Geoscience Reference
In-Depth Information
along with existing information about local faulting system of a particular area,
these seismology investigations help in identifying hidden faults and release points
of stress.
4 Conclusion
Among all surface and near surface phenomena and events which are supposed to
be, theoretically or experimentally, related to the seismic activities during a major
earthquake SLHF and temperature have been of most interest due to the capability
of current remote sensing devices to record their variations. Other factors are either
very hard to extract from satellite-based datasets or need costly and time-con-
suming in situ measurements on wide areas. These heat-based precursors are,
somehow, considered as the underlying ones which may be supported by other
clues such as changes in relative humidity or other factors for some case studies.
The quality and precision of previous reports have always been a function of the
recording facilities of data providers, data manipulation capabilities of data ven-
dors, and types of the analyses used by researchers. Although, almost all
researchers who worked on the topic of detection of the above-mentioned basic
precursory events reported successful attempts, yet, most of them failed to perform
accurate and encompassing spatio-temporal analyses which take into account the
geological and geotechnical settings. In addition to assessing the condition in the
epicentral region, one should bear in mind that, in most parts of the world,
earthquakes are triggered by activities in the fault zones miles away from the
epicenters. Statistical data of an epicenter could be of much importance, however,
it will be more useful if the changing patterns of SLHF, surface and air temper-
ature are mapped on wide scales and long time periods before and after a main
event. On the other hand, Any research on this kind should be, more or less,
complied with a chain of the events suggested by one of the available (micro or
macro scale) geophysical or geochemical theories about the interactions take place
during the gradual movements, compression, and decompression during the
preparation stage of a major earthquake. This would need using all the possible
ground or remote based information reflecting underground activities. Most of the
theories on the underground changes in the earth insist on the movements which
cause the generation and build-up of elastic strain in the crust. Seismograph sta-
tions, if dense enough and located at the immediate neighborhood, could be used
to detect weak shakes prior to the main shakes which are not often reported by
national or international bodies. The resultant shake maps may be used to deter-
mine the concurrency of ground movements and appearances of remotely sensible
precursors, and also, for detection of possible local hidden or unmapped faults
considering this fact that the partial releases of very energy that triggers the main
event causes possible foreshocks weeks to days before the sensible shake.
