YELLOWSTONE NATIONAL PARK — The latest Caldera Chronicles from the Yellowstone Volcano Observatory (YVO) is calling 2024 in Yellowstone National Park (YNP) “the year of the hydrothermal explosion” for two noteworthy events.
Most people are aware of the well-documented, July 23 explosion of Black Diamond Pool at Biscuit Basin. According to the YVO, this event occurred just before 10 a.m. local time with dozens of people in the area who had to run for safety “as an unheralded explosion hurled rocks, mud, liquid water and steam hundreds of feet into the air.”
Fortunately, the YVO confirms there were no injuries, even though geologists later mapped over 1400 rocks with a long dimension greater than a foot that were ejected by the event. The YVO writes that a majority of the debris was thrown in the direction of the Firehole River, although the boardwalk adjacent to Black Diamond Pool was severely damaged.
Smaller explosive events reaching a few tens of feet in height and additional surges of water have continued to occur from the pool into the fall and winter months.
However, there was an additional hydrothermal explosion earlier in the year in Norris Geyser Basin that went largely unwitnessed by the public. The explosion occurred on a terrace overlooking Porcelain Basin on April 15, the YVO confirms, a site of high thermal activity over the past few years.
The YVO writes that the April 15 explosion left a crater about 10 feet across, along with an area of disrupted ground. While few people were in the Park during the seasonal closure, the activity was detected in acoustic and seismic monitoring, including new sensors that had been installed in September 2023.
“This event has the distinction of being the first hydrothermal explosion in Yellowstone to have been detected by monitoring instruments,” the YVO writes. “Of course, with no witnesses, the April 15 explosion went mostly unnoticed by the public.”
In contrast to the interesting hydrothermal activity, the YVO notes that 2024 was seismically calm. There were 1,173 earthquakes located in the YNP region during last year, which the YVO confirms is at the low end of the typical annual seismicity (usually about 1,500 to 2,500 located earthquakes each year). The largest event was a M3.3 that occurred on Jan. 3, 2024, as part of a swarm of 112 located earthquakes that took place during Jan. 1 to 6, 2024.
Only seven earthquakes during 2024 were reported to be felt.
