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					Earthquake prediction
 Earthquake hazards
      Earthquake Prediction and Control
1. Long term monitoring/forecasting:
Use of Paleoseismology:
                                             Seismic Gaps:
Seismic gaps - A seismic gap is a zone along a tectonically active area where no earthquakes have occurred recently,
but it is known that elastic strain is building in the rocks. If a seismic gap can be identified, then it might be an area
expected to have a large earthquake in the near future.
  Short-Term Prediction

Short-term predication involves monitoring of processes that
occur in the vicinity of earthquake prone faults for activity that
signify a coming earthquake.


  Precursor events signal a coming earthquake;
  These events are processes that happen before an earthquake
  takes place and include:

  Ground uplift and tilting due to swelling of rocks caused by
  strain building on the fault.

  May lead to numerous small cracks (microcracks), which in turn
  can lead to foreshocks (small earthquakes).
Foreshocks - Prior to a 1975 earthquake in China, the observation of
numerous foreshocks led to successful prediction of an earthquake and
evacuation of the city of the Haicheng. The magnitude 7.3 earthquake that
occurred, destroyed half of the city of about 100 million inhabitants, but
resulted in only a few hundred deaths because of the successful evacuation..

Water Level in Wells - As rocks become strained in the vicinity of a fault,
changes in pressure of the groundwater (water existing in the pore spaces
and fractures in rocks) occur. This may force the groundwater to move to
higher or lower elevations, causing changes in the water levels in wells.

Emission of Radon Gas - Increases in the amount of radon emissions have
been reported prior to some earthquakes.

Changes in the Electrical Resistivity of Rocks - In some cases a 5-10%
drop in electrical resistivity has been observed prior to an earthquake.

Strange Animal Behavior - Prior to a magnitude 7.4 earthquake in Tanjin,
China, zookeepers reported unusual animal behavior. Snakes refusing to go
into their holes, swans refusing to go near water, pandas screaming, etc.
Ground Deformation




      Earthquakes may cause both uplift and subsidence of the
      land surface.
       Hazards Associated with Earthquakes
                                   These men barely
► Ground                           escaped when the front
    Shaking                        of the Anchorage J.C.
                                   Penny's collapsed
    Intensity of ground            during the 1964 Good
    shaking depends on:            Friday earthquake

► Local geologic
  conditions in the area.
► Size of the Earthquake.
► Distance from the
  Epicenter.
► Damage to structures
  from shaking depends
  on the type of
    construction.

     One side of this Anchorage street
     dropped drastically during the 1964
     Good Friday earthquake.
           Liquefaction
San Francisco Bay




                            Loma
                          Prieta EQ,   These buildings in Japan toppled
                             1989      when the soil underwent
                                       liquefaction.
A section of freeway
880 collapsed where
anchors were placed in
soft mud.




  Soft mud along the edge of San Francisco Bay amplified the
  ground motion under the freeway by a factor of 5 to 8 despite the
  90 km -distance to the epicenter.
  Loma Prieta earthquake, 1989
    Landslides




Earthquake-induced landslide damage to
a house built on artificial fill, after the   The 2001 El Salvador earthquake-induced
2004, Niigata Prefecture, Japan               landslide located in a neighborhood near San
earthquake. Photo by Prof. Kamai, Kyoto       Salvador, Santa Tecla. Photo by Ed Harp,
Univ., Japan.                                 USGS - for more information and photos
                                              please see this publication:
                                              http://landslides.usgs.gov/research/other/ce
                                              ntralamerica.php.
Flooding
Fire




       1906 San Francisco Earthquake




                               1923 Great Kanto
                               Earthquake
There are two classes of earthquake effects: direct, and secondary.

Direct effects are solely those related to the deformation of the
ground near the earthquake fault itself. Thus direct effects are limited to the
area of the exposed fault rupture.

Secondary Effects
Most of the damage done by earthquakes is due to their secondary
effects, those not directly caused by fault movement, but resulting instead
from the propagation of seismic waves away from the fault rupture.

•seismic shaking;
•landslides;
•liquefaction;
•fire;
•flooding;
•triggering of aftershocks and additional earthquakes.
Earthquakes don’t kill people,
   falling buildings and highway
   structures do.
Most of the hazards to people
  come from man-made
  structures themselves and
  the shaking they receive
  from the earthquake. The
  real dangers to people are
  being crushed in a collapsing
  building, drowning in a flood
  caused by a broken dam or
  levee, getting buried under a
  landslide, or being burned in
  a fire.
       Community Adjustments
Earthquake hazard risk depend on

►   Location of critical facilities
►   Construction standards (building codes)
►   Emergency preparedness
Landuse planning and building codes are the best
defenses against death, injuries and property
damage.

Zoning
- should limit development in areas along active faults, situations
prone to landslides or on soft mud

Example Armenian earthquake, 1988
  Armenia Earthquake,
         1988



Source: Modified after: www.gadr.giees.uncc.edu/PPT_SLIDES/SPITAK%20EARTHQUAKE.ppt
Spitak Earthquake
SPITAK EARTHQUAKE: UN-
ANCHORED FLOOR PLANKS
SPITAK EARTHQUAKE: UN-
 REINFORCED MASONRY
SPITAK EARTHQUAKE: UN-
 REINFORCED MASONRY
   SPITAK EARTHQUAKE:
CONCRETE FRAME BUILDINGS
SPITAK EARTHQUAKE: NEW
 BUILDINGS PERFORMED
        POORLY
SPITAK EARTHQUAKE:
CULTURAL HERITAGE
SPITAK EARTHQUAKE: DEBRIS
 AND TRAFFIC HINDERED EM
         RESPONSE




          RECONSTRUCTION COSTS OF ABOUT
                   $16 BILLION
SPITAK EARTHQUAKE: SEARCH
        AND RESCUE




MEDICAL SERVICES WERE UNAVAILABLE IN THE
HOUR OF GREATEST NEED.
  Lessons learned after the
   SPITAK EARTHQUAKE
       THRUST FAULTS” WERE
► “BLIND
 AVOIDED

► THE“NEW” SPITAK IS A 4-STORY
 CITY WITH MUCH MORE STEEL

► EARTHQUAKEENGINEERING
 EMERGED AS A HIGH PRIORITY