Magnitude
7.6
Date-Time
Tuesday, March 20, 2012 at 18:02:48 UTC
Tuesday, March 20, 2012 at 12:02:48 PM at epicenter
Tuesday, March 20, 2012 at 08:02:48 AM HST
Location
16.662°N, 98.188°W
Depth
17.5 km (10.9 miles)
Region
OAXACA, MEXICO
Distances
25 km (15 miles) E (95°) from Ometepec, Guerrero, Mexico
42 km (26 miles) NNW (335°) from Pinotepa Nacional, Oaxaca, Mexico
87 km (54 miles) SW (219°) from Tlaxiaco, Oaxaca, Mexico
162 km (101 miles) WSW (255°) from Oaxaca, Oaxaca, Mexico
186 km (115 miles) E (96°) from Acapulco, Guerrero, Mexico

TSUNAMI BULLETIN NUMBER 001
PACIFIC TSUNAMI WARNING CENTER/NOAA/NWS
ISSUED AT 1813Z 20 MAR 2012

THIS BULLETIN APPLIES TO AREAS WITHIN AND BORDERING THE PACIFIC OCEAN AND ADJACENT SEAS…EXCEPT ALASKA…BRITISH COLUMBIA… WASHINGTON…OREGON AND CALIFORNIA.

… TSUNAMI INFORMATION BULLETIN …

THIS BULLETIN IS FOR INFORMATION ONLY.

THIS BULLETIN IS ISSUED AS ADVICE TO GOVERNMENT AGENCIES. ONLY NATIONAL AND LOCAL GOVERNMENT AGENCIES HAVE THE AUTHORITY TO MAKE DECISIONS REGARDING THE OFFICIAL STATE OF ALERT IN THEIR AREA AND ANY ACTIONS TO BE TAKEN IN RESPONSE.

AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS

ORIGIN TIME – 1803Z 20 MAR 2012
COORDINATES – 17.0 NORTH 98.1 WEST
DEPTH – 10 KM
LOCATION – GUERRERO MEXICO
MAGNITUDE – 7.8

EVALUATION

A DESTRUCTIVE WIDESPREAD TSUNAMI WAS NOT GENERATED BASED ON EARTHQUAKE AND HISTORICAL TSUNAMI DATA. HOWEVER, THERE IS THE POSSIBILITY OF SOME LOCAL TSUNAMI EFFECTS. THIS EARTHQUAKE IS LOCATED INLAND FROM THE COAST.

THIS WILL BE THE ONLY BULLETIN ISSUED FOR THIS EVENT UNLESS ADDITIONAL INFORMATION BECOMES AVAILABLE.

THE WEST COAST/ALASKA TSUNAMI WARNING CENTER WILL ISSUE PRODUCTS FOR ALASKA…BRITISH COLUMBIA…WASHINGTON…OREGON…CALIFORNIA.

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.