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Metro Manila’s other earthquake risks
Except for the Guadalupe formation, which in my column last week I had described as bedrock, the ground of Metro Manila consists mainly of layers and layers, in different proportions in differing places, of silty clay, clay, sandy alluvium and fill. When a strong earthquake occurs, the response of the ground in the whole area will accordingly range from weakest for ground that is on bedrock to strongest for areas atop fill of 30 meters or more. Since most of Metro Manila is not on a thin overlay of soil over bedrock, it makes sense to understand the dangers most of us we will be facing when, if I may be excused by Ayn Rand, Atlas shrugs.