Table 1 Main Factors contributing to earthquake-triggered landslide events

Intensity I

M, D

Arias Intensity AI computed according to Eqs. 1 and 2

AI > 1: I = \( \sqrt{AI} \)

IF AI ≤ 1: I = AI

Fault factor F

Location, type and length of activated fault

FLF: Location with respect to mountain range MR

FT: Fault type mechanism

FL: Fault length

a) Fault inside MR: FLF = 2

Near MR: FLF = 1.5; outside MR: FLF = 1

b) Dip-slip fault: FT = 1.5; Strike-slip: FT = 1

c) Fault length ≥ 100 km: FL = 2

Fault length between 20 and 100 km: FL = 1

Fault length < 20 km: FL = 0.5

F = FLF*FT*FL; Range F: 0.5-6

Topographic energy TE

Google Earth analysis

Maximum altitude difference A_dif over 100 km² tested for sample areas in affected zones.

Adif > 1500 m : TE = 4

1000 < A_dif ≤ 1500 m : TE = 3

500 < A_dif ≤ 1000 m : TE = 2

A_dif ≤ 500 m (but hilly): TE = 1

Flat with bluffs: TE = 0.5

Climatic background CB

Climatic information extracted from any published sources

Qualitative estimate considering

-antecedent rainfall AR

-general climatic conditions (CC: arid – wet climate)

Proved AR-yes

and/or CC wet: CB = 2

General conditions (or if not known): CB = 1

Arid climate: CB = 0.5

Very arid climate: CB = 0.2

Lithological factor LF

Published geological information

Qualitative estimate considering the presence of Quaternary (Q) or Tertiary (T) layers and bedrock

Extensive cover of Q-layers: LF = 4

Wide presence of T-layers: LF = 2

Other cases or not known: LF = 1