These eruptions wear down the lava dome holding the magma down, and it disintegrates, leading to much more quiet and continuous eruptions. Thus an early sign of future Vulcanian activity is lava dome growth, and its collapse generates an outpouring of pyroclastic material down the volcanos slope. Deposits near the source vent consist of large volcanic blocks and bombs, with so-called "bread-crust bombs" being especially common. These deeply cracked volcanic chunks form when the exterior of ejected lava cools quickly into a glassy or fine-grained shell, but the inside continues to cool and vesiculate. The center of the fragment expands, cracking the exterior. However the bulk of Vulcanian deposits are fine grained ash. The ash is only moderately dispersed, and its abundance indicates a high degree of fragmentation, the result of high gas contents within the magma. In some cases these have been found to be the result of interaction with meteoric water, suggesting that Vulcanian eruptions are partially hydrovolcanic.Volcanoes that have exhibited Vulcanian activity include:

Sakurajima, Japan has been the site of Vulcanian activity near-continuously since 1955. Tavurvur, Papua New Guinea, one of several volcanoes in the Rabaul Caldera. Irazú Volcano in Costa Rica exhibited Vulcanian activity in its 1965 eruption. Anak Krakatoa, Indonesia, repeated vulcanian activities since its rise in 1930 until the present time.Vulcanian eruptions are estimated to make up at least half of all known Holocene eruptions.
Symptoms for spinal tumors may vary due to factors such as the type of tumor, the region of the spine, and the health of the patient. Back pain is the most common symptom and it can be a problem if the pain is severe, has a time frame that lasts longer than it would for a normal injury, and becomes worse while laying down or at rest. Other symptoms, excluding back pains, are loss of muscle function, loss of bowel or bladder function, pain in the legs, scoliosis, or even unusual sensations in the legs. The primary tumor has no known cause, although there are possible answers that scientists have researched. Cancer may be linked to genes because research shows that in certain families, the incidents of spinal tumors are higher. Two of the genetic disorders that may affect spinal tumors, include Von Hippel-Lindau disease and Neurofibromatosis 2. Von Hippel-Lindau disease is a non-cancerous tumor of blood vessels that occur in the brain, spinal cord, or even tumors in the kidneys. The Neuroflibromatosis 2 is a non-cancerous tumor that usually affects the nerves for hearing. Loss of hearing in one or both ears, is a common effect of this genetic disorder. References


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