The Tatun Volcano Group lies at the northern tip of Taiwan only 15 km north of the capital Taipei. A seismic array consisting of 5 stations equipped with both broadband and short‐period sensors was installed in 2003 in order to monitor the seismic activity of the area. It recorded a variety of events including common volcano‐tectonic earthquakes and volcanoseismic signals like tornillos, short duration monochromatic events (10–15 s) and long duration spasmodic bursts (∼15 min). An analysis of the complex frequencies of the tornillo/monochromatic signals shows that Q‐values are of the order of several hundreds. Based on the model of a fluid‐filled crack, such Q‐values can result from the oscillations of a crack containing a misty or dusty gas. These observations put into doubt the long‐standing suggestion that the Tatun volcanoes are extinct and prompt for a thorough assessment of the volcanic hazard for this area.

No abstract

The Geophysical Database Management System (GDMS) is an integrated and web-based open data service which has been developed by the Central Weather Bureau (CWB), Taiwan, ROC since 2005. This service went online on August 1, 2008.

No abstract

Abundant earthquakes clustered within a particular zone often reflect an active geological feature, such as clustering seismicity along a fault zone and a huge number of volcanic-earthquakes around the erupting conduit. Herein we perform a double-difference tomographic inversion and relocate the seismicity at the long-resting tatun volcano group (tVG) in northern taiwan. A dramatic improvement of the earthquake location model surprisingly show that, from 2014 to 2017, two clustered seismic zones are identified in the TVG. One major group of events (>1000) persistently clustered within a ~500 m diameter vertical conduit with a ~2 km height. The clustering seismicity conduit is just located nearby Dayoukeng, one of the strongest fumaroles in the tVG, and is connected to a fracture zone characterized by low Vp/Vs in the shallow crust. the other group of events is clustered within a spherelike zone beneath Mt. Chihsin around the depths between 0.5 km and 2 km. Both seismic zones are probably triggered by the significantly volcanic gases and fluids ascending from the deep magma reservoir. combined with a variety of results from literature, the seismicity conduit near the strong fumarole is the evidence for an active volcano and also identifies a likely pathway for ascending magma if the TVG erupts again in the future. But possibility of developing different magma pathways at other clustered seismic zones such as beneath Mt. chihsin may not be totally excluded. The evaluation of whether or not a volcano will erupt often relies on the classification of it as active, dormant, or extinct; however, the exact definition of an active volcano may still be debatable. Two criteria are often employed to classify an active volcano: (1) the volcano erupted within the past ~10,000 years or (2) the identification of magma chambers beneath the volcano 1. However, those definitions are not set in stone because some eruptions have surprisingly occurred in dormant or extinct volcanoes, which are long-resting volcanoes without evidence of any magma chambers beneath them. Thus, some other criteria may be involved in the evaluation of the possibility of eruptions in long-resting volcanoes, in particular. The Tatun volcano group (hereinafter "TVG") in the northern tip of Taiwan is a typical long-resting volcano because there was no eruption record in human history. From the volcanic hazard point of view, it is important to know whether or not the TVG is active because it is located near the Taipei metropolis, with more than 6 million residents living in both Taipei City and New Taipei City in northern Taiwan (Fig. 1). The distance between Mt. Chihsin (the highest peak of 1120 m in the TVG) and the Taipei 101 skyscraper building (a landmark in downtown of Taipei City 2) is less than 15 km. In other words, the TVG is a typical "City on Volcano" case if it is active. Apart from the Taipei metropolis, it is worth highlighting the two nuclear power plants located around the northern boundary of the TVG. Thus, even a small volcanic eruption at th...