values are directly related to the (A/T)z values of 1-Hz, Lg-wave ground motion. By comparison with the intensity values of a reference earthquake, magnitudes are calculated for 41 western and central United States earthquakes. Magnitudes of these earthquakes also are determined independently, in the conventional manner, using teleseismic P-wave amplitudes. Comparison of the two sets of magnitude values indicates that the assumed relation between 1-Hz, Lg-wave (A/T)z values and MM intensity does not hold exactly over the mb range of 4.0 to 6.2. An empirical equation is derived to adjust the mb values obtained from intensity data so that they agree with the teleseismic P-wave magnitudes. The method then is applied to estimate mb of some historical earthquakes which occurred prior to 1962. These include the set for which Kanamori and Jennings (1978) estimated ML from strong-motion accelerograms. Some noteworthy United States earthquakes also are considered. These include: the 1811 New Madrid earthquake for which mb is estimated to be 7.3; the 1886 Charleston, South Carolina earthquake, for which mb is estimated to be 6.6 to 6.9; the 1897 Giles County, Virginia earthquake, for which mb is estimated to be 5.8; the 1906 San Francisco, California earthquake, for which mb is estimated to be 6.8 to 7.1. The intensity-attenuation method cannot be used for estimating mb of all historical earthquakes because the intensity data are not always adequate. In some cases, however, the total felt area or the area enclosed by the Modified Mercalli IV isoseism can be determined. It was found that empirical equations relating mb to these areas, which were derived for central and northeastern United States earthquakes, also apply for events in the southeast. These empirical methods are used to estimate mb values for a set of historical Virginia earthquakes.

Horizontal particle velocity and its relation to magnitude in the Western United States

1979 ◽  
Vol 69 (6) ◽  
pp. 2037-2061
Author(s):  
A. F. Espinosa
Keyword(s):  
United States ◽  
Data Base ◽  
San Francisco ◽  
Seismic Waves ◽  
Scaling Law ◽  
Direct Determination ◽  
Strong Motion ◽  
Western United States ◽  
Short Period ◽  
Horizontal Particle

abstract A magnitude (ML) scaling law has been derived from the strong-motion data base of the San Fernando earthquake of February 9, 1971, and the results have been compared with other strong-motion recordings obtained from 62 earthquakes in the Western United States. The relationship derived is ML = 3.21 + 1.35 log10Δ + log10v. An excellent agreement was obtained between the determined ML values in this study and those evaluated by Kanamori and Jennings (1978). This scaling law is applicable to the collected data from 63 earthquakes whose local magnitudes range from about 4.0 to 7.2, recorded at epicentral distances between about 5 to 300 km, and with short-period seismic waves in the range of 0.2 to 3.0 sec. The Long Beach earthquake of 1933, with an ML = 6.3 (PAS) and an ML = 6.43 ± 0.36 as determined by Kanamori and Jennings is in agreement with an ML = 6.49 ± 0.32 obtained in this study. The Imperial Valley earthquake of 1940, with an ML = 6.5 (PAS), compares well with an ML = 6.5 as determined in this study. The Kern County earthquake of 1952, with an ML = 7.2 (BRK), is in fairly good agreement with the ML = 7.0 ± 0.2 obtained in this investigation. This value is significantly lower than the commonly quoted 7.7 value for this event. The San Francisco earthquake of 1957, with an ML = 5.3 (BRK), agrees very well with an ML = 5.3 ± 0.1 as determined in this study. The Parkfield earthquake of 1966 has an ML = 5.8 ± 0.3, which is consistent with the 5.6 (PAS). The procedure developed here is applied to the data base obtained from the Western United States strong-motion recordings. The procedure allows the evaluation of ML for moderate and larger earthquakes from the first integration of the strong-motion accelerograms and allows the direct determination of ML from the scaled amplitudes in a rapid, economical, and accurate manner. It also has allowed for the extension of the trend of the attenuation curve for horizontal particle velocities at distances less than 5 km for different size events.

Systematic difference in the ISC body-wave magnitude-seismic moment relationship between intermediate and deep earthquakes

1992 ◽  
Vol 82 (2) ◽  
pp. 819-835
Author(s):  
Keiko Kuge
Keyword(s):  
Seismic Moment ◽  
Body Wave ◽  
Systematic Difference ◽  
P Wave ◽  
Local Structures ◽  
Dependent Relationship ◽  
Deep Earthquakes ◽  
Amplitude Data ◽  
Body Wave Magnitude ◽  
Distance Correction

Abstract There exists a systematic difference in the ISC body-wave magnitude (mbISC) - seismic moment (M0) relationship between intermediate and deep earthquakes around Japan. For earthquakes with the same M0, the mbISC for intermediate events is larger than that for deep events by 0.2 to 0.3 units. The mbISC discrepancy is attributed to the depth-distance correction in the procedure for determining the mbISC; a larger depth-distance correction (≈ 0.2) is made for the intermediate events than the deep events, irrespective of station distance. The discrepancy disappears if no depth-distance correction is made. I observe no depth-dependent relationship between the M0 and the JMA magnitudes (MJMA), which make a different depth-distance correction. No significant depth-dependent mbISC discrepancy appears in other regions; for example, around Tonga, I observe larger ISC P-wave amplitudes from deep events than intermediate events, which could cancel the effect of the depth-distance correction. The depth-dependent mbISC - M0 relationship around Japan is observed irrespective of whether the magnitudes are determined using the amplitude data at far or near stations, or whether stations are used in the dipping direction of the slab or not. The mbISC discrepancy for the same M0 cannot arise from local structures, radiation patterns, and station coverages. This is not attributable to the dataset of the M0 itself because no significant depth-dependent relationship between M0 and MJMA is observed.

Estimates of magnitudes and short-period wave attenuation of Chinese earthquakes from Modified Mercalli intensity data

1984 ◽  
Vol 74 (3) ◽  
pp. 957-968
Author(s):  
Peishan Chen ◽  
Otto W. Nuttli
Keyword(s):  
Wave Attenuation ◽  
Body Wave ◽  
Empirical Relation ◽  
Historical Earthquakes ◽  
The Body ◽  
Intensity Data ◽  
Mountainous Regions ◽  
Short Period ◽  
Recent Earthquakes ◽  
Period Wave

Abstract Intensity data for Chinese earthquakes are used to estimate the body-wave magnitude, mb, of selected historical earthquakes and to estimate Q0, the 1-sec period Q value of Lg waves for various geographical areas of China. In order to derive the necessary empirical relation between the intensity distribution and mb, data are used from recent earthquakes, for which instrumentally obtained mb values as well as isoseismal maps are available. Average Qo values are approximately 175 for the mountainous regions of southwest China, 550 for southeastern China, and 150 for Taiwan. These values agree qualitatively with those obtained by Evernden (1983) and Chen et al. (1983), who utilized a different method of analysis of the intensity data

Seismic source functions and magnitude determinations for underground nuclear detonations

1977 ◽  
Vol 67 (1) ◽  
pp. 135-158
Author(s):  
John R. Murphy
Keyword(s):  
Body Wave ◽  
Broad Band ◽  
Seismic Source ◽  
Source Model ◽  
The Body ◽  
P Wave ◽  
Cube Root ◽  
Motion Data ◽  
Surface Wave Data ◽  
Body Wave Magnitude

abstract A variety of near-regional, regional, and teleseismic ground-motion data have been used to evaluate proposed models of the nuclear seismic source function for underground detonations in tuff/rhyolite emplacement media. It has been found that both the near-regional broad-band seismic data and the teleseismic body-wave magnitude data are consistent with the modified source model proposed by Mueller and Murphy (1971) but not with the simple cube-root of the yield-scaling source model. In particular, the observed linearity and slopes of the body-wave magnitude-yield curves as well as the observed variation of P-wave period with yield have been found to be fully compatible with the modified source model. On the other hand, it has been concluded that the observed long-period surface-wave data are inconsistent with a simple, spherically symmetric source model. The results of a preliminary analysis have suggested that this discrepancy may be related to the spall closure phenomenon.

scholarly journals The fouling serpulids (Polychaeta: Serpulidae) from United States coastal waters: an overview

2017 ◽  
Author(s):  
J. Rolando Bastida-Zavala ◽  
Linda D. McCann ◽  
Erica Keppel ◽  
Gregory M. Ruiz
Keyword(s):  
United States ◽  
South Carolina ◽  
Gulf Of Mexico ◽  
San Francisco ◽  
Rhode Island ◽  
East Coast ◽  
The United States ◽  
Northern Gulf Of Mexico ◽  
Corpus Christi ◽  
Indian River

Serpulids are an important component of fouling communities. This paper provides an overview of the serpulid species found in North America, as part of a broader study of fouling invertebrates focused on NIS (non-indigenous species) in United States coastal ecosystems. Almost 4400 serpulid specimens were examined from selected fouling plates. Fouling plates were deployed in 26 bays and coastal lagoons along the continental coasts of the United States and Hawaiian islands, primarily in bays and lagoons with salinities averaging 20‰ or greater. Twenty-five serpulid species were identified, including four new records for the United States (Ficopomatus uschakovi, Hydroides cf. brachyacantha, H. longispinosa and Protula longiseta), three known NIS, two presumed NIS, three cryptogenic serpulids, and several range extensions. Crucigera websteri extends its northward range from Santa Barbara Island to Humboldt Bay, California; Ficopomatus enigmaticus, first recorded in North America from San Francisco, California in 1920, Rockport, Texas in 1952 and Barnegat Bay, New Jersey in 1980, is now recorded at additional localities on the east coast (Chesapeake Bay, Virginia, Charleston, South Carolina and Indian River, Florida) and the northern Gulf of Mexico (Galveston Bay, Texas); F. miamiensis extends its westward range from Louisiana to Texas; F. uschakovi, an Indo-Pacific and Western African species, was recorded formally for the first time from the northern Gulf of Mexico (Galveston Bay and Corpus Christi, Texas) and the east coast of Florida (Jacksonville). Hydroides cf. brachyacantha extends its northward range from Curaҫao to Pensacola Bay, Florida; H. dirampha from Veracruz, Mexico to Corpus Christi, Texas; H. floridana extends its westward range from Louisiana to Texas; H. gracilis extends its northward range from Pacific Grove to San Francisco, California; Salmacina huxleyi from Cape Hatteras, North Carolina to Rhode Island; and Spirobranchus minutus from Veracruz, Mexico to Pensacola Bay, Florida. The following additional species range extensions are provisional in that they represent only one record or were not found in the most recent surveys (e.g., Hydroides elegans - east coast): H. longispinosa from Marshall Islands to Oahu, Hawaii; Protula balboensis from Florida to Texas; P. longiseta from the Mexican Caribbean to the Indian River, Florida; H. elegans from San Francisco to Humboldt Bay, northern California and on the east coast from the Indian River, Florida, to Cape Cod, Massachusetts. Among surveyed bays, Biscayne Bay, Florida and Corpus Christi, Texas (northern Gulf of Mexico) had the greatest number of species (14 and 8, respectively); in contrast, almost all sites in Alaska, Washington, Oregon (northwest Pacific), Rhode Island, Virginia and South Carolina (Atlantic) had only one or two species each. Hydroides dianthus was, by far, the most abundant serpulid species on fouling plates in the northern Gulf of Mexico and the east coast, while Pseudochitinopoma occidentalis was the most abundant serpulid detected on the west coast. For each species recorded herein, we include the synonyms and some key references, a material studied section, a diagnosis, and updated distributional information. A checklist and identification key to the known shallow-water serpulids sensu stricto of the United States are included.

scholarly journals The Forensic Engineering in an Earthquake Scenario What We Can Expect When The Big One Hits

1988 ◽  
Vol 5 (1) ◽  
Author(s):  
Robert E. Garrett
Keyword(s):  
United States ◽  
South Carolina ◽  
San Francisco ◽  
Mississippi River ◽  
Large Earthquake ◽  
The United States ◽  
Earthquake Damage ◽  
Earthquake Scenario ◽  
Richter Scale ◽  
Forensic Engineering

Many of you may not feel concerned regarding earthquake damage, and what may occur when the expected large earthquake of the magnitude which hit San Francisco in 1906 reoccurs. The experts tell us it is not a question of if, but when. And the when could be in the next decade or two. That is not just a California problem. Be aware that there are 39 states in the United States which may be subject to substantial earthquake damage. The largest earthquake ever in the United States was along the New Madrid fault in southeast Missouri. That occurred about 1812, and was estimated to be 8.3 to 8.7 on the Richter scale. Of course, there were no scales then, or many people there at the time. It did, however, rearrange the Mississippi River. If such an earthquake hit at this point today, Memphis and St. Louis would be leveled. There is also another known fault near Charleston, South Carolina. Boston has been hit by earthquakes. The upper tier of states near the St. Lawrence River is

The Sharpsburg, Kentucky, earthquake 27 July 1980: Main shock parameters and isoseismal maps

1982 ◽  
Vol 72 (1) ◽  
pp. 221-236
Author(s):  
Frederick J. Mauk ◽  
Doug Christensen ◽  
Steve Henry
Keyword(s):  
Body Wave ◽  
P Wave ◽  
Eastern United States ◽  
Slip Vector ◽  
Small Component ◽  
Slip Event ◽  
Felt Area ◽  
Body Wave Magnitude ◽  
Epicentral Region ◽  
Average Body

abstract An earthquake having an average body-wave magnitude of 5.1 occurred on Sunday, 27 July 1980 near Sharpsburg, Kentucky. The earthquake was widely felt throughout the Eastern United States and had a maximum Modified Mercalli intensity of VII in the epicentral region. The total felt area was approximately 673,000 km2. The well-constrained focal mechanism based on 128 P-wave first motions combined with other geological and seismological evidence indicates a fault plane striking N42°E, dipping 50°E with a slip vector 184° of the strike. This is a right-lateral strike-slip event with a small component of thrust. Isoseismal data strongly suggest a northeast-directed rupture. The strike is parallel to the trend of the West Hickman Creek fault zone but 30 km to the east of any known faults.

The body-wave magnitude mb: an attempt to rationalize the distance-depth correction q(Δ, h)

2020 ◽  
Vol 223 (1) ◽  
pp. 270-288
Author(s):  
Nooshin Saloor ◽  
Emile A Okal
Keyword(s):  
Large Scale ◽  
Body Wave ◽  
Exact Algorithm ◽  
Large Data ◽  
The Body ◽  
P Wave ◽  
Small Scale ◽  
Data Sets ◽  
Data Set ◽  
Body Wave Magnitude

SUMMARY We explore the possible theoretical origin of the distance–depth correction q(Δ, h) introduced 75 yr ago by B. Gutenberg for the computation of the body-wave magnitude mb, and still in use today. We synthesize a large data set of seismograms using a modern model of P-wave velocity and attenuation, and process them through the exact algorithm mandated under present-day seismological practice, to build our own version, qSO, of the correction, and compare it to the original ones, q45 and q56, proposed by B. Gutenberg and C.F. Richter. While we can reproduce some of the large scale variations in their corrections, we cannot understand their small scale details. We discuss a number of possible sources of bias in the data sets used at the time, and suggest the need for a complete revision of existing mb catalogues.

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