The structure of a caldera may influence its activity, making its understanding crucial for hazard assessment. Here, we analysed high-resolution seismic profiles in the Campi Flegrei (southern Italy) offshore sector. We recognised two main fault systems, including those associated with the formation of the caldera and those affecting the resurgent dome. The former system comprises three broadly concentric fault zones (inner, medial and outer ring fault zones) depicting a nested caldera geometry. Considering the relations between faults and seismic units that represent the marine and volcaniclastic successions filling the caldera, all ring faults were formed during the Campanian Ignimbrite eruption (40 ka) and subsequently reactivated during the Neapolitan Yellow Tuff eruption (15 ka). In this last caldera-forming event, the inner and medial fault zones accommodated most of the collapse and were episodically reactivated during the younger volcano-tectonic activity. The second fault system occurs in the apical zone of the resurgent dome and comprises dominantly high-angle normal faults that are mainly related to the volcano-tectonic collapse that followed the Agnano-Monte Spina Plinian eruption (4.55 ka). Finally, we provide a volcano-tectonic evolutionary model of the last 40 kyr, considering the interplay among ring and dome faults activity, volcaniclastic sedimentation, ground deformation and sea-level changes.

火山口的结构可能会影响其活动，因此对其的理解对于危害评估至关重要。在这里，我们分析了 Campi Flegrei（意大利南部）海上部门的高分辨率地震剖面。我们认识到两个主要的断层系统，包括与火山口形成相关的断层系统和影响复活圆顶的断层系统。前一个系统包括三个大致同心的断层带（内环、中环和外环断层带），描绘了嵌套的火山口几何形状。考虑到断层和代表填充火山口的海洋和火山碎屑层序的地震单元之间的关系，所有环断层都是在坎帕尼亚火山喷发（40 ka）期间形成的，随后在那不勒斯黄色凝灰岩喷发（15 ka）期间重新激活。在这最后一次火山口形成事件中，内部和内侧断层带容纳了大部分崩塌，并在较年轻的火山构造活动期间偶尔重新激活。第二个断层系统发生在复活穹顶的顶端带，主要由高角度正断层组成，主要与 Agnano-Monte Spina Plinian 喷发 (4.55 ka) 后的火山构造塌陷有关。最后，我们提供了过去 40 kyr 的火山构造演化模型，考虑了环和穹顶断层活动、火山碎屑沉积、地面变形和海平面变化之间的相互作用。第二个断层系统发生在复活穹顶的顶端带，主要由高角度正断层组成，主要与 Agnano-Monte Spina Plinian 喷发 (4.55 ka) 后的火山构造塌陷有关。最后，我们提供了过去 40 kyr 的火山构造演化模型，考虑了环和穹顶断层活动、火山碎屑沉积、地面变形和海平面变化之间的相互作用。第二个断层系统发生在复活穹顶的顶端带，主要由高角度正断层组成，主要与 Agnano-Monte Spina Plinian 喷发 (4.55 ka) 后的火山构造塌陷有关。最后，我们提供了过去 40 kyr 的火山构造演化模型，考虑了环和穹顶断层活动、火山碎屑沉积、地面变形和海平面变化之间的相互作用。