MAPPING
THE RISKS: AN INTRODUCTION TO GEOHAZARD MAPS
Due
to its geologic setting and geographic location, the Philippines
ranks among the most vulnerable to disasters caused by natural phenomenon.
Earthquakes, volcanic eruptions and landslides are the most common
causes of geological disasters. The more devastating occurrences
in recent years include the 1990 Luzon earthquake, the 1991 Mt.
Pinatubo eruption and the Cherry Hills landslide of 1999. Since
geologic hazards transcend political boundaries, their recognition
is of utmost value in planning urban communities. Geohazard maps
provide the basic information necessary for such plans.
DENR-MGB
Geohazard Maps
The Department of Environment and Natural Resources – Mines
and Geosciences Bureau (DENR-MGB) produces geohazard maps of selected
urbanized and urbanizing areas in the country. Published so far
are the geohazard maps of Metro
Manila, Baguio
City, Cagayan
de Oro City, Zamboanga
City, Butuan
City, Subic
and Olongapo City, Davao
City, Surigao
City, Oriental Mindoro and portions of Cavite
City and San Pedro, Laguna. Processing of information
from Cebu City and Tuguegarao, Cagayan is on-going.
Government
Policy
With the issuance of DENR
Administrative Order No. 2000-28 on March 14,
2000, Urban Geology Units in the MGB Central Office and Regional
Offices were formally established. Among the mandates of these entities
is the assessment of geologic hazards in urban areas. To realize
this, the DAO No. 2000-28 has institutionalized the Engineering,
Geological and Geohazard Assessment (EGGA) system, which requires
all development projects an EGGA Report as an additional requirement
to the Environmental Compliance Certificate (ECC) applications.
The production of a geohazard map of the site of a specific project
is inherent to this system.
To
know more about the EGGAR for Private Entity Projects, click here.
To
know more about the EGGAR for Government Projects, click here.
Maps
meant not to scare but to warn
Geohazard maps normally provide information on potential areas of
landslides, liquefaction, subsidence and other ground instabilities.
The appreciation of the effects of such ground movements is a necessity
in the design of infrastructure. Once geologic hazards are properly
identified and characterized, their effects can be mitigated, if
not eliminated, by instituting preventive measures normally implemented
through appropriate engineering design. As such, geohazard maps
therefore do not mean to scare investors and developers, but instead
warn them of the risks, if any exist, their projects are faced with.
Indicative
Maps
Processed at a regional scale of 1:50,000, the geohazard maps published
by the MGB should be treated as indicative maps. This implies the
necessity of still performing site-specific geohazard studies in
development projects, especially those which are of national interest.
Related
Stories:
For
inquiries, contact:
THE
LANDS GEOLOGICAL SURVEY DIVISION
Tel. No. 02-9288819; 9288544
geology@mgb.gov.ph
|
