Japanese Tsunami Wall, Tsu-Shi

Along some coastal areas of japan where population density is high, tsunami walls are extensively built as tsunami protection. Japan is the more prominent country which has used tsunami walls to have protection against locally generated tsunami. These walls are of 4.5 metres. Theses walls are also designed to redirect water in the event of a tsunami facilitating  floodgates and channel.

Tectonic Summary Of Magnitude 8.9 - Near the East Coast Of Honshu, Japan (2011 March 11 05:46:23 UTC)

The thrust faulting on or near the subduction zone interface plate boundary between the Pacific and North America plates results earthquake near the east coast of Honshu, Japan (03/11/2011). The preliminary magnitude is 8.9. At the latitude of this earthquake, the Pacific plate moves approximately westwards with respect to the North America plate at a velocity of 83 mm/yr. The Pacific plate thrusts underneath Japan at the Japan Trench, and dips to the west beneath Eurasia. The location, depth, and focal mechanism of the March 11 earthquake are consistent with the event having occurred as thrust faulting associated with subduction along this plate boundary. Note that some authors divide this region into several microplates that together define the relative motions between the larger Pacific, North America and Eurasia plates; these include the Okhotsk and Amur microplates that are respectively part of North America and Eurasia.

Legend for fig-1to fig-3(Earthquake Location)

 

fig-1

 

fig-2

 fig-3

The March 11 earthquake was preceded by a series of large foreshocks over the previous two days, beginning on March 9th with an M 7.2 event approximately 40 km from the March 11 earthquake, and continuing with a further 3 earthquakes greater than M 6 on the same day.

 fig-4 ( Map of JAPAN)

The Japan Trench subduction zone has hosted 9 events of magnitude 7 or greater since 1973. The largest of these was an M 7.8 earthquake approximately 260 km to the north of the March 11 event, in December 1994, which caused 3 fatalities and almost 700 injuries. In June of 1978, an M 7.7 earthquake 35 km to the southwest caused 22 fatalities and over 400 injuries

PEAK GROUND VELOCITY OF SOUTH ISLAND, NEW ZEALAND EARTHQUAKE, 11/02/21 23:51 UTC

2011 February 21 23:51:43 UTC: SOUTH ISLAND, NEW ZEALAND

Magnitude           : 6.3

Date-Time           : Monday, February 21, 2011 at 23:51:43 UTC

                              Tuesday, February 22, 2011 at 12:51:43 PM at epicenter 

Location               : 43.600°S, 172.710°E 

Depth                   : 5 km (3.1 miles) 

Region                 : SOUTH ISLAND OF NEW ZEALAND 

Distances             :  NEAR Christchurch, New Zealand
           225 km (140 miles) SSE of Westport, New Zealand
           305 km (190 miles) SSW of WELLINGTON, New Zealand
           310 km (190 miles) NE of Dunedin, New Zealand

Location Uncertainty  : horizontal +/- 12.2 km (7.6 miles); depth +/- 0.6 km (0.4 miles) 

Parameters          : Nph= 0, Dmin=0 km, Rmss=0.98 sec, Gp= 0,
                             M-type="moment" magnitude from initial P wave (tsuboi method) (Mi/Mwp),      

                               Version=D  (Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand)

FIG: Peak Ground Velocity( in cm/s) (USGS Shakemap)

Testing rig for compressive test on pile using tension piles for reaction

UNCERTAINTY OF SOUTH ISLAND, NEW ZEALAND EARTHQUAKE, 11/02/21 23:51 UTC

2011 February 21 23:51:43 UTC: SOUTH ISLAND, NEW ZEALAND

Magnitude           : 6.3

Date-Time           : Monday, February 21, 2011 at 23:51:43 UTC

                              Tuesday, February 22, 2011 at 12:51:43 PM at epicenter 

Location               : 43.600°S, 172.710°E 

Depth                   : 5 km (3.1 miles) 

Region                 : SOUTH ISLAND OF NEW ZEALAND 

Distances             :  NEAR Christchurch, New Zealand
           225 km (140 miles) SSE of Westport, New Zealand
           305 km (190 miles) SSW of WELLINGTON, New Zealand
           310 km (190 miles) NE of Dunedin, New Zealand

Location Uncertainty  : horizontal +/- 12.2 km (7.6 miles); depth +/- 0.6 km (0.4 miles) 

Parameters          : Nph= 0, Dmin=0 km, Rmss=0.98 sec, Gp= 0,
                             M-type="moment" magnitude from initial P wave (tsuboi method) (Mi/Mwp),      

                               Version=D  (Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand)

FIG: PGA/SIGMA Map( in%g) (USGS Shakemap)

Tectonic Summary of South Island, New Zealand Earthquake, 11/02/21 23:51 UTC

The February 21st earthquake involved oblique-thrust faulting at the easternmost limit of previous aftershocks, and like the mainshock itself is broadly associated with regional plate boundary deformation as the Pacific and Australia plates interact in the central South Island, New Zealand. The February 21, 2011 South Island, New Zealand earthquake occurred as part of the aftershock sequence of the M 7.0 September 3, 2010 Darfield, NZ earthquake.

Legend for all fig:  Major Tectonic Boundaries: Subduction Zones -purple, Ridges -red and Transform Faults -green.

This latest shock is significantly closer to the main population center of Christchurch, NZ, than is the September 2010 mainshock, in the vicinity of several other moderate (M 4 to 5) sized aftershocks located east of the main rupture zone of the 2010 event.

There is no specific structure directly linking this event to the main fault of the 2010 mainshock, although there have been numerous aftershocks along generally east-west linear trends extending east from the end of the previous rupture. The north or north-east trends to the possible fault planes and the oblique thrust faulting mechanism as seen in the focal mechanism solution may reflect an association with similarly-trending faults previously mapped in the Port Hills region, just to the south of Christchurch. 

Since the September 3, 2010 mainshock, there have been approximately 6 M>=5.0 aftershocks in the Christchurch region. The February 21st earthquake represents the largest aftershock to date, more that half a magnitude unit larger than the previous largest aftershock.

Seismicity in the vicinity of Christchurch, New Zealand, following the September 3, 2010, M7.0, Darfield earthquake (yellow circles) and the February 21, 2011, M6.3, Christchurch earthquake (orange circles). Data from GNS Science, New Zealand.

Testing rig for compressive test on pile using cable anchors for reaction