5 May 2014 M_W6.1 Mae Lao (Northern Thailand) Earthquake: Interpretations of Recorded Ground Motion and Structural Damage

Abstract

A moderate left-lateral strike-slip earthquake of MW 6.1 occurred on 5 May 2014 in northern Thailand, causing damage to the town of Mae Lao and nearby municipalities. Based on an instrumental earthquake catalog, the Mae Lao earthquake is the second largest earthquake in modern Thai history after the MW 6.3 Nan earthquake in 1935. In this study, the strong-motion records from the epicentral area are analyzed in order to investigate the characteristics of the ground motions. In addition, post-earthquake field observations and statistics for typical structural damage in the affected area, such as the soft story effect and the shear failure of columns, are summarized. Besides major structural damage, the majority of structures in the epicentral area withstood the strong motion, which could be due to the low stress drop of the main shock (40 bars) leading to below average ground motions for an MW 6.1 earthquake.

Seismotectonics of the 2014 Chiang Rai, Thailand, earthquake sequence

“…Direct measurements of the shaking from the M w 6.2 Mae Lao main shock are somewhat limited, because of the relatively sparse network of seismic stations near the source region. Ornthammarath and Warnitchai [] reported a peak horizontal acceleration at the strong motion recorder installed at the Mae Suai dam (15.2 km to the west of the epicenter of the main shock) of 0.30 g. They note that this station is installed at the top of the abutment of the dam; thus, the acceleration recorded here may be amplified due to the response of the dam. They also reported that the peak horizontal accelerations at the MACR (27 km from epicenter) and the PAYA (47 km from the epicenter) stations were 0.13 g and 0.06 g, respectively.…”

Probabilistic seismic hazard assessments for Northern Southeast Asia (Indochina): Smooth seismicity approach

“…For the current study, Campbell and Bozorgnia (2014), Boore et al (2014), and Chiou and Youngs (2014) GMMs are applied with equal logic tree weight for active shallow region including BG-1 and BG-2, and for active fault models. Comparison of recorded PGA and spectral acceleration ( T = 1.0 s) from recent earthquakes with next generation attenuation (NGA) and NGA-W2 equations suggests that the chosen NGA-W2 GMMs provide relatively a good fit to local data over the applicable distance range from 0 to 200 km (Ornthammarath, 2013; Ornthammarath and Warnitchai, 2016). Although there is a suggestion to include additional GMMs from other databases (e.g.…”

“…Although, strong ground motion data have been recorded by local seismic networks and compared with existing GMMs from three recent earthquakes in NSA with magnitude greater than 6.0 (i.e. the 2011 M W 6.8 Tarlay earthquake in Myanmar, Ornthammarath, 2013; 2014 M W 6.1 Mae Lao earthquake in Thailand, Ornthammarath and Warnitchai, 2016; and 2016 M W 6.8 Chuak earthquake in Myanmar, Zaw et al, 2019), there was still debate in our recent meetings regarding their applicability for other parts of NSA where damaging ground motion has not yet been observed (e.g. southern Vietnam).…”

Seismic damage to ancient monuments in Chiang Saen (Northern Thailand): implication for historical earthquakes in Golden Triangle area

“…Despite severe damage in the epicentral area, damage in Chiang Saen was very limited. No severe damage to local buildings was reported based on seismic reconnaissance surveys [1][2][3]. The felt intensity in Chiang Saen from these recent tremors was between IV and VI based on these field survey data.…”