Geologic and engineering observations from the Van earthquake of 2011 SCHARER, K., USGS Pasadena KUTERDEM, K.; ERKMEN, C.; TEKIN, B.; ÇOLAKOĞLU, Z., AFAD ÇELEBI, M.; HOLZER, T., USGS Menlo Park

Lake Van

Lake Ercek

Van

Ercis

M5.6

USGS

AFAD

EMSC

KOERI

50 km

Mw depth

AFAD 7.0 19

EMSC 7.2 10

KOERI 7.2 5

USGS 7.1 16

Lake Van

Lake Ercek

Van

Ercis

M5.6

USGS

AFAD

EMSC

KOERI

50 km

S N

Mw depth

AFAD 7.0 19

EMSC 7.2 10

KOERI 7.2 5

USGS 7.1 16

EMSC aftershocks

Lake Van

Lake Ercek

Van

Ercis

M5.6

USGS

AFAD

EMSC

KOERI

50 km

Main shock: Van: 5-6 collapses, ~25 severely damaged Ercis: 1095 collapsed and severely damaged Nov 9 Aftershock : Van >100 collapses Complex structure, young lake deposits

Engineering Observations

Cities: moment resistant reinforced concrete frames with masonry infill walls

Rural areas: adobe buildings, minimally reinforced

Fielding, Van Supersite Turkish Geodetic Survey, 1961 USGS DEM

Geologic Observations

ITU Report Akyüz et al.

MTA Report Emre et al.

AFAD Report Kandilli Reports Dept of EE

ITU: formed just after earthquake

ITU

ITU

North side up. ITU, Location 4: 10 cm reverse, 3 cm left lateral

South side up

10 cm right lateral, slip vector ~10, N65E

AFAD

MTA

North side up

10 cm reverse, 4 cm left lateral motion, north side up

ITU

45-50°

ITU, Location 5: Compressional surface deformation traced for 750 m along NE trend. ITU

ITU, Location 1: Northern block is uplifted along N70E direction. Tiny cracks observed for 200 m on the natural surface, lost after heavy rain and snow.

ITU

Ground deformation:

• <10 cm slip preserved in brittle man-made structures

• Concentrated along 12 km lineament with inconsistent, but oblique-reverse motion

• Co-located with existing fault in late Pleistocene deposits and near old scarps at range front

USGS-BW

USGS-CMT EB/FFM

KOERI

Depth (km

)

10

20

0 20 40

10X VE

A

B

A B

Fielding, Van Supersite

Regional view: • Lineament aligned with western margin of InSAR uplift pattern: axial surface associated with limb rotation

• 3D geometry of the hypocenter, lineament, and uplift pattern require multiple or curved fault

• Maximum uplift is region low topography

Fielding, Van Supersite MTA Report

Lake Van

Lake Ercek

GEOLOGY • 10 locations with oblique reverse slip along 11.6 km long lineament, largely preserved in brittle structures • Co-located with fault dipping 45-50° in 16ka deposits of Lake Van highstand • Trend is subparallel to range front, aligned with older scarps, indicating past activity • Based on InSAR, deformation likely product of bending at axial surface during limb rotation • Vs. hypocenters, lineament would require offset faults, or curved fault plane • Similarities to Northridge (no rupture, <1m uplift) and Loma Prieta (Langenheim et al., 1998) ENGINEERING • TOKI buildings performed well • Need for increased use of shear wall systems and construction oversight • Challenge of aftershocks on community response and rebuilding efforts

Thanks and best wishes to the people of Van