Geologic Background:
The small 2-km-wide island of Farallon de
Pajaros (Uracas), the northernmost and most active
volcano of the Marianas Islands, has been referred to as
the "lighthouse of the western Pacific." The symmetrical,
sparsely vegetated summit is the central cone within a
caldera, remnants of which are seen on the SE side. Flank
fissures have fed lava flows during historical time that
form platforms along the coast. Both summit and flank
vents have been active during historical time. Eruptions
have also been observed from submarine vents, and
Makhahnas seamount lies about 10 km to the SE.
Historic Activity:
- Farallon de Pajaros has erupted frequently in the
20th century. However, because it is at the northern end
of the chain about 400 km from Saipan, the volcano is
observed only intermittently, and low-level eruptive
activity might be missed.
- Frequent Strombolian activity and accompanying lava
flows were observed in 1952-53 from the Uracas crater.
Recent Activity:
- Strong seismic and acoustic signals apparently
generated by submarine volcanism were recoreded on Sept.
21-22, Dec. 22-24, and Dec 26-27, 1989. Probably
originated from a site about 30 km south of Farallon de
Pajoros
Data Sources:
- Smithsonian's SEAN Bulletin (V. 6, No. 9)
- Global Volcanism Network (V. 15, No. 10 to V. 17, No.
6)
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