A very unusual triple swarm of earthquakes were recently recorded in the Yellowstone National Park and scientists believe that these are aftershocks of the earthquake back in 1959.

Bob Smith, a geophysics professor in the University of Utah, was baffled with the recorded seismic activities since it was the first time such activities were observed. He has been monitoring seismic activities for 53 years. The events happened in Lewis Lake, the Lower Geyser Basin and the northwest part of Norris Geyser Basin.

Earthquake swarm is a series of earthquakes happening in a relatively short period of time. According to the U.S Geological Survey, the repeat usually happens in days, weeks, or months. Earthquake swarms often happen before a volcanic eruption.

Smith investigated the sudden occurrence of earthquake swarms in Yellowstone which led him to a conclusion that the two of the triple swarms of earthquakes are related.

The unusual first earthquake swarm occurred on Sept. 10 while the last one was Sept. 16. The largest with a 3.6 magnitude happened Sept. 15 about six miles north of the Old Faithful Geyser. Seismologists detected that the epicenter was located in the Yellowstone National Park.

The University of Utah issued a statement a total of 130 earthquakes with magnitudes ranging from 0.6 to 3.6 have been noted in the area and most of them happened in the Lower Geyser Basin.

The latest swarms of earthquakes created four more earthquakes, though not large, they were enough in size to be felt.

Smith believes that the recent swarms of earthquakes may be connected to the 1959 earthquake. That 7.5 magnitude earthquake happened in the Hebgen Lake. It was so strong that it may have reconstructed the geysers near the area.

“We think that much of the seismicity is still aftershocks from that event in 1959. It can go on for hundreds of years,” Smith told GuardianLV.