Abstract: More than 40 late Cenozoic monogenetic volcanoes formed a volcanic belt striking NNW from Keluo, through Wudalianchi to Erkeshan in NE China. These volcanoes belong to a unified volcano system, namely Wudalianchi volcanic belt(WVB for short). Based on the volcanic evolution history and the nature of monogenetic volcanic system, we estimate that the volcanic system of WVB is still active and has the potential to erupt again. Hence, this paper studied the temporal-spatial distribution and volcanic eruption types to evaluate the possible eruption hazard types and areas of influence in the future.
Volcanic field characteristics and K-Ar radiometric data suggest two episodes of volcanism in the WVB, the Pliocene to early Pleistocene volcanism(4.59~1.00MaBP)and the middle Pleistocene to Holocene volcanism(0.79Ma to now). The early episode volcanoes are distributed only in the north of WVB(mainly in Keluo volcanic field), featured by effusive eruption, and mainly formed monogenetic shield, whose base diameter is large and slope is gentle. However, the late episode eruptions occurred over the entire WVB. The explosive eruption in this stage formed numerous relatively intact scoria cones of explosive origin. Meanwhile the effusive eruption formed widely distributed lava flows.
Both effusive eruption and explosive eruption are common in WVB. The effusive eruption formed monogenetic shields and lava flows. The resulting pahoehoe lava, aa lava and block lava appeared in WVB. There are three end-member types of explosive eruption driven by magmatic volatile. Violent Strombolian eruption has the highest degree of fragmentation and mass flux, characterized by eruption column. Strombolian eruption has the high degree of fragmentation, but low mass flux, featured by pulse eruption. Hawaiian eruption has low degree of fragmentation, but high in mass flux, generating large scoria cones. In addition, this paper for the first time found phreatomagmatic eruption in WVB, which formed tuff cone. Transitional eruptions are also common in WVB, which have certain characteristics among the end-member eruption types. Besides, certain volcanoes displayed multiple explosive eruption types during the whole eruption span.
According to the volcanic temporal-spatial distribution and eruption characteristics in WVB, the potential volcanic hazards in future are constrained. It appears that the violent Strombolian and Strombolian eruption will not have significant impact on aviation safety in the vertical direction. In the radial direction, the ejected volcanic bomb can reach as far as 1km from the vents and the fallout tephra may disperse downwind over a distance ranging from 1~10km. The major hazard of Hawaiian eruption and effusive eruption comes from lava flow, and its migration distance may reach 3.0~13.5km for pahoehoe lava and 2.9~14.9km for aa lava. The base surge in phreatomagmatic eruption can reach a velocity of 200~400m/s, and the migration distance is around 10km. This is a big threat that people should pay more attention to and take precautions in advance. Besides, it is necessary to strengthen the real-time observation of the volcanoes in the WVB, especially those formed in the late episode as well as near the active fault.

Key words: Wudalianchi volcanic belt, K-Ar chronology, volcanic eruption type, volcanic hazard prediction

摘要： 沿科洛-五大连池-二克山NNW向分布的五大连池火山带上分布了约40座第四纪单成因火山。通过野外地质特征结合火山岩年代学数据分析表明，研究区火山活动分为2期：上新世-早更新世期火山活动主要分布在北部的科洛火山区，以熔岩溢流式喷发为主；中更新世-全新世期火山活动分布在整个火山带，爆破式喷发形成大量火山碎屑锥，溢流式喷发产生结壳熔岩、渣状熔岩与块状熔岩，形成广泛分布的熔岩流。野外调查发现了夏威夷型、斯通博利型与强斯通博利型等岩浆爆破式火山喷发的典型堆积剖面，首次发现并报道研究区射汽岩浆型火山喷发堆积剖面。结合火山活动历史与火山地质特征，分析认为五大连池火山带的火山系统仍有再次活动的潜力。基于火山时空分布与喷发特征，文中对五大连池火山带未来可能喷发的方式和危险区进行评估。如若发生强斯通博利型喷发，将形成高度<10km的喷发柱，产生的火山灰一般不会对航空运输产生影响；斯通博利型喷发产生的火山碎屑最远可抛射约1km；夏威夷型喷发及溢流式喷发产生的熔岩流是主要的灾害源，计算得出结壳熔岩运移的距离为3.0~13.5km，渣状熔岩运移的距离为2.9~14.9km；射汽岩浆型喷发产生的基浪速度可达200~400m/s，运移距离≤ 10km，是潜在的重要灾害类型，应该引起更多重视，并积极进行防范。

关键词: 五大连池火山带, K-Ar年代学, 火山喷发类型, 火山灾害预测