Atlantis Online
March 29, 2024, 06:45:32 am
Welcome, Guest. Please login or register.

Login with username, password and session length
News: ARE Search For Atlantis 2007 Results
http://mysterious-america.net/bermudatriangle0.html
 
  Home Help Arcade Gallery Links Staff List Calendar Login Register  

Pico Island

Pages: [1] 2   Go Down
  Print  
Author Topic: Pico Island  (Read 1561 times)
0 Members and 64 Guests are viewing this topic.
dhill757
Administrator
Superhero Member
*****
Posts: 3896



« on: December 20, 2012, 01:41:34 am »

    Pico Volcano - It occupies the western portion of the island, and corresponds to the central volcano with a 2341 meter altitude. Along its flanks are diverse lava and spatter cones that are formed along radial fractures and faults.

Generally, the island of Pico's tectonic structures are oriented along a west-northwest to east-southeast and a northeast to southwest axis. The main axis controls the main structures, especially the main mountain of Pico, while the secondary axises affect the radial fractures and faults along the central plain and eastern volcano.

Similar to the geomorphological structures described above, the volcanic landforms have been identified by Madeira (1998) in the following units:

    Volcanic Complex of Lajes - pertains to the oldest volcanic structures, comprising volcanoes, lavas and debris that are between 35-300,000 million years old; it makes up the structures of the eastern part of the island, including the ancient volcano of Topo.
    Volcanic Complex of Calheta de Nesquim - dating to about 230,000 million years ago, this is a fissural zone of cones and basaltic lavas, associated with the Achada Plain, and the many faults along the central plateau of the island.
    Volcanic Complex of Madalena - the most recent volcanic complex, with both geological and historical eruptions; it includes the basaltic stratovolcano of Pico, but also many of the cones, faults and lava fields that circle the 2,351 meter summit.

The last volcanic eruption (which is debatable) occurred in 1963, in a small submarine eruption off the northwest coast (north of Cachorro in Santa Luzia). Prior to this, major volcanic activity was only evident in lava fields generated in the areas of Prainha (1562–64), Santa Luzia (1718), São João (1718) and Silveira (1720). The paths of the lava flows are still visible, those in the 16th Century and 1718 were particularly substantial, extending for over 10 km. Today, the only visible evidence of active volcanism appears on the summit of Pico, in the base and interior of the Piqueninho (the mini-peak on the summit); there are irregular emissions from cracks in this zone. Additionally, there are emissions on the eastern flanks between 1500 and 2000 meters altitude. There have also been found areas of de-gasification along the a fault associated with the Lagoa do Capitão and another in the Topo Volcano, as well as a spring rich in CO2 in the area of Silveira.

Pico, much like the other islands, are susceptible to seismic events, although their epicenters have primarily been localized in the Faial-Pico or Pico-São Jorge Channels. The strongest earthquake registered in the last 30 years occurred on July 9, 1998, and had its epicenter 5 kilometers northeast of Ponta da Ribeirinha, on the island of Faial, reaching a 5.8 magnitude. It was felt on Pico, with a maximum intensity level of VII on the Mercalli scale; some homes were damaged and possessions were buffeted. Other violent earthquakes which have affected the island include: the 1957-58 seismic events associated with the eruption of the Capelinhos volcano (on Faial), the February 1964 earthquake on the island of São Jorge, and the 1926 earthquake, whose epicenter was registered in the Faial-Pico Channel.
Report Spam   Logged
Pages: [1] 2   Go Up
  Print  
 
Jump to:  

Powered by EzPortal
Bookmark this site! | Upgrade This Forum
SMF For Free - Create your own Forum
Powered by SMF | SMF © 2016, Simple Machines
Privacy Policy