ABSTRACT
It is alarming to note that from August to September 1999 alone, four (4) major earthquakes hit various countries – Mexico, Taiwan, Los Angeles, and Turkey with magnitude 7.4, 7.6, 7.0, and 7.8 respectively. Economic and human losses resulting from these earthquakes highlight the need for evaluating potentially active crustal faults.
Manila City for which encompasses a land area of 38.3 square kilometers, which is populated by nearly 1.7 million persons at a density of 44,387 persons per sq. km. And has 133,575 buildings which represent the highest building density of 44,387 persons per sq. km. And has 133,575 buildings which represent the highest building density in metro Manila, is comparably subject to the consequences as a seismic event. Available records from the Philippine Institute of Volcanology and Seismology (PHILVOCS) indicate that the City of Manila has been affected by at least 28 major earthquakes having intensities ranging from Intensity VII to IX. Knowing that an earthquake is a re-occurring event and those coming from the MVFS will most likely generate the strongest levels of ground shaking in the City of Manila.With these developments and the series of earthquakes and the series of earthquake related events experienced here and abroad it is logical to review our own code and consider any new provisions or changes for possible implementation locally. In the same way, seismic map model is necessary with proper consideration of the geological and seismic related area data to ensure that geological situation is completely understood. The study uses the input-process approach with feedback serving as a major conduit for upgrading of the code . The procedure consists of two major activities-first is the evaluation of the specific section of the UBC-2005 and NSCP-2001 second is the creation of seismic model of Manila as tool in the base shear computation incorporating the near source concept. As such, seismic map model through the aid of AUTOCAD and AUTOLISP programming language will be created incorporating all the necessary data and base shear computations which serves as an initial tool necessary for initial site investigation necessary to the seismic design analysis. As an initial step to create the map mode, the topographic map of the City of manila will be secured from the City Engineering Office while the map of the Marikina Valley fault System will be acquired from PHILVOLCS, then overlaid and scale approximately using AUTOCAD program. After establishing the map and the Marikina Valley fault l;line, sets of database files will be created serving attributes necessary for the formulation of the required information expected on the map model. The AUTOLISP programming will be used to compute the base shear. In the light of series of earthquakes happening here and abroad, the government as well as those concerned groups should take serious consideration the danger that may pose by the hazard of seismic related events. As such, are local code should be responsive enough to the design criteria comparable abroad and can sustain the worst possible grounds motion that may occur. Given the above scenario coupled with emergent development needs and trends in seismic related cases, there is the urgency to assess for possible upgrading the local code and develop information technology tool to ensure geological and seismic related situation are completely understood to the extend possible
