vni, a, 4 Saderra Maso and Smith: Seismic Disturbances 221 



direction, thence to the west coast of Panay, ending finally between Basilan 

 and Jolo. The general topographic features suggest that this is a very 

 characteristic tectonic or structural line, although definite geological recon- 

 naissances are wanting to confirm such a hypothesis. 



Line E — E passes through many epicenters. It lies just west of the 

 epicenter near Bayombong, Nueva Vizcaya, passes through some epi- 

 centers near the east coast of Luzon and Lamon Bay and at the south- 

 east corner of Leyte, and connects with the epicenters located around the 

 northern point of Surigao Peninsula. This line is seen to conform to the 

 Central Cordillera of Leyte, to the coast range of Masbate, and the syn- 

 cline marked by Ragay Gulf; but we are not certain that it conforms 

 to any particular lineament in Luzon, as it passes through country about 

 which there is little geological information. There are closely folded 

 sediments whose strike is northwest-southeast in the eastern portion of 

 Masbate, and Adams 2i has visited Leyte and mapped the cordillera showing 

 its axis to be approximately along this line. 



Line H — H, which has been called "The Taal Volcano line," 28 starts 

 from the northwestern part of Mindoro and in a nearly northeast direction 

 crosses Taal Volcano, the western portion of Laguna de Bay, extending 

 into the Eastern Cordillera, east of Manila, and thence runs toward Baler 

 and Casiguran Bays. The southern portion of this important line from 

 Mindoro Strait to Laguna de Bay has been accurately identified ; M while 

 the probability of its continuation across the Eastern Cordillera toward 

 the Pacific has been demonstrated by Saderra Maso. This line passes 

 through the epicenter of Manila, located in the Eastern Cordillera, east 

 and east-northeast of this city. 



Line F — F is located along the epicenters west of the Zambales coast 

 and another located a short distance north of Mindoro. It intersects 

 several of the lines, already mentioned, near Cape Santiago, southern 

 Luzon. It does not follow any well-marked rift, but follows approximately 

 the trend of the Bataan coast of Luzon. 



Line G — G begins north of Mindoro, passes along the western coast of 

 Cavite, follows the western border of the Central Plain, across Pangasinan 

 Province, and thence along the axis of the coastal ranges of La Union 

 Province. A displacement along this line would account for the earth- 

 quakes described in charts VI, X, XIII, XV, XVI, XIX, and XXIII " with 

 their epicenters apparently around or in the northern part of Manila Bay. 

 It is a contact line between andesite with the alluvium of the central plains 

 and between Tertiary sedimentaries and igneous rocks in Union Province. 



Line / — / cuts through the Dapitan epicenter and three others which lie 

 close to it. It also follows approximately the long axis of the Island of 

 Cebu and of the Zamboanga Peninsula, but it is drawn west of the axis 

 of the Zamboanga Peninsula as it is believed that some earthquakes have 

 originated from displacements along the west coast of this peninsula. 



Line J — J does not nass through any very important epicenter, but 

 cuts through San Bernardino Channel and follows the east coast of 



M This Journal, Sec. A (1909), 4, 339. 



25 Saderra Maso, Miguel, Bull. P. I. Weather Bur. (1911), 409. 

 "'' Pratt, Wallace E., The eruption of Taal Volcano, This Journal, Sec. A 

 (1911), 6, 63. 



-' La Seismologia en Filipinas. Manila Observatory (1895). 



