bluuebunny/crossref_metadata_2025_split huggingface dataset:
Probabilistic Forecasting of Hydraulic Fracturing-Induced Seismicity Using an Injection-Rate Driven ETAS Model
Authors: Mancini Simone , Werner Maximilian Jonas , Segou Margarita , Baptie Brian 
Published: May 2021

Abstract
The development of robust forecasts of human-induced seismicity is highly desirable to mitigate the effects of disturbing or damaging earthquakes. We assess the performance of a well-established statistical model, the epidemic-type aftershock sequence (ETAS) model, with a catalog of ∼93,000 microearthquakes observed at the Preston New Road (PNR, United Kingdom) unconventional shale gas site during, and after hydraulic fracturing of the PNR-1z and PNR-2 wells. Because ETAS was developed for slower loading rate tectonic seismicity, to account for seismicity caused by pressurized fluid, we also generate three modified ETAS with background rates proportional to injection rates. We find that (1) the standard ETAS captures low seismicity between and after injections but is outperformed by the modified model during high-seismicity periods, and (2) the injection-rate driven ETAS substantially improves when the forecast is calibrated on sleeve-specific pumping data. We finally forecast out-of-sample the PNR-2 seismicity using the average response to injection observed at PNR-1z, achieving better predictive skills than the in-sample standard ETAS. The insights from this study contribute toward producing informative seismicity forecasts for real-time decision making and risk mitigation techniques during unconventional shale gas development.
Intensity of Induced Earthquakes in Northeast British Columbia, Canada
Authors: Babaie Mahani Alireza , Venables Stuart , Kao Honn , Visser Ryan , Gaucher Michelle , Dokht Ramin M. H. , Johnson Jeff 
Published: May 2021

Abstract
The damage potential of induced earthquakes associated with fluid injection is a major concern in hydrocarbon resource development. An important source of data for the assessment of damage is macroseismic intensity perceived by people and structures. In the Western Canada Sedimentary Basin (WCSB) where the occurrence of seismicity is mostly related to oil and gas activities, the collection of intensity data is incomplete. In this study, we present a comprehensive dataset gathered by the BC Oil and Gas Commission in the period 2016–2020. We assign intensities to individual felt reports according to the modified Mercalli intensity (MMI) scale and associate each MMI value to an earthquake. The isoseismal map of the largest earthquake in the Septimus region of northeast British Columbia is also provided using the compiled intensity dataset complemented with data from the U.S. Geological Survey and Natural Resources Canada “Did You Feel It?” systems along with the intensities converted from ground-motion amplitudes. We consider an approximate 10 km radius around the mainshock of 30 November 2018 earthquake with moment magnitude of 4.6 to be the meizoseismal area based on maximum intensities of 4–5. We also investigate the distance decay of intensity for shallow induced earthquakes in comparison with deeper natural events with the same magnitudes. Although intensities from shallow earthquakes (depth≤5  km) can be higher than deep events (depth≥10  km) at close distances (10–15 km), they tend to decrease abruptly at greater distances to become lower than deep events. The localization of large intensities from induced earthquakes within the meizoseismal area warrants special attention in future resource developments and call for systematic intensity data collection in the WCSB.
The future development of the metropolitan area surrounding San Francisco Bay1
Authors: Lee Charles H. 
Published: May 2021

Author's Abstract
The purpose of this paper is to picture the essential facts and problems relating to the present and future metropolitan area of San Francisco Bay, and to outline what might be done to reduce future hazards to life and property from earthquake and earthquake fires.
The conclusion is reached that the future metropolitan area will include the region immediately tributary to San Francisco, within an average radius of forty miles from the Ferry Building at San Francisco, and embracing fifty-four per cent of the nine Bay counties. The included land which will be capable of intensive development covers 876,300 acres.
The ultimate population of this area will be between 5,000,000 and 6,000,000, and the true value of all taxable property at least $12,000,000,000, of which fifty per cent will be more or less destructible. The future metropolitan area will include an eleven-fold greater land area than at present, a fourfold increase in population, and a sixfold growth in value of all property.
A limiting feature in the attainment of this population will be water supply. The future demand will be at least 1,075 million gallons daily, of which 250 million gallons may be developed from local sources. Of the latter quantity, 100 million gallons daily have already been developed. To meet future demands, outside sources must be brought in equivalent to the full development proposed for the Hetch Hetchy, Mokelumne, and Eel River Projects. The Sacramento-San Joaquin River at the head of the Bay may also be drawn upon.
Systematic establishment of open spaces in the form of broad thoroughfares, highways, parks, public grounds, etc., to act as fire-breaks and places of refuge for the inhabitants. Preservation of an adequate and efficient ferry system in conjunction with trans-Bay bridges or tubes when built. Revision or adoption of building codes designed to promote earthquake-proof construction and use of fire-resistant building materials. Adoption of a definite program to be followed by electric and gas utilities at the occurrence of an earthquake, to reduce fire hazard from these sources. Increasing the amount of local storage capacity in the water distribution systems of different communities so as to provide a reserve for domestic and fire use in case of serious interruption in supply mains. Utilizing all feasible reservoir sites in the Bay region for reserve storage, and as far as possible interconnecting all reservoirs and distribution systems, with the ultimate aim of completely circling the Bay with transmission pipe line or conduit capable of drawing water from any major reservoirs in case of emergency. Establishment of a plan of organization, both local and general, for handling the water problems of the future metropolitan area.
Nature of certain discontinuities in the earth
Authors: Daly Reginald A. 
Published: May 2021

Abstract
Four different kinds of experimental evidence suggest that the seismically effective compressibility of a rock is of the order of one-fifth less than its compressibility as determined by the high-pressure method. Additional, specially designed experiments to test this idea are urgently needed. As it stands, the tentative conclusion implies that the crystalline Sial of a continental block is essentially granitic down to a depth not far from thirty kilometers. Below that shell a second shell of granodiorite or quartz diorite is indicated. At the depth of about forty-five kilometers is a major discontinuity, which, interpreted on the same basis, represents the interface between the second shell and crystalline basalt, or gabbro. According to Gutenberg's hypothesis, this third shell contacts with a fourth, underlying shell of vitreous basalt, the thickness of which is not now to be readily determined from the wave-velocities in depth. So far as seismological evidence goes, that thickness may possibly approach 1,200 kilometers. A shell of either crystalline or vitreous peridotite near the earth's surface is not suggested by the wave-velocities. The master discontinuity at the depth of 2,900 kilometers seems capable of at least two different explanations.
On the question of dispersion in the first preliminary seismic waves1
Authors: Sommer H. Henrietta 
Published: May 2021

AbstractSummaryBy use of the Byerly-Jeffreys travel-time curve for P, and Geiger's method of least-squares adjustment, the epicenter of the Alaskan earthquake of October 24, 1927, was placed at5 7 ° 26 ' ± 5 0 ' N . 13 7 ° 03 ' ± 1 9 ' W .and the time of occurrence was placed at 15h 59m 55s ± 2s, G.M.C.T.A second solution was obtained using Mohorovičić's multiple travel-time curves for P. The co-ordinates of the epicenter were the same as those given above, but the time of occurrence was found to be 16h00m, G.M.C.T.It has been held by some seismologists that anomalous dispersion can be observed in the first preliminary waves; i.e., that shorter periods travel faster than long ones. Investigations of periods were made with a view to testing this hypothesis, with the following results:The general conclusion is that observation of periods gives no evidence for dispersion in waves of longitudinal type.It is shown that, if dispersion did exist, the travel time of the beginning would be a continuous function of epicentral distance, and, therefore, Mohorovičić's curves are not evidence for dispersion. The observations of the epicentral distances at which P2, P1, and Pn are most frequently recorded first are contrary to dispersion.In the Alaskan earthquake the distribution of first motion (condensation or rarefaction) is very complicated. Dispersion offers no explanation for this fact, and it is believed that complex movements at the source are responsible for the observed distribution.
On supposed discontinuities in the mantle of the Earth
Authors: Gutenberg B. , Richter C. F. 
Published: May 2021

SummaryInvestigations of the Mexican shocks of January 2, 15, and 17, 1931, as recorded at stations in California have shown that the travel-time curve of the P-waves at distances between 9° and 15° is nearly a straight line. At these distances the amplitudes of the P-waves are very small, as is to be expected from theory. At greater distances dt/dΔ decreases, and the amplitudes are larger. The data are not sufficient to decide whether the changes are abrupt or not. No S-waves could be found between 9° and 15°. The calculated velocities of the P-waves are near 8.2 kilometers per second at depths between 40 and 100 kilometers, increasing slightly with greater depths. It is possible that the velocity decreases very slightly at some depths between 40 and 80 kilometers, but there is no sign of any discontinuity at depths between 40 and more than 500 kilometers. The S-waves seem to be affected a little more at depths between 40 and 100 kilometers than the P-waves. It is not impossible that at some depth between 40 and 80 kilometers there is a transition from the crystalline to the glassy state.
The Cedar Mountain, Nevada, earthquake of December 20, 1932*
Authors: Gianella Vincent P. , Callaghan Eugene 
Published: May 2021

SummaryThe Cedar Mountain, Nevada, earthquake took place at about 10h 10m 04s p.m., December 20, 1932. It was preceded by a foreshock noted locally and followed by thousands of aftershocks, which were reported as still continuing in January 1934. No lives were lost and there was very little damage.The earthquake originated in southwest central Nevada, east of Mina. A belt of rifts or faults in echelon lies in the valley between Gabbs Valley Range and Pilot Mountains on the west and Cedar Mountain and Paradise Range on the east. The length of this belt is thirty-eight miles in a northwesterly direction, and the width ranges from four to nine miles. The rifts consist of zones of fissures which commonly reveal vertical displacement and in a number of places show horizontal displacement. The length of the rifts ranges from a few hundred feet to nearly four miles, and the width may be as much as 400 feet. The actual as well as indicated horizontal displacement is represented by a relative southward movement of the east side of each rift. The echelon pattern of the rifts within the rift area indicates that the relative movement of the adjoining mountain masses is the same. The direction of relative horizontal movement corresponds to that along the east front of the Sierra Nevada at Owens Valley and on the San Andreas rift.
The Central California earthquakes of May 16, 1933, and June 7, 1934
Authors: Byerly Perry , Wilson James T. 
Published: May 2021

Abstract
Isoseismalsare drawn and field intensities listed for the Niles earthquake of May 16, 1933. The epicenter is placed at 37° 38′ N, 121° 57′ W. Isoseismals are drawn and field intensities listed for the Parkfield earthquakes of June 7, 1934. The epicenter of the shock at 8h 48mp.m. (P.S.T.) is placed at 35° 56′ N, 120° 29′ W. The epicenter of the shock at 8h 30m is placed about 4 km. north of this. Travel-time curves are drawn for each of these three shocks. It is shown that the Owens Valley stations, Tinemaha and Haiwee, did not record the normal P (v = 8.0 km/sec., ca.) for any of these earthquakes. It is concluded that there exists some barrier to these waves under the Great Valley of California (or possibly under the Sierra), which prevents their observation at stations so close to the valley as Tinemaha and Haiwee when the source is in the Coast Range region. The interpretation of the data of difficult, but there is some evidence for identifying P waves traveling through three successive layers of the earth's crust. A tentative computation of this structure is made.
Velocity of P waves in the earth calculated from the Macelwane P curve, 1933*
Authors: Dahm Cornelius G. 
Published: May 2021

Summary
The Macelwane P curve is based on the data of the Tango, Hawke Bay, and Long Beach earthquakes, all of 10–12 km. focal depth. This curve was modified and adjusted to fit a spheroid of 6355 km. radius, the outer part of which has the same properties as those immediately under the Mohorovičić discontinuity in Japan. The original and the adjusted P curve are given as well as the velocity-depth and depth-distance data obtained by applying the Herglotz-Wiechert method to the adjusted P curve. The inversion and slight decrease of the velocity-depth function at 2730 km. depth are discussed and the continued validity of the Herglotz-Wiechert method under those circumstances is shown.
Elasticity and internal friction in a long column of granite*
Authors: Birch Francis , Bancroft Dennison 
Published: May 2021

Abstract
The forced resonant vibrations of a long column of Quincy granite have been studied with the object of discovering the effect of frequency upon the velocities of elastic waves. Longitudinal, flexural, and torsional modes were used, covering the frequency range 140-4500 cycles per second. For these frequencies the velocities were independent of frequency to within 1 per cent or less. The internal friction was also roughly independent of frequency, with Q = 150. The damping of seismic waves is considered with reference to these results.
Tsunamis and earthquakes*
Authors: Gutenberg B. 
Published: May 2021

Summary
Tsunamis (“tidal waves,” “maremotos”) may be produced by submarine volcanic eruptions, submarine slides started by earthquakes, submarine faulting, and atmospheric conditions. The hypothesis that at least some of the largest tsunamis have been produced by submarine slides with earthquake waves as a trigger force has been advanced by a notable number of those seismologists who have studied tsunamis. The macroseismic as well as the microseismic data of the Atacama earthquake of November 11, 1922, indicate clearly that the fault movement occurred inland; the tsunamis originated from a submarine slide near a relatively feebly shaken stretch of the coast where the surface slopes steeply to a considerable depth. On gently sloping coasts, such as those of California, large tsunamis are rare and the relatively small tsunamis there are probably produced by faulting at the bottom of the ocean.
The Chelmsford, Massachusetts, earthquake of June 23, 1938*
Authors: Linehan Daniel 
Published: May 2021

Summary
The Chelmsford earthquake of June 23, 1938, occurred at 03h 57m 56s.5 G.C.T. The epicentral determination made by the writer of this article is 71° 25′ W, 42° 37′ N. The distance-arcual intersection occurs at the southernmost tip of an ellipse of greatest intensity, and this may be due to the fact that all three stations employed in the determination were to the south and west of the area, or that structural conditions elongated the greatest intensity area. The major axis of the ellipse does coincide with the strike of the geologic structure in this area. The greatest intensity given by the writer is IV on the Rossi-Forel Scale.
The problem of the earth's density variation*
Authors: Bullen K. E. 
Published: May 2021

Summary
The present paper examines the problem of the earth's density variation and includes a quantitative discussion of the errors likely to be involved. Figures are given for the density distribution of the earth's outer mantle, and it is shown that all these are probably accurate within about 0.05 gm/cm.3 On the figures presented, the density in the earth's mantle ranges from 3.32 gm/cm.3 at the base of the crustal layers to 5.68 gm/cm.3 at the base of the mantle. The mean density of the central core is shown to be 10.7 gm/cm.3 within an error of order 0.1 gm/cm.3 Application of equations derived by Birch from Murnaghan's theory of finite strain indicates agreement with the density figures found, but it is to be noted that the rigidity of the lower portion of the earth's mantle appears to increase more slowly with increase of depth than would be consistent with the equations of Birch. Values which are expected to need very little future amendment are also given for the pressure and gravitational attraction within the earth's mantle.
Periodicity of deep-focus earthquakes*
Authors: McMurry Howard 
Published: May 2021

Summary and Conclusions
Data were assembled of about 320 earthquakes, including nearly all those available for which the determinations of epicentral location, time of occurrence, and focal depth were considered reliable. They were analyzed collectively and in selected geographical groups by the method of periodogram analysis which appeared most suitable. Tests were made on periods of 6, 12, and 14 months and for correlation with twice the lunar and solar hour angles. None of the results could be interpreted as other than accidental. However, the Japanese group gave a slight indication of a correlation with twice the solar hour angle, and the South American earthquakes with twice the lunar hour angle. Many additional data must first be accumulated and tested before any special significance can be attached to these results.
The manner whereby small fluctuations in stress might be expected to determine the exact time of occurrence of an earthquake was reviewed. A study was then made of three possible sources of such trigger stresses which could be effective at great depth, namely, tidal stresses in the solid earth, stresses due to changes in sea level, and stresses due to variations in barometric pressure. Tidal stresses alone were considered in detail.
It was concluded that tidal stress variations approximate harmonic changes sufficiently well to warrant a search for lunar hour angle correlations by the methods of periodogram analysis, but they are nevertheless too irregular to make the statistical results of such studies valuable in supplying information concerning the mechanics and environment of deep-seated earthquakes. Periodicity investigations of this type, even if successful, can be expected to do little more than indicate the causes which can influence earthquake occurrence times.
The importance of other agencies in causing stress variations within the earth was studied. It was concluded that oceanic tidal loads, and to a much less degree erratic barometric fluctuations, are capable of producing stress changes comparable with those due to tides in the earth. The stresses from the earth tides in general dominate the others, although the effect of ocean tidal loading may be of primary importance under special circumstances. The irregularity of both ocean loads and barometric pressure fluctuations renders them unsuitable subjects for study.
For the reasons given, the only stress changes that appear to warrant study with reference to their effect on earthquakes are those due to earth tides.
The best chance of finding a definite correlation world be from a study of data of a large number of earthquakes which had occurred within relatively small regions, as only then is it justifiable to assume that all the earthquakes had been similarly affected by the triggering stress. Data at present available are far from sufficient to provide a satisfactory basis for such a study.
A contribution to the seismic history of Missouri*
Authors: Heinrich Ross R. 
Published: May 2021

Abstract
The status of Missouri as a state which contains active seismic areas has been a subject for speculation ever since the New Madrid earthquakes of 1811 and 1812. Local seismic research, however, was slow in starting, owing principally to the lack of available instruments to supply data sufficiently accurate for detailed work.
Two events which gave great impetus to the progress of Missouri earthquake study were, first, the installation of the seismograph at St. Louis University in 1909, and second, the inauguration of the definite regional study plan which was proposed by Father Macelwane in 1925. The various stages in the development of regional earthquake study in Missouri have influenced the availability of data on the historical sequence of Missouri earthquakes.
This paper, which is offered as a contribution to the seismic history of Missouri, reflects somewhat the growth of interest in local tremors. This growth, as shown by the increase in sources of data in the more recent years, is emphasized in order to avoid the misleading interpretation that the seismicity of Missouri is increasing. It is shown that although tabulation of the earthquakes, recorded by years, showed an increase in the yearly average from 0.6 in 1911 to 4.0 for the years 1930-1939, the latter figure seems the more nearly correct, and the former may be somewhat low owing to the incomplete data for the first half century following the New Madrid disaster.
The earthquakes which have been felt in Missouri or which may possibly have been felt are listed by years, together with as many of the pertinent details as are available or space permits. By an examination of this list of shocks it can be seen that most of the earthquakes which have been felt in Missouri originate in more or less definite seismic districts. Six such districts are suggested for Missouri and they are called because of their locations the New Madrid, St. Marys, St. Louis, Hannibal, Springfield, and Northwestern Missouri seismic districts. Some of the earthquakes which have been felt in Missouri have apparently originated from seismic areas outside of the state boundaries. Four of these out-of-state areas are recognized, namely, the Centralia and Harrisburg districts in Illinois, the Anna, Ohio, region, and the Kansas-Nebraska Nemaha belt.
It is shown that nearly 85 per cent of all the seismic activity of Missouri origin comes from two seismic areas: about 60 per cent from the New Madrid area, and about 25 per cent from the St. Marys fault region. A tabulation of the earthquakes by intensities indicates that most of the earthquakes of strong intensities also seem to come from the southeastern Mossouri area although only about 7 ½ per cent of the total of earthquakes recorded since 1816 have been strong enough to endanger life.