Temporal variation of seismicity and spectrum of small earthquakes preceding the 1952 Kern County, California, earthquake

The spatio-temporal variation of seismicity in the epicentral area of the 1952 Kern County California, earthquake (M_s = 7.7, 34°58.6′N; 119°02′W) was examined for the period prior to the main shock. Most of the events that occurred in the epicentral area were relocated by using the main shock as a master event. A large part of the fault plane of the Kern County earthquake had been seismically quiet for nearly 15 yr before the main shock. However, the activity in the immediate vicinity of the epicenter had been very high during the same period. The temporal variation of the activity in the vicinity of the epicentral area exhibits a pattern very similar to that found for the 1971 San Fernando earthquake. During the 1 1/2 yr period immediately before the main shock, tight clustering of activity around the main-shock epicenter occurred. This clustering may be considered to be foreshock activity. This period of increased activity was preceded by a quiet period for 2 yr from 1949 to 1950; no event was located on the fault plane of the Kern County earthquake during this period. This pattern, quiescence followed by clustering, seems to have repeated several times prior to 1949. Thus, this pattern alone cannot be used as a definite indicator of a large earthquake, but in terms of a fault model with asperities, it can be a manifestation of progressive stress concentration toward the eventual hypocenter. Spectral analyses of the Pasadena Wood-Anderson seismograms of the events that occurred near the epicentral area showed that the frequency of the spectral peak is systematically higher for the foreshocks than the events prior to 1949. A similar trend was found for the 1971 San Fernando earthquake. These results are consistent with the model of stress concentration around the eventual hypocenter

The foreshock activity of the 1971 San Fernando earthquake, California

All of the earthquakes which occurred in the epicentral area of the 1971 San Fernando earthquake during the period from 1960 to 1970 were relocated by using the master-event method. Five events from 1969 to 1970 are located within a small area around the main shock epicenter. This cluster of activity is clearly separated spatially from the activity in the surrounding area, so these five events are considered foreshocks. The wave forms of these foreshocks recorded at Pasadena are, without exception, very complex, yet they are remarkably similar from event to event. The events which occurred in the same area prior to 1969 have less complex wave forms with a greater variation among them. The complexity is most likely the effect of the propagation path. A well located aftershock which occurred in the immediate vicinity of the main shock of the San Fernando earthquake has a wave form similar to that of the foreshocks, which suggests that the foreshocks are also located very close to the main shock. This complexity is probably caused by a structural heterogeneity in the fault zone near the hypocenter. The seismic rays from the foreshocks in the inferred heterogeneous zone are interpreted as multiple-reflected near the source region which yielded the complex wave form. The mechanisms of the five foreshocks are similar to each other but different from either the main shock or the aftershocks, suggesting that the foreshocks originated from a small area of stress concentration where the stress field is locally distorted from the regional field. The number of small events with S-P times between 3.8 to 6 sec recorded at Mt. Wilson each month suggests only a slight increase in activity of small earthquakes near the epicentral area during the 2-month period immediately before the main shock. However, because of our inability to locate these events, the evidence is not definitive. Since the change in the wave forms is definite the present result suggests that detailed analyses of wave forms, spectra, and mechanism can provide a powerful diagnostic method for identifying a foreshock sequence

The spatio-temporal variation of seismicity before the 1971 San Fernando Earthquake, California

The spatio-temporal variation of seismicity prior to the 1971 San Fernando, California, earthquake is studied for the area within 35 km of the epicenter. During the period from 1932 to 1961, the seismicity in this area was relatively low and random. A remarkable NE-SW trending alignment of activity occurred during the period from 1961 to 1964, the period corresponding to the inferred onset of the Palmdale uplift. During the period from 1965 to 1968, the seismicity around the epicentral area became extremely low; no event was located within 13 km from the epicenter. During the period from 1969 to the occurrence of the San Fernando earthquake, activity around the epicentral area increased. This activity may be considered to be foreshock activity in a broad sense

Moon Dog [Translation]

A Japanese to English translation of the poem Moon Dog originally written by Mizuho Ishid

The Nutritional Status of Japanese Black Breeding Cows Grazed in a Larger Abandoned Paddy Field

Because rice consumption has decreased in Japan, the number of abandoned paddy fields has increased. Some of the abandoned paddy fields are being used for livestock grazing, effectively using the abandoned fields and reducing the production costs on livestock farms. Such grazing may use an integrated grazing system of scattered small pastures where each of the small abandoned paddy fields scattered in a given agriculture area is defined as one grazing yard, and a herd consisting of two or three head of cattle is moved from one grazing yard to another. However, because the number of abandoned paddy fields has increased, it may be possible to have cattle grazing in larger fields made by combining multiple abandoned paddy fields (Shindo and Tejima 2006). Here we examined the nutritional status of Japanese Black breeding cows that stayed in larger-sized abandoned paddy fields to graze from spring to autumn

Nephrotoxicity with VCM and Nephrotoxins

There is a growing concern about the relationship between vancomycin-associated nephrotoxicity (VAN) and concomitant use of nephrotoxins. We examined this relationship by combined retrospective analyses of two real-world databases. Initially, the FDA Adverse Event Reporting System (FAERS) was analyzed for the effects of concomitant use of one or more nephrotoxins on VAN and the types of combinations of nephrotoxins that exacerbate VAN. Next, electronic medical records (EMRs) of patients who received vancomycin (VCM) at Tokushima University Hospital between January 2006 and March 2019 were examined to confirm the FAERS analysis. An elevated reporting odds ratio (ROR) was observed with increases in the number of nephrotoxins administered (VCM + one nephrotoxin, adjusted ROR (95% confidence interval [CI]) 1.67 [1.51–1.85]; VCM + ≥ 2 nephrotoxins, adjusted ROR [95% CI] 1.54 [1.37–1.73]) in FAERS. EMRs analysis showed that the number of nephrotoxins was associated with higher incidences of VAN [odds ratio: 1.99; 95% CI: 1.42–2.78]. Overall, concomitant use of nephrotoxins was associated with an increased incidence of VAN, especially when at least one of those nephrotoxins was a renal hypoperfusion medication (furosemide, non-steroidal anti-inflammatory drugs, and vasopressors). The concomitant use of multiple nephrotoxins, especially including renal hypoperfusion medication, should be avoided to prevent VAN

Concomitant Use of Multiple Nephrotoxins including Renal Hypoperfusion Medications Causes Vancomycin-Associated Nephrotoxicity: Combined Retrospective Analyses of Two Real-World Databases

There is a growing concern about the relationship between vancomycin-associated nephrotoxicity (VAN) and concomitant use of nephrotoxins. We examined this relationship by combined retrospective analyses of two real-world databases. Initially, the FDA Adverse Event Reporting System (FAERS) was analyzed for the effects of concomitant use of one or more nephrotoxins on VAN and the types of combinations of nephrotoxins that exacerbate VAN. Next, electronic medical records (EMRs) of patients who received vancomycin (VCM) at Tokushima University Hospital between January 2006 and March 2019 were examined to confirm the FAERS analysis. An elevated reporting odds ratio (ROR) was observed with increases in the number of nephrotoxins administered (VCM + one nephrotoxin, adjusted ROR (95% confidence interval [CI]) 1.67 [1.51-1.85]; VCM + ≥2 nephrotoxins, adjusted ROR [95% CI] 1.54 [1.37-1.73]) in FAERS. EMRs analysis showed that the number of nephrotoxins was associated with higher incidences of VAN [odds ratio: 1.99; 95% CI: 1.42-2.78]. Overall, concomitant use of nephrotoxins was associated with an increased incidence of VAN, especially when at least one of those nephrotoxins was a renal hypoperfusion medication (furosemide, non-steroidal anti-inflammatory drugs, and vasopressors). The concomitant use of multiple nephrotoxins, especially including renal hypoperfusion medication, should be avoided to prevent VAN