arXiv AI

Unsupervised Consensus-Based Anomaly Detection for Spatiotemporal Malaria Incidence in Ghana

arXiv:2607. 21559v1 Announce Type: new Abstract: A consensus anomaly detection framework was applied to monthly malaria surveillance data from Ghana (2014-2023) to identify atypical transmission patterns.

arXiv Machine Learning
Oct 9

RIFT: Relative Isolation From Trees For Anomaly Detection

RIFT (Relative Isolation From Trees) is a deterministic anomaly detection method that builds a minimum spanning tree and scores points by the sum of apparent edge sizes from each point. For one-dimensional data, RIFT reproduces the closed-form limit of Isolation Forest exactly, while in higher dimensions it offers a parameter‑free, robust alternative that avoids axis‑parallel artifacts and handles varying density and clustered anomalies. An ensemble variant is proposed for large datasets, and experiments on synthetic data and the ADBench benchmark show comparable accuracy to Isolation Forest with reduced variance across random seeds.

By Mark Daniel Szalai, Gabor Horvath
arXiv Computer Vision
Sep 18

Earth Surface Immune System for Rapid Monitoring of Unknown Anomalies

The paper introduces ESIA, an Earth Surface Immune System that detects and recognizes unknown anomalies in satellite imagery without prior category knowledge. It uses a non‑specific innate stage for rapid localization and a specific adaptive stage that matches image patches to text prompts via a multi‑modal model, achieving high F1 scores. The system adapts to new scenes in seconds and has been validated on a large global dataset, with applications to farmland degradation after the Kakhovka Dam collapse and burn severity assessment from the 2025 Palisades Fire.

By Jingtao Li, Qian Zhu, Xinyu Wang, Deren Li, Liangpei Zhang, Yanfei Zhong
arXiv Machine Learning
Oct 23

Future of Time Series Anomaly Detection: From Historical Review to Unified Outlook

The paper surveys recent advances in time series anomaly detection (TSAD), highlighting new architectures such as diffusion models, state space models, and large language models. It introduces a refined anomaly taxonomy, evaluates existing metrics through extensive experiments, and releases an open-source benchmark with algorithms, datasets, and evaluation tools. The authors also identify open research challenges, including dynamic thresholding, interpretability, zero‑shot transfer, multi‑modal alignment, and foundational models for time series.

By Zhijie Zhong, Zhiwen Yu, Pengyu Li, Liujian Zhang, Qiaoli Ni, Jiang Jun, Jianming Lv, Kaixiang Yang, C. L. Philip Chen
arXiv Machine Learning
Oct 8

MORA: Modeling Observed Changes for Drift-Robust Time-Series Anomaly Detection

MORA is a drift‑robust time‑series anomaly detection framework that addresses the ambiguity between distribution drift and true anomalies by defining a temporal change disambiguation problem. It reconstructs a local target from paired short‑ and long‑term views, using the reconstruction gap as a measure of contextual support to adjust the primary anomaly score. The method requires no drift annotations or online adaptation and demonstrates strong robustness to non‑stationarity while maintaining sensitivity to genuine anomalies on four TSAD benchmarks.

By Xudong Mou, Tiejun Wang, Rui Wang, Hui Wang, Pin Liu, Tianyu Wo, Xudong Liu, Renyu Yang
arXiv Machine Learning
Aug 14

Which Site, and When: A Free-Satellite-Data Test of Himalayan Glacial Lake Bursts, Landslides, and Ice Floods

arXiv:2608. 12422v1 Announce Type: new Abstract: Two free satellite signals carry real information about glacial-lake outburst risk in the Nepal Himalaya: radar interferometry sees a moraine dam slowly sagging, and satellite weather marks the weeks when a primed lake is under stress.

By Matthew Kahn, Milan Arjel, Nirmala Adhikari, Mingmar Sherpa, James Pope
arXiv AI
Aug 26

Structured Frequency-Domain Evidence for LLM-Based Time-Series Anomaly Detection

The paper introduces a zero‑shot time‑series anomaly detection framework that augments traditional indexed, de‑seasonalized observations with compact frequency‑domain evidence derived from the Fast Fourier Transform. This evidence is provided at two resolutions: a global summary of sequence‑level periodicity and a local snapshot of time‑localized spectral deviations. Experiments on the AnomLLM benchmark using several large language models—including InternVL2‑LLaMA3‑76B, Qwen2.5‑VL‑72B‑Instruct, Gemini‑2.5‑Flash, and GPT‑4o—demonstrate that incorporating explicit frequency‑domain evidence improves anomaly detection performance over existing LLM‑based baselines.

By Jungwook Seo, Sangwon Son, Minjeong Kim, Seungmin Han, Seojin Yoo, Sungyong Baik