The Earthquake’s Relative Location Algorithms Effected by Data Recorded at Nearby Station

Based on the primary theory of location, it is found that the data recorded at nearby stations are applicable in double difference relocation algorithm, but not in other relative location algorithms. Equation derivation and simulated calculation demonstrate that double difference algorithm allows to get the absolute locations of earthquakes with certain accuracy by using the nearby stations records. The errors of relative location become larger when using the nearby station records alone than that using the distant station records. Combining the nearby and distant station records, the best locations are obtained. In the case that hypocenter depth is far less than the epicenter distance without depth phases available, only the relative epicenter distribution could be obtained accurately by double difference method, the depth determined would be not stable. The relocation test of a part of aftershocks in Jiashi earthquake sequence verify the effect of nearby station records on the double difference algorithm mentioned above.

On the similarity of the short-period pressure variation over large areas

In a paper presented in June last to the Society, we pointed out the existence of a short-period oscillation of barometric pressure over the Indian area corresponding generally with a variation in, the percentage number of prominences recorded on the sun’s limb. This oscillation was further shown not to be limited to the Indian area, but to be marked at a far distant station, as Cordoba, in South America. The present paper, which is a continuation of this investigation, was undertaken to extend the research over a larger area.

1. On the Splitting up of Electric Currents, as detected by the Telephone, and the founding thereon of a Sounder to call attention from one Telephone to another

The telephone is of no use as a “far-speaker,” without some means of calling the attention of the attendant at the distant station. Nothing could well be better than the “electric-bell call,” and the sounder which I am about to describe makes no pretensions of competing with the bell, except on the points of simplicity, cheapness, and facility of use; and although its employment is limited to short length lines, it may be assumed that it is upon short length lines that the telephone will be most frequently used. I have had this sounder in experimental use for more than three months, and have shown it to many persons as a very obvious expedient. However, as it does not appear to have been referred in any publication, I venture to bring it as a Note before the Society; it is of too trifling a nature to be made the subject of a formal paper.