Global dating network
Note that tectonic earthquakes of M 4.4 and 4.0 occurred on 17 December 2004 and 15 April 2005, respectively, and are not related to this trend or Tianchi volcano (Liu and others, 2011).Following the seismic crisis, the number of earthquakes declined slowly, reaching background levels by 2006 (Liu and others, 2011).A histogram of the annual number of earthquakes from 2002 through 2005 shows a peak in 2003.M 2 and larger earthquakes became common in 2002, and peaked in late 2004.Liu and others (2011) report that TVO's system "can detect M 0.1 volcanic events and give the [detailed] location of M 1.0 and larger volcanic events." ).Figure 4 and table 1 illustrate that the increased seismicity occurred both in terms of the magnitude and the number of seismic events recorded.The mantle is depleted (relative to the crust and atmosphere) in gas flux increases in October and November 2006, again associated with volcano-seismicity (as well as an M 2.6 tectonic earthquake on 11 November 2006). A news report on 3 November noted that gas emissions from the summit are frequent, many minor volcanic earthquakes have been felt during the last two years, and nearby hot springs were also emitting volcanic gases.
The much better exposed pyroclastic deposits on the North Korean side studied by Horn and Schmincke are extremely thick and include major ignimbrites.
These springs were next to the trail to the waterfall and on up to the lake's edge; eggs were boiled in the spring water for sale to tourists.
A weak sulfur smell was detected, but it was not as pronounced as at some springs in Yellowstone or Long Valley (USA).
The 60-km-diameter volcano was constructed over the Changbaishan (Laoheidingz) shield volcano and has a 5-km-wide summit caldera.
One of the world's largest known Holocene explosive eruptions took place around 1000 A.