228 The Philippine Journal of Science wis 



Only one earthquake (2, 3) is shown on this chart, and that 

 seems clearly to have originated along line A — A. 



Earthquakes of July 23 and 24, 1885 (5, 6). The first seems 

 to have its epicenters northwest of Dapitan Peninsula. In 1897 

 another destructive earthquake occurred under the sea in the 

 same region due to the same origin. It is very likely that this 

 is of intertectonic origin, due to line / — I. There is no record 

 of any volcanic demonstration emanating from the Dapitan 

 Peninsula. It seems very clear from the great lineal extent of 

 the destructive area of this earthquake north and south that 

 the line / — / is responsible; hence this would be called tectonic. 

 The earthquake of the 24th of the same month seems to be 

 similar to that of December 17, 1884. 



Earthquake of November 16, 1885 (7, 8). This is clearly of 

 volcanic origin as it seems to have been most generally felt in 

 the southwest volcanic region of Luzon. 



Earthquake of November 19, 1885 (5), is similar to that of 

 July 24, 1885, and is also tectonic. 



Earthquakes of April 10 (15) and August 2, 1886 (7). The 

 first one is undoubtedly tectonic and is connected with line J — J. 

 The second may be in part volcanic, but, on account of its 

 extension to the northwest, we believe that it can be referred 

 to the tectonic line G — G. 



Earthquakes of February 1 (3) and 2, 1887 (14) . The former 

 seems to have been localized in north-central Luzon and may 

 or may not be tectonic. It is possible that this disturbance was 

 due to rockfall. The latter earthquake seems to have affected 

 the whole Island of Panay, and was probably due to rockfall, 

 because a recent examination of this island has shown that 

 landslides of considerable magnitude are of frequent occurrence 

 on this island. In these two regions violent earthquakes of like 

 character and probably of the same origin occurred in 1902 

 and 1904. 



Earthquake of March 24, 1887 (10), was unquestionably of 

 volcanic origin due to disturbances in the southeastern volcanic 

 cluster of Luzon. The two earthquakes here shown of June 

 19 (6, 8) and October 1, 1887 (10, 11, 12), respectively, were 

 only light ones. The second one emanated from the same 

 volcanic region as the earthquake just mentioned, but that of 

 June 19 was undoubtedly of tectonic origin in the Eastern 

 Cordillera. 



Earthquakes of June 27 (20, 21), May 3 (2, 3), and August 

 19 (4), 1888. The first is undoubtedly tectonic as we know of 

 no volcanoes anywhere in that portion of Mindanao, but we 



