[ { "id": "authors:k0gdx-hkz04", "collection": "authors", "collection_id": "k0gdx-hkz04", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121204-143300103", "type": "article", "title": "Reply to Comment by J. Zhang and N. Makris on \"Estimates of the Ground Accelerations at Point Reyes Station during the 1906 San Francisco Earthquake\" by A. Anooshehpoor, T. H. Heaton, B. Shi, and J. N. Brune", "author": [ { "family_name": "Anooshehpoor", "given_name": "A.", "clpid": "Anooshehpoor-A" }, { "family_name": "Heaton", "given_name": "T. H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" }, { "family_name": "Shi", "given_name": "B.", "clpid": "Shi-Baoping" }, { "family_name": "Brune", "given_name": "J. N.", "clpid": "Brune-J-N" } ], "abstract": "Contrary to the comments by Zhang and Makris (hereafter, ZM), our equations of motion governing the rocking response of a rectangular block subjected to a full-sine acceleration pulse are correct. Therefore, the first part of ZM's discussion, which is based primarily upon the assumption that the equations of motion in our article were incorrect, is inappropriate. In the second part of the discussion, ZM present new results for mode 2, toppling without impact. We did not consider this mode because it was not relevant to the Point Reyes train, which by eyewitness accounts, had overturned after experiencing one impact. However, as explained in this reply, toppling with no impact is never the minimum condition for overturning, and would in general involve very large horizontal accelerations, especially at frequencies where mode 2 is the only overturning mode.", "doi": "10.1785/0119990157", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "2000-10", "series_number": "5", "volume": "90", "issue": "5", "pages": "1349-1351" }, { "id": "authors:ansev-w4m60", "collection": "authors", "collection_id": "ansev-w4m60", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20121121-134211441", "type": "article", "title": "Estimates of the ground accelerations at Point Reyes Station during the 1906 San Francisco earthquake", "author": [ { "family_name": "Anooshehpoor", "given_name": "Abdolrasool", "clpid": "Anooshehpoor-A" }, { "family_name": "Heaton", "given_name": "Thomas H.", "orcid": "0000-0003-3363-2197", "clpid": "Heaton-T-H" }, { "family_name": "Shi", "given_name": "Baoping", "clpid": "Shi-Baoping" }, { "family_name": "Brune", "given_name": "James N.", "clpid": "Brune-J-N" } ], "abstract": "We have developed an analytical solution for the rocking and overturning response of a two-dimensional, symmetric rigid block subject to a full sine wave of horizontal ground acceleration. We use this solution to provide lower-bound estimates of the peak ground acceleration at Point Reyes Station, California, during the 1906 San Francisco earthquake that toppled the San Francisco-bound train. Our results, for a 3% damping ratio, indicate that for a single cycle of a sine wave the minimum toppling accelerations at 1, 1.5, and 2 Hz are 0.35g, 0.5g, and 1.05g, respectively. For more realistic accelerograms the toppling accelerations are about 1.1g (complex synthetic) and 0.76g (Lucerne record of the 1992 Landers earthquake).", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1999-08", "series_number": "4", "volume": "89", "issue": "4", "pages": "845-853" }, { "id": "authors:yf4tg-f7f77", "collection": "authors", "collection_id": "yf4tg-f7f77", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140910-092137385", "type": "article", "title": "Evidence for Unusually Strong Near-field Ground Motion on the Hanging Wall of the San Fernando Fault during the 1971 Earthquake", "author": [ { "family_name": "Allen", "given_name": "Clarence R.", "clpid": "Allen-C-R" }, { "family_name": "Brune", "given_name": "James N.", "clpid": "Brune-J-N" }, { "family_name": "Cluff", "given_name": "Lloyd S.", "clpid": "Cluff-L-S" }, { "family_name": "Barrows", "given_name": "Allan G., Jr.", "clpid": "Barrows-A-G-Jr" } ], "abstract": "Reports of unusually intense ground motions in the very near fields of faults that have ruptured during earthquakes are becoming more common, particularly with the markedly increased worldwide strong-motion instrumentation in recent years (e.g., Heaton and Wald, 1994). The reported ground motions are sufficiently strong to have significant potential engineering impact (Hall et al., 1995). In addition to fault proximity, two other factors that have contributed to unusually high strong motions are rupture directivity (e.g., Somerville et al., 1997) and locations on the hanging walls of thrust faults (e.g., Nason, 1973; Abrahamson and Somerville, 1996; Brune, 1996a; Brune, 1996b). Perhaps nowhere has the sharp distinction between damage on the hanging wall and footwall of a thrust fault been more dramatically documented than during the 1945 Mikawa earthquake, Japan (Iida, 1985).", "doi": "10.1785/gssrl.69.6.524", "issn": "0895-0695", "publisher": "Seismological Society of America", "publication": "Seismological Research Letters", "publication_date": "1998-11", "series_number": "6", "volume": "69", "issue": "6", "pages": "524-531" }, { "id": "authors:mkaz4-esr63", "collection": "authors", "collection_id": "mkaz4-esr63", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150618-084705001", "type": "article", "title": "A New U.S.-U.S.S.R. Seismological Program", "author": [ { "family_name": "Berger", "given_name": "J.", "clpid": "Berger-J" }, { "family_name": "Brune", "given_name": "J. N.", "clpid": "Brune-J-N" }, { "family_name": "Bodin", "given_name": "P. A.", "clpid": "Bodin-P-A" }, { "family_name": "Gomberg", "given_name": "J. S.", "clpid": "Gomberg-J-S" }, { "family_name": "Carrel", "given_name": "D. M.", "clpid": "Carrel-D-M" }, { "family_name": "Priestley", "given_name": "K. F.", "clpid": "Priestley-K-F" }, { "family_name": "Chavez", "given_name": "D. E.", "clpid": "Chavez-D-E" }, { "family_name": "Walter", "given_name": "W. R.", "clpid": "Walter-W-R" }, { "family_name": "Archambeau", "given_name": "C. B.", "clpid": "Archambeau-C-B" }, { "family_name": "Cochran", "given_name": "T. B.", "clpid": "Cochran-T-B" }, { "family_name": "Nersesov", "given_name": "I. L.", "clpid": "Nersesov-I-L" }, { "family_name": "Gokhberg", "given_name": "M. B.", "clpid": "Gokhberg-M-B" }, { "family_name": "Stolyrov", "given_name": "O. A.", "clpid": "Stolyrov-O-A" }, { "family_name": "Daragen", "given_name": "S. K.", "clpid": "Daragen-S-K" }, { "family_name": "Tarassov", "given_name": "N. D.", "clpid": "Tarassov-N-D" }, { "family_name": "Sutelov", "given_name": "Y. A.", "clpid": "Sutelov-Y-A" } ], "abstract": "On July 9, 1986, a team of researchers from the University of California, San Diego; University of Nevada, Reno; and the University of Colorado, Boulder established the first of three seismic stations to be located in the vicinity of the Soviet nuclear test site in eastern Kazakhstan (KTS) (see cover). Under an agreement reached between the Soviet Academy of Sciences and the Natural Resources Defense Council, a nonprofit U.S. environmental organization, these stations, which are configured to meet the specifications of the proposed new global seismographic network [Incorporated Research Institutions for Seismology (IRIS), 1984], will be complemented by three similarly equipped stations to be installed in the vicinity of the U.S. nuclear test site in southern Nevada (NTS). The stations are to be operated cooperatively by Soviet and U.S. personnel (Figure 1).", "doi": "10.1029/EO068i008p00105-01", "issn": "0096-3941", "publisher": "American Geophysical Union", "publication": "EOS Transactions", "publication_date": "1987-02-24", "series_number": "8", "volume": "68", "issue": "8", "pages": "105-111" }, { "id": "authors:dvthy-rr019", "collection": "authors", "collection_id": "dvthy-rr019", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140825-162911416", "type": "article", "title": "The horse canyon earthquake of August 2, 1975\u2014Two-stage stress-release process in a strike-slip earthquake", "author": [ { "family_name": "Hartzell", "given_name": "Stephen", "clpid": "Hartzell-S-H" }, { "family_name": "Brune", "given_name": "James N.", "clpid": "Brune-J-N" } ], "abstract": "A moderate strike-slip earthquake (M_L = 4.8) occurred on the San Jacinto fault system about 60 km northwest of the Salton Sea on August 2, 1975. Analysis of main shock and aftershock data suggest that stress release during this earthquake took place in two stages. During one stage faulting occurred over a relatively small source area (source radius of \u223c0.5 km), with a rapid dislocaton rate (rise time \u223c0.1 sec), possibly associated with an asperity on the fault. During the second stage of faulting, the rupture front grew, but at a much slower rate (rise time \u223c10 sec), to a final source radius of \u223c1.0 km. The above model explains the larger moment estimate based on 20-sec surface waves compared to shorter period body-wave estimates, and also the apparent increase in source dimension with time. The model allows for large stress drops over small source dimensions, but when averaged over the final extent of the rupture plane, stress drops are much lower. The rupture of the asperity is characterized by a moment of 6.5 \u00d7 10^(22) dyne-cm and a stress drop of about 225 bars. The total moment is about 3.0 \u00d7 10^(23) dyne-cm with an averaged stress drop over the fault plane of approximately 90 bars and a dislocation of 25 cm. Observations similar to the ones reported on here have been noted for other earthquakes with a wide range of magnitudes, including: a few large earthquakes in Japan, the 1971 San Fernando earthquake and some of its aftershocks, the 1975 Oroville earthquake, and some swarm events in the Imperial Valley. These observations suggest that a two-stage rupture mechanism may be a fairly common occurrence in shallow faulting and may reflect possible large variations in stress over a length scale of kilometers within the crust.", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1979-08", "series_number": "4", "volume": "69", "issue": "4", "pages": "1161-1173" }, { "id": "authors:aatvt-mnw22", "collection": "authors", "collection_id": "aatvt-mnw22", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140813-093429653", "type": "article", "title": "A permanent seismograph array around the Gulf of California", "author": [ { "family_name": "Brune", "given_name": "James N.", "clpid": "Brune-J-N" }, { "family_name": "Lomnitz", "given_name": "Cinna", "clpid": "Lomnitz-C" }, { "family_name": "Allen", "given_name": "Clarence", "clpid": "Allen-C-R" }, { "family_name": "Mooser", "given_name": "Federico", "clpid": "Mooser-F" }, { "family_name": "Lehner", "given_name": "Francis", "clpid": "Lehner-F-E" }, { "family_name": "Reyes", "given_name": "Alfonso", "clpid": "Reyes-A" } ], "abstract": "A permanent seismographic array has been established around the Gulf of California. Solar-powered stations are operating at Caborca, Bahia de los Angeles, Guaymas, Topolobampo and La Paz. Trailer stations using local 60-cycle power are operating at San Felipe, Rio Hardy, Rancho Meling, and Ensenada. The array is unique in the following aspects: (1) It is the only array operating in close proximity to an active region of sea-floor spreading; (2) its sophisticated low-power design and use of solar energy made siting choices simpler so that local noise sources could be minimized; (3) it is the first accurately timed array to operate in northwest Mexico.\n\nThe array has already provided important information on seismicity in the Gulf of California and has aided in several sonobuoy studies of swarms and aftershock sequences. As more data accumulate, many of the important questions concerning the seismicity, tectonics, and structure of the Gulf of California will be answered.", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1976-06", "series_number": "3", "volume": "66", "issue": "3", "pages": "969-978" }, { "id": "authors:tmcvq-a7h80", "collection": "authors", "collection_id": "tmcvq-a7h80", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140825-162221190", "type": "article", "title": "Regional variations of source properties in southern California estimated from the ratio of short- to long-period amplitudes", "author": [ { "family_name": "Wyss", "given_name": "Max", "clpid": "Wyss-M" }, { "family_name": "Brune", "given_name": "James N.", "clpid": "Brune-J-N" } ], "abstract": "The ratio of short- to long-period amplitude is expressed in terms of apparent stress, rigidity times energy over moment (\u03bcE_G/M_0), for 277 earthquakes in California. A map showing the apparent stresses is compiled. In general, the Mendocino and San Andreas faults as well as the Gulf of California area are regions of large surface-wave excitation and little short-period radiation (low apparent stress). Away from the main fault zones, the apparent stresses tend to be higher. Regions of conspicuously low surface-wave excitation (high apparent stress) are the Laguna Salada-Sierra Juarez region in northern Baja California, the California-Nevada border region north of Bishop, and the region associated with the bend of the San Andreas between San Bernardino and San Gorgonio Mountain. A detailed comparison of earthquakes with accurately-known depths at Parkfield and Borrego Mountain indicates two important differences in apparent stresses between these two source regions. The apparent stress at all depths is larger at Borrego Mountain than at Parkfield, and it increases with depth at Borrego Mountain, whereas it remains constant at all depths at Parkfield. The explanation for the variation of surface-wave excitation (apparent stress) is not known for certain, but it could be related to variations in true stress.", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1971-10", "series_number": "5", "volume": "61", "issue": "5", "pages": "1153-1167" }, { "id": "authors:6dchg-asj27", "collection": "authors", "collection_id": "6dchg-asj27", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141118-135845716", "type": "article", "title": "Seismic Study of an Oceanic Ridge Earthquake Swarm in the Gulf of California", "author": [ { "family_name": "Thatcher", "given_name": "Wayne", "clpid": "Thatcher-W" }, { "family_name": "Brune", "given_name": "James N.", "clpid": "Brune-J-N" } ], "abstract": "Detailed seismic investigation of an unusually intense earthquake swarm which occurred in the northern Gulf of California during March 1969 has provided new information about seismic processes which occur on actively spreading oceanic ridges and has placed some constraints on the elastic wave velocities beneath them. Activity during this swarm was similar to that of a foreshock-mainshock-aftershock sequence, but with a 'mainshock' composed of over 70 events with magnitudes between 4 and 5.5 occurring in a 6-hr period about a day after swarm activity was initiated. 'Aftershocks', including many events greater than magnitude 5, continued for over two weeks. Near-source travel-time data indicate all sources located are within 5\u201310 km of each other and that hypocentres are confined to the upper crust. Teleseismic P-delays for rays travelling beneath this ridge may be interpreted in terms of an upper mantle with compressional velocities 5\u201310 per cent less than normal mantle to a depth of 200 km. Average apparent stresses for all swarm events studied are very similar, show no consistent pattern as a function of time, and are close to values obtained from other ridges. The focal mechanism solution shows a large component of normal faulting. An apparent non-orthogonality of nodal planes common to this mechanism solution and to normal faulting events on other ridges disappears when the indicated low upper mantle velocities beneath the source are taken into account. \n\nA survey of recent seismicity (post 1962) in the northern Gulf suggests seismic coupling across about 200 km between adjacent inferred spreading ridge segments. \n\nSurface waves from these Gulf Swarm earthquakes have amplitudes from one to two orders of magnitude greater than Northern Baja California events with similar short period body wave excitation.", "doi": "10.1111/j.1365-246X.1971.tb03615.x", "issn": "0016-8009", "publisher": "Royal Astronomical Society", "publication": "Geophysical Journal of the Royal Astronomical Society", "publication_date": "1971-05", "series_number": "5", "volume": "22", "issue": "5", "pages": "473-489" }, { "id": "authors:69yd0-pxq15", "collection": "authors", "collection_id": "69yd0-pxq15", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140924-091244669", "type": "article", "title": "Seismicity and Tectonics of the Northern Gulf of California Region, Mexico. Preliminary Results", "author": [ { "family_name": "Lomnitz", "given_name": "Cinna", "clpid": "Lomnitz-C" }, { "family_name": "Mooser", "given_name": "Federico", "clpid": "Mooser-F" }, { "family_name": "Allen", "given_name": "Clarence R.", "clpid": "Allen-C-R" }, { "family_name": "Brune", "given_name": "James N.", "clpid": "Brune-J-N" }, { "family_name": "Thatcher", "given_name": "Wayne", "clpid": "Thatcher-W" } ], "abstract": "Three new seismographic statioms have been established\u00b7 in the\nnorthern Gulf of California region; Mexico. Seismicity ,during a\nrepresentative period in April and May of 1969 was concentrated\non the Imperial, San Jacinto, Sierra Juarez, .and San Miguel\nfaults, and the spread of epicentral locations was m\\!Ch less than\nhad previously been indicated. An intense earthquake swarm in\nMarch of\u00b7 1969 occurred near Consag Rock in the northern Gulf,\nand its study contributes to our understanding of the regional\ntectonics. In the northern Gulf of California and adjacent Salton\ntrough, the tectonic framework may be. approximated by a series\nof six transform faults connected by five spreading centers (ridge,\nsegments) evidenced by geothermal areas, recent .. volcanic activity,\nearthquake swarms, and submarine topographic depressions. Complexities\nin the fault pattern may be related to a northward decrease\nin spreading rates along the ridge segment,s. Five new high;\nquality seismographic stations around the \u2022Gulf of California are\nnow under construction in order to understand in more detail the\npattern of sea-floor spreading in this unique, and important region.", "issn": "0016-7169", "publisher": "Union Fisica Mexicana", "publication": "Geofisica Internacional", "publication_date": "1970-04-01", "series_number": "2", "volume": "10", "issue": "2", "pages": "37-48" }, { "id": "authors:94r3h-j6j80", "collection": "authors", "collection_id": "94r3h-j6j80", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140812-162229454", "type": "article", "title": "Locations of small earthquakes near the trifurcation of the San Jacinto fault southeast of Anza, California", "author": [ { "family_name": "Arabasz", "given_name": "Walter J.", "clpid": "Arabasz-W-J" }, { "family_name": "Brune", "given_name": "James N.", "clpid": "Brune-J-N" }, { "family_name": "Engen", "given_name": "Gladys R.", "clpid": "Engen-G-R" } ], "abstract": "About 100 small earthquakes (M \u2248 1/2 to 2) which occurred near the trifurcation of the San Jacinto fault southeast of Anza, California, have been accurately located using five- and six-station arrays with dimensions of about 10 km. The pattern of epicenters is complex and extends several km outside of the area outlined by the traces of faulting. Patterns of seismicity observed on opposite sides of the San Jacinto fault are significantly different. On the southwest side, a concentration of foci lies at a depth of about 4-7 km along the projected extension of the Coyote Creek fault a few km northwest of the last surface evidence of faulting. On the northeast side, earthquakes are concentrated at depths between 10 and 15 km. A group of the latter events recorded about 1 week after the magnitude 4.7 earthquake of May 21, 1967 forms a linear pattern parallel to the San Jacinto fault with depths from 3 to 15 km. This pattern may represent the zone of energy release or slip for that earthquake and possibly the plane of the San Jacinto fault at depth, although the epicenters are located about 2 to 3 km to the northeast of the trace of the San Jacinto fault. Most of the earthquakes located in this study are not aftershocks in the usual sense, i.e., easily correlated with a preceding large earthquake. They represent a complex pattern of seismicity which has continued at least for the last 3 years on the micro-earthquake level and for the last 30 years on the macroseismic level.", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1970-04", "series_number": "2", "volume": "60", "issue": "2", "pages": "617-627" }, { "id": "authors:gp7cd-dcf38", "collection": "authors", "collection_id": "gp7cd-dcf38", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140424-113014914", "type": "article", "title": "Earthquakes and Nuclear Detonations", "author": [ { "family_name": "Anderson", "given_name": "Don L.", "clpid": "Anderson-D-L" }, { "family_name": "Archambeau", "given_name": "Charles B.", "clpid": "Archambeau-C-B" }, { "family_name": "Brune", "given_name": "James N.", "clpid": "Brune-J-N" }, { "family_name": "Richter", "given_name": "Charles F.", "clpid": "Richter-C-F" }, { "family_name": "Smith", "given_name": "Stewart W.", "clpid": "Smith-S-W" } ], "abstract": "The report by Emiliani et al. (1)\nasserts some statistical results which\nwould be important if well substantiated.\nTo the undersigned, their evidence appears inadequate. Since it is\nlikely that the conclusions, if unchallenged,\nwill be accepted as authoritative, and misapplied by readers not\nwell versed in the subject, critical remarks\nare offered.", "doi": "10.1126/science.167.3920.1011", "issn": "0036-8075", "publisher": "American Association for the Advancement of Science", "publication": "Science", "publication_date": "1970-02-13", "series_number": "3920", "volume": "167", "issue": "3920", "pages": "1011-1012" }, { "id": "authors:xmkjt-82r67", "collection": "authors", "collection_id": "xmkjt-82r67", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140812-123426096", "type": "article", "title": "Complexity of energy release during the Imperial Valley, California, earthquake of 1940", "author": [ { "family_name": "Trifunac", "given_name": "Mihailo D.", "clpid": "Trifunac-M-D" }, { "family_name": "Brune", "given_name": "James N.", "clpid": "Brune-J-N" } ], "abstract": "The pattern of energy release during the Imperial Valley, California, earthquake of 1940 is studied by analyzing the El Centro strong motion seismograph record and records from the Tinemaha seismograph station, 546 km from the epicenter. The earthquake was a multiple event sequence with at least 4 events recorded at El Centro in the first 25 seconds, followed by 9 events recorded in the next 5 minutes. Clear P, S, and surface waves were observed on the strong motion record. Although the main part of the earthquake energy was released during the first 15 seconds, some of the later events were as large as M = 5.8 and thus are important for earthquake engineering studies. The moment calculated using Fourier analysis of surface waves agrees with the moment estimated from field measurements of fault offset after the earthquake. The earthquake engineering significance of the complex pattern of energy release is discussed. It is concluded that a cumulative increase in amplitudes of building vibration resulting from the present sequence of shocks would be significant only for structures with relatively long natural period of vibration. However, progressive weakening effects may also lead to greater damage for multiple event earthquakes.", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1970-02", "series_number": "1", "volume": "60", "issue": "1", "pages": "137-160" }, { "id": "authors:d9gm7-8nr52", "collection": "authors", "collection_id": "d9gm7-8nr52", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141008-140727339", "type": "article", "title": "Seismic methods for monitoring underground nuclear explosions, an assessment of the status and outlook [Book Review]", "author": [ { "family_name": "Brune", "given_name": "James N.", "clpid": "Brune-J-N" } ], "abstract": "This optimistic assessment of the status and outlook for the use of seismic methods to monitor\nunderground nuclear explosions is timely, comprehensive, and competent. It is valuable for anyone\ninterested in monitoring of underground nuclear explosions, whether seismologist or not, and\ngives background as well as current information necessary for adequate understanding of the\nproblem. It is not a scientific treatise, but a consensus with a collection of scientific opinions from\nwhich the consensus was derived. In general it is clearly written--there is a certain amount of\nconfusion introduced because the seismological discussion is primarily carried out in terms of\nmagnitude, whereas the consensus statement only discusses yield. The study group responsible\nfor the report consisted of a group of seismologists from Canada, Czechoslovakia, France, India,\nJapan, Romania, Sweden, the Union of Soviet Socialist Republics, the United Kingdom and the\nUnited States of America (Constantinescu, Ericsson, Herrin, Karnik, Mechler, Miyamura,\nPasechnik, Press, Thirlaway, Whittam, Varghese). Dr. D. Davies, the Rapporteur, was responsible\nfor much of the work of compiling the report.", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1969-06", "series_number": "3", "volume": "59", "issue": "3", "pages": "1427-1428" }, { "id": "authors:aywns-tba90", "collection": "authors", "collection_id": "aywns-tba90", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140801-162416402", "type": "article", "title": "Excitation of mantle Love waves and definition of mantle wave magnitude", "author": [ { "family_name": "Brune", "given_name": "James N.", "clpid": "Brune-J-N" }, { "family_name": "Engen", "given_name": "Gladys R.", "clpid": "Engen-G-R" } ], "abstract": "A study is made of the excitation of mantle Love waves of 100 seconds period as a function of magnitude. 153 measurements of Love wave spectral density for earthquakes since 1930 ranging in magnitude from 6.0 to 8.9 are used to determine an excitation curve. The observations were first corrected to a standard distance of 90\u00b0. The excitation curve supports earlier results for mantle Rayleigh waves and, for strike-slip motion, an earlier curve for seismic moment versus mantle-wave magnitude. For dip-slip motion, the moments should be multiplied by a factor of about 2 1/2. A definition of mantle wave magnitude M_M, is set up, and the largest earthquake since 1930 found on this scale is the Alaskan earthquake of March 28, 1964 where M_M = 8.9. Other comparably large earthquakes, M_M = 8.8, were the Kamchatka earthquake of November 4, 1952 and the Chilean earthquake of May 22, 1960. It is suggested that mantle-wave magnitudes be used as a diagnostic aid in estimating the Tsunami potential of earthquakes.", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1969-04", "series_number": "2", "volume": "59", "issue": "2", "pages": "923-933" }, { "id": "authors:rnkdr-hk453", "collection": "authors", "collection_id": "rnkdr-hk453", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190918-073551603", "type": "article", "title": "Seismic moment, stress, and source dimensions for earthquakes in the California-Nevada region", "author": [ { "family_name": "Wyss", "given_name": "Max", "clpid": "Wyss-M" }, { "family_name": "Brune", "given_name": "James N.", "clpid": "Brune-J-N" } ], "abstract": "The source mechanism of earthquakes in the California\u2010Nevada region was studied using surface wave analyses, surface displacement observations in the source region, magnitude determinations, and accurate epicenter locations. Fourier analyses of surface waves from thirteen earthquakes in the Parkfield region have yielded the following relationship between seismic moment, M_0 and Richter magnitude, M_L: log M_0 = 1.4 M_L + 17.0, where 3 < M_L < 6. The following relation between the surface wave envelope parameter AR and seismic moment was obtained: log M_0 = log AR_(300) + 20.1. This relation was used to estimate the seismic moment of 259 additional earthquakes in the western United States. The combined data yield the following relationship between moment and local magnitude: log M_0 = 1.7 M_L + 15.1, where 3 < ML < 6. These data together with the Gutenberg\u2010Richter energy\u2010magnitude formula suggest that the average stress multiplied by the seismic efficiency is about 7 bars for small earthquakes at Parkfield and in the Imperial Valley, about 30 bars for small earthquakes near Wheeler Ridge on the White Wolf fault, and over 100 bars for small earthquakes in the Arizona\u2010Nevada and Laguna Salada (Baja California) regions. Field observations of displacement associated with eight Parkfield shocks, along with estimates of fault area, indicate that fault dimensions similar to the values found earlier for the Imperial earthquake are the rule rather than the exception for small earthquakes along the San Andreas fault. Stress drops appear to be about 10% of the average stress multiplied by the seismic efficiency. The revised curve for the moment versus magnitude further emphasizes that small earthquakes are not important in strain release and indicate that the zone of shear may be about 6 km in vertical extent for the Imperial Valley and even less for oceanic transform faults.", "doi": "10.1029/JB073i014p04681", "issn": "0148-0227", "publisher": "American Geophysical Union", "publication": "Journal of Geophysical Research", "publication_date": "1968-07-15", "series_number": "14", "volume": "73", "issue": "14", "pages": "4681-4694" }, { "id": "authors:q1gva-y6p62", "collection": "authors", "collection_id": "q1gva-y6p62", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140808-162822683", "type": "article", "title": "The Borrego Mountain, California, earthquake of 9 April 1968: A preliminary report", "author": [ { "family_name": "Allen", "given_name": "C. R.", "clpid": "Allen-C-R" }, { "family_name": "Grantz", "given_name": "A.", "clpid": "Grantz-A" }, { "family_name": "Brune", "given_name": "J. N.", "clpid": "Brune-J-N" }, { "family_name": "Clark", "given_name": "M. M.", "clpid": "Clark-M-M" }, { "family_name": "Sharp", "given_name": "R. V.", "clpid": "Sharp-R-V" }, { "family_name": "Theodore", "given_name": "T. G.", "clpid": "Theodore-T-G" }, { "family_name": "Wolfe", "given_name": "E. W.", "clpid": "Wolfe-E-W" }, { "family_name": "Wyss", "given_name": "M.", "clpid": "Wyss-M" } ], "abstract": "The largest earthquake to hit California in more than 15 years occurred at\n02:28:58.9 GCT on 9 April 1968 near Borrego Mountain, on the western edge of\nthe Imperial Valley. The Seismological Laboratory at Pasadena has tentatively\nassigned the shock a magnitude of 6.5, an epicentral location of 33 \u00b0 08.8' N, 116 \u00b0\n07.5' W, and a focal depth of 20 km. The earthquake was felt throughout most\nof southern California and adjacent areas, but the absence of severe damage and\ncasualties was in large part due to the relatively undeveloped nature of the epicentral\nregion. Indeed, it would have been difficult to pick a location in the southernmost\npart of the State more remote from centers of population.", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1968-06", "series_number": "3", "volume": "58", "issue": "3", "pages": "1183-1186" }, { "id": "authors:f0py9-tq653", "collection": "authors", "collection_id": "f0py9-tq653", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140811-122717394", "type": "article", "title": "Excitation of mantle Rayleigh waves of period 100 seconds as a function of magnitude", "author": [ { "family_name": "Brune", "given_name": "James N.", "clpid": "Brune-J-N" }, { "family_name": "King", "given_name": "Chi-Yu", "clpid": "King-C-Y" } ], "abstract": "The excitation of mantle Rayleigh waves of 100 seconds period as a function of magnitude is studied using data from 91 earthquakes in the magnitude range 5.0 to 8.9. The data were recorded on a wide variety of instruments including Milne-Shaw horizontal pendulums and modern long-period high-gain inertial seismographs. The larger earthquakes studied range in time from 1923 to 1964. Mantle Rayleigh wave amplitudes are corrected to a distance of 90\u00b0 and plotted as a function of surface wave magnitude. The data are compared with theoretical curves based on a moving source model and two statistical models discussed by Aki. It is concluded that for large earthquakes the source may be approximated by a point couple which propagates a distance given approximately by the length of the aftershock zone.", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1967-12", "series_number": "6", "volume": "57", "issue": "6", "pages": "1355-1365" }, { "id": "authors:7aj35-a8476", "collection": "authors", "collection_id": "7aj35-a8476", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140808-153514769", "type": "article", "title": "The Alaska earthquake of 28 March 1964: A complex multiple rupture", "author": [ { "family_name": "Wyss", "given_name": "Max", "clpid": "Wyss-M" }, { "family_name": "Brune", "given_name": "James N.", "clpid": "Brune-J-N" } ], "abstract": "The seismograms of the Alaskan earthquake of 28 March 1964 are characterized by multiple P-phases not predicted by the travel-time curves.\n\nSeismograms with low magnifications from 80 stations covering distances from 40\u00b0 to 90\u00b0 and a wide range of azimuths were analyzed. The character of the P-wave portion of the seismograms is interpreted in terms of an approximate multiple-event source mechanism where the propagating rupture triggers larger distinct events. Six events were located using the Gutenberg sine-curve method. The times after the initial origin time were 9, 19, 28, 29, 44 and 72 sec respectively, and the events were located 35, 66, 89, 93, 165 and 250 km away from the initial epicenter. Dividing the distance by the delay-time gives an average rupture velocity of 3.5 km/sec.", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1967-10", "series_number": "5", "volume": "57", "issue": "5", "pages": "1017-1023" }, { "id": "authors:2pp2x-6qv73", "collection": "authors", "collection_id": "2pp2x-6qv73", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140801-141944225", "type": "article", "title": "A low-stress-drop, low-magnitude earthquake with surface faulting: The Imperial, California, earthquake of March 4, 1966", "author": [ { "family_name": "Brune", "given_name": "James N.", "clpid": "Brune-J-N" }, { "family_name": "Allen", "given_name": "Clarence R.", "clpid": "Allen-C-R" } ], "abstract": "Right-lateral surface displacement reaching 1 1/2 centimeters occurred over a ten-kilometer section of the Imperial fault in association with a magnitude 3.6 earthquake on March 4, 1966, the smallest known earthquake yet associated with surface displacement. The displacement is documented by field observations of en-echelon cracking in pavement and the offset of the white center line of Highway 80. The association of the observed displacement with the March 4 earthquake is supported by the shallow depth of the earthquake source, the high excitation of waves in the top layer of sediments, the high excitation of Love waves of period 8-15 seconds, the distribution of aftershocks, and the agreement between the source moment as calculated from the observed faulting and from the amplitudes of Love waves. Calculations based on faulting theory indicate a fault depth of 1.1 km, a net moment of 2 \u00d7 10^(22) dyne-cm, a stress drop of 1.1 bar and an energy release of 10^(17) ergs. The remarkable internal consistency of the various calculations provides strong support for the faulting mechanism. It is suggested that low stress drops and relatively large fault lengths may be associated with many other small earthquakes and that allowance must be made for a wide range in the stress drops and fault lengths for any given magnitude range.", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1967-06", "series_number": "3", "volume": "57", "issue": "3", "pages": "501-514" }, { "id": "authors:qsz6v-95m54", "collection": "authors", "collection_id": "qsz6v-95m54", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140801-111341811", "type": "article", "title": "A micro-earthquake survey of the San Andreas fault system in southern California", "author": [ { "family_name": "Brune", "given_name": "James N.", "clpid": "Brune-J-N" }, { "family_name": "Allen", "given_name": "Clarence R.", "clpid": "Allen-C-R" } ], "abstract": "Micro-earthquakes have been systematically recorded with magnitudes down to -1.3 at more than 60 sites along the San Andreas fault system in southern California during intervals of 2 days to 1 year, representing more than 35,000 hours of usable records. Eight trailer-mounted instruments were operated with peak gains of 4-8 million at 20 cps with noise levels averaging about 0.1 mu amplitude of ground motion.\n\nObserved micro-earthquake activity varies from virtually nil along the central section of the San Andreas fault to more than 75 shocks daily in the Imperial Valley. Quietest is the 300-km segment between Cholame and Valyermo; more than one year of recording at Lake Hughes indicates an average of only one micro-earthquake within 24 km every nine days. Activity increases northward from Cholame toward Hollister, and southward it increases abruptly near Valyermo and continues high along major branches of the fault southeast into Mexico, with the exception of the Banning-Mission Creek fault southeast of Desert Hot Springs. Most areas where regional strain or fault creep have been demonstrated by geodetic measurements are also areas of high micro-earthquake activity. Existence of an area of minimal micro-earthquake activity within a broad region of active tectonism, and indeed along the very segment of the fault that broke in the great 1857 earthquake, suggests that short-term micro-earthquake activity is not necessarily positively correlated with long-term activity and with earthquake hazard, and in some areas the relationship may be inverse. However, areal distribution of micro-earthquake activity is grossly similar to that of larger earthquakes (M \u2267 3) during the past 29 years, and in many areas micro-earthquake activity can be approximately predicted by extrapolation of 29-year recurrence curves based solely on larger earthquakes.", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1967-04", "series_number": "2", "volume": "57", "issue": "2", "pages": "277-296" } ]