We herein propose an alternative model for deformation caused by an eruption at Sakurajima, which has been previously interpreted as being due to a Mogi-type spherical point source beneath Minami-dake. On November 13, 2017, a large explosion with a plume height of 4200 m occurred at Minami-dake. During the 3 min following the onset of the explosion (November 13, 2017, 22:07–22:10 (Japan standard time (UTC + 9); the same hereinafter), phase 1, a large strain with changes up to 120 nstrain was detected at the Arimura observation tunnel (AVOT) located approximately 2.1 km southeast from the Minami-dake crater. After the peak of the explosion (November 13, 2017, 22:10–24:00), phase 2, a large deflation was detected at every monitoring station due to the continuous Strombolian eruption. Subsidence toward Minami-dake was detected at five out of six stations, whereas subsidence toward the north of Sakurajima was detected at the newly installed Komen observation tunnel (KMT), located approximately 4.0 km northeast from the Minami-dake crater. The large strain change at AVOT as well as small tilt changes at all stations and small strain changes at the Harutayama observation tunnel (HVOT) and KMT during phase 1 can be explained by a very shallow deflation source beneath Minami-dake at 0.1 km below sea level (bsl). For phase 2, a deeper deflation source beneath Minami-dake at a depth of 3.3 km bsl was found in addition to the shallow source beneath Minami-dake, which turned inflation after the deflation that occurred during phase 1. However, this model cannot explain the tilt change of KMT. Adding a spherical deflation source beneath Kita-dake at a depth of 3.2 km bsl can explain the tilt and strain change at KMT and the other stations. The Kita-dake source was also found in a previous study of long-term ground deformation. Not only the deeper Minami-dake source M_D, but also the Kita-dake source deflated due to the Minami-dake explosion.

我们在此提出了一种替代模型，用于预测由樱岛喷发引起的变形，该模型先前已被解释为是由于南岳下方的Mogi型球形点源造成的。2017年11月13日，南岳发生了羽高4200 m的大爆炸。在爆炸发生后的3分钟内（2017年11月13日，22：07–22：10（日本标准时间（UTC + 9）；下同）），阶段1，大应变，变化高达120 ns。在距离南岳火山口东南约2.1公里的Arimura观测隧道（AVOT）中发现了爆炸，在爆炸的高峰期（2017年11月13日，22：10–24：00），第2阶段，发生了大的通缩。由于连续的Strombolian爆发，在每个监测站都检测到了。在六个站中的五个站中，发现了对南岳的沉降，而在距离南岳的火山口东北约4.0公里的新安装的Komen观测隧道（KMT）中，发现了朝樱岛北部的沉降。在第一阶段，AVOT的大应变变化以及所有站点的小倾角变化以及Harutayama观测隧道（HVOT）和KMT的小应变变化可以通过海面以下0.1 km的南岳下方的非常浅的通缩源来解释。级别（bsl）。对于第2阶段，除了在南大湖下面的浅层气源之外，还发现了南大湖下面3.3 km bsl的更深通货紧缩源，后者在第1阶段发生通货紧缩后变成了通货膨胀。但是，该模型无法解释国民党的倾斜度变化 在Kita-dake下方以3.2 km bsl的深度添加球形放气源可以解释KMT和其他站点的倾斜和应变变化。在长期的地面变形的先前研究中也发现了北尾气源。不只是更深的南岳源M _D，还有因南尾爆炸而放空的北尾源。