This work analyses seismic signals at the Irazú volcano (83°51′09″ W, 9°58′45″ N; active stratovolcano in Central America) in a continuous 34-day record starting on 13 April 2013. Since December 2012, the activity of the volcano was increasing and along with it the frequency of occurrence of certain long-period (LP) signals. In this work, 6 families of LP signals have been identified, with 83 total events. These events show energy concentrated mainly in the frequency range between 1 and 3 Hz, significant variations in amplitude, and some locations on the SW flank from the volcano at 1900 m.a.s.l. (corrected for site effects). The LP signals are interpreted as linked to the interaction between the fluids of the active hydrothermal system and a fault system (NE-SW direction) in the west slope of the Irazú volcano, but without being associated with magma ascent. This contribution provides useful information for the evaluation of the volcanic hazard of the Irazú volcano, in terms of the analysis of possible precursors.

这项工作分析了伊拉苏火山（西经 83°51′09″，北纬 9°58′45″；中美洲的活层火山）自 2013 年 4 月 13 日开始的连续 34 天记录中的地震信号。自 2012 年 12 月以来，火山活动不断增加，某些长周期（LP）信号的出现频率也随之增加。在这项工作中，已识别出 6 个 LP 信号家族，总共 83 个事件。这些事件显示能量主要集中在 1 至 3 Hz 的频率范围内，振幅存在显着变化，并且在 1900 masl 处位于火山西南侧的某些位置（已根据场地效应进行校正）。LP 信号被解释为与活性流体之间的相互作用有关伊拉苏火山西坡有热液系统和断层系统（NE-SW 方向），但与岩浆上升无关。该贡献为评估伊拉苏火山的火山灾害、分析可能的前兆提供了有用的信息。