My next climb will be in Mt. Pinatubo this coming January 24, 2015. I'm so excited...
Here are something we need to know about Mt. Pinatubo:
Mount Pinatubo is an active stratovolcano in the Cabusilan Mountains on the island of Luzon, near the tripoint of the Philippine provinces of Zambales, Tarlac, and Pampanga.[3][3][4] Before the volcanic activities of 1991, its eruptive history was unknown to most people. It was heavily eroded, inconspicuous and obscured from view. It was covered with dense forest which supported a population of several thousand indigenous people, the Aetas, who fled to the mountains during the Spanish conquest of the Philippines.
Mt. Pinatubo before the eruption:
Mount Pinatubo's summit before the 1991 eruption was 1,745 m (5,725 ft) above sea level, only about 600 m (2,000 ft) above nearby plains, and only about 200 m (660 ft) higher than surrounding peaks, which largely obscured it from view.[13] It is part of a chain of volcanoes which lie along the western side of the edge of the island of Luzon called theZambales Mountains.[14]
Pinatubo belongs to the Cabusilan Mountains, the central range of the Zambales Mountains, which consists of Mt. Cuadrado, Mt. Negron, Mt. Mataba and Mt. Pinatubo.[15] They are subduction volcanoes, formed by the Eurasian Plate sliding under the Philippine Mobile Belt along the Manila Trench to the west. Mount Pinatubo and the other volcanoes on this volcanic belt arise due to magma occlusion from this subduction plate boundary.[16]
Pinatubo is flanked on the west by the Zambales Ophiolite Complex, which is an easterly-dipping section of Eocene oceanic crust uplifted during the late Oligocene. The Tarlac Formation north, east and southeast of Pinatubo consists of marine, nonmarine and volcaniclastic sediments formed in the late Miocene and Pliocene.[17]
The most recent study of Mount Pinatubo before the activities of 1991 was the overall geological study in 1983 and 1984 made by F. G. Delfin for the Philippine National Oil Company as part of the surface investigations of the area before exploratory drilling and well testing for geothermal energy sources in 1988 to 1990. He recognized two life histories of the mountain, which he classified as 'ancestral' and 'modern' Pinatubo.[17][18]
Mt. Pinatubo during eruption in 1991:
1991 activities leading to the eruption[edit]
On March 15, 1991, a succession of earthquakes were felt by villagers on the northwestern side of the volcano. Further earthquakes of increasing intensity were felt over the next two weeks, and it became clear some kind of volcanic activity was likely. On April 2, the volcano awoke, with phreatic eruptions occurring near the summit along a 1.5 km (0.93 mi) long fissure. Over the next few weeks, small eruptions continued, dusting the surrounding areas with volcanic ash. Seismographs recorded hundreds of small earthquakes every day.
Scientists immediately installed monitoring equipment and analyzed the volcano for clues as to its previous eruptive history. Radiocarbon dating of charcoal found in old volcanic deposits revealed the last three major explosive eruption periods in recent millennia, about 5500, 3500 and 500 years ago. Geological mapping showed that much of the surrounding plains were formed by lahar deposits from previous eruptions.
Volcanic activity increased throughout May. Measurements of sulfur dioxide emissions showed a rapid increase from 500 t (550 short tons) per day by May 13 to 5,000 t (5,500 short tons) per day by May 28. This implied that there was a rising column of fresh magma beneath the volcano. After May 28, the amount of SO
2 being emitted decreased substantially, raising fears that the degassing of the magma had been blocked somehow, leading to a pressure build-up in the magma chamber and a high likelihood of explosive eruptions.
The first magmatic eruptions occurred on June 3, and the first large explosion on June 7 generated an ash column 7 km (4.3 mi) high. The Philippine Institute of Volcanology and Seismology (PHIVOLCS) issued a warning indicating the possibility of a major eruption within two weeks.
Mt. Pinatubo NOW:
Now Mt. Pinatubo is the most hiked or trekked place in Zambales.
