M 4.8 in Tonga on 20 Apr 2011 03:09 UTC

Hazard models

EQ parameters
Shakemap
Tsunami

Event summary

This earthquake is expected to have a low humanitarian impact based on the magnitude and the affected population and their vulnerability.

Earthquake Magnitude: 4.8M
Depth: Km
Lat/Lon: -20.8478 , -175.53
Event Date: 20 Apr 2011 03:09 UTC
19 Apr 2011 15:09 Local
Exposed Population:
about 89000 people within 100km
Source: NEIC usc0002vem
Inserted at: 20 Apr 2011 03:29 UTC

GDACS Score

For more info on GDACS alert score click here.
  Earthquake GDACS score
NEIC 0.5 0.5
usc0002vem Scaled population (vector) n.a  
  C1 earthquake n.a  
  C2 earthquake n.a  
  Country Vulnerability n.a  
  INFORM_normalised n.a  
Maximum expected impact using different data sources.

Episode Timeline

IDAlertScoreDateMag, DepthMMI*Population**Tsunami risk***Delay (hh:mm)Source
107457 0.5 20 Apr 2011 03:09 4.8M, 104.6km N/A 90 thousand (in 100km) 00:19 NEIC
The episode that generated the alert; the next major evaluations beyond 12 hours will not trigger additional alerts.
The episode that has the last updated information.
* The max MMI detected for sources having shakemaps;
** The population detected in MMI>=7 for episode with shakemap or in a 100km radius;
*** The tsunami max height.

Exposed population

The earthquake happened in Tonga , of Tonga (population 98,000) . The nearest places are Foui, Nukunuku, Houma, Nuku'alofa, Pea, Mua, Kolonga, Fatumu, Niutoua, and Fuaamotu.

Radius Population
100 km 83000 people
75 km 78000 people
50 km 56000 people
20 km no people
10 km no people
5 km no people
2 km no people

Affected Provinces

Region Province Country Population
Tonga Tonga 98000 people

Affected populated places

Name Region Province Country City class Population Distance
Foui Tonga Village - 36 km
Nukunuku Tonga Village - 40 km
Houma Tonga Village - 43 km
Nuku'alofa Tonga Capital 24000 people 46 km
Pea Tonga Village - 47 km
Mua Tonga Village - 57 km
Kolonga Tonga Village - 57 km
Fatumu Tonga Village - 59 km
Niutoua Tonga Village - 61 km
Fuaamotu Tonga Village - 61 km

see full list

Critical infrastructure

Airports, ports, nuclear plants and hydrodams at risk, if affected, are listed below.

Airports

Name IATA Code Elevation (m) Usage Runway type IFR Runway Length (ft) Distance
Fua'amotu International TBU 38 Civ. Paved Yes 8700 59 km
Eua Kaufana EUA unknown 0 84 km

Ports

Name LOCODE Country Distance
Nuku'alofa TOTBU Tonga 46 km
Eua Island Tonga 86 km

More information

For a full list of available products related to this event, please refer to the GDACS Resources page.