Two Models for Earthquake Forerunners

Mjachkin, V. I.; Brace, W. F.; Соболев, Г. А.; Dieterich, James H.

doi:10.1007/978-3-0348-5534-1_15

Cited by 38 publications

(44 citation statements)

References 14 publications

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“…The FIC mechanical percolation model is very similar to the well-known physical models of seismic process evolution, namely dilatancydiffusion and avalanche fracturing models (Mjachkin et al, 1975;Scholz et al, 1973). Based on the above-mentioned considerations, it might be concluded that many transport properties are activated before the collapse of the sample (Paterson, 1978;Chelidze, 1986).…”

Section: On the Discrimination Of Thresholds For Transport And Fractumentioning

confidence: 63%

On the puzzling feature of the silence of precursory electromagnetic emissions

Eftaxias

Potirakis

Chélidzé

2013

Nat. Hazards Earth Syst. Sci.

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Abstract. It has been suggested that fracture-induced MHzkHz electromagnetic emissions (EME), which emerge from a few days up to a few hours before the main seismic shock occurrence permit a real-time monitoring of the damage process during the last stages of earthquake preparation, as it happens at the laboratory scale. Despite fairly abundant evidence, electromagnetic (EM) precursors have not been adequately accepted as credible physical phenomena. These negative views are enhanced by the fact that certain "puzzling features" are repetitively observed in candidate fractureinduced pre-seismic EME. More precisely, EM silence in all frequency bands appears before the main seismic shock occurrence, as well as during the aftershock period. Actually, the view that "acceptance of "precursive" EM signals without convincing co-seismic signals should not be expected" seems to be reasonable. In this work we focus on this point. We examine whether the aforementioned features of EM silence are really puzzling ones or, instead, reflect well-documented characteristic features of the fracture process, in terms of universal structural patterns of the fracture process, recent laboratory experiments, numerical and theoretical studies of fracture dynamics, critical phenomena, percolation theory, and micromechanics of granular materials. Our analysis shows that these features should not be considered puzzling.

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Section: On the Discrimination Of Thresholds For Transport And Fractumentioning

confidence: 63%

On the puzzling feature of the silence of precursory electromagnetic emissions

Eftaxias

Potirakis

Chélidzé

2013

Nat. Hazards Earth Syst. Sci.

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“…When we talk of precursory radon anomalies associated with earthquakes, especially in light of Russian data at Tashkent [Ulomov and Mayashey, 1968], most authors [Press, 1975;Scholz et al, 1973;Mjachkin et al, 1975;King, 1976;Craig et al, 1976] anticipate a radon high as a precursor. However, Liu et al [1975], with a much larger data base, pointed out that the distribution of the shape of the anomaly on the ground surface has some definite relationship with the source mecha- Ho (magnitude 7.9), Bo Hi (magnitude 7.4), Fung Nan (magnitude 5.2), and Sa Hu (magnitude 5.2) earthquakes, positive radon anomalies were observed before the earthquake when the observation points were located in the ever, in view of •he simultaneous onset of the radon and velocity anomalies we term the seismic events between February 8/9 and the main shock on February 23 foreshocks.…”

Section: The Top Row Inmentioning

confidence: 99%

Radon anomalies and microearthquakes at Lake Jocassee, South Carolina

Talwani¹,

Moore²,

Chiang³

1980

J. Geophys. Res.

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Continuous low‐level seismic activity was found to occur at Lake Jocassee after the impoundment of the reservoir in 1975. In addition to monitoring seismic activity we began (in January 1976) a series of geochemical measurements in an effort to search for precursors to ML ∼ 2–2.5 events. Discrete water samples were collected from wells and a spring, and their radon content was determined by scintillation counting. These data were comparable to those obtained from a continuous Rn monitor in the spring using an ionization chamber. Soil Rn measurements in track etch cups were started in 1977. The results of the data collected so far indicate (1) that long‐term fluctuations occur in the radon concentrations in the spring water with a period of ∼44 weeks (the radon content being 50–100% lower in summer and fall), (2) that anomalous changes in the radon concentrations have occurred both before and after earthquakes, the timing of the anomaly being dependent on the distance of the epicenter to the radon sample site, (3) that both high and low anomalous radon values occur, and (4) that the soil randon method using track etch cups is useful in determining areas of high and low Rn concentration but not for a study of short‐term temporal changes.

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“…The temporal character of doming around the Hebgen Lake area suggested by the preceding analysis appears to rule out coseismic strain release as the cause of the observed movement. Although uplift prior to the earthquake is consistent with the dilatancy model [Scholz et al, 1973;Mjachkin et al, 1975], dilatancy should be recoverable and thus cannot account for continuing uplift after the earthquake. An attempt was made to model the observed doming around the Hebgen Lake area as surface deformation associated with dip slip faulting by using the method of Savage and Hastie [1966].…”

Section: For Crustal Movements In Seismically Active Areas Those Conmentioning

confidence: 94%

Recent vertical crustal movements from precise leveling data in southwestern Montana, western Yellowstone National Park, and the Snake River Plain

Reilinger¹,

Citron²,

Brown³

1977

J. Geophys. Res.

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Repeated levelings in southwestern Montana, the western portion of Yellowstone National Park, and the Snake River Plain provide information on the pattern of relative vertical crustal movement throughout this region. Except for the coseismic deformation associated with the 1959 Hebgen Lake earthquake the most outstanding and best defined feature of the data is contemporary doming at a rate of 3–5 mm/yr involving approximately 8000 km2 including the epicentral area and aftershock zone of the 1959 Hebgen Lake earthquake. On the basis of observations over different time intervals, doming appears to have continued throughout the time the movements were monitored, beginning at least 25 years prior to the 1959 earthquake and continuing at least 1 year after the earthquake. The character of the coseismic deformation associated with the 1959 earthquake and the high regional elevation are consistent with the observed doming. It is suggested that doming preceded the earthquake for a considerable time (of the order of hundreds to thousands of years, perhaps longer), giving rise to tensional stresses in the upper crust. When these stresses, combined with the regional tectonic stresses, exceeded some critical value, faulting and collapse in response to gravity occurred, resulting in the 1959 earthquake. The voluminous Tertiary and younger volcanics in the vicinity of the doming region suggest that magma intrusion into the crust is the most likely cause of the observed uplift. The proximity of the doming region to the thermally active Yellowstone area supports this suggestion. Secondary features of the data include (1) a spatial correlation between tilting and historic seismic activity; (2) uplift within the Norris‐Mammoth corridor in Yellowstone National Park relative to nearby bench marks to the north and south; (3) regional subsidence of the eastern Snake River Plain relative to points north and west of this physiographic province, including subsidence of the Pleistocene Island Park caldera floor relative to its rim fractures; and (4) rapid tilting in the vicinity of the Continental fault east of Butte, the intersection of the Gardiner, Mammoth, and Reese faults just north of Yellowstone National Park, and the Madison Range fault in eastern Idaho.

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Two Models for Earthquake Forerunners

Cited by 38 publications

References 14 publications

On the puzzling feature of the silence of precursory electromagnetic emissions

On the puzzling feature of the silence of precursory electromagnetic emissions

Radon anomalies and microearthquakes at Lake Jocassee, South Carolina

Recent vertical crustal movements from precise leveling data in southwestern Montana, western Yellowstone National Park, and the Snake River Plain

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