Landslide characterization using active and passive seismic imaging techniques: a case study from Kerala, India
- PDF / 2,666,353 Bytes
- 20 Pages / 439.37 x 666.142 pts Page_size
- 36 Downloads / 243 Views
Landslide characterization using active and passive seismic imaging techniques: a case study from Kerala, India Francisco J. Chávez‑García1 · Thulasiraman Natarajan2 · Martín Cárdenas‑Soto3 · Kusala Rajendran4 Received: 6 June 2020 / Accepted: 5 October 2020 © Springer Nature B.V. 2020
Abstract The unusually intense precipitations of the 2018 monsoon triggered numerous landslides in the Western Ghats region, southwest of India. Although the landslides caused no casualties, significant damage to property and infrastructure was observed. We present, as a case study, the results of active and passive seismic prospecting at two of those landslides with the goal of characterizing them, in a first application of shallow seismic exploration to landslides in the region. Our deployments included both sites perturbed by the landslides and unperturbed slopes adjacent to them with the purpose of identifying possible structural differences between slopes that underwent landsliding from slopes that were not affected. We analyze seismic sections obtained using the multi-channel analysis of surface waves technique and compare the results with seismic noise analyzed using seismic interferometry. We show that different analyses give similar results. The lateral variations observed in the shear-wave velocity distribution below the different profiles are well correlated with dominant frequency determined from seismic noise horizontal-to-vertical spectral ratios. Our measurements were taken after the landslides occurred. In hindsight, our results suggest that soil thickness played a major role in the triggering of landslides. Keywords Near surface geophysics · MASW · Seismic interferometry · Seismic tomography
* Francisco J. Chávez‑García [email protected] 1
Instituto de Ingeniería, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 Coyoacán, CDMX, Mexico
2
Geodynamics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560064, India
3
Facultad de Ingeniería, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 Coyoacán, CDMX, Mexico
4
Center for Earth Science, Indian Institute of Sciences, CV Raman Rd, Bengaluru, Karnataka 560012, India
13
Vol.:(0123456789)
Natural Hazards
1 Introduction Landslides, the gravity-caused movement of rock, debris or earth down a slope, are a major risk factor in many regions of the world. Landslides are known to have been triggered by strong ground motion during large earthquakes. However, most landslides are due to gravity failure. For this reason, topographic slope gradient is a significant indicator of susceptible areas (Dai et al. 2002). A major triggering factor for landslides is often simply the rain, which may vary largely in intensity, sometimes taking a catastrophic character. A tragic example is given by the consequences of typhoon Morakot which struck Taiwan in August 2009. In addition to severe flooding, this typhoon triggered landslides and debris flows causing massive destruction to roads and bridges. The largest
Data Loading...
