Yellowstone earthquake activity is currently at elevated levels compared with typical background activity. This is largely due to an energetic earthquake swarm about 10 km (6 miles) north of West Yellowstone, Montana that started on June 12. Monitored locations within the Yellowstone caldera continue to slowly subside.
In their monthly update released 14:56 UTC on July 1, 2017, the Yellowstone Volcano Observatory reports 1 171 earthquakes were recorded in the Yellowstone National Park (YNP) region during the month of June. The largest event was a light earthquake of magnitude 4.4 at 00:48 UTC on June 16, located about 14.5 km (9 miles) NNW of West Yellowstone, Montana. The earthquake was reported felt in the towns of Gardiner and West Yellowstone, MT.
This earthquake is part of an energetic sequence of earthquakes in the same area that began on June 12. It is is the largest earthquake to occur in Yellowstone National Park since March 30, 2014, when a magnitude 4.8 event occurred 29 km (18 miles) to the east, near Norris Geyser Basin. The March 30, 2014 earthquake was the largest earthquake at Yellowstone since February 22, 1980.
June 2017 seismicity in Yellowstone was marked by four distinct clusters of episodic earthquakes:
1) An energetic swarm of 1 027 earthquakes, ~9.6 km (6 miles) N of West Yellowstone, MT, began June 12 and is ongoing, including the largest event of the month on June 16 (magnitude 4.4). This swarm also consists of five earthquakes in the magnitude 3 range and 72 earthquakes in the magnitude 2 range.
2) 41 events occurred in a small swarm ~22.5 km (14 miles) ENE of West Yellowstone, MT, with swarm activity occurring June 14 and 15. The largest earthquake of the swarm (magnitude 2.3) occurred June 14, at 13:39 UTC ~22.5 km (14 miles) ENE of West Yellowstone. This swarm includes two earthquakes in the magnitude 2 range.
3) A small swarm of 22 earthquakes, ~22.5 km (14 miles) SSW of Mammoth, WY, took place on June 1 and 2 (UTC), with the largest event (magnitude 2.6) occurring June 2, at 02:29 UTC. This swarm includes 3 earthquakes in the magnitude 2 range.
4) A small swarm of 13 earthquakes, ~25.7 km (16 miles) ENE of West Yellowstone, occurred June 13. The largest earthquake (magnitude 1.7) occurred June 13, at 13:14 UTC.
Earthquake sequences like these are common and account for roughly 50% of the total seismicity in the Yellowstone region. Yellowstone earthquake activity is currently at elevated levels compared with typical background activity, YVO said.
Monitored locations within the Yellowstone caldera continue to slowly subside. Uplift north of the caldera, centered near the Norris Geyser Basin continues at a low rate. Behavior is similar to the past several months. Current deformation patterns at Yellowstone remain within historical norms.
The Yellowstone Plateau volcanic field developed through three volcanic cycles spanning two million years that included some of the world's largest known eruptions. Eruption of the >2450 km3 Huckleberry Ridge Tuff about 2.1 million years ago created the more than 75-km-long (46 miles) Island Park caldera. The second cycle concluded with the eruption of the Mesa Falls Tuff around 1.3 million years ago, forming the 16-km-wide (9.9 miles) Henrys Fork caldera at the western end of the first caldera.
Activity subsequently shifted to the present Yellowstone Plateau and culminated 640 000 years ago with the eruption of the >1000 km3 Lava Creek Tuff and the formation of the present 45 x 85 km (28 x 52 miles) caldera. Resurgent doming subsequently occurred at both the NE and SW sides of the caldera and voluminous (1000 km3) intracaldera rhyolitic lava flows were erupted between 150 000 and 70 000 years ago. No magmatic eruptions have occurred since the late Pleistocene, but large hydrothermal eruptions took place near Yellowstone Lake during the Holocene. Yellowstone is presently the site of one of the world's largest hydrothermal systems including Earth's largest concentration of geysers.
Featured image: June 2017 earthquake swarm in Yellowstone National Park. Credit: USGS/YVO