Magnitude
4.3

Depth
11.5 km

Time
2016-07-23
07:16:05.250 (UTC)
21:16:05.250 HST

TSUNAMI SEISMIC INFORMATION STATEMENT NUMBER 1
NWS PACIFIC TSUNAMI WARNING CENTER EWA BEACH HI
920 PM HST FRI JUL 22 2016

TO – EMERGENCY MANAGEMENT IN THE STATE OF HAWAII

SUBJECT – LOCAL TSUNAMI INFORMATION STATEMENT

THIS STATEMENT IS FOR INFORMATION ONLY. NO ACTION REQUIRED.

AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS

ORIGIN TIME – 0916 PM HST 22 JUL 2016
COORDINATES – 19.5 NORTH 155.9 WEST
LOCATION – ON THE WESTERN FLANK OF MAUNA LOA
MAGNITUDE – 4.0

EVALUATION

NO TSUNAMI IS EXPECTED. REPEAT. NO TSUNAMI IS EXPECTED.

THIS WILL BE THE ONLY STATEMENT ISSUED FOR THIS EVENT UNLESS ADDITIONAL DATA ARE RECEIVED.

Magnitude-4.3 earthquake northwest of Captain Cook, Island of Hawaiʻi

By USGS/HVO

The U.S. Geological Survey’s Hawaiian Volcano Observatory (HVO) recorded a magnitude-4.3 earthquake beneath the Island of HawaiÊ»i on Friday, July 22, 2016, at 9:16 p.m., HST. The Pacific Tsunami Warning Center determined that no damaging tsunami was generated (http://ptwc.weather.gov/?region=2)

According HVO, the earthquake was centered about 5.4 km (3.3 mi) northwest of Captain Cook at a depth of 11.5 km (7.1 mi). A map showing its location is posted on the HVO website at http://hvo.wr.usgs.gov/seismic/volcweb/earthquakes/

The USGS “Did you feel it?” Web site (http://earthquake.usgs.gov/eqcenter/dyfi/) received more than 400 felt reports within one hour of the earthquake. Most of these felt reports were from the west side of the Island of HawaiÊ»i, which is consistent with the location and depth of the earthquake. Most reports described light shaking (Intensity IV). At that intensity, damage to buildings or structures is not expected.

As of 10:30 p.m., one small aftershock was recorded.

During the past 30 years, there have been 3 earthquakes, including tonight’s event, with magnitudes greater than 4.0 and at depths of 5–15 km (3–9 mi) in the Kealakekua area of West Hawaiʻi.

Earthquakes at this depth off the west coast of the Island of Hawaiʻi are typically caused by abrupt motion on the boundary between the old ocean floor and the volcanic material of the island, and are not directly tied to volcanic activity.

According to HVO’s Scientist-in-Charge, Christina Neal, the earthquake had no apparent effect on KÄ«lauea Volcano’s ongoing eruptions.

For information on recent earthquakes in Hawaii and eruption updates, visit the USGS Hawaiian Volcano Observatory website at http://hvo.wr.usgs.gov

USGS: How large does an earthquake have to be to cause a tsunami?

Magnitudes below 6.5
Earthquakes of this magnitude are very unlikely to trigger a tsunami.

Magnitudes between 6.5 and 7.5
Earthquakes of this size do not usually produce destructive tsunamis. However, small sea level changes may be observed in the vicinity of the epicenter. Tsunamis capable of producing damage or casualties are rare in this magnitude range but have occurred due to secondary effects such as landslides or submarine slumps.

Magnitudes between 7.6 and 7.8
Earthquakes of this size may produce destructive tsunamis especially near the epicenter; at greater distances small sea level changes may be observed. Tsunamis capable of producing damage at great distances are rare in the magnitude range.

Magnitude 7.9 and greater
Destructive local tsunamis are possible near the epicenter, and significant sea level changes and damage may occur in a broader region.

Note that with a magnitude 9.0 earthquake, the probability of an aftershock with a magnitude exceeding 7.5 is not negligible. To date, the largest aftershock recorded has been magnitude 7.1 that did not produce a damaging tsunami.