Zone
(see Fig. 3)

a₀

T_a

T_b

γ

Mexico City

I

0.04

0.2

0.6

1/2

II

0.08

0.3

1.5

2/3

III

0.1

0.6

3.9

1

Zone
(see Fig.4)

Soil type
(see Table 3)

a₀

T_a

T_b

γ

116 cities except Mexico City throughout the country

A

I

0.03

0.3

0.8

1/2

II

0.045

0.55

2.0

2/3

III

0.06

0.75

3.3

1

B

I

0.03

0.3

0.8

1/2

II

0.045

0.5

2.0

2/3

III

0.06

0.8

3.3

1

C

I

0.05

0.25

0.67

1/2

II

0.08

0.45

1.6

2/3

III

0.1

0.6

2.9

1

D

I

0.09

0.15

0.55

1/2

II

0.14

0.3

1.4

2/3

III

0.18

0.45

2.7

1

Soil type

descriptions

I

Bedrock and stiff soils such as compacted volcanic ashes, moderately cemented sandstones, and highly compacted clays.

II

Soils of low stiffness and medium to high density, such as uncemented sands or soils, clays of medium density, and deposits of compacted alluvial soils; all with a depth of less than 40 m.

III

Highly compressible clays, loose deposits of alluvial soils, and sand deposits in delta areas; all with a depth greater than 40 m.