Cleveland and Tana are remote volcanoes located in the central Aleutian volcanic arc on the eastern end of the Islands of Four Mountains (IFM). The persistently active Mount Cleveland volcano, on the western side of Chuginadak Island, is surrounded by several closely spaced Quaternary volcanic centers including Carlisle, Herbert, Kagamil, Tana, and Uliaga, and numerous small satellite vents on Chiginadak between Cleveland and Tana. The Alaska Volcano Observatory (AVO) installed two permanent broadband seismometers on Chuginadak Island in 2014, and we operated a temporary broadband network focused on the western side of the island in 2015–2016. Collectively, these stations provided the first seismic observations of this frequently active volcano and the surrounding Holocene-aged volcanic vents. During the study period (July 2014–January 2019), eruptive activity at Cleveland was characterized by small explosions separated by periods of lava effusion that formed small domes in the volcano's summit crater. We characterize seismicity beneath Chuginadak Island through automated analysis of event waveform frequency content, development of a one-dimensional P-wave velocity model, calculation of earthquake hypocenters, magnitudes, focal mechanisms, and identification of earthquake families. This analysis reveals the full range of seismic event types expected in a highly active volcanic environment and includes Volcano-Tectonic (VT) earthquakes, Long-Period (LP) events, and explosion signals. LP events appear to cluster at shallow depth beneath the active crater of Mount Cleveland and almost all of the explosions occur without identifiable short-term (hours to days) seismic precursors. VT earthquakes beneath Mount Cleveland occur at depths of 2 to 8 km below sea level (BSL) and range in magnitude from −0.2 to 1.8. VT focal mechanisms have horizontal P-axes that align with the regional axis of maximum stress. These observations, and a relatively slow one-dimensional seismic velocity model, are consistent with a shallow body of magma that is fed through a deeper conduit system. The time-history of VT earthquakes and shallow LP events suggest their occurrence may track the transfer of magma and fluids from the mid-crust to the shallow portions of the conduit system and may provide a means to anticipate future explosions and periods of dome growth. VT hypocenters also extend ~7 km northeast of Cleveland's summit at depths of 5 to 10 km BSL, under a group of Holocene-aged vents between Mount Cleveland and Tana. These earthquakes have vertically-oriented P-axes and a greater percentage occur in families. These observations, combined with observations of vent orientation and morphology and gas flux, suggest the area between Cleveland and Tana represents a zone of complicated volcano-tectonic interaction, similar to calderas elsewhere in the Aleutian arc. The presence of a larger volcanic system in the eastern IFM could influence magmatism and account for the multiple closely spaced volcanic centers in this region.

克利夫兰和塔娜是位于四山群岛（IFM）东端阿留申火山弧中部的偏远火山。丘吉纳达克岛西侧的克利夫兰山火山一直活跃，周围环绕着几个紧密间隔的第四纪火山中心，包括卡来尔，赫伯特，卡加米尔，塔娜和乌利亚加，以及在克利夫兰和塔娜之间奇吉纳达克的许多小型卫星喷口。阿拉斯加火山天文台（AVO）于2014年在Chuginadak岛安装了两个永久性宽带地震仪，2015-2016年，我们在该岛的西侧运营了一个临时宽带网络。这些台站共同提供了该活跃火山和周围全新世时代火山喷口的首次地震观测。在研究期间（2014年7月至2019年1月），克利夫兰的火山喷发活动的特征是，小规模的爆炸被熔岩喷出的时间分隔开，在火山的山顶火山口形成了小圆顶。我们通过事件波形频率内容的自动分析，一维P波速度模型的开发，地震震源的计算，震级，震源机制以及地震族群的识别，来表征楚吉纳达克岛下方的地震活动。该分析揭示了在高度活跃的火山环境中预期的全部地震事件类型，包括火山-构造（VT）地震，长周期（LP）事件和爆炸信号。LP事件似乎聚集在克利夫兰山活动火山口下方的浅深度，几乎所有爆炸都是在没有可识别的短期（几小时到几天）地震前兆的情况下发生的。克利夫兰山下的VT地震发生在海平面（BSL）下方2至8 km的深度，震级范围为-0.2至1.8。VT聚焦机构的水平P轴与最大应力的区域轴对齐。这些观测结果以及相对较慢的一维地震速度模型，与通过较深管道系统馈入的浅岩浆体一致。VT地震和浅层LP事件的时程表明，它们的发生可能跟踪岩浆和流体从中地壳到管道系统浅层的转移，并可能提供一种预测未来爆炸和穹顶生长的方式。VT震中在克里夫兰山和塔娜之间的全新世时期喷口的下方，也在克利夫兰山顶的东北方约7公里处，位于BSL的5至10公里深度处。这些地震的垂直轴为P轴，家庭中发生的百分比更高。这些观察结果与通风口方向，形态和气体通量的观察结果相结合，表明克利夫兰和塔那之间的区域代表着复杂的火山-构造相互作用带，类似于阿留申弧线其他地方的火山口。IFM东部较大的火山系统的存在可能影响岩浆作用，并解释了该地区多个密集的火山中心。