Symposium on Microseisms 



Gutenburg, B., Die Seismische Bodenruhe, Inaugural- 

 Dissertation. Goettingen, 1911. 



Gutenburg, B., Die seismische Bodenruhe, Gerlands 

 Beitr. z. Geoph., v. 11, pp. 314-353, 1912. 



Gutenburg, B., Untersuchungen uber die Bodenruhe 

 mit perioden von 4s-10s, in Europa, Veroeffentl. 

 des Zentralbur. der Int. Seism. Assoc., 1914, pp. 

 1-106, 1921. 



Gutenburg, B., Die seismische Bodenruhe in Zi-ka-wei, 

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Gutenburg, B., Die Bodenruhe durch Brandling, Zeit. 

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Gutenburg, B., Bodenruhe durch Brandung und durch 

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Gutenburg, B., Microseisms in North America, Bull. 

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Gutenburg, B., On Microseisms, Bull. Seism. Soc. 

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HECKER, 0., Versuche zur Bestimmung der Fortpflant- 

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Honda, H., Geophys. Mag., v. 8, pp. 177-181. 



IMBO, G., Agitazione del mare e microsis>nika a Cantan- 

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OMORI, F., Report on the observation of pulsatory oscil- 

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Ramirez, J. E., An experimental investigation of the 

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 1940. 



Von Rebeur-Paschwitz, E., Horizontalpendel-beobach- 

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Shaw, J. J., Communication de M. J. J. Shaw sur les 

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 1922. 



Trommsdorff, Fro., Untersuchen uber die naturliche 

 Bodenunruhe (mikroseismik) mit transportablen 

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 304-320, 1939. 



WlECHERT, E., Verhandl. der 2 Intern. Seism. Konf., 

 1905, Snppl. 2, pp. 41-44, Gerlands Beitr. z. Geoph., 

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Zannon, F. S., / cicloni dell'atlantico settentrionale i 

 microsismi a Venezia Boll. Soc. Sism. Italiana, v. 

 34, pp. 35-53, 116-133, 1936. 



Zanon, F. S., / microsismi registrati in Venezia causati 

 da cicloni sull Atlantico e sull Adriatico, Boll. Soc. 

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Klotz, 0., On microseisms, C. R. Int. Assoc. Seism. 

 Zermatt, pp. 73-74, 1909. 



Krug, H. G., Ausbreitung der naturlichen Bodenun- 

 ruhe nach Aufzeichnungen mit transportablen Hor- 

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 328-348, 1937. 



Laska, W., Ueber pendelanruhe, Verhandl. der 1. In- 

 tern. Seism. Konf. Strassburg 1901, Gerlands Beitr. 

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LONGUET HlGGINS, M. S., A theory of the origin of mic- 

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Milne, J., Trans. Seismol. Soc. of Japan, v. Ill, pp. 

 12-61, 1881. 



MlLNE, J., Earth pulsations, Trans. Seismol. Soc. of 

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Milne, J., Earth tremors, Trans. Seismol. Soc. of Japan, 

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Milne, J., Earth tremors in Central Japan recorded 

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Omori, F., Publications of the Earthquake Investiga- 

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Discussion 



B. Gutenberg 

 California Institute of Technology 



The paper by Father Macelwane gives an 

 excellent summary. However, the reported 

 statement by European seismologists, that 

 beats are not observed in European micro- 

 seisms, does not correspond to the facts and is 

 probably caused by an incorrect translation of 

 the expression "beats" by scientists from Cen- 

 tral Europe. "Schwebungen" (beats) are dis- 

 cussed in several European and especially Ger- 

 man publications on microseisms (see e.g. the 

 author's Handbuch der Geophysik, vol. 4, p. 

 282). They are also frequently found in mi- 

 croseisms recorded at Pasadena and other sta- 

 tions near the Pacific coast. There is no evi- 

 dence that beats or groups in the regular type 

 of microseisms with periods of 4-10 seconds 

 are restricted to certain areas. 



A few words may be added concerning the 

 history of the division of microseisms into dif- 

 ferent types. The first detailed description of 

 such types was given by Hecker [1906]. He 

 distinguished four kinds of microseisms de- 

 pending on whether the period was less than 

 4, about 7, about 30 seconds, or of the order of 

 1 minute. The first type is usually caused by 

 local disturbances. Gutenberg [1910, 1912] 



