A magnitude 4.2 earthquake woke some residents up early Friday morning.

No tsunami was generated.

The earthquake, in the ocean about 38 miles south of Waimanalo and 34 miles southwest of Maunaloa, Molokai, was about 4 miles deep and struck at 2:37 a.m., according to the U.S. Geological Survey.

The USGS updated its initial estimate of the magnitude and epicenter Friday and said it can be difficult to determine accurate earthquake locations and depths because of the sparse coverage of seismometers on Molokai and adjacent islands. 

USGS initially reported it to be magnitude-4.1 earthquake with a depth of about 12 miles, about 45 miles southwest of Lanai.

It was widely felt throughout the islands, especially on the Windward side of Oahu, with a number of responses on the USGS “Did you feel it?” website from Kailua, Kaneohe, Haiku and Waimanalo.

It was also felt in Kailua-Kona; Kihei and Makawao on Maui; Lanai City; Maunaloa, Molokai; and Wahiawa.

The Hawaiian Volcano Observatory’s records show there have been three earthquakes of magnitude 3 or larger in the same area over the last 25 years.

According to the observatory’s seismic network manager, Wes Thelen, earthquakes outside of Hawaii island are not uncommon and are typically caused by a structural adjustment of the mantle in response to the weight of the Hawaiian Islands. 

“This event is a good reminder that the Island of Hawaii is not the only Hawaiian island prone to earthquakes,” Thelen said in a news release.

No aftershocks were reported and aftershocks do not typically follow earthquakes of this magnitude and depth, Thelen said.

“The earthquake today caused no detectable changes on the active volcanoes on the Island of Hawai’i,” said Jim Kauahikaua, HVO’s Scientist-in-Charge.

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The Associated Press contributed to the story.