| 摘要: | 本研究探討台灣北部大屯火山群（TVG）的火山彈道拋體（VBP）可能產生的危害。VBP的直徑大於0.1米，在噴發期間以近乎拋物線的軌跡從排氣口噴出。研究中討論地熱型和佛卡諾型兩種噴發模式。基於舊有研究中的已知參數建立地熱爆炸模型，其中提到以瞬間降低的液體壓力來獲取VBP的初始速度。以這些速度建立每次噴發場景的彈道拋體模型。佛卡諾型的噴發模式考慮了當火山蓋層噴發時急速減壓的能量。火山蓋層碎片的壓力被視為噴發VBP的能量來源。計算VBP的距離除了使用軌道方程式外，並考慮到減小的阻力區域和風速，而VBP直徑分別為0.2、1.0和2.0公尺。研究中的可能產生危害的示意圖是以大屯火山群的地形透過每個場景映射影響點來繪製。從VBP的50m / s初始速度對水熱爆炸的影響來看，表示其距離七星山西北方的小油坑噴氣孔不超過310公尺。 此研究也指出，由水熱爆炸所引起的VBP曾被記錄到最高起始速度為200m/s。由於水熱爆炸危險區範圍狹窄，則在VBP直徑為2公尺時，有一個花園會處於危險範圍內。值得注意的是，由於小油坑噴氣孔位於國家公園內，VBP可能對造訪小油坑的遊客構成嚴重的威脅。在具有370m / s初始速度的佛卡諾型噴發中，VBP影響的範圍可達到半徑5158米，在七星山的山頂附近。在佛卡諾型噴發的危險範圍示意圖中，可看到區域內包括學校、辦公室和中央氣象局觀測站。 而因為其最高可達2,450米，VBP也可能對飛機造成威脅。
此外，在著陸動能調查中，直徑0.2 公尺的VBP可能無法穿透RC板的建築物，而直徑大於0.2公尺的VBP則可穿透本研究中的所有建築物。;This study investigates the hazard produced by Volcanic Ballistic Projectiles (VBP) at Tatun Volcano Group (TVG), northern Taiwan. VBP is a material with a diameter more than 0.1 m ejected from a vent during an explosive eruption and following nearly parabolic trajectories. Two eruption models are considered: hydrothermal and vulcanian. Hydrothermal explosion model is built based on the parameters known from previous studies which describe the sudden fluid pressure drop in order to obtain the initial velocity of VBP. These velocities are then used to obtain the ballistic trajectory model for each eruption scenario. The model for a vulcanian eruption considers the energy during rapid decompression when a caprock is blasted. The remaining pressure after fragmentation of caprock is then considered as able to produce energy to eject the VBPs. The ballistic equation is used to investigate the distance of VBP which also takes into account the reduced drag zone, wind speed, and VBP diameter of 0.2, 1.0, and 2.0 meters. Hazard maps are generated by mapping the points of impacts according to each scenario considering also the topography at TVG. VBP impact on hydrothermal explosions with 50 m/s initial velocity shows that it reaches no more than 310 m from Hsiaoyoukeng fumarole at NW of Mt. Chishin. This study also determines the VBPs produced by the highest initial velocity on hydrothermal explosion ever recorded, which is 200 m/s. Due to the narrow extent of hydrothermal explosion hazard zones, the only place that is inside the danger zone is a public garden which is within the landing area of VBPs with diameter of 2.0 m. However, since Hsiaoyoukeng fumarole is located in a national park, it should be noted that the VBPs may be a serious threat to the tourists visiting the fumarole. During a vulcanian eruption with 370 m/s initial velocity, the maximum extent of VBPs reached a much larger area, with radius of 5,158 m, around the peak of Mt. Chishin. The hazard maps for vulcanian eruption show that the danger zone covers schools, offices, and Central Weather Bureau stations for all eruption scenarios. The VBP may also cause threat to the aircraft as its maximum height, 2,450 m, may reach the flightpath of an airplane. Moreover, during the investigation of landing kinetic energy, the VBPs with diameter 0.2 m may not be able to penetrate building made of RC slabs, while the bigger ones are able to penetrate all building materials investigated in this study. |
