Archive for February, 2013

February 18, 2013

Tokachi, Hokkaido 6.5ML, 6.9Mw, 2/02/2013

Lat/Long: 42.689 143.236
UTC: 02/02/2013 14:17:35
JST: 02/02/2013 23:17:35
Depth: 107.7km
Mag: 6.5ML/6.9Mw
Status: Final
Energy Released: 84,802.4 tonnes of TNT (based on ML)
Source: JMA
Ten people suffered minor injuries due to falling objects, broken glass and other incidents, but authorities said no serious damage was reported and the quake did not generate a tsunami. The shaking lasted about a minute, and video taken in the offices of NHK Hokkaido showed computer screens swaying and shelves threatening to give way. Bottles smashed to the ground in supermarkets, some areas had power blackouts and a number of highways were closed. Trains were stopped on rural tracks as a precaution.
“Beware of possible landslides and buildings that could have been weakened,” an official from Japan’s Meteorological Agency warned at a press conference. The most violent tremors were felt in the eastern part of Hokkaido – the nation’s second largest island – but the northern part of the island was also shaken along with parts of the main island of Honshu, where Tokyo is located.
Utility firms said no abnormalities were reported at the Tomari nuclear plant in Hokkaido’s west, nor in the nuclear facilities in Aomori, the northernmost prefecture on Honshu.
Shortly before Saturday’s quake hit, an alert was broadcast on television and radio through an early warning system established by the weather agency, and programs were interrupted on NHK. “Make yourself safe, turn off the gas, beware of falling objects, and if you are outside do not approach the coast,” a broadcaster said.

Network Plots

Other Networks estimates of the event
Network, When, Lat, Long, Magnitude
GEOFON=14:17:33.8, 42.73, 143.73, Mw=6.9
USGS=14:17:35.0, 42.758, 143.106, Mw= 6.9
RASGS=14:17:33.5, 42.72, 143.3, mb= 6.9
NIED=14:17:44.0, 42.8, 143.5, ML=6.8
GCMT=14:17:40.9, 42.88, 143.37, Mw=6.9, Ms= 6.9
EMSC=14:17:34.4, 42.79, 143.17, Mw= 6.9
LDEO=14:17:35.0, 42.75, 143.25, Ms=7.0
CENC=14:17:32.0, 42.73, 143.26, Ms=6.4


gfz moment tensor solution


The total number of aftershocks recorded in the first 30 days was 458, releasing the equivalent energy of 84,837.45 tonnes of TNT. The initial energy was the 6.9Mw, next largest aftershock was a 4.0ML recorded 05:49 minutes after the main shock.

The maps below show the locations of all the aftershocks, as marked in the titles.

12 hrs

showing cumulative 157 (84,827.7 TTNT)

24 hrs

showing cumulative 212, ( new 54) (84,829 TTNT)

24-48 hrs

showing new 43, ( 0.9116 TTNT)

0-48 hrs (cumulative)

showing cumulative 255, ( 84,830 TTNT)

48-72 hrs

showing new 26, ( 2.3307 TTNT)

0-72 hrs (3 days)

showing cumulative 281, ( 84,832.3 TTNT)

Aftershock Graph 72hrs

aftershocks graph 72 hours

more Aftershocks


showing new 62 (1.841 TTNT)


showing cumulative 343 (84,834.13 TTNT)

7-14 days

showing new 56, ( 0.5457 TTNT)


showing cumulative 399, ( 84,834.68 TTNT)

14-21 days

showing new 32, ( 2.0271 TTNT)

0-21 days

showing cumulative 431, ( 84836.7 TTNT)

21-30 days

showing new 27, ( 0.7407 TTNT)

0-30 days

showing cumulative 458, ( 84,837.45 TTNT)

Aftershock Graph 30 days

aftershocks graph 30 days