Reported activities of the iconic Mauna Loa in Hawaii included multiple small-scale earthquakes in 2014. Since early September 2015, the volcano has been showing signs of continued disturbance that led to increased alerts from the United States Geological Survey (USGS).

The amplified levels of ground motion and inflation raised alert levels from yellow - or normal - to advisory. Scientists recounted increased occurrence of 2.5-magnitude earthquakes - from 10 to 40 per week.

Past eruptions in 1975 and 1984 revealed that these "signs of unrest" manifest prior to an eruption. The Hawaiian Volcano Observatory (HVO) said that the volcano's existing turmoil does not predict a pending outbreak. However, its current behavior might affect the activities being carried out on its slopes such as the National Aeronautics and Space Administration's (NASA) Mars simulation program called HI-SEAS.

"An ADVISORY/YELLOW status is declared when one or more volcano monitoring parameters are above the background range of activity, which is the current situation on Mauna Loa," USGS said. Mauna Loa was given the same alert level in 2004 and 2009. The volcano's activities were beyond what was normal during these years. In 2010, Mauna Loa's volcanic activities went back to normal and the alert was lifted.

The island state of Hawaii is home to five volcanoes: Mauna Kea, Hualalai, Kilauea, Kohala and Mauna Loa. Three of these iconic giants are active volcanoes. Kohala is Hawaii's oldest volcano with an estimated age of one million years old. It erupted 60,000 years ago and showed no signs of unrest since the catastrophe. Mauna Kea, which is also around one million years old, broke out 4,500 years ago and remained dormant since.

In the last 3,000 years, reports on Mauna Loa showed it erupts once in six years. Latest reports confirmed that its current energy level is significantly lower compared to its rating during the pre-eruption in 1984. It is still early to predict if the current state is a precursor to the next eruption, added HVO scientist Tina Neal. Its present activity serves as a reminder that Mauna Loa is the largest active volcano in the world, added Geologist Frank Trusdell.